(249 days)
Not Found
No
The device description focuses on PCR, microarray hybridization, and fluorescence-based detection. The data analysis is described as "computer software for data acquisition, analysis, and display," which does not explicitly indicate the use of AI/ML. The performance studies describe traditional analytical and clinical validation methods, not AI/ML model training or testing.
No.
The iC-GPC Assay is an in vitro diagnostic test designed to detect and identify potentially pathogenic gram positive bacteria and resistance markers directly from positive blood cultures. It aids in the diagnosis of bacterial bloodstream infections by providing information on the presence of specific organisms and resistance markers, but it is not used to treat or directly manage disease, which is the primary function of a therapeutic device.
Yes
The "Intended Use / Indications for Use" section explicitly states that the iC-GPC Assay is an "in vitro diagnostic test" to "aid in the diagnosis of bacterial bloodstream infections".
No
The device description clearly outlines hardware components (iC-Processor, iC-Reader, disposable cassette) that are integral to the device's function of DNA extraction, amplification, hybridization, and detection. While software (iC-Report) is used for data analysis and display, it is part of a larger system that includes physical hardware.
Yes, this device is an IVD (In Vitro Diagnostic).
The "Intended Use / Indications for Use" section explicitly states: "The iCubate iC-GPC Assay for use on the iC-System is a qualitative, multiplexed, in vitro diagnostic test for the detection and identification of potentially pathogenic gram positive bacteria, which may cause bloodstream infection (BSI)."
This statement directly identifies the device as an in vitro diagnostic test.
N/A
Intended Use / Indications for Use
The iCubate iC-GPC Assay for use on the iC-System is a qualitative, multiplexed, in vitro diagnostic test for the detection and identification of potentially pathogenic gram positive bacteria, which may cause bloodstream infection (BSI). The iC-GPC Assay is performed directly on positive blood cultures, confirmed by Gram stain to contain gram positive cocci. Cultures demonstrating mixed Gram stain results should not be tested with the assay. The iC-GPC Assay is validated for use with select BACTEC, BacTIALERT and VersaTREK blood culture bottles. The iC-GPC Assay is indicated for use in conjunction with other clinical and laboratory findings, such as blood culture isolate identification and antimicrobial susceptibility testing, to aid in the diagnosis of bacterial bloodstream infections; however, it is not used to monitor bloodstream infections.
The iC-GPC Assay detects organism DNA and identifies the following bacterial species and resistance markers:
Bacterial Species
Staphylococcus aureus
Staphylococcus epidermidis
Streptococcus pneumoniae
Enterococcus faecalis
Enterococcus faecium
Resistance Markers
mecA- associated with methicillin resistance
vanA- associated with vancomycin resistance
vanB- associated with vancomycin resistance
The iC-GPC Assay detects the mecA resistance marker, inferring mecA-mediated methicillin resistance, and the vanA and vanB resistance markers, inferring vanAlvanB-mediated vancomycin resistance. In mixed growth, the iC-GPC Assay does not specifically attribute van-mediated vancomycin resistance to either E. faecalis or E. faecium, or mecA-mediated methicillin resistance to either S. aureus or S. epidermidis.
Sub-culturing of positive blood cultures is necessary to recover organisms for susceptibility testing. identification of organisms not detected by the iC-GPC Assay, differentiation of mixed growth, association of antimicrobial resistance marker genes to a specific organism, or for epidemiological typing.
Product codes (comma separated list FDA assigned to the subject device)
PAM, NSU
Device Description
The iC-GPC Assay utilizes polymerase chain reaction (PCR) for the amplification of specific targets and detects the amplified target DNA with fluorescence-based microarray hybridization. The iC-GPC Assay uses proprietary ARM-PCR (Amplicon Rescued Multiplex PCR) technology allowing for multiple targets to be amplified in one reaction. Targets are detected directly from patient positive blood cultures, confirmed by Gram stain to contain gram positive cocci. Testing is performed within a closed, disposable cassette that contains all the reagents required to complete the iC-GPC Assay, including a universal microarray.
To operate, the user opens the iC-GPC Cassette cap and pipettes an aliquot of the positive blood culture sample into the sample well of the cassette is then inserted into the iC-Processor, which performs the processes of DNA extraction, multiplex amplification, and microarray After processing is complete, the cassette is inserted into the iC-Reader for hybridization. fluorescence-based detection and data analysis. Final results are generated by iC-Report, computer software for data acquisition, analysis, and display.
Extraction, amplification, and hybridization are defined by an assay script controlled by the iC-Processor. The processing script is defined within a barcode label positioned on the top of each iC-GPC Cassette which communicates with the iC-Processor. To access and pierce the foil-sealed reagent wells located in the bottom well plate of the cassette, the processor manipulates the cassette to move the internal pipette horizontally and vertically. The script directs the transfer of reagents between the wells in the bottom well plate and finally to the array within the cassette. The iC-Processor is capable of processing 4 iC-Cassettes with random access.
Once processing is complete, the cassette is manually transferred from the iC-Processor to the iC-Reader where the microarray within the cassette is read. The iC-Reader is capable of reading up to 4 iC-Cassettes at one time. The results are interpreted via the iC-Report software and displayed for the user on an iMac computer. Raw data and result interpretations are stored within the iMac; raw data is accessible to authorized personnel only and is not available to the end user.
Mentions image processing
Not Found
Mentions AI, DNN, or ML
Not Found
Input Imaging Modality
Not Found
Anatomical Site
bloodstream
Indicated Patient Age Range
Not Found
Intended User / Care Setting
Prescription Use
Not Found
Description of the training set, sample size, data source, and annotation protocol
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Description of the test set, sample size, data source, and annotation protocol
A method comparison study was performed at four geographically dispersed clinical sites to evaluate the performance of the iC-GPC Assay for use on the iC-System. Sites tested 966 leftover, de-identified specimens from aerobic and anaerobic blood culture bottles flagged as positive by their respective continuous monitoring blood culture system. Three of the commonly used blood culture systems were included in the study: BD BACTEC, bioMérieux BacT/ALERT, and Thermo Fisher VersaTREK. Positive blood cultures were confirmed by Gram stain to contain gram positive cocci prior to being entered into the study. Specimens demonstrating mixed Gram stain results were excluded from the study.
A total of 966 positive blood culture specimens, confirmed by Gram stain to contain gram positive cocci, were enrolled in the iC-GPC Assay Method Comparison Study. A total of 53 samples were withdrawn from the study. Of the 913 samples in the study after identified samples were withdrawn, 879 were fresh prospective samples and 34 were frozen prospective samples.
An additional 168 contrived samples were evaluated for low prevalence organisms and resistance markers. Contrived specimens were prepared by inoculating low concentrations of organisms into BD BACTEC Plus Aerobic blood culture bottles with human blood added and incubating the blood culture system until bottle positivity. Multiple strains of S. pneumoniae, E. faecium were used to prepare contrived specimens.
Summary of Performance Studies (study type, sample size, AUC, MRMC, standalone performance, key results)
Method Comparison Study:
-
Sample Size: 913 prospective samples (879 fresh, 34 frozen) and 168 contrived samples.
-
Study Type: Comparison against an FDA-cleared multiplex assay and traditional laboratory reference methods (culture, biochemicals/MALDI-TOF, AST).
-
Key Results (vs. FDA-Cleared Multiplex Assay):
- Staphylococcus aureus (nuc):
- Fresh Prospective: 96.9% Positive Agreement (249/257), 99.7% Negative Agreement (620/622)
- Frozen Prospective: 100% Positive Agreement (9/9), 100% Negative Agreement (25/25)
- TOTAL: 97.0% Positive Agreement (258/266), 99.7% Negative Agreement (645/647)
- Staphylococcus epidermidis (gseA):
- Fresh Prospective: 98.3% Positive Agreement (227/231), 98.0% Negative Agreement (635/648)
- Frozen Prospective: 100% Positive Agreement (4/4), 96.7% Negative Agreement (29/30)
- TOTAL: 98.3% Positive Agreement (231/235), 97.9% Negative Agreement (664/678)
- Streptococcus pneumoniae (lytA):
- Fresh Prospective: 82.6% Positive Agreement (19/23), 99.9% Negative Agreement (855/856)
- Frozen Prospective: 100% Positive Agreement (4/4), 100% Negative Agreement (30/30)
- TOTAL: 85.2% Positive Agreement (23/27), 99.9% Negative Agreement (885/886)
- Enterococcus faecalis (ddl):
- Fresh Prospective: 96.6% Positive Agreement (56/58), 99.9% Negative Agreement (820/821)
- Frozen Prospective: 100% Positive Agreement (3/3), 100% Negative Agreement (31/31)
- TOTAL: 96.7% Positive Agreement (59/61), 99.9% Negative Agreement (851/852)
- Enterococcus faecium (fcm):
- Fresh Prospective: 96.4% Positive Agreement (27/28), 99.8% Negative Agreement (849/851)
- Frozen Prospective: 100% Positive Agreement (1/1), 100% Negative Agreement (33/33)
- TOTAL: 96.6% Positive Agreement (28/29), 99.8% Negative Agreement (882/884)
- mecA (methicillin resistance):
- Fresh Prospective: 96.1% Positive Agreement (269/280), 98.2% Negative Agreement (588/599)
- Frozen Prospective: 100% Positive Agreement (5/5), 100% Negative Agreement (29/29)
- TOTAL: 96.1% Positive Agreement (274/285), 98.2% Negative Agreement (617/628)
- vanA (vancomycin resistance):
- Fresh Prospective: 94.7% Positive Agreement (18/19), 99.4% Negative Agreement (855/860)
- Frozen Prospective: 100% Positive Agreement (1/1), 100% Negative Agreement (33/33)
- TOTAL: 95.0% Positive Agreement (19/20), 99.4% Negative Agreement (888/893)
- vanB (vancomycin resistance):
- Fresh Prospective: 100% Positive Agreement (2/2), 99.9% Negative Agreement (876/877)
- TOTAL: 100% Positive Agreement (2/2), 99.9% Negative Agreement (888/893)
- Staphylococcus aureus (nuc):
-
Key Results (vs. Traditional Culture and Susceptibility):
- Staphylococcus aureus (nuc): 95.9% Positive Agreement (259/270), 99.8% Negative Agreement (610/611)
- Staphylococcus epidermidis (gseA): 96.0% Positive Agreement (216/225), 96.5% Negative Agreement (633/656)
- Streptococcus pneumoniae (lytA): 100% Positive Agreement (21/21), 99.8% Negative Agreement (866/868)
- Enterococcus faecalis (ddl): 96.8% Positive Agreement (60/62), 99.9% Negative Agreement (828/829)
- Enterococcus faecium (fcm): 96.6% Positive Agreement (28/29), 99.7% Negative Agreement (859/862)
- mecA (methicillin resistance): 90.2% Positive Agreement (257/285), 97.0% Negative Agreement (804/823)
- vanA/B (vancomycin resistance): 88.0% Positive Agreement (22/25), 99.8% Negative Agreement (861/863)
Reproducibility Study:
- Study Type: Multi-site, multi-operator, multi-lot reproducibility testing.
- Sample Size: Replicates of three, across five non-consecutive days.
- Key Results: Confirmed reproducible performance across sites, operators, systems, and cassette lots for all targets at initial bottle positivity and eight hours beyond.
Limit of Detection (LoD) Study:
- Study Type: Analytical study to determine the lowest detectable concentration.
- Sample Size: Replicates of twenty on three unique cassette lots for nineteen organisms.
- Key Results: LoDs determined for all 8 targets, ranging from 3.0 x 10^5 to 5.8 x 10^6 CFU/mL for bacterial species and 7.4 x 10^5 to 1.1 x 10^7 CFU/mL for resistance markers.
Analytical Reactivity (Inclusivity) Study:
- Study Type: Evaluation of detection across diverse strains.
- Sample Size: 106 organisms, tested near LoD (2-3x LoD) or at lowest bottle positivity.
- Key Results: All expected targets were detected.
Analytical Exclusivity Study:
- Study Type: Evaluation of cross-reactivity with non-target microorganisms.
- Sample Size: 94 exclusivity organisms tested at high concentrations.
- Key Results: One organism, Streptococcus bovis, demonstrated reproducible cross-reactivity with Enterococcus faecalis. Other initial false positives were negative upon retesting.
Microbial Interference Study:
- Study Type: Evaluation of iC-GPC Assay performance with high concentrations of exclusivity organisms combined with target organisms near LoD.
- Sample Size: 85 exclusivity organisms in combination with iC-GPC target organisms.
- Key Results: Microbial interference was not observed for the majority of organism combinations. For those with initial false negatives, repeat testing at same or higher concentration yielded 100% detection.
Competitive Inhibition Study:
- Study Type: Evaluation of iC-GPC Assay performance with combinations of two target analytes (one near LoD, one at high concentration).
- Sample Size: 20 combinations of five target organisms.
- Key Results: High concentration organisms were always detected. Low concentration organisms were detected in 3/20 (15%) combinations, indicating potential competitive inhibition when a second target organism is present at higher concentrations.
Blood Culture Bottle Equivalency Study:
- Study Type: Evaluation of performance across different blood culture media types.
- Sample Size: Nineteen target organisms plus one non-target in 10 BCB media types.
- Key Results: Performance in all BACTEC and VersaTREK bottle types and BacT/ALERT SA Standard Aerobic media met acceptance criteria (>=95%). Increased false positive E. faecium results observed in BacT/ALERT FA Aerobic FAN and FA Plus Aerobic media, suggesting the need for confirmation with alternative methods for E. faecium with these bottles.
Interfering Substances Study:
- Study Type: Evaluation of iC-GPC Assay performance in the presence of potentially inhibiting substances.
- Sample Size: Five target organisms plus one non-target with various interferents.
- Key Results: Additional SPS at concentrations greater than 0.03% w/v and total protein (gamma-globulin and albumin) in concentrations greater than 3g/dL were found to interfere, potentially causing false negative results or positive controls check failures.
Carryover and Cross-Contamination Study:
- Study Type: Confirmed absence of false positives due to carryover or cross-contamination.
- Sample Size: High positive samples alternated with negative samples.
- Key Results: No false positives indicative of sample carryover or cross-contamination were observed.
Mixed Culture Results Analysis:
- Analyzed mixed culture specimens detected by iC-GPC, comparator assay, or both, and against traditional methods. Competitive inhibition can lead to non-detection of lower concentration targets in mixed cultures.
Expected Values (Positivity Rates):
- Based on 913 prospectively collected specimens.
- Overall, at least one organism detected in 66.9% (611/913) of specimens.
- At least one resistance marker detected in 33.4% (305/913) of specimens.
- Provided positivity rates for each organism and resistance marker by U.S. state.
Error Rates and Sample Withdrawals:
- Initial error rate of 7.6% (83/1098).
- After retesting, error rate reduced to 1.5% (17/1098).
- 53 samples were withdrawn, primarily due to mixed Gram stain results, repeat iC-GPC errors, or repeat comparator assay errors.
Key Metrics (Sensitivity, Specificity, PPV, NPV, etc.)
The document presents Percent Agreement Positive and Percent Agreement Negative, which are proxies for Sensitivity and Specificity, respectively, when comparing against a comparator method.
Against FDA-Cleared Multiplex Assay:
- Staphylococcus aureus (nuc): Positive Agreement 97.0%, Negative Agreement 99.7%
- Staphylococcus epidermidis (gseA): Positive Agreement 98.3%, Negative Agreement 97.9%
- Streptococcus pneumoniae (lytA): Positive Agreement 85.2%, Negative Agreement 99.9%
- Enterococcus faecalis (ddl): Positive Agreement 96.7%, Negative Agreement 99.9%
- Enterococcus faecium (fcm): Positive Agreement 96.6%, Negative Agreement 99.8%
- mecA (methicillin resistance): Positive Agreement 96.1%, Negative Agreement 98.2%
- vanA (vancomycin resistance): Positive Agreement 95.0%, Negative Agreement 99.4%
- vanB (vancomycin resistance): Positive Agreement 100%, Negative Agreement 99.9%
Against Traditional Culture and Susceptibility:
- Staphylococcus aureus (nuc): Positive Agreement 95.9%, Negative Agreement 99.8%
- Staphylococcus epidermidis (gseA): Positive Agreement 96.0%, Negative Agreement 96.5%
- Streptococcus pneumoniae (lytA): Positive Agreement 100%, Negative Agreement 99.8%
- Enterococcus faecalis (ddl): Positive Agreement 96.8%, Negative Agreement 99.9%
- Enterococcus faecium (fcm): Positive Agreement 96.6%, Negative Agreement 99.7%
- mecA (methicillin resistance): Positive Agreement 90.2%, Negative Agreement 97.0%
- vanA/B (vancomycin resistance): Positive Agreement 88.0%, Negative Agreement 99.8%
Predicate Device(s): If the device was cleared using the 510(k) pathway, identify the Predicate Device(s) K/DEN number used to claim substantial equivalence and list them here in a comma separated list exactly as they appear in the text. List the primary predicate first in the list.
Reference Device(s): Identify the Reference Device(s) K/DEN number and list them here in a comma separated list exactly as they appear in the text.
Not Found
Predetermined Change Control Plan (PCCP) - All Relevant Information for the subject device only (e.g. presence / absence, what scope was granted / cleared under the PCCP, any restrictions, etc).
Not Found
§ 866.3365 Multiplex nucleic acid assay for identification of microorganisms and resistance markers from positive blood cultures.
(a)
Identification. A multiplex nucleic acid assay for identification of microorganisms and resistance markers from positive blood cultures is a qualitative in vitro device intended to simultaneously detect and identify microorganism nucleic acids from blood cultures that test positive by Gram stain or other microbiological stains. The device detects specific nucleic acid sequences for microorganism identification as well as for antimicrobial resistance. This device aids in the diagnosis of bloodstream infections when used in conjunction with other clinical and laboratory findings. However, the device does not replace traditional methods for culture and susceptibility testing.(b)
Classification. Class II (special controls). The special control for this device is FDA's guideline document entitled “Class II Special Controls Guideline: Multiplex Nucleic Acid Assay for Identification of Microorganisms and Resistance Markers from Positive Blood Cultures.” For availability of the guideline document, see § 866.1(e).
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Image /page/0/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo consists of a circular seal with the text "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" arranged around the perimeter. Inside the circle is an abstract symbol that resembles three stylized human profiles facing to the right, with flowing lines beneath them.
Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002
August 8, 2017
ICUBATE, INC. C/O FRAN WHITE MDC ASSOCIATES, LLC 180 CABOT STREET BEVERLY, MA 01915
Re: K163390
Trade/Device Name: iC-GPC Assay, iC-System Regulation Number: 21 CFR 866.3365 Regulation Name: Multiplex nucleic acid assay for identification of microorganisms and resistance markers from positive blood cultures Regulatory Class: Class II Product Code: PAM, NSU Dated: July 14, 2017 Received: July 17, 2017
Dear Ms. White:
We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food. Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration. Iisting of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.
If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.
Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Parts 801 and 809); medical device reporting (reporting of
1
medical device-related adverse events) (21 CFR 803); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.
If you desire specific advice for your device on our labeling regulation (21 CFR Part 801), please contact the Division of Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address
http://www.fda.gov/MedicalDevices/Resourcesfor You/Industry/default.htm. Also, please note the regulation entitled. "Misbranding by reference to premarket notification" (21CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to
http://www.fda.gov/MedicalDevices/Safety/ReportaProblem/default.htm for the CDRH's Office of Surveillance and Biometrics/Division of Postmarket Surveillance.
You may obtain other general information on your responsibilities under the Act from the Division of Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address
http://www.fda.gov/MedicalDevices/ResourcesforYou/Industry/default.htm.
Sincerely,
Steven R. Gitterman -S for
Uwe Scherf, M.Sc., Ph.D. Director, Division of Microbiology Devices Office of In Vitro Diagnostics and Radiological Health Center for Devices and Radiological Health
Enclosure
2
Indications for Use
510(k) Number (if known) K163390
Device Name iC-GPC Assay for use on the iC-System
Indications for Use (Describe)
The iCubate iC-GPC Assay for use on the iC-System is a qualitative, multiplexed, in vitro diagnostic test for the detection and identification of potentially pathogenic gram positive bacteria, which may cause bloodstream infection (BSI). The iC-GPC Assay is performed directly on positive blood cultures, confirmed by Gram stain to contain gram positive cocci. Cultures demonstrating mixed Gram stain results should not be tested with the assay. The iC-GPC Assay is validated for use with select BACTEC, BacTIALERT and VersaTREK blood culture bottles. The iC-GPC Assay is indicated for use in conjunction with other clinical and laboratory findings, such as blood culture isolate identification and antimicrobial susceptibility testing, to aid in the diagnosis of bacterial bloodstream infections; however, it is not used to monitor bloodstream infections.
The iC-GPC Assay detects organism DNA and identifies the following bacterial species and resistance markers:
Bacterial Species Staphylococcus aureus Staphylococcus epidermidis Streptococcus pneumoniae Enterococcus faecalis Enterococcus faecium
Resistance Markers
mecA- associated with methicillin resistance vanA- associated with vancomycin resistance vanB- associated with vancomycin resistance
The iC-GPC Assay detects the mecA resistance marker, inferring mecA-mediated methicillin resistance, and the vanA and vanB resistance markers, inferring vanAlvanB-mediated vancomycin resistance. In mixed growth, the iC-GPC Assay does not specifically attribute van-mediated vancomycin resistance to either E. faecalis or E. faecium, or mecA-mediated methicillin resistance to either S. aureus or S. epidermidis.
Sub-culturing of positive blood cultures is necessary to recover organisms for susceptibility testing. identification of organisms not detected by the iC-GPC Assay, differentiation of mixed growth, association of antimicrobial resistance marker genes to a specific organism, or for epidemiological typing.
Type of Use (Select one or both, as applicable) | |
---|---|
× Prescription Use (Part 21 CFR 801 Subpart D) | Over-The-Counter Use (21 CFR 801 Subpart C) |
CONTINUE ON A SEPARATE PAGE IF NEEDED.
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510(k) SUMMARY
Date of Summary: | August 2, 2017 |
---|---|
Product Name | iC-GPC Assay™ for use on the iC-System™ |
Sponsor | iCubate® |
601 Genome Way | |
Huntsville, AL 35806 |
Correspondent MDC Associates, LLC Fran White, President 180 Cabot Street Beverly, MA 01915 Phone: (978) 705-5011
Device Trade or Proprietary Name
iC-GPC Assay™ for use on the iC-System™
Common Name
Gram positive bacteria and their resistance markers
Regulation
21 CFR 866.3365, Multiplex nucleic acid assay for identification of microorganisms and resistance markers from positive blood cultures.
Fax: (800) 498-9121
Product Codes
PAM, NSU
Classification
Class II
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Substantial Equivalency
| Characteristic | iC-GPC Assay™ for use on the iC-System™
(New Device) | VERIGENE® Gram Positive Blood Culture Nucleic
Acid Test (BC-GP) (K122514)
(Primary Predicate Device) | | | | |
|----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--|--|--|--|
| Similarities | | | | | | |
| Intended Use | The iCubate iC-GPC Assay™ for use on the iC-
System™ is a qualitative, multiplexed, in vitro
diagnostic test for the detection and
identification of potentially pathogenic gram
positive bacteria, which may cause bloodstream
infection (BSI). The iC-GPC Assay™ is performed
directly on positive blood cultures, confirmed by
Gram Stain to contain gram positive cocci.
Cultures demonstrating mixed Gram stain results
should not be tested on the assay. The iC-GPC
Assay™ is validated for use with select BACTEC™,
BacT/ALERT® and VersaTREK® blood culture
bottles. The iC-GPC Assay™ is indicated for use in
conjunction with other clinical and laboratory
findings, such as blood culture isolate
identification and antimicrobial susceptibility
testing, to aid in the diagnosis of bacterial
bloodstream infections; however, it is not used to
monitor bloodstream infections.
The iC-GPC Assay™ detects organism DNA and
identifies the following bacterial species and
resistance markers: | The Verigene® Gram Positive Blood Culture Nucleic
Acid Test (BC-GP) performed using the sample-to-
result Verigene System is a qualitative, multiplexed in vitro diagnostic test for the simultaneous detection
and identification of potentially pathogenic gram-
positive bacteria which may cause bloodstream
infection (BSI). BC-GP is performed directly on
positive blood culture using BACTEC™ Plus Aerobic/F
and BacT/ALERT FA FAN® Aerobic blood culture
bottles, which contain gram positive bacteria. BC-GP
is indicated for use in conjunction with other clinical
and laboratory findings, such as culture, to aid in the
diagnosis of bacterial bloodstream infections;
however, it is not used to monitor bloodstream
infections.
BC-GP detects and identifies the following bacterial
genera and species:
Staphylococcus spp.
Staphylococcus aureus
Staphylococcus epidermidis
Staphylococcus lugdunensis
Streptococcus spp.
Streptococcus pneumoniae
Streptococcus pyogenes
Streptococcus agalactiae
Streptococcus anginosus group
Enterococcus faecalis
Enterococcus faecium
Listeria spp.
In addition, BC-GP detects the mecA
resistance marker, inferring mecA -mediated
methicillin resistance, and
the vanA and vanB resistance markers, inferring
vanA/vanB -mediated vancomycin resistance. In
mixed growth, BC-GP does not specifically attribute
van -mediated vancomycin resistance to either E.
faecalis or E. faecium , or mecA -mediated methicillin
resistance to either S. aureus or S. epidermidis . | | | | |
| | Bacterial Species Resistance
Markers Staphylococcus aureus
Staphylococcus epidermidis
Streptococcus pneumoniae
Enterococcus faecalis
Enterococcus faecium mecA - associated
with methicillin
resistance
vanA - associated
with vancomycin
resistance
vanB - associated
with vancomycin
resistance The iC-GPC Assay™ detects the mecA resistance
marker, inferring mecA -mediated methicillin
resistance, and the vanA and vanB resistance
markers, inferring vanA/vanB -mediated
vancomycin resistance. In mixed growth, the iC-
GPC Assay™ does not specifically attribute van -
mediated vancomycin resistance to either E . | | | | | |
Comparison of New Device with Predicate Device TABLE 1.
6
| Characteristic | iC-GPC Assay™ for use on the iC-System™
(New Device) | VERIGENE® Gram Positive Blood Culture Nucleic
Acid Test (BC-GP) (K122514)
(Primary Predicate Device) |
|----------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| | faecalis or E. faecium , or mecA-mediated
methicillin resistance to either S. aureus or S.
epidermidis . | |
| | Sub-culturing of positive blood cultures is
necessary to recover organisms for susceptibility
testing, identification of organisms not detected
by the iC-GPC Assay™, differentiation of mixed
growth, association of antimicrobial resistance
marker genes to a specific organism, or for
epidemiological typing. | |
| Indication for
Use | The iC-GPC Assay™ is indicated for use in
conjunction with other clinical and laboratory
findings to aid in the diagnosis of bacterial
bloodstream infections; however, is not to be
used to monitor these infections. Sub-culturing of
positive blood cultures is necessary to recover
organisms for susceptibility testing, identification
of organisms not detected by the iC-GPC Assay™,
differentiation of mixed growth, association of
antimicrobial resistance marker genes to a
specific organism, or for epidemiological typing. | BC-GP is indicated for use in conjunction with other
clinical and laboratory findings to aid in the diagnosis
of bacterial bloodstream infections; however, is not
to be used to monitor these infections. Sub-culturing
of positive blood cultures is necessary to recover
organisms for susceptibility testing, identification of
organisms not detected by BC-GP, differentiation of
mixed growth, association of antimicrobial resistance
marker genes to a specific organism, or for
epidemiological typing. |
| Sample Type | Positive Blood Culture | Positive Blood Culture |
| | Differences | |
| Instrument
Requirements | iC-System™ | VERIGENE® System |
| Test Principal | Arm-PCR | Gold nanoparticle probe-based PCR |
| Compatible
Blood Culture
Bottles | BACTEC™ Standard Aerobic/Anaerobic, BACTEC™
Plus Aerobic/Anaerobic, BACTEC™ Lytic/10
Anaerobic, BacT/ALERT Standard Aerobic,
BacT/ALERT FA Aerobic FAN®, BacT/ALERT FA
Plus Aerobic, VersaTREK® REDOX 1/2 | BACTEC™ Standard Aerobic/Anaerobic, BACTEC™
Plus Aerobic/Anaerobic, BACTEC™ Lytic/10
Anaerobic, BACTEC™ Peds Plus, BacT/ALERT
Standard Aerobic/Anaerobic, BacT/ALERT FA Aerobic
FAN®, BacT/ALERT FN Anaerobic FAN®, BacT/ALERT
PF Pediatric FAN, VersaTREK® REDOX 1/2 |
| Throughput | Four (4) samples/iC-Processor™ | One (1) sample/processor |
7
Intended Use
The iCubate iC-GPC Assay™ for use on the iC-System™ is a qualitative, multiplexed, in vitro diagnostic test for the detection and identification of potentially pathogenic gram positive bacteria, which may cause bloodstream infection (BSI). The iC-GPC Assay™ is performed directly on positive blood cultures, confirmed by Gram stain to contain gram positive cocci. Cultures demonstrating mixed Gram stain results should not be tested on the assay. The iC-GPC Assay™ is validated for use with select BACTEC™, BacT/ALERT® and VersaTREK® blood culture bottles. The iC-GPC Assay™ is indicated for use in conjunction with other clinical and laboratory findings, such as blood culture isolate identification and antimicrobial susceptibility testing, to aid in the diagnosis of bacterial bloodstream infections; however, it is not used to monitor bloodstream infections.
The iC-GPC Assay™ detects organism DNA and identifies the following bacterial species and resistance markers:
Bacterial Species | Resistance Markers |
---|---|
Staphylococcus aureus | |
Staphylococcus epidermidis | |
Streptococcus pneumoniae | |
Enterococcus faecalis | |
Enterococcus faecium | mecA- associated with methicillin resistance |
vanA- associated with vancomycin resistance | |
vanB- associated with vancomycin resistance |
The iC-GPC Assay™ detects the mecA resistance marker, inferring mecA-mediated methicillin resistance, and the vanA and vanB resistance markers, inferring vanA/vanB-mediated vancomycin resistance. In mixed growth, the iC-GPC Assay™ does not specifically attribute van-mediated vancomycin resistance to either E. faecalis or E. faecium, or mecA-mediated methicillin resistance to either S. aureus or S. epidermidis.
Sub-culturing of positive blood cultures is necessary to recover organisms for susceptibility testing, identification of organisms not detected by the iC-GPC Assay™, differentiation of mixed growth, association of antimicrobial resistance marker genes to a specific organism, or for epidemiological typing.
Limitations
For prescription use only.
Please refer to the iC-GPC Assay™ labeling for a more complete list of warnings, precautions and contraindications.
8
Methodology
The iC-GPC Assay™ utilizes polymerase chain reaction (PCR) for the amplification of specific targets and detects the amplified target DNA with fluorescence-based microarray hybridization. The iC-GPC Assay™ uses proprietary ARM-PCR (Amplicon Rescued Multiplex PCR) technology allowing for multiple targets to be amplified in one reaction. Targets are detected directly from patient positive blood cultures, confirmed by Gram stain to contain gram positive cocci. Testing is performed within a closed, disposable cassette that contains all the reagents required to complete the iC-GPC Assay™, including a universal microarray.
To operate, the user opens the iC-GPC Cassette™ cap and pipettes an aliquot of the positive blood culture sample into the sample well of the cassette is then inserted into the iC-Processor™, which performs the processes of DNA extraction, multiplex amplification, and microarray After processing is complete, the cassette is inserted into the iC-Reader™ for hybridization. fluorescence-based detection and data analysis. Final results are generated by iC-Report, computer software for data acquisition, analysis, and display.
Extraction, amplification, and hybridization are defined by an assay script controlled by the iC-Processor™. The processing script is defined within a barcode label positioned on the top of each iC-GPC Cassette™ which communicates with the iC-Processor™. To access and pierce the foil-sealed reagent wells located in the bottom well plate of the cassette, the processor manipulates the cassette to move the internal pipette horizontally and vertically. The script directs the transfer of reagents between the wells in the bottom well plate and finally to the array within the cassette. The iC-Processor™ is capable of processing 4 iC-Cassettes™ with random access.
Once processing is complete, the cassette is manually transferred from the iC-Processor™ to the iC-Reader™ where the microarray within the cassette is read. The iC-Reader™ is capable of reading up to 4 iC-Cassettes™ at one time. The results are interpreted via the iC-Report™ software and displayed for the user on an iMac® computer. Raw data and result interpretations are stored within the iMac®; raw data is accessible to authorized personnel only and is not available to the end user.
9
Performance Data
For ease of reference, the following table defines iC-GPC target organisms, corresponding gene targets, and common acronyms used in the following study descriptions.
TABLE 1: iC-GPC Assay Targets | ||
---|---|---|
Organism | Target Gene | Acronym |
Staphylococcus epidermidis | gseA | SE |
Staphylococcus aureus | nuc | SA |
Streptococcus pneumoniae | lytA | SPN |
Enterococcus faecalis | ddl | EFLS |
Enterococcus faecium | fcm (ddlEFCM) | EFCM |
Bottle Ring
A study was performed to establish the lowest level of each iC-GPC Assay target organism at initial bottle positivity (bottle "ring"). The nineteen organisms used to define target limits of detection were evaluated. Organisms were inoculated into BD BACTEC Plus Aerobic blood culture bottles with human Bottles were allowed to incubate on the blood culture system until initial bottle blood added. positivity. Bottles were removed from the incubator within two hours of bottle ring, and plating and subsequent colony counts were performed to confirm organism concentrations. A minimum of five bottles were evaluated for each strain. The average concentrations at bottle ring are presented in Table 2 below. These concentrations, representative of the lowest levels that may be observed in a clinical setting, are equivalent to or greater than the respective target limits of detection (see below).
TABLE 2: Target Organism Concentrations at Bottle "Ring" | |
---|---|
Organism | Average Concentration (CFU/mL) |
SE 700566 | $2.68 \times 10^7$ |
SE 35984 | $2.04 \times 10^7$ |
SE 12228 | $2.59 \times 10^7$ |
SE 49134 | $1.01 \times 10^7$ |
SA 700699 | $5.00 \times 10^8$ |
SA BAA 1768 | $5.24 \times 10^7$ |
SA BAA 977 | $1.14 \times 10^8$ |
SA 25923 | $6.06 \times 10^8$ |
SPN 6301 | $5.40 \times 10^6$ |
SPN 700673 | $5.95 \times 10^6$ |
EFLS 51299 | $4.72 \times 10^{10}$ |
EFLS 700802 | $2.22 \times 10^8$ |
EFLS JMI 12536 | $2.27 \times 10^8$ |
EFLS 29212 | $5.53 \times 10^{10}$ |
EFLS BAA 2128 | $5.77 \times 10^7$ |
EFCM 700221 | $1.16 \times 10^9$ |
EFCM 51559 | $5.87 \times 10^8$ |
EFCM 35667 | $2.86 \times 10^7$ |
EFCM BAA 2127 | $2.70 \times 10^8$ |
10
Reproducibility
To confirm site-to-site, operator, system-to-system, and lot-to-lot reproducibility of the iC-GPC Assay, a representative panel of target organisms and one non-target organism were tested at two concentrations: initial bottle positivity and eight hours beyond initial bottle positivity. Organisms were grown to the appropriate concentration in BD BACTEC Plus Aerobic/F blood culture bottles with human blood added on the BD BACTEC System. Testing was performed by two independent operators at each of three sites, two external and one in-house. The six organism panel was tested in replicates of three across five, non-consecutive days. Testing was evaluated across three cassette lots and four iC-Systems. Table 3 below summarizes results by iC-GPC Assay target and concentration. Testing confirmed that performance of the iC-GPC Assay for use on the iC-System is reproducible across sites, operators, systems, and lots.
TABLE 3: iC-GPC Reproducibility Performance by Target & Concentration | ||||||
---|---|---|---|---|---|---|
Organism/Gene Target/ | ||||||
Concentration | Overall | |||||
Performance | Overall | |||||
Performance % | ||||||
[95% CI] | False | |||||
Negatives | False | |||||
Positives | Positive Controls | |||||
Check Failures | System | |||||
Failures | ||||||
S. epidermidis (gseA) | ||||||
Bottle Ring | 89/89 | 100.0 | ||||
[95.86-100.0] | 0/89 | |||||
(0.00%) | 1/976 | |||||
(0.10%) | 0/90 | |||||
(0.00%) | 1/90 | |||||
(1.11%) | ||||||
S. epidermidis (gseA) | ||||||
Bottle Ring + 8 hours | 90/90 | 100.0 | ||||
[95.91-100.0] | 0/90 | |||||
(0.00%) | 0/975 | |||||
(0.00%) | 0/90 | |||||
(0.00%) | 0/90 | |||||
(0.00%) | ||||||
S. aureus (nuc) | ||||||
Bottle Ring | 89/89 | 100.0 | ||||
[95.86-100.0] | 0/89 | |||||
(0.00%) | 0/976 | |||||
(0.00%) | 1/90 | |||||
(1.11%) | 0/90 | |||||
(0.00%) | ||||||
S. aureus (nuc) | ||||||
Bottle Ring + 8 hours | 89/90 | 98.9 | ||||
[93.97-99.80] | 1/90 | |||||
(1.12%) | 0/975 | |||||
(0.00%) | 0/90 | |||||
(0.00%) | 0/90 | |||||
(0.00%) | ||||||
S. pneumoniae (lytA) | ||||||
Bottle Ring | 88/88 | 100.0 | ||||
[95.82-100.0] | 0/88 | |||||
(0.00%) | 0/977 | |||||
(0.00%) | 1/90 | |||||
(1.11%) | 1/90 | |||||
(1.11%) | ||||||
S. pneumoniae (lytA) | ||||||
Bottle Ring + 8 hours | 89/89 | 100.0 | ||||
[95.86-100.0] | 0/89 | |||||
(0.00%) | 0/976 | |||||
(0.00%) | 0/90 | |||||
(0.00%) | 1/90 | |||||
(1.11%) | ||||||
E. faecalis (ddl) | ||||||
Bottle Ring | 89/89 | 100.0 | ||||
[95.86-100.0] | 0/89 | |||||
(0.00%) | 2/976 | |||||
(0.20%) | 0/90 | |||||
(0.00%) | 1/90 | |||||
(1.11%) | ||||||
E. faecalis (ddl) | ||||||
Bottle Ring + 8 hours | 89/89 | 100.0 | ||||
[95.86, 100.0] | 0/89 | |||||
(0.00%) | 3/976 | |||||
(0.31%) | 1/90 | |||||
(1.11%) | 0/90 | |||||
(0.00%) | ||||||
E. faecium (fcm) | ||||||
Bottle Ring | 90/90 | 100.0 | ||||
[95.91-100.0] | 0/90 | |||||
(0.00%) | 0/975 | |||||
(0.00%) | 0/90 | |||||
(0.00%) | 0/90 | |||||
(0.00%) | ||||||
E. faecium (fcm) | ||||||
Bottle Ring + 8 hours | 89/89 | 100.0 | ||||
[95.86-100.0] | 0/89 | |||||
(0.00%) | 0/976 | |||||
(0.00%) | 1/90 | |||||
(1.11%) | 0/90 | |||||
(0.00%) | ||||||
mecA | ||||||
Bottle Ring | 177/178 | 99.4 | ||||
[96.89-99.90] | 1/178 | |||||
(0.56%) | 1/887 | |||||
(0.11%) | 1/180 | |||||
(0.56%) | 1/180 | |||||
(0.56%) | ||||||
mecA | ||||||
Bottle Ring + 8 hours | 180/180 | 100.0 | ||||
[97.91-100.0] | 0/180 | |||||
(0.00%) | 0/885 | |||||
(0.00%) | 0/180 | |||||
(0.00%) | 0/180 | |||||
(0.00%) | ||||||
vanA | ||||||
Bottle Ring | 90/90 | 100.0 | ||||
[95.91-100.0] | 0/90 | |||||
(0.00%) | 0/975 | |||||
(0.00%) | 0/90 | |||||
(0.00%) | 0/90 | |||||
(0.00%) | ||||||
vanA | ||||||
Bottle Ring + 8 hours | 89/89 | 100.0 | ||||
[95.86-100.0] | 0/89 | |||||
(0.00%) | 0/976 | |||||
(0.00%) | 1/90 | |||||
(1.11%) | 0/90 | |||||
(0.00%) | ||||||
vanB | ||||||
Bottle Ring | 89/89 | 100.0 | ||||
[95.86-100.0] | 0/89 | |||||
(0.00%) | 0/976 | |||||
(0.00%) | 0/90 | |||||
(0.00%) | 1/90 | |||||
(1.11%) | ||||||
vanB | ||||||
Bottle Ring + 8 hours | 89/89 | 100.0 | ||||
[95.86, 100.0] | 0/89 | |||||
(0.00%) | 0/976 | |||||
(0.00%) | 1/90 | |||||
(1.11%) | 0/90 | |||||
(0.00%) |
11
Limit of Detection (LoD)
A study was conducted to determine the limit of detection, defined as the lowest concentration (CFU/mL) of analyte that can be detected approximately 95% of the time, for the eight targets detected by the iC-GPC Assay. A panel of nineteen organisms was evaluated, including a minimum of two bacterial strains per target analyte. Three concentrations were tested for each LoD panel member in replicates of twenty on three unique cassette lots. The LoD of each target is considered the lowest concentration with an approximately 95% detection rate, presented in Table 4 below.
TABLE 4: iC-GPC Assay Target LoD | ||
---|---|---|
iC-GPC Assay Target | Phenotype Identification | Defined LoD (CFU/mL) |
gseA | Staphylococcus epidermidis | $1.6 \times 10^6 - 1.7 \times 10^7$ |
nuc | Staphylococcus aureus | $1.7 \times 10^6 - 4.4 \times 10^6$ |
mecA | Associated with methicillin resistance | $7.4 \times 10^5 - 9.5 \times 10^6$ |
lytA | Streptococcus pneumoniae | $1.3 \times 10^6 - 6.0 \times 10^6$ |
ddl | Enterococcus faecalis | $3.0 \times 10^5 - 5.8 \times 10^6$ |
fcm | Enterococcus faecium | $4.9 \times 10^6 - 7.9 \times 10^6$ |
vanA | Associated with vancomycin resistance | $7.2 \times 10^5 - 1.1 \times 10^7$ |
vanB | Associated with vancomycin resistance | $3.9 \times 10^6 - 5.8 \times 10^6$ |
Analytical Reactivity (Inclusivity)
The analytical reactivity (inclusivity) for each iC-GPC Assay target was evaluated using multiple wellcharacterized and clinically relevant strains chosen to represent temporal, geographic, and genetic diversity. Inclusivity panel organisms included the following:
- 5 Staphylococcus epidermidis, mecA negative strains O
- 6 Staphylococcus epidermidis, mecA positive strains O
- O 5 Staphylococcus aureus, mecA negative strains
- 58 Staphylococcus aureus, mecA positive strains, representing various pulse-O
- field gel electrophoresis types and including the following:
- . Vancomycin-intermediate SA (VISA)
- . Panton-Valentine Leukocidin (PVL)-producing SA
- . ATCC 43300 (hetero-resistant, mecA positive)
- field gel electrophoresis types and including the following:
- 2 borderline oxacillin-resistant Staphylococcus aureus strains (BORSA) O
- O 10 Streptococcus pneumoniae strains
- 5 Enterococcus faecalis, vanA/vanB negative strains O
- 5 Enterococcus faecalis, vanA or vanB positive strains O
- 5 Enterococcus faecium, vanA/vanB negative strains O
- 5 Enterococcus faecium, vanA or vanB positive strains O
A total of 106 organisms were evaluated for iC-GPC Assay Inclusivity testing. Strains were tested near the target LoD (2-3x LoD) or at the lowest level of bottle positivity. Testing was performed in the event of a false negative result, the stain was retested near the target LoD in replicates of ten. All expected targets were detected by the iC-GPC Assay. Results of inclusivity testing are summarized in Table 5 below.
12
TABLE 5: iC-GPC Inclusivity Results | ||||
---|---|---|---|---|
Species | Strain ID | Other IDs/Notes | Targets Detected/ | |
Total Replicates | ||||
S. epidermidis | Z318 | N/A | 3/3 | |
S. epidermidis | Z0801689 | HER 1292 | 3/3 | |
S. epidermidis | ATCC 700583 | N/A | 3/3 | |
S. epidermidis | Z291 | ATCC 14990 | 3/3 | |
S. epidermidis | Z049 | N/A | 3/3 | |
S. epidermidis, mecA (+) | Z0801651 | RP62A | 3/3 | |
S. epidermidis, mecA (+) | Z256 | N/A | 3/3 | |
S. epidermidis, mecA (+) | Z257 | N/A | 3/3 | |
S. epidermidis, mecA (+) | Z258 | N/A | 12/13 | |
S. epidermidis, mecA (+) | Z259 | N/A | 3/3 | |
S. epidermidis, mecA (+) | ATCC 29887 | N/A | 3/3 | |
S. aureus | Z021 | ATCC 6538P | 3/3 | |
S. aureus | ATCC 12600 | N/A | 3/3 | |
S. aureus | Z0801675 | N/A | 3/3 | |
S. aureus | Z057 | N/A | 3/3 | |
S. aureus | Z153 | N/A | 3/3 | |
S. aureus, mecA (+) | HM-466 | 131 | 3/3 | |
S. aureus, mecA (+) | HM-467 | 177 | 3/3 | |
S. aureus, mecA (+) | NR-10129 | TCH60 | 3/3 | |
S. aureus, mecA (+) | NR-10189 | HFH-30364, USA400, PVL+ | 3/3 | |
S. aureus, mecA (+) | NR-10192 | HFH-30106, non USA100-1100 | 3/3 | |
S. aureus, mecA (+) | NR-13524 | H342087 | 3/3 | |
S. aureus, mecA (+) | NR-28983 | S0385 | 3/3 | |
S. aureus, mecA (+) | NR-45872 | HIP07930, USA600 | 3/3 | |
S. aureus, mecA (+) | NR-45880 | LIM1 | 3/3 | |
S. aureus, mecA (+) | NR-45890 | BR 5, VISA | 3/3 | |
S. aureus, mecA (+) | NR-46062 | H2138 (isolate 10) | 3/3 | |
S. aureus, mecA (+) | NR-46063 | P1V44, VISA | 3/3 | |
S. aureus, mecA (+) | NR-46072 | 1078, USA700 | 3/3 | |
S. aureus, mecA (+) | NR-46080 | AIS 2006061, USA1000, PVL+ | 3/3 | |
S. aureus, mecA (+) | NR-46081 | HIP12899, USA1100, PVL+ | 3/3 | |
S. aureus, mecA (+) | NR-46218 | GA-442, USA700 | 3/3 | |
S. aureus, mecA (+) | NR-46070 | USA300-0114 | 3/3 | |
S. aureus, mecA (+) | NR-46171 | CA-126, USA100 | 3/3 | |
S. aureus, mecA (+) | NR-46172 | CA-127, USA300, PVL+ | 3/3 | |
S. aureus, mecA (+) | NR-46177 | CA-347, USA600 | 3/3 | |
S. aureus, mecA (+) | NR-46180 | CA-409, USA200 | 3/3 | |
S. aureus, mecA (+) | NR-46182 | CA-513, USA800 | 3/3 | |
S. aureus, mecA (+) | NR-46191 | CO-34, USA300, PVL+ | 3/3 | |
S. aureus, mecA (+) | NR-46197 | CO-72, USA800 | 3/3 | |
TABLE 5: iC-GPC Inclusivity Results | ||||
Species | Strain ID | Other IDs/Notes | Targets Detected/ | |
Total Replicates | ||||
S. aureus, mecA (+) | NR-46199 | CT-110, USA100 | 3/3 | |
S. aureus, mecA (+) | NR-46207 | CT-58, USA500 | 3/3 | |
S. aureus, mecA (+) | NR-46215 | GA-356 | 3/3 | |
S. aureus, mecA (+) | NR-46221 | GA-656, USA800 | 3/3 | |
S. aureus, mecA (+) | NR-46223 | GA-92, USA300, PVL+ | 3/3 | |
S. aureus, mecA (+) | NR-46224 | NY-315, USA600 | 3/3 | |
S. aureus, mecA (+) | NR-46250 | OR-130, USA100 | 3/3 | |
S. aureus, mecA (+) | NR-46251 | OR-131, USA200 | 3/3 | |
S. aureus, mecA (+) | NR-46261 | TN-112, USA300 | 3/3 | |
S. aureus, mecA (+) | NR-46269 | TN-82, USA200 | 3/3 | |
S. aureus, mecA (+) | NR-41875 | M0001 | 3/3 | |
S. aureus, mecA (+) | NR-41876 | M0006 | 3/3 | |
S. aureus, mecA (+) | NR-41877 | M0055 | 3/3 | |
S. aureus, mecA (+) | NR-41878 | M0102 | 3/3 | |
S. aureus, mecA (+) | NR-41879 | M0108 | 3/3 | |
S. aureus, mecA (+) | NR-41880 | M0197 | 3/3 | |
S. aureus, mecA (+) | NR-41881 | M0200 | 3/3 | |
S. aureus, mecA (+) | NR-41882 | M0288 | 3/3 | |
S. aureus, mecA (+) | NR-41883 | M0334 | 3/3 | |
S. aureus, mecA (+) | NR-41887 | M0663 | 3/3 | |
S. aureus, mecA (+) | NR-41889 | M0934 | 3/3 | |
S. aureus, mecA (+) | NR-41890 | M0943 | 3/3 | |
S. aureus, mecA (+) | NR-41895 | M1510 | 12/13 | |
S. aureus, mecA (+) | NR-41896 | M1565 | 3/3 | |
S. aureus, mecA (+) | NR-10187 | HFH-29994, USA100 | 3/3 | |
S. aureus, mecA (+) | NR-13525 | F338081 | 3/3 | |
S. aureus, mecA (+) | NR-13526 | W342179 | 3/3 | |
S. aureus, mecA (+) | NR-13533 | S247312 | 3/3 | |
S. aureus, mecA (+) | NR-13546 | SU-1 | 3/3 | |
S. aureus, mecA (+) | NR-30544 | HI049, USA300, PVL+ | 3/3 | |
S. aureus, mecA (+) | NR-45924 | LinR #12 | 3/3 | |
S. aureus, mecA (+) | ATCC 700698 | N/A | 3/3 | |
S. aureus, mecA (+) | ATCC BAA44 | N/A | 3/3 | |
S. aureus, mecA (+) | ATCC 43300 | Hetero-resistant | 3/3 | |
BORSA | MCW 109 | N/A | 3/3 | |
BORSA | MCW 141 | N/A | 3/3 | |
S. pneumoniae | Z022 | Clinical isolate, serotype 19F | 3/3 | |
S. pneumoniae | Z073 | Clinical isolate, serotype 19F | 3/3 | |
S. pneumoniae | Z319 | Clinical isolate, serotype 12F | 3/3 | |
S. pneumoniae | Z278 | ATCC BAA-255, R6 (non-virulent) | 3/3 | |
TABLE 5: iC-GPC Inclusivity Results | ||||
Species | Strain ID | Other IDs/Notes | Targets Detected/ | |
Total Replicates | ||||
S. pneumoniae | Z279 | PHE NCTC 11910, serotype 23F | 3/3 | |
S. pneumoniae | Z280 | PHE NCTC 11897, serotype 9V | 3/3 | |
S. pneumoniae | Z282 | ATCC 33400, NCTC 7465, serotype 1 | 3/3 | |
S. pneumoniae | Z295 | ATCC 49619, serotype 19F | 3/3 | |
S. pneumoniae | Z261 | Clinical isolate | 3/3 | |
S. pneumoniae | Z262 | Clinical isolate | 3/3 | |
E. faecalis | Z0801637 | N/A | 3/3 | |
E. faecalis | ATCC 33186 | N/A | 3/3 | |
E. faecalis | ATCC 49532 | N/A | 3/3 | |
E. faecalis | Z289 | ATCC 19433 | 3/3 | |
E. faecalis | Z266 | ATCC 6055 | 3/3 | |
E. faecalis, vanB (+) | Z0801693 | vanB | 3/3 | |
E. faecalis, vanA (+) | Z324 | vanA | 3/3 | |
E. faecalis, vanA (+) | Z267 | PHE NCTC 12201- vanA | 3/3 | |
E. faecalis, vanA (+) | Z269 | PHE NCTC 12203- vanA | 3/3 | |
E. faecalis, vanB (+) | ATCC 51575 | vanB | 3/3 | |
E. faecium | Z322 | N/A | 3/3 | |
E. faecium | ATCC 8459 | N/A | 3/3 | |
E. faecium | Z265 | ATCC 9756 | 3/3 | |
E. faecium | Z290 | ATCC 19434 | 3/3 | |
E. faecium | Z320 | ATCC 19634 | 3/3 | |
E. faecium, vanA (+) | Z0801892 | vanA | 3/3 | |
E. faecium, vanB (+) | Z323 | vanB | 3/3 | |
E. faecium, vanA (+) | Z270 | PHE NCTC 12202- vanA | 3/3 | |
E. faecium, vanA (+) | Z271 | PHE NCTC 12204- vanA | 3/3 | |
E. faecium, vanA (+) | Z260 | vanA | 3/3 |
13
14
Analytical Exclusivity
Analytical specificity of the iC-GPC Assay was evaluated by testing a comprehensive panel of non-target microorganisms that may be encountered in positive blood cultures. Exclusivity panel members included organisms phylogenetically related to iC-GPC target organisms as well as common blood culture contaminants. A total of ninety-four (94) exclusivity organisms were tested. Potential cross-reactivity was evaluated by testing the exclusivity panel organisms at high concentrations in blood culture bottle/blood media. Exclusivity results are presented in Table 6 below; performance is based on the observation of all expected negative results. In the event of a false positive result, the organism was retested in replicates of three (3) or ten (10). One organism, Streptococcus bovis, demonstrated reproducible cross-reactivity with the iC-GPC target Enterococcus faecalis.
15
| TABLE 6: iC-GPC Exclusivity Results | Test Concentration (CFU/mL, or
as designated, bottle ring or
TCID50/mL) | Exclusivity |
|--------------------------------------------|-------------------------------------------------------------------------------|-------------|
| Abiotrophia defectiva | 3.09 × 108 | 3/3 |
| Acinetobacter baumannii | 6.55 × 108 | 3/3 |
| Acinetobacter lwoffi | 5.70 × 108 | 3/3 |
| Aerococcus viridans | 5.05 × 107 | 3/3 |
| Aeromonas hydrophila | 3.50 × 108 | 3/3 |
| Alcaligenes faecalis | 1.01 × 1010 | 3/3 |
| Anaerococcus tetradius | 3.55 × 108 | 3/3 |
| Aspergillus niger | 8.10 × 107 | 3/3 |
| Bacillus cereus | 7.30 × 106 | 3/3 |
| Bacteroides fragilis | 4.20 × 109 | 3/3 |
| Campylobacter coli | 2.55 × 108 | 3/3 |
| Campylobacter jejuni | 2.24 × 108 | 3/3 |
| Candida albicans | 8.00 × 107 | 3/3 |
| Candida catenulata | 1.14 × 109 | 3/3 |
| Candida dubliniensis | 7.05 × 106 | 3/3 |
| Candida glabrata | 1.15 × 108 | 3/3 |
| Candida guilliermondii | 1.03 × 107 | 3/3 |
| Candida krusei | 2.82 × 107 | 5/61 |
| Candida parapsilosis | 3.15 × 107 | 3/3 |
| Candida tropicalis | 7.65 × 107 | 2/2 |
| Citrobacter amalonaticus | 2.35 × 109 | 3/3 |
| Citrobacter freundii | 6.40 × 108 | 3/3 |
| Citrobacter koseri | 3.29 × 109 | 3/3 |
| Citrobacter sedlakii | 1.70 × 109 | 3/3 |
| Clostridium difficile (NAP-1 toxigenic) | 2.44 × 107 | 3/3 |
| Clostridium difficile (non-toxigenic) | 2.97 × 107 | 3/3 |
| Clostridium oedematiens (novyi) | 5.70 × 106 | 3/3 |
| Collinsella aerofaciens | 5.95 × 107 | 3/3 |
| Corynebacterium amycolatum | 3.79 × 108 | 5/62 |
| Corynebacterium genitalium | 2.50 × 108 | 3/3 |
| Corynebacterium jeikeium | 4.19 × 108 | 3/3 |
| Coxsackie virus | 1 × 106.34 (TCID50) | 3/3 |
| Cryptococcus neoformans | 1.08 × 108 | 3/3 |
| Cytomegalovirus | 1 × 105.07 (TCID50) | 3/3 |
| Echovirus | 1 × 107.77 (TCID50) | 3/3 |
| Edwardsiella tarda | 5.05 × 109 | 3/3 |
| Eggerthella lenta | 1.42 × 108 | 3/3 |
| Enterobacter aerogenes | 6.50 × 109 | 3/3 |
| TABLE 6: iC-GPC Exclusivity Results | | |
| Exclusivity Organism | Test Concentration (CFU/mL, or
as designated, bottle ring or
TCID50/mL) | Exclusivity |
| Enterococcus avium | $5.85 \times 10^7$ | 3/3 |
| Enterococcus casseliflavus | $9.60 \times 10^6$ | 3/3 |
| Enterococcus cecorum | $3.80 \times 10^8$ | 3/3 |
| Enterococcus dispar | $6.10 \times 10^8$ | 3/3 |
| Enterococcus gallinarum | $3.20 \times 10^8$ | 3/3 |
| Enterococcus hirae | $1.04 \times 10^9$ | 3/3 |
| Enterococcus raffinosus | $4.67 \times 10^8$ | 3/3 |
| Enterovirus Type 71 | $1 \times 10^{6.10}$ (TCID50) | 3/3 |
| Escherichia coli | $1.27 \times 10^9$ | 3/3 |
| Escherichia hermannii | $3.09 \times 10^9$ | 3/3 |
| Fusobacterium varium | $1.25 \times 10^9$ | 3/3 |
| Klebsiella oxytoca | $7.25 \times 10^9$ | 3/3 |
| Klebsiella pneumoniae | $2.27 \times 10^9$ | 3/3 |
| Kocuria kristinae | $3.45 \times 10^8$ | 3/3 |
| Kytococcus schroeteri | $1.85 \times 10^8$ | 3/3 |
| Lactobacillus acidophilus | $5.30 \times 10^7$ | 3/3 |
| Lactobacillus plantarum subsp.plantarum | $1.53 \times 10^9$ | 3/3 |
| Lactobacillus reuteri | $1.24 \times 10^8$ | 5/63 |
| Lactococcus lactis | $2.57 \times 10^9$ | 3/3 |
| Leminorella grimontii | $1.22 \times 10^9$ | 3/3 |
| Leuconostoc mesenteroides | $3.17 \times 10^7$ | 3/3 |
| Micrococcus luteus | $1.13 \times 10^7$ | 3/3 |
| Oerskovia enterophila | $1.33 \times 10^{10}$ | 3/3 |
| Pediococcus pentosaceus | $2.82 \times 10^9$ | 3/3 |
| Planococcus citreus | $1.14 \times 10^9$ | 3/3 |
| Propionibacterium acnes | $9.75 \times 10^7$ | 3/3 |
| Proteus mirabilis | $9.25 \times 10^8$ | 3/3 |
| Proteus penneri | $1.11 \times 10^9$ | 3/3 |
| Proteus vulgaris | $1.13 \times 10^9$ | 3/3 |
| Providencia alcalifaciens | $1.62 \times 10^9$ | 10/114 |
| Providencia rettgeri | $1.05 \times 10^9$ | 3/3 |
| Providencia stuartii | $1.48 \times 10^9$ | 3/3 |
| Pseudomonas aeruginosa | $2.14 \times 10^8$ | 3/3 |
| Pseudomonas putida | $4.95 \times 10^8$ | 3/3 |
| Rothia mucilaginosus | $1.60 \times 10^8$ | 3/3 |
| Salmonella spp (typhimurium) | $4.45 \times 10^9$ | 3/3 |
| Staphylococcus capitis | $4.05 \times 10^7$ | 3/3 |
| Staphylococcus delphini | $2.12 \times 10^9$ | 3/3 |
| TABLE 6: iC-GPC Exclusivity Results | | |
| Exclusivity Organism | Test Concentration (CFU/mL, or
as designated, bottle ring or
TCID50/mL) | Exclusivity |
| Staphylococcus hominis | $1.87 \times 10^8$ | 3/3 |
| Staphylococcus intermedius | $8.55 \times 10^7$ | 5/65 |
| Staphylococcus lugdunensis | $3.05 \times 10^9$ | 3/3 |
| Staphylococcus lutrae | $6.00 \times 10^9$ | 3/3 |
| Staphylococcus pettenkoferi | $1.36 \times 10^9$ | 3/3 |
| Staphylococcus schleiferi | $2.67 \times 10^9$ | 3/3 |
| Staphylococcus schleiferi subsp. coagulans | $2.67 \times 10^8$ | 5/66 |
| Staphylococcus warneri | $6.48 \times 10^8$ | 3/3 |
| Streptococcus agalactiae | $6.05 \times 10^8$ | 13/147 |
| Streptococcus anginosus | $4.65 \times 10^8$ | 13/148 |
| Streptococcus bovis | $5.50 \times 10^8$ | 3/149 |
| Streptococcus dysgalactiae | $8.35 \times 10^6$ | 3/3 |
| Streptococcus intermedius | Bottle ring + 8 hours | 11/1210 |
| Streptococcus mitis | Bottle ring + 8 hours | 3/3 |
| Streptococcus pseudopneumoniae | Bottle ring + 8 hours | 3/3 |
| Streptococcus pyogenes | $8.20 \times 10^8$ | 3/3 |
| Streptococcus salivarus | $8.85 \times 10^7$ | 3/3 |
| Streptococcus uberis | $7.45 \times 10^7$ | 3/3 |
16
17
Candida krusei: 1/3 false positive E. faecalis in initial testing, 3/3 repeats negative. 1)
-
Corynebacterium amycolatum: 1/3 false positive S. epidermidis in initial testing, 3/3 repeats negative.
-
Lactobacillus reuteri: 1/3 false positive mecA in initial testing, 3/3 repeats negative. Note that mecA would not be reported as the S. aureus and S. epidermidis targets were negative as expected.
-
- Providencia alcalifaciens: 1/3 false positive S. aureus in initial testing, 8/8 repeats negative.
Staphylococus intermedius: 1/3 false positive mecA in initial testing, 3/3 repeats negative. Note that mecA would not be 5) reported as the S. aureus and S. epidermidis targets were negative as expected.
- Providencia alcalifaciens: 1/3 false positive S. aureus in initial testing, 8/8 repeats negative.
-
୧) Staphylococus schlejferi subsp. coagulans: 1/3 false positive mecA in initial testing, 3/3 repeats negative. Note that mecA would not be reported as the S. aureus and S. epidermidis targets were negative as expected.
-
- Streptococus agalactiae: 1/3 false positive mecA in initial testing, 11/11 repeats negative. Note that mecA would not be reported as the S. aureus and S. epidermidis targets were negative as expected.
-
Streptococcus anginosus: 1/2 false positive E. faecalis in initial testing, 12/12 repeats negative. 8)
-
- Streptococcus bovis: 1/2 false positive E. faecalis in initial testing, 10/12 false positive E. faecalis in repeat testing
-
- Streptococcus intermedius: 1/3 false positive E. faecalis in initial testing, 9/9 repeats negative
Microbial Interference
Potential microbial interference was evaluated by testing high concentrations of 85 exclusivity organisms in combination with iC-GPC target organisms present near LoD concentrations. Microbial interference results are presented in Table 7 below; performance is based on all expected targets detected. In the event of a false negative result, the combination was repeated with the target organism near target LoD concentrations in replicates of 10. If additional false negative results were observed, testing was repeated with the target organism at bottle ring concentrations. Microbial interference was not observed for the majority of organism combinations. For those combinations with unexpected initial false negative results, additional replicate testing at the same concentration or at a higher "bottle ring" concentration generated 100% iC-GPC Assay target detection as expected.
18
TABLE 7: iC-GPC Microbial Interference Results | ||||||
---|---|---|---|---|---|---|
SE | SA | SPN | EFLS | EFCM | ||
Exclusivity Organism | Test Concentration | |||||
(CFU/mL) | Test Concentration for initial three replicates (CFU/mL) | |||||
1.4 x 107 | 1.4 x 107 | Bottle | ||||
Ring | 1.2 x 107 | 1.2 x 107 | ||||
Abiotrophia defective | 1.54 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Acinetobacter baumannii | 3.28 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Acinetobacter lwoffi | 2.85 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Aerococcus viridans | 2.53 x 107 | 3/3 | 3/3 | 3/3 | 12/131 | 3/3 |
Aeromonas hydrophila | 1.75 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Anaerococcus tetradius | 1.78 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Bacillus cereus | 3.65 x 106 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Bacteroides fragilis | 2.10 × 109 | 3/3 | 3/3 | 2/2 | 3/3 | 3/3 |
Campylobacter coli | 1.28 x 108 | 3/3 | 18/222 | 3/3 | 3/3 | 3/3 |
Campylobacter jejuni | 1.12 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Candida albicans | 4.00 × 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Candida catenulate | 5.68 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Candida dubliniensis | 3.53 × 106 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Candida glabrata | 5.75 x 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Candida guilliermondii | 5.15 x 106 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Candida krusei | 1.41 x 107 | 3/3 | 3/3 | 3/3 | 20/223 | 3/3 |
Candida parapsilosis | 1.58 x 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Candida tropicalis | 3.83 x 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Citrobacter amalonaticus | 1.18 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 5/64 |
Citrobacter freundii | 3.20 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Citrobacter koseri | 1.64 x 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Citrobacter sedlakii | 8.50 × 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Clostridium difficile (NAP-1 | ||||||
toxigenic) | 1.22 x 107 | 3/3 | 5/65 | 3/3 | 3/3 | 3/3 |
Clostridium difficile (non- | ||||||
toxigenic) | 1.48 x 107 | 5/66 | 3/3 | 3/3 | 3/3 | 3/3 |
Clostridium oedematiens (novyi) | 2.85 x 106 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Collinsella aerofaciens | 2.98 x 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Corynebacterium amycolatum | 1.89 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Corynebacterium genitalium | 1.25 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Corynebacterium jeikeium | 2.09 × 108 | 3/3 | 3/3 | 3/3 | 2/2 | 3/3 |
Edwardsiella tarda | 2.53 × 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Enterobacter aerogenes | 3.25 × 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Enterobacter cloacae | 1.36 × 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Enterococcus avium | 2.93 x 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Enterococcus casseliflavus | 4.80 x 106 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Enterococcus cecorum | 1.90 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Enterococcus dispar | 3.05 × 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
TABLE 7: iC-GPC Microbial Interference Results | ||||||
SE | SA | SPN | EFLS | EFCM | ||
Exclusivity Organism | Test Concentration | |||||
(CFU/mL) | Test Concentration for initial three replicates (CFU/mL) | |||||
1.4 x 107 | 1.4 x 107 | Bottle | ||||
Ring | 1.2 x 107 | 1.2 x 107 | ||||
Enterococcus gallinarum | 1.60 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Enterococcus hirae | 5.18 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Enterococcus raffinosus | 2.33 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Escherichia coli | 6.35 × 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Escherichia hermannii | 1.54 × 109 | 3/3 | 3/3 | 3/3 | 11/127 | 3/3 |
Fusobacterium varium | 6.23 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Klebsiella oxytoca | 3.63 x 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Klebsiella pneumoniae | 1.13 x 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Kocuria kristinae | 1.73 x 108 | 3/3 | 12/138 | 3/3 | 3/3 | 3/3 |
Kytococcus schroeteri | 9.25 x 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Lactobacillus acidophilus | 2.65 x 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Lactobacillus plantarum | ||||||
subsp.plantarum | 7.63 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Lactobacillus reuteri | 6.18 x 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Lactococcus lactis | 1.28 × 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Leminorella grimontii | 6.08 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Leuconostoc mesenteroides | 1.58 x 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Micrococcus luteus | 5.63 x 106 | 3/3 | 11/129 | 3/3 | 3/3 | 3/3 |
Oerskovia enterophila | 6.63 x 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Pediococcus pentosaceus | 1.41 × 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Propionibacterium acnes | 4.88 x 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Proteus mirabilis | 4.63 x 108 | 3/3 | 12/1310 | 3/3 | 11/1211 | 3/3 |
Proteus penneri | 5.55 x 108 | 3/3 | 11/1312 | 3/3 | 3/3 | 3/3 |
Proteus vulgaris | 5.63 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Providencia alcalifaciens | 8.08 × 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Providencia rettgeri | 5.25 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Providencia stuartii | 7.40 x 108 | 3/3 | 5/613 | 3/3 | 3/3 | 3/3 |
Pseudomonas aeruginosa | 1.07 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Pseudomonas putida | 2.48 x 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Rothia mucilaginosus | 8.00 × 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Salmonella spp (typhimurium) | 2.23 x 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Staphylococcus capitis | 2.03 x 107 | 3/3 | 21/2314 | 3/3 | 3/3 | 3/3 |
Staphylococcus delphini | 1.06 x 109 | 3/3 | 12/1315 | 3/3 | 3/3 | 3/3 |
Staphylococcus haemolyticus | 9.75 x 106 | 3/3 | 3/3 | 11/1216 | 3/3 | 3/3 |
Staphylococcus hominis | 9.33 x 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Staphylococcus intermedius | 4.28 x 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Staphylococcus lugdunensis | 1.53 × 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Staphylococcus lutrae | 3.00 x 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
TABLE 7: iC-GPC Microbial Interference Results | ||||||
Exclusivity Organism | Test Concentration | |||||
(CFU/mL) | SE | SA | SPN | EFLS | EFCM | |
Test Concentration for initial three replicates (CFU/mL) | ||||||
1.4 × 107 | 1.4 × 107 | Bottle | ||||
Ring | 1.2 × 107 | 1.2 × 107 | ||||
Staphylococcus pettenkoferi | 6.78 × 108 | 12/1317 | 3/3 | 3/3 | 3/3 | 3/3 |
Staphylococcus schleiferi | 1.33 × 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Staphylococcus schleiferi subsp. | ||||||
coagulans | 1.22 × 109 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Staphylococcus warneri | 3.20 × 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Streptococcus agalactiae | 3.03 × 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Streptococcus anginosus | 2.33 × 108 | 3/3 | 3/3 | 3/3 | 3/3 | 12/1318 |
Streptococcus bovis | 2.75 × 108 | 5/619 | 3/3 | 3/3 | 3/3 | 3/3 |
Streptococcus dysgalactiae | 4.18 × 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Streptococcus intermedius | 8.25 × 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Streptococcus mitis | Bottle ring + 8 hours | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Streptococcus pseudopneumoniae | Bottle ring + 8 hours | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Streptococcus pyogenes | 4.10 × 108 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Streptococcus salivarus | 4.43 × 107 | 3/3 | 12/1320 | 3/3 | 3/3 | 2/2 |
Streptococcus uberis | 3.73 × 107 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
19
20
1 false negative vanB in initial testing (2/3), 10/10 repeats passed 1)
2 false negative S. aureus and 1 false negative mec4 in initial testing (1/3), 2 false negative mecA 2) in repeat testing near LoD (8/10). No false negatives in repeat testing at bottle ring concentration (9/9).
-
- 1 false negative vanB in initial testing (2/3), 1 false negative vanB in repeat testing near LoD (9/10). No false negatives in repeat testing at bottle ring concentration (9/9).
- 1 false positive mec4 in initial testing (2/3), 3/3 repeats passed. Note that mecA would not be reported as the S aureus and S. 4) epidermidis targets were negative as expected.
-
- 1 false positive S. epidermidis in initial testing (2/3), 3/3 repeats passed
-
- 1 false positive S. aureus in initial testing (2/3), 3/3 repeats passed
-
- 1 false negative vanB in initial testing (2/3), 9/9 repeats passed
-
- 1 false negative S. aureus and 1 false negative mecA in initial testing (2/3), 10/10 repeats passed
- 1 false negative S. aureus and 1 false negative mecA in initial testing (2/3), 9/9 repeats passed 9)
-
- 1 false negative S. aureus in initial testing (2/3), 10/10 repeats passed
-
- 1 false negative vanB in initial testing (2/3), 9/9 repeats passed
-
- 2 false negative mecA in initial testing (1/3), 10/10 repeats passed
-
- 1 false positive S. epidermidis in initial testing (2/3), 3/3 repeats passed
-
- 1 false negative mecA in initial testing (2/3), 1 false negative mecA in repeat testing near LoD (9/10). No false negatives in repeat testing at bottle ring concentration (9/9).
-
- 1 false negative S. aureus and 1 false negative mecA in initial testing (2/3), 10/10 repeats passed
-
- 1 false negative S. pneumoniae in initial testing (1/2), 10/10 repeats passed at bottle ring concentration.
-
- 1 false negative mecA in initial testing (2/3), 10/10 repeats passed
-
- 1 false negative E. faecium in initial testing (2/3), 10/10 repeats passed
-
- 1 false positive E. faecalis in initial testing (2/3), 3/3 repeats passed
-
- 1 false negative S. aureus in initial testing (2/3), 10/10 repeats passed
21
Competitive Inhibition
iC-GPC Assay performance was evaluated with combinations of target analytes that may be found in mixed positive blood cultures. One target organism was tested at a concentration near LoD ("low organism") in combination with a second target organism at a concentration of bottle ring + 8 hours ("high organism"). Combinations of five organisms representing each of the iC-GPC Assay targets were tested, for a total of 20 combinations. Competitive inhibition results are summarized in Table 8 below. Results represent the number of detected targets out of the total number of replicates tested. All high concentration iC-GPC targeted organisms were detected in all organism combinations. Due to competitive inhibition, low concentration organism targets were only detected in 3/20 (15%) of organism combinations. Target organisms present near LoD concentrations may not be detected by the iC-GPC Assay when a second target organism is present in the blood culture specimen.
TABLE 8: iC-GPC Competitive Inhibition Performance | Target Performance | ||||
---|---|---|---|---|---|
LoD Strain | High Strain | Low Organism | |||
(~2-3x LoD) | Low Resistance | ||||
Marker | |||||
(~2-3x LoD) | High Organism | ||||
(Bottle ring |
- 8 hours) | High Resistance
Marker (Bottle
ring + 8 hours) |
| S. epidermidis
(SE/mecA) | SA/mecA | 0/3 | 3/3* | 3/3 | 3/3* |
| | SPN | 3/3 | 3/3 | 3/3 | NA |
| | EFLS/vanB | 0/3 | 0/3 | 3/3 | 3/3 |
| | EFCM/vanA | 0/3 | 0/3 | 3/3 | 3/3 |
| S. aureus
(SA/mecA) | SE/mecA | 0/3 | 3/3* | 3/3 | 3/3* |
| | SPN | 3/3 | 3/3 | 3/3 | NA |
| | EFLS/vanB | 0/3 | 0/3 | 3/3 | 3/3 |
| | EFCM/vanA | 0/3 | 0/3 | 3/3 | 3/3 |
| S. pneumoniae
(SPN) | SE/mecA | 0/3 | NA | 3/3 | 3/3 |
| | SA/mecA | 0/3 | NA | 3/3 | 3/3 |
| | EFLS/vanB | 0/3 | NA | 3/3 | 3/3 |
| | EFCM/vanA | 0/3 | NA | 3/3 | 3/3 |
| E. faecalis
(EFLS/vanB) | SE/mecA | 0/3 | 0/3 | 3/3 | 3/3 |
| | SA/mecA | 1/3 | 0/3 | 3/3 | 3/3 |
| | SPN | 3/3 | 2/3 | 3/3 | NA |
| | EFCM/vanA | 0/3 | 0/3 | 3/3 | 3/3 |
| E. faecium
(EFCM/vanA) | SE/mecA | 0/3 | 3/3** | 3/3 | 3/3 |
| | SA/mecA | 0/3 | 3/3** | 3/3 | 3/3 |
| | SPN | 3/3 | 3/3 | 3/3 | NA |
| | EFLS/vanB | 0/3 | 2/3 | 3/3 | 3/3 |
| Total | | 13/60 (21.7%) | 25/48 (52.1%) | 60/60 (100%) | 48/48 (100%) |
*The source of the resistance marker cannot be distinguished between high concentration organism and low concentration organism.
** Results include all positive resistance marker detections, regardless of associated organism detection. In the absence of a positive Enterococcus detection, vanA would not be reported.
Blood Culture Bottle Equivalency
Commonly used blood culture bottle (BCB) media types were evaluated to demonstrate that variability in BCB media composition does not interfere with iC-GPC Assay performance. Nineteen representative iC-GPC target
22
organisms plus one non-target organism were tested in 10 BCB media types (see Table 9 below). Target organisms were tested near LoD concentrations (2-3x LoD). Target performance is based on all expected targets identified and no false positive targets detected. Non-target performance is based on expected negative results. Performance in all BACTEC™ and VersaTREK® bottle types and BacT/ALERT® SA Standard Aerobic media met acceptance criteria of ≥ 95%; these bottles are validated for use with the iC-GPC Assay.
False positive Enterococcus faecium results were observed in 15/59 (25.4%) of BacT/ALERT® FAN and 13/60 (21.7%) of BacT/ALERT® FA Plus Aerobic media. Testing in these bottle types was repeated at higher concentrations, approximately 5-10x LoD, with false positive E. faecium results observed in 8/59 (13.6%) and 5/60 (8.3%) of BacT/ALERT FA Aerobic FAN and BacT/ALERT FA Plus Aerobic media, respectively. Overall performance results are presented in the table below.
TABLE 9: iC-GPC Assay BCB Equivalency Results | |||||
---|---|---|---|---|---|
Blood Culture Bottle Type | Overall | ||||
Performance (%) | Target | ||||
Performance (%) | False | ||||
Negatives (%) | Non-Target | ||||
Performance (%) | False Positives | ||||
(%) | |||||
BACTEC™ Plus Aerobic | 69/70 (98.6%) | 66/67 (98.5%) | 1/67 (1.5%)1 | 3/3 (100.0%) | 0/70 (0.0%) |
BACTEC™ Plus Anaerobic | 70/72 (97.2%) | 67/69 (97.1%) | 1/69 (1.4%)2 | 3/3 (100.0%) | 1/72 (1.4%)3 |
BACTEC™ Standard Aerobic | 62/63 (98.4%) | 59/60 (98.3%) | 1/60 (1.7%)4 | 3/3 (100.0%) | 0/63 (0.0%) |
BACTEC™ Standard | |||||
Anaerobic | 77/80 (96.3%) | 74/77 (96.1%) | 2/77 (2.6%)5 | 3/3 (100.0%) | 1/80 (1.3%)6 |
BACTEC™ Lytic/10 | |||||
Anaerobic | 78/81 (96.3%) | 75/78 (96.2%) | 2/78 (2.6%)7 | 3/3 (100.0%) | 1/81 (1.2%)8 |
VersaTREK® REDOX 1 | 60/60 (100.0%) | 57/57 (100.0%) | 0/57 (0.0%) | 3/3 (100.0%) | 0/60 (0.0%) |
VersaTREK® REDOX 2 | 59/59 (100.0%) | 56/56 (100.0%) | 0/56 (0.0%) | 3/3 (100.0%) | 0/59 (0.0%) |
BacT/ALERT® SA Standard | |||||
Aerobic | 60/60 (100.0%) | 57/57 (100.0%) | 0/57 (0.0%) | 3/3 (100.0%) | 0/60 (0.0%) |
BacT/ALERT® FA Aerobic | |||||
FAN (2-3x LoD) | 44/59 (74.6%) | 44/56 (78.6%) | 0/56 (0.0%) | 0/3 (0.0%) | 15/59 (25.4%)9 |
BacT/ALERT® FA Aerobic | |||||
FAN (5-10x LoD) | 51/59 (86.4%) | 51/57 (89.5%) | 0/57 (0.0%) | 0/2 (0.0%) | 8/59 (13.6%)10 |
BacT/ALERT® FA Plus | |||||
Aerobic (2-3x LoD) | 47/60 (78.3%) | 46/57 (80.7%) | 0/57 (0.0%) | 1/3 (33.3%) | 13/60 (21.7%)11 |
BacT/ALERT® FA Plus | |||||
Aerobic (5-10x LoD) | 55/60 (91.7%) | 54/57 (94.7%) | 0/57 (0.0%) | 1/3 (33.3%) | 5/60 (8.3%)12 |
- 1 false negative mecA 1)
- 1 false negative S. epidermidis 2)
- 1 false positive E. faecalis 3)
- 1 false negative S. epidermidis 4)
-
- 1 false negative S. epidermidis, 1 false negative vanA
- 1 false positive S. epidermidis ର)
-
- 1 false negative S. epidermidis, 1 false negative S. pneumonige
-
- 1 false positive E. faecalis/vanB
- 15 false positive E. faecium 9)
-
- 8 false positive E. faecium
-
- 12 false positive E. faecium, 1 false positive S. aureus
-
- 5 false positive E. faecium
23
Further investigation suggests that the increased percentage of false positive E. faecium results observed in BacT/Alert® FA Aerobic FAN and BacT/Alert® FA Plus Aerobic media may be due to the presence of remnant nucleic acids and/or non-viable organisms in the culture media. FA Aerobic FAN media was further evaluated in clinical method comparison studies. In 96 clinical FA Aerobic FAN blood culture specimens tested, no false positive E. faecium results were observed, suggesting the risk of false positive results for E. faecium may be minimized when other organisms are present at bottle positivity concentrations in this bottle type.
Positive E. faecium results should be confirmed using alternative methods when using BacT/ALERT® FA Aerobic FAN or FA Plus Aerobic blood culture bottles.
The iC-GPC Assay is not recommended for use with BacT/ALERT® SN Standard Anaerobic, FN Anaerobic FAN, or FN Plus Anaerobic blood culture bottles.
Interfering Substances
iC-GPC Assay performance was evaluated in the presence of potentially inhibiting substances encountered in blood and blood culture media. Five representative target organisms plus one gram positive, non-target organism (Group B Streptococus) were evaluated. Target organisms were tested near LoD concentrations in combination with potential interferents at "worst-case" concentrations. Target performance is based on all expected targets detected, while non-target performance is based on all negative results. In the event of a false negative result, the organism/interferent was retested in replicates of ten. In the event of a false positive result or other system failure, the organism/interferent was retested in replicates of three. If the discordant result was not observed upon repeat testing, the compound was not considered an iC-GPC Assay interferent (Table 10). If the discordant result was observed upon repeat testing, the combination was retested at a decreased inhibitor concentration until interference was no longer observed (Table 11). Interference testing was performed in BD BACTEC Plus Aerobic blood culture bottle media with a sodium polyanetholesulfonate (SPS) concentration of 0.05% w/v. Additional SPS at concentrations greater than 0.03% w/v was found to interfere with iC-GPC Assay performance. Total protein (gamma-globulin and albumin) in concentrations greater than 3g/dL was also found to interfere with iC-GPC Assay performance. Both interferents may result in false negative results or positive controls check failures.
TABLE 10: Non-Interfering Substances Performance | |||||||
---|---|---|---|---|---|---|---|
Target Performance | |||||||
Potential Interferent | Test Concentration | SE | SA | SPN | EFLS | EFCM | Group B Strep |
Hemoglobin | 14 g/L | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 | 5/6¹ |
Triglyceride | 1000 mg/dL | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Conjugated bilirubin | 20 mg/dL | 3/3 | 3/3 | 12/13² | 12/13³ | 3/3 | 3/3 |
Unconjugated bilirubin | 20 mg/dL | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Human genomic DNA | 1 x 10⁶ cells/mL | 3/3 | 3/3 | 3/3 | 12/13⁴ | 3/3 | 3/3 |
Vancomycin | 100 mg/mL | 3/3 | 3/3 | 12/13⁵ | 3/3 | 3/3 | 3/3 |
Piperacillin | 160 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Meropenem | 80 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Cefepime | 80 mg/mL | 3/3 | 12/13⁶ | 11/12⁷ | 3/3 | 3/3 | 3/3 |
Ceftriaxone | 80 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Fluconazole | 125 mg/mL | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 | 3/3 |
Gentamicin | 100 mg/mL | 3/3 | 3/3 | 11/12⁸ | 12/14⁹ | 3/3 | 3/3 |
1 false positive E. faecalis, 3/3 repeats passed 1)
24
- 1 false negative S. pneumoniae, 10/10 repeats passed 기
-
- 1 false negative vanB, 10/10 repeats passed
-
- 1 false negative vanB, 10/10 repeats passed
-
- 1 false negative S. pneumoniae, 10/10 repeats passed
- 1 false negative mecA, 10/10 repeats passed ୧)
- 1 false negative S. pneumoniae, 9/9 repeats passed 7)
-
- 1 false negative S. pneumoniae, 9/9 repeats passed
- 1 false negative vanB, 1 false positive S. epidermidis, 11/11 repeats passed 9)
TABLE 11: Interfering Substances Performance | |||||||||
---|---|---|---|---|---|---|---|---|---|
Target Performance | |||||||||
Interferent | Test Concentration | SE | SA | SPN | EFLS | EFCM | Group B Strep | ||
Total Protein | |||||||||
(γ-globulin + albumin) | 3 g/dL | 2/2 | 3/3 | 3/3 | 2/31 | 3/3 | 3/3 | ||
Total Protein | |||||||||
(γ-globulin + albumin) | 6g/dL* | 0/3 | 0/3 | 2/3 | 0/3 | 0/3 | 2/3 | ||
SPS | 0.03% w/v | 3/3 | 12/132 | 3/3 | 3/3 | 3/3 | 5/63 | ||
SPS | 0.04% w/v* | 2/3 | 2/3 | 2/2 | 1/3 | 3/3 | 3/3 |
*Concentration at which interference observed; concentration decreased for subsequent testing.
-
-
- 1 false negative S. aureus/mecA, 10/10 repeats passed
-
- 1 false positive mecA, 3/3 repeats passed
Carryover and Cross-Contamination
The iC-System is a closed system, designed to eliminate the potential for carryover or cross-contamination between samples. Testing was performed to confirm that no false positive results from carryover or crosscontamination will occur from a high positive sample into a negative sample. Two representative iC-GPC target organisms, Staphylococcus aureus ATCC BAA977 (nuc positive) and Enterococcus faecium ATCC 700221 (fcm positive, vanA positive), were tested as representative positive samples. A gram positive nontarget organism, Corynebacterium striatum, was used as the negative sample. All organisms were tested at high concentrations, eight hours beyond initial bottle positivity. Positive, target organism samples were tested in an alternating pattern with negative, non-target organism samples across eight blades of an iC-Processor. Performance was based on accurate iC-GPC Assay target detection. No false positives indicative of sample carryover or cross-contamination were observed.
Method Comparison
A method comparison study was performed at four geographically dispersed clinical sites to evaluate the performance of the iC-GPC Assay™ for use on the iC-System™. Sites tested 966 leftover, de-identified specimens from aerobic and anaerobic blood culture bottles flagged as positive by their respective continuous monitoring blood culture system. Three of the commonly used blood culture systems were included in the study: BD BACTEC™, bioMérieux BacT/ALERT®, and Thermo Fisher VersaTREK®. Positive blood cultures were confirmed by Gram stain to contain gram positive cocci prior to being entered into the study. Specimens demonstrating mixed Gram stain results were excluded from the study.
Performance of the iC-GPC Assay was compared to an FDA-cleared multiplex assay that detects gram positive organisms and associated resistance markers directly from positive blood culture specimens. PCR and bidirectional sequencing were also performed for all specimens with positive results for resistance markers by either the iC-GPC Assay or the FDA-cleared multiplex assay. These PCR and bi-directional sequencing results were used to analyze discordant results between the iC-GPC Assay and the FDA-cleared multiplex assay.
25
Additionally, performance of the iC-GPC Assay was compared to conventional reference methods including subculture, identification of isolates using biochemical methods or MALDI-TOF, and phenotypic antimicrobial susceptibility testing (AST). PCR and bi-directional sequencing were not used for discordant analysis between iC-GPC and conventional reference method results.
A total of 966 positive blood culture specimens, confirmed by Gram stain to contain gram positive cocci, were enrolled in the iC-GPC Assay Method Comparison Study. A total of 53 samples were withdrawn from the study (see below). Of the 913 samples in the study after identified samples were withdrawn, 879 were fresh prospective samples and 34 were frozen prospective samples.
An additional 168 contrived samples were evaluated for low prevalence organisms and resistance markers. Contrived specimens were prepared by inoculating low concentrations of organisms into BD BACTEC Plus Aerobic blood culture bottles with human blood added and incubating the blood culture system until bottle positivity. Multiple strains of S. pneumoniae, E. faecium were used to prepare contrived specimens.
Performance vs. FDA-Cleared Multiplex Assay:
When performance of the iC-GPC Assay was compared to the FDA-cleared multiplex assay, there was no statistical difference in performance noted between the four study sites or between the three blood culture systems. The following blood culture bottle types were evaluated: BD BACTEC Standard Aerobic, VersaTREK REDOX 1/2, BacT/ALERT SA Standard Aerobic, and BacT/ALERT FA Aerobic FAN.
Performance of the iC-GPC Assay in comparison to the FDA-cleared multiplex assay is provided in the tables Performance is stratified by prospectively tested fresh specimens, prospectively collected and below. retrospectively tested frozen specimens, and contrived specimens.
iC-GPC Assay Performance: Staphylococcus aureus (nuc) | iC-GPC Assay Performance: Staphylococcus epidermidis (gseA) | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Specimen Type | N= | Percent Agreement | |||||||||
Positive (95% CI) | Percent Agreement | ||||||||||
Negative (95% CI) | Comparator Method | Specimen Type | N= | Percent Agreement | |||||||
Positive (95% CI) | Percent Agreement | ||||||||||
Negative (95% CI) | Comparator Method | ||||||||||
Prospective | Fresh | 879 | 96.9% | ||||||||
249/257 | |||||||||||
(94.0-98.4) | 99.7% | ||||||||||
620/622 | |||||||||||
(98.8-99.9) | FDA-Cleared | ||||||||||
Multiplex Assay | Fresh | 879 | 98.3% | ||||||||
227/231 | |||||||||||
(95.6-99.3) | 98.0% | ||||||||||
635/648 | |||||||||||
(96.6-98.8) | FDA-Cleared | ||||||||||
Multiplex Assay | |||||||||||
Frozen | 34 | 100% | |||||||||
9/9 | |||||||||||
(70.1-100) | 100% | ||||||||||
25/25 | |||||||||||
(86.7-100) | Frozen | 34 | 100% | ||||||||
4/4 | |||||||||||
(51.0-100) | 96.7% | ||||||||||
29/30 | |||||||||||
(83.3-99.4) | |||||||||||
TOTAL | 913 | 97.0% | |||||||||
258/266* | |||||||||||
(94.2-98.5) | 99.7% | ||||||||||
645/647** | |||||||||||
(98.9-99.9) | TOTAL | 913 | 98.3% | ||||||||
231/235* | |||||||||||
(95.7-99.3) | 97.9% | ||||||||||
664/678** | |||||||||||
(96.6-98.8) | |||||||||||
Contrived | 168 | - | |||||||||
0/0 |
- | 100%
168/168
(97.8-100) | | | Contrived | 168 | -
0/0 - | 100%
168/168
(97.8-100) | | |
*Of the 8 observed false negative S. aureus results by the iC-GPC Assay, 7/8 were positive for S. aureus by PCR/bi-directional sequencing.
** Of the 2 observed false positive S. aureus results by the iC-GPC Assay, 1/2 was positive for S. aureus by PCR/bi-directional sequencing. One sample was not available for discordant analysis.
*Of the 4 observed false negative S. epidermidis results by the iC-GPC Assay, 3/4 were positive for S. epidermidis by PCR/bi-directional sequencing.
**Of the 14 observed false positive S. epidermidis results by the iC-GPC Assay, 9/14 were positive for S. epidermidis by PCR/bi-directional sequencing.
26
iC-GPC Assay Performance: Streptococcus pneumoniae (lytA) | ||||
---|---|---|---|---|
Specimen | ||||
Type | N= | Percent Agreement | Comparator | |
Method | ||||
Positive | ||||
(95% CI) | Negative | |||
(95% CI) | ||||
Prospective | Fresh | 82.6%* | ||
19/23 | ||||
(62.9-93.0) | 99.9% | |||
855/856 | ||||
(99.3-100) | FDA- | |||
Cleared | ||||
Multiplex | ||||
Assay | ||||
Frozen | 100% | |||
4/4 | ||||
(51.0-100) | 100% | |||
30/30 | ||||
(88.6-100) | ||||
TOTAL | 85.2% | |||
23/27* | ||||
(67.5-94.1) | 99.9% | |||
885/886** | ||||
(99.4-100) | ||||
Contrived | 168 | 100% | ||
36/36 | ||||
(90.4-100) | 100% | |||
132/132 | ||||
(97.2-100) |
*Of the 4 observed false negative S. pneumoniae results by the iC-GPC Assay, 0/4 were positive for S. pneumoniae by PCR/bi-directional sequencing and 0/4 culture isolates obtained from these specimens were positive for S. pneumoniae by MALDI ID.
**Of the 1 observed false positive S. pneumoniae result by the iC-GPC Assay, 1/1 was positive for S. pneumoniae by PCR/bi-directional sequencing.
| Specimen
Type | N= | Percent Agreement | Comparator
Method | | |
|------------------|-----------|----------------------|--------------------------------|----------------------------------|---------------------------------------|
| | | Positive
(95% CI) | Negative
(95% CI) | | |
| Prospective | Fresh | 879 | 96.6%
56/58
(88.3-99.0) | 99.9%
820/821
(99.3-100) | FDA-
Cleared
Multiplex
Assay |
| | Frozen | 34 | 100%
3/3
(43.8-100) | 100%
31/31
(89.0-100) | |
| | TOTAL | 913 | 96.7%
59/61*
(88.8-99.1) | 99.9%
851/852**
(99.3-100) | |
| | Contrived | 168 | 100%
90/90
(95.9-100) | 100%
78/78
(95.3-100) | |
*Of the 2 observed false negative E. faecalis results by the iC-GPC Assay, 1/2 was positive for E. faecalis by PCR/bi-directional sequencing. **Of the 1 observed false positive E. faecalis result by the iC-GPC Assay, 0/1 was positive for E. faecalis by PCR/bi-directional sequencing.
iC-GPC Assay Performance: Enterococcus faecium (fcm) | iC-GPC Assay Performance: mecA (methicillin resistance) | ||||||
---|---|---|---|---|---|---|---|
Specimen Type | N= | Percent Agreement Positive (95% CI) | Percent Agreement Negative (95% CI) | Specimen Type | N= | Percent Agreement Positive (95% CI) | Percent Agreement Negative (95% CI) |
Fresh | 879 | 96.4% | |||||
27/28 | |||||||
(82.3-99.4) | 99.8% | ||||||
849/851 | |||||||
(99.1-99.9) | Fresh | 879 | 96.1% | ||||
269/280 | |||||||
(93.1-97.8) | 98.2% | ||||||
588/599 | |||||||
(96.7-99.0) | |||||||
Frozen | 34 | 100% | |||||
1/1 | |||||||
(20.7-100) | 100% | ||||||
33/33 | |||||||
(89.6-100) | Frozen | 34 | 100% | ||||
5/5 | |||||||
(56.6-100) | 100% | ||||||
29/29 | |||||||
(88.3-100) | |||||||
TOTAL | 913 | 96.6% | |||||
28/29* | |||||||
(82.8-99.4) | 99.8% | ||||||
882/884** | |||||||
(99.2-99.9) | TOTAL | 913 | 96.1% | ||||
274/285† | |||||||
(93.2-97.8) | 98.2% | ||||||
617/628** | |||||||
(96.9-99.0) | |||||||
Contrived | 168 | 100% | |||||
42/42 | |||||||
(91.6-100) | 100% | ||||||
126/126 | |||||||
(97.0-100) | Contrived | 168 | - | ||||
0/0 |
-
| 100%
168/168
(97.8-100) |
Comparator Percent Agreement Method N= Positive Negative (95% CI) (95% CI) 96.1% 98.2% sh 879 269/280 588/299 FDA-(93.1-97.8) (96.7-99.0) Cleared 100% 100% Multiplex 34 5/5 29/29 en Assay (56.6-100) (88.3-100) 96.1% 98.2% 274/285** AL ਰੇਹਤ 617/628** (96.9-99.0) (93.2-97.8) 100% -0/0 ed 168 168/168 (97.8-100) -
*Of the 1 observed false negative E. faecium result by the iC-GPC Assay, 1/1 was positive for E. faecium by PCR/bi-directional sequencing.
**Of the 2 observed false positive E. faecium results by the iC-GPC Assay, 1/2 were positive for E. faecium by PCR/bi-directional sequencing.
TOf the 274 observed true positive mecA results by the iC-GPC Assay, 269/274 were positive for mecA by PCR/bi-directional sequencing. *Of the 11 observed false negative mecA results by the iC-GPC Assay, 10/11 were positive for mecA by PCR/bi-directional sequencing.
27
8/11 were positive for mecA by PCR/bi-directional sequencing.
iC-GPC Assay Performance: vanA (vancomycin resistance) | iC-GPC Assay Performance: vanB (vancomycin resistance) | |||||||
---|---|---|---|---|---|---|---|---|
Specimen Type | N= | Percent Agreement Positive (95% CI) | Percent Agreement Negative (95% CI) | Specimen Type | N= | Percent Agreement Positive (95% CI) | Percent Agreement Negative (95% CI) | Comparator Method |
Fresh | 879 | 94.7% | ||||||
18/19 | ||||||||
(75.4-99.1) | 99.4% | |||||||
855/860 | ||||||||
(98.6-99.8) | Fresh | 879 | 100% | |||||
2/2 | ||||||||
(34.2-100) | 99.9% | |||||||
876/877 | ||||||||
(99.4-100) | FDA-Cleared Multiplex Assay | |||||||
Prospective | Frozen | 34 | 100% | |||||
1/1 | ||||||||
(20.7-100) | 100% | |||||||
33/33 | ||||||||
(89.6-100) | Frozen | 34 | - | |||||
0/0 |
-
| |
| | TOTAL | 913 | 95.0%
19/20†*
(76.4-99.1) | 99.4%
888/893**
(98.7-99.8) | TOTAL | 913 | 100%
2/2†
(34.2-100) | |
| Contrived | 168 | 100%
40/40
(91.2-100) | 100%
128/128
(97.1-100) | Contrived | 168 | 100%
56/56
(93.6-100) | 100%
112/112
(96.7-100) | |
Of the 19 observed true positive vanA results by the iC-GPC Assay, 19/19 were positive for vanA by PCR/bi-directional sequencing. *Of the 1 observed false negative vanA result by the iC-GPC Assay, 1/1 was positive for vanA by PCR/bi-directional sequencing. **Of the 5 observed false positive vanA results by the iC-GPC Assay, 2/5 were positive for vanA by PCR/bi-directional sequencing.
'Of the 2 observed true positive vanB results by the iC-GPC Assay, were positive for vanB by PCR/bi-directional sequencing. *Of the 1 observed false positive vanB result by the iC-GPC Assay, 0/1 was positive for vanB by PCR/bi-directional sequencing.
The following tables provide the performance of prospective clinical samples in comparison to the FDA-cleared multiplex assay for mecA detection with S. aureus/S. epidermidis, vanA detection with E. faecium, and vanB detection with E. faecalis/E. faecium.
Detection of mecA with S. aureus: Prospective | |||||
---|---|---|---|---|---|
FDA-Cleared Comparator Assay | |||||
Staphylococcus aureus/mecA | SA+/mecA+ | SA+/mecA- | SA- | TOTAL | |
iCubate | |||||
iC-GPC™ | SA+/mecA+ | 111 | 3 | 0 | 114 |
SA+/mecA- | 0 | 144 | 2 | 146 | |
SA- | 4 | 4 | 645 | 653 | |
TOTAL | 115 | 151 | 647 | 913 | |
Staphylococcus aureus/mecA | 95% C.I. | ||||
% Agreement (SA+/mecA+) | 96.5% (111/115) | 91.4% | 98.6% | ||
% Agreement (SA+/mecA-) | 95.4% (144/151) | 90.7% | 97.7% | ||
% Agreement (SA-) | 99.7% (645/647) | 98.9% | 99.2% |
28
Detection of mecA with S. epidermidis: Prospective | |||||
---|---|---|---|---|---|
Staphylococcus | |||||
epidermidis/mecA | FDA-Cleared Comparator Assay | ||||
SE+/mecA+ | SE+/mecA- | SE- | TOTAL | ||
SE+/mecA+ | 163 | 2 | 6 | 171 | |
iCubate | |||||
iC-GPC™ | SE+/mecA- | 4 | 62 | 8 | 74 |
SE- | 3 | 1 | 664 | 668 | |
TOTAL | 170 | 65 | 678 | 913 | |
Staphylococcus epidermidis/mecA | 95% C.I. | ||||
% Agreement (SE+/mecA+) | 95.9% (163/170) | 91.8% | 98.0% | ||
% Agreement (SE+/mecA-) | 95.4% (62/65) | 87.3% | 98.4% | ||
% Agreement (SE-) | 97.9% (664/678) | 96.6% | 98.8% |
Detection of vanA with E. faecalis: Prospective | |||||
---|---|---|---|---|---|
Enterococcus faecalis/vanA | FDA-Cleared Comparator Assay | ||||
Efs+/vanA+ | Efs+/vanA- | Efs- | TOTAL | ||
iCubate | |||||
iC-GPC™ | Efs+/vanA+ | 0 | 2 | 1 | 3 |
Efs+/vanA- | 0 | 57 | 0 | 57 | |
Efs- | 0 | 2 | 851 | 853 | |
TOTAL | 0 | 61 | 852 | 913 | |
Enterococcus faecalis/vanA | 95% C.I. | ||||
% Agreement (Efs+/vanA+) | - | - | - | ||
% Agreement (Efs+/vanA-) | 93.4% (57/61) | 84.3% | 97.4% | ||
% Agreement (Efs-) | 99.9% (851/852) | 99.3% | 99.9% |
Detection of vanB with E. faecalis: Prospective | |||||
---|---|---|---|---|---|
Enterococcus faecalis/vanB | FDA-Cleared Comparator Assay | ||||
Efs+/vanB+ | Efs+/vanB- | Efs- | TOTAL | ||
iCubate | |||||
iC-GPC™ | Efs+/vanB+ | 2 | 0 | 1 | 3 |
Efs+/vanB- | 0 | 57 | 0 | 57 | |
Efs- | 0 | 2 | 851 | 853 | |
TOTAL | 2 | 59 | 852 | 913 | |
Enterococcus faecalis/vanB | 95% C.I. | ||||
% Agreement (Efs+/vanB+) | 100.0% (2/2) | 34.2% | 100.0% | ||
% Agreement (Efs+/vanB-) | 96.6% (57/59) | 88.5% | 99.1% | ||
% Agreement (Efs-) | 99.9% (851/852) | 99.3% | 99.9% |
29
Detection of vanA with E. faecium: Prospective | |||||
---|---|---|---|---|---|
FDA-Cleared Comparator Assay | |||||
Enterococcus faecium/vanA | Efm+/vanA+ | Efm+/vanA- | Efm- | TOTAL | |
iCubate | |||||
iC-GPC™ | Efm+/vanA+ | 19 | 2 | 2 | 23 |
Efm+/vanA- | 0 | 7 | 0 | 7 | |
Efm- | 1 | 0 | 882 | 883 | |
TOTAL | 20 | 9 | 884 | 913 | |
Enterococcus faecium/vanA | 95% C.I. | ||||
% Agreement (Efm+/vanA+) | 95.0% (19/20) | 76.4% | 99.1% | ||
% Agreement (Efm+/vanA-) | 77.8% (7/9) | 45.3% | 93.7% | ||
% Agreement (Efm-) | 99.8% (882/884) | 99.2% | 99.9% |
Detection of vanB with E. faecium: Prospective | |||||
---|---|---|---|---|---|
FDA-Cleared Comparator Assay | |||||
Enterococcus faecium/vanB | Efm+/vanB+ | Efm+/vanB- | Efm- | TOTAL | |
iCubate | |||||
iC-GPC™ | Efm+/vanB+ | 0 | 0 | 1 | 1 |
Efm+/vanB- | 0 | 28 | 1 | 29 | |
Efm- | 0 | 1 | 882 | 883 | |
TOTAL | 0 | 29 | 884 | 913 | |
Enterococcus faecium/vanB | 95% C.I. | ||||
% Agreement (Efm+/vanB+) | - | - | - | ||
% Agreement (Efm+/vanB-) | 96.6% (28/29) | 82.8% | 99.4% | ||
% Agreement (Efm-) | 99.8% (882/884) | 99.2% | 99.9% |
The following tables provide the performance of contrived samples for vanA/vanB detection with E. faecalis and E. faecium.
Detection of vanA with E. faecalis: Contrived | |||||
---|---|---|---|---|---|
vanA/E. faecalis | Expected Result | ||||
POS | NEG | TOTAL | |||
iCubate | |||||
iC-GPC™ | POS | 16 | 0 | 16 | |
NEG | 0 | 152 | 152 | ||
TOTAL | 16 | 152 | 168 | ||
vanA/E. faecalis | 95% C.I. | ||||
Positive % Agreement | 100.0% | 80.6% | 100.0% | ||
Negative % Agreement | 100.0% | 97.5% | 100.0% | ||
Detection of vanA with E. faecium: Contrived | |||||
vanA/E. faecium | Expected Result | ||||
POS | NEG | TOTAL | |||
iCubate | |||||
iC-GPC™ | POS | 24 | 0 | 24 | |
NEG | 0 | 144 | 144 | ||
TOTAL | 24 | 144 | 168 | ||
vanA/E. faecium | 95% C.I. | ||||
Positive % Agreement | 100.0% | 86.2% | 100.0% | ||
Negative % Agreement | 100.0% | 97.4% | 100.0% |
30
Detection of vanB with E. faecalis: Contrived | ||||
---|---|---|---|---|
vanB/E. faecalis | Expected Result | |||
POS | NEG | TOTAL | ||
iCubate | ||||
iC-GPC™ | POS | 56 | 0 | 56 |
NEG | 0 | 112 | 112 | |
TOTAL | 56 | 112 | 168 | |
vanB/E. faecalis | 95% C.I. | |||
Positive % Agreement | 100.0% | 93.6% | 100.0% | |
Negative % Agreement | 100.0% | 96.7% | 100.0% | |
Detection of vanB with E. faecium : Contrived | ||||
vanB/E. faecium | Expected Result | |||
POS | NEG | TOTAL | ||
iCubate | ||||
iC-GPC™ | POS | 0 | 0 | 0 |
NEG | 0 | 168 | 168 | |
TOTAL | 0 | 168 | 168 | |
vanB/E. faecium | 95% C.I. | |||
Positive % Agreement | - | - | - | |
Negative % Agreement | 100.0% | 97.8% | 100.0% |
Performance vs. Traditional Culture and Susceptibility:
Performance of the iC-GPC Assay was compared to traditional laboratory reference methods: culture followed by testing blood culture isolates with conventional biochemicals/MALDI-TOF and AST testing (cefoxitin disc for mecA and vancomycin Etest for vanA/vanB).
Performance of the iC-GPC Assay in comparison to traditional laboratory reference methods is provided in the tables below. Performance is stratified by prospectively tested fresh specimens and prospectively collected, retrospectively tested frozen specimens.
iC-GPC Assay Performance: Staphylococcus aureus (nuc) | iC-GPC Assay Performance: Staphylococcus epidermidis (gseA) | ||||||||
---|---|---|---|---|---|---|---|---|---|
Specimen Type | N= | Percent Agreement Positive (95% CI) | Percent Agreement Negative (95% CI) | Reference Method | Specimen Type | N= | Percent Agreement Positive (95% CI) | Percent Agreement Negative (95% CI) | Reference Method |
Fresh | 849 | 95.8% | |||||||
250/261 | |||||||||
(92.6-97.6) | 99.8% | ||||||||
587/588 | |||||||||
(99.0-100) | Culture & Biochemicals | Fresh | 849 | 95.9% | |||||
213/222 | |||||||||
(92.5-97.9) | 96.5% | ||||||||
605/627 | |||||||||
(94.7-97.7) | Culture & Biochemicals | ||||||||
Frozen | 32 | 100% | |||||||
9/9 | |||||||||
(70.1-100) | 100% | ||||||||
23/23 | |||||||||
(85.7-100) | Frozen | 32 | 100% | ||||||
3/3 | |||||||||
(43.8-100) | 96.6% | ||||||||
28/29 | |||||||||
(82.8-99.4) | |||||||||
TOTAL | 881 | 95.9% | |||||||
259/270 | |||||||||
(92.9-97.7) | 99.8% | ||||||||
610/611 | |||||||||
(99.1-100) | TOTAL | 881 | 96.0% | ||||||
216/225 | |||||||||
(92.6-97.9) | 96.5% | ||||||||
633/656 | |||||||||
(94.8-97.7) |
31
iC-GPC Assay Performance: Streptococcus pneumoniae (lytA) | iC-GPC Assay Performance: Enterococcus faecalis (ddl) | ||||||||
---|---|---|---|---|---|---|---|---|---|
Specimen Type | N= | Percent Agreement | |||||||
Positive (95% CI) | Percent Agreement | ||||||||
Negative (95% CI) | Specimen Type | N= | Percent Agreement | ||||||
Positive (95% CI) | Percent Agreement | ||||||||
Negative (95% CI) | |||||||||
Prospective | Fresh | 856 | 100% | ||||||
18/18 | |||||||||
(82.4-100) | 99.9% | ||||||||
837/838 | |||||||||
(99.3-100) | Prospective | Fresh | 858 | 96.6% | |||||
57/59 | |||||||||
(88.5-99.1) | 99.9% | ||||||||
798/799 | |||||||||
(99.3-100) | |||||||||
Frozen | 33 | 100% | |||||||
3/3 | |||||||||
(43.8-100) | 96.7% | ||||||||
29/30 | |||||||||
(83.3-99.4) | Frozen | 33 | 100% | ||||||
3/3 | |||||||||
(43.8-100) | 100% | ||||||||
30/30 | |||||||||
(88.6-100) | |||||||||
TOTAL | 889 | 100% | |||||||
21/21 | |||||||||
(84.5-100) | 99.8% | ||||||||
866/868 | |||||||||
(99.2-99.9) | TOTAL | 891 | 96.8% | ||||||
60/62 | |||||||||
(89.0-99.1) | 99.9% | ||||||||
828/829 | |||||||||
(99.3-100) | |||||||||
Culture & Biochemicals | Culture & Biochemicals |
iC-GPC Assay Performance: Enterococcus faecium (fcm) | iC-GPC Assay Performance: mecA (methicillin resistance) | ||||||||
---|---|---|---|---|---|---|---|---|---|
Specimen | |||||||||
Type | N= | Percent Agreement | Comparator | ||||||
Method | Specimen | ||||||||
Type | N= | Percent Agreement | Comparator | ||||||
Method | |||||||||
Positive | |||||||||
(95% CI) | Negative | ||||||||
(95% CI) | Positive | ||||||||
(95% CI) | |||||||||
Fresh | 858 | 96.4% | |||||||
27/28 | |||||||||
(82.3-99.4) | 99.6% | ||||||||
827/830 | |||||||||
(98.9-99.9) | Culture & | ||||||||
Biochemicals | Fresh | 848 | 90.0% | ||||||
252/280 | |||||||||
(85.9-93.0) | 97.0% | ||||||||
551/568 | |||||||||
(95.3-98.1) | Culture, | ||||||||
Biochemicals | |||||||||
& Cefoxitin | |||||||||
Disc | |||||||||
Prospective | Frozen | 33 | 100% | ||||||
1/1 | |||||||||
(20.7-100) | 100% | ||||||||
32/32 | |||||||||
(89.3-100) | Frozen | 32 | 100% | ||||||
5/5 | |||||||||
(56.6-100) | |||||||||
TOTAL | 891 | 96.6% | |||||||
28/29 | |||||||||
(82.8-99.4) | 99.7% | ||||||||
859/862 | |||||||||
(99.0-99.9) | TOTAL | 880 | 90.2% | ||||||
257/285 | |||||||||
(86.2-93.1) |
- Of the 28 observed false negative mecA results by the iC-GPC Assay,
14/28 were positive for mecA by multiple FDA-cleared multiplex assays.
Repeat AST testing also confirmed See note below.
32
iC-GPC Assay Performance: vanA/B (vancomycin resistance) | |||||
---|---|---|---|---|---|
Specimen | |||||
Type | N= | Percent Agreement | Comparator | ||
Method | |||||
Positive | |||||
(95% CI) | |||||
Negative | |||||
(95% CI) | |||||
Prospective | Fresh | 855 | 87.5% | ||
21/24 | |||||
(69.0-95.7) | 99.8% | ||||
829/831 | |||||
(99.1-99.9) | Culture, | ||||
Biochemicals | |||||
& | |||||
Vancomycin | |||||
Etest | |||||
Frozen | 33 | 100% | |||
1/1 | |||||
(20.7-100) | 100% | ||||
32/32 | |||||
(89.3-100) | |||||
TOTAL | 888 | 88.0%* | |||
22/25 | |||||
(70.0-95.8) | 99.8% | ||||
861/863 | |||||
(99.2-99.9) |
*Of the 3 observed false negative results by the iC-GPC Assay, 1/3 was positive for vanA/vanB by the FDA-cleared multiplex assay.
The following tables provide the performance of prospective clinical samples in comparison to traditional laboratory reference methods for mecA detection with S. oureus and S. epidermidis and vanA/vanB detection with E. faecalis and E. faecium.
NOTE: Of the 21 observed false negative mecA results by the iC-GPC Assay for specimens identified to contain methicillin-resistant S. aureus by conventional identification methods and cefoxitin disc testing, 16 were also mecA negative by the FDA-cleared multiplex assay used for method comparison testing. To further investigate, isolates from 14 of the specimens identified at a single site were tested with an alternate real-time PCR assay that detects mecA and mecC. This assay confirmed the isolates to be negative for both mecA and mecC. Cefoxitin disc testing was also repeated on the 14 sample isolates. All isolates were found to be susceptible to cefoxitin with a zone size of 22mm. These tests confirm the iC-GPC result of mecA negative for 14 of the 21 discrepant results.
Detection of mecA with S. aureus : Prospective | |||||
---|---|---|---|---|---|
Culture, Biochemicals & Cefoxitin Disc Testing | |||||
Staphylococcus aureus/mecA | SA+/ mecA + | SA+/ mecA - | SA- | TOTAL | |
iCubate | |||||
iC-GPC™ | SA+/ mecA + | 113 | 1 | 0 | 114 |
SA+/ mecA - | 16 | 128 | 1 | 145 | |
SA- | 5 | 6 | 610 | 621 | |
TOTAL | 134 | 135 | 611 | 880 | |
Staphylococcus aureus/mecA | 95% C.I. | ||||
% Agreement (SA+/ mecA +) | 84.3%* (113/134) | 77.2% | 89.5% | ||
% Agreement (SA+/ mecA -) | 94.8% (128/135) | 89.7% | 97.5% | ||
% Agreement (SA-) | 99.8% (610/611) | 99.1% | 100% | ||
*Corrected based on reviewer comments |
See note above
33
Detection of mecA with S. epidermidis : Prospective | |||||
---|---|---|---|---|---|
Culture, Biochemicals & Cefoxitin Disc Testing | |||||
Staphylococcus epidermidis/mecA | SE+/ mecA + | SE+/ mecA - | SE- | TOTAL | |
iCubate | |||||
iC-GPC™ | SE+/ mecA + | 144 | 10 | 15 | 169 |
SE+/ mecA - | 2 | 60 | 8 | 70 | |
SE- | 5 | 4 | 632 | 641 | |
TOTAL | 151 | 74 | 655 | 880 | |
Staphylococcus epidermidis/mecA | 95% C.I. | ||||
% Agreement (SE+/ mecA +) | 95.4% (144/151) | 90.7% | 97.7% | ||
% Agreement (SE+/ mecA -) | 81.2% (60/74) | 70.7% | 88.4% | ||
% Agreement (SE-) | 96.5% (632/655) | 94.8% | 97.7% |
Detection of vanA/vanB with E. faecalis : Prospective | |||||
---|---|---|---|---|---|
Culture, Biochemicals & Vancomycin AST | |||||
E. faecalis/vanA/vanB | Efs+/van+ | Efs+/van- | Efs- | TOTAL | |
iCubate | |||||
iC-GPC™ | Efs+/van+ | 1 | 1 | 1 | 3 |
Efs+/van- | 2 | 53 | 0 | 55 | |
Efs- | 0 | 2 | 828 | 830 | |
TOTAL | 3 | 56 | 829 | 888 | |
E. faecalis/vanA/vanB | 95% C.I. | ||||
% Agreement (Efs+/van+) | 33.3% (1/3) | 6.2% | 79.2% | ||
% Agreement (Efs+/van-) | 94.6% (53/56) | 85.4% | 98.2% | ||
% Agreement (Efs-) | 99.9% (828/829) | 99.3% | 100% |
Detection of vanA/vanB with E. faecium: Prospective | |||||
---|---|---|---|---|---|
E. faecalis/vanA/vanB | Culture, Biochemicals & Vancomycin AST | ||||
Efm+/van+ | Efm+/van- | Efm- | TOTAL | ||
iCubate | |||||
iC-GPC™ | Efm+/van+ | 20 | 1 | 3 | 24 |
Efm+/van- | 0 | 7 | 0 | 7 | |
Efm- | 1 | 0 | 856 | 857 | |
TOTAL | 21 | 8 | 859 | 888 | |
E. faecium/vanA/vanB | 95% C.I. | ||||
% Agreement (Efm+/van+) | 95.2% (20/21) | 77.3% | 99.2% | ||
% Agreement (Efm+/van-) | 87.5% (7/8) | 52.9% | 97.8% | ||
% Agreement (Efm-) | 99.7% (856/859) | 99.0% | 99.9% |
34
Mixed Culture Results:
In total, there were seven (7) mixed culture specimens that were detected by the iC-GPC Assay, the FDAcleared multiplex assay, or both. The tables below lists the mixed target combinations detected by iC-GPC and the comparator assay in the clinical study. There was one (1) discrepant mixed sample for which iC-GPC detected a target that was not detected by the comparator assay. There was one (1) discrepant mixed sample for which the comparator assay detected targets that were not detected by iC-GPC. Due to competitive inhibition, target organisms present near LoD concentrations may not be detected by the iC-GPC Assay when a second target organism is present at higher concentrations.
| Multiple Detections by iC-GPC | | | | | | Total
Targets
Detected | Discrepant
Targets | Discrepant Results
(Targets Not Detected by
FDA-Cleared Multiplex
Assay) |
|-------------------------------|------|----------------------------|-----------------------|-----------------------|----------|------------------------------|-----------------------|-----------------------------------------------------------------------------------|
| Site | ID | Target 1 | Target 2 | Target 3 | Target 4 | | | |
| LAC | 1081 | Staphylococcus aureus | Enterococcus faecalis | | | 2 | 0 | NA |
| LAC | 1149 | Staphylococcus epidermidis | mecA | Enterococcus faecalis | | 3 | 0 | NA |
| LAC | 1150 | Enterococcus faecalis | Enterococcus faecium | vanA | | 3 | 1 | vanA |
| LAC | 1289 | Staphylococcus aureus | mecA | Enterococcus faecalis | vanB | 4 | 0 | NA |
| LAC | 1403 | Staphylococcus epidermidis | mecA | Enterococcus faecalis | | 3 | 0 | NA |
| TGH | 4029 | Staphylococcus aureus | Enterococcus faecalis | | | 2 | 0 | NA |
| Multiple Detections by FDA-Cleared Multiplex Assay | | | | | | Total Targets
Detected | Discrepant
Targets | Discrepant Results
(Targets Not Detected by
iC-GPC) |
|----------------------------------------------------|------|----------------------------|-----------------------|-----------------------|----------|---------------------------|-----------------------|-----------------------------------------------------------|
| Site | ID | Target 1 | Target 2 | Target 3 | Target 4 | | | |
| LAC | 1081 | Staphylococcus aureus | Enterococcus faecalis | | | 2 | 0 | NA |
| LAC | 1149 | Staphylococcus epidermidis | mecA | Enterococcus faecalis | | 3 | 0 | NA |
| LAC | 1150 | Enterococcus faecalis | Enterococcus faecium | | | 2 | 0 | NA |
| LAC | 1289 | Staphylococcus aureus | mecA | Enterococcus faecalis | vanB | 4 | 0 | NA |
| LAC | 1403 | Staphylococcus epidermidis | mecA | Enterococcus faecalis | | 3 | 0 | NA |
| MCW | 2134 | Staphylococcus aureus | mecA | Enterococcus faecium | vanA | 4 | 2 | Staphylococcus aureus,
mecA |
| TGH | 4029 | Staphylococcus aureus | Enterococcus faecalis | | | 2 | 0 | NA |
Of the six (6) mixed culture specimens detected by the iC-GPC Assay, there were two (2) discrepant samples for which iC-GPC detected a target that was not detected by culture, biochemicals, and AST testing.
Multiple Detections by iC-GPC | Total Targets Detected | Discrepant Targets | Discrepant Results (Targets Not Detected by Culture/AST) | |||||
---|---|---|---|---|---|---|---|---|
Site | ID | Target 1 | Target 2 | Target 3 | Target 4 | |||
LAC | 1081 | Staphylococcus aureus | Enterococcus faecalis | 2 | 0 | NA | ||
LAC | 1149 | Staphylococcus epidermidis | mecA | Enterococcus faecalis | 3 | 0 | NA | |
LAC | 1150 | Enterococcus faecalis | Enterococcus faecium | vanA | 3 | 3 | Enterococcus faecium, vanA | |
LAC | 1289 | Staphylococcus aureus | mecA | Enterococcus faecalis | vanB | 4 | 0 | vanB (E-Test Intermediate) |
LAC | 1403 | Staphylococcus epidermidis | mecA | Enterococcus faecalis | 3 | 0 | NA | |
TGH | 4029 | Staphylococcus aureus | Enterococcus faecalis | 2 | 0 | NA |
There were fifty-six (56) mixed culture specimens detected by culture and biochemicals, including organisms not detected by the iC-GPC Assay. The table below lists the mixed target combinations detected by traditional reference methods. There were twelve (12) discrepant samples for which the reference methods detected targets that were not detected by iC-GPC (false negatives). There were nine (9) discrepant samples for which iC-GPC detected targets were not detected by the reference
35
methods (false positives). Of these, two (2) were positive mecA results associated with an iC-GPC target organism where reference testing associated the mecA with a non-target organism.
Multiple Detections by Culture, Biochemicals & AST | |||||
---|---|---|---|---|---|
Target 1 | Target 2 | Target 3 | Frequency | No. w/ Discrepant Targets | Discrepant Target |
Staphylococcus aureus | Enterococcus faecalis | 3 | 1 | Staphylococcus aureus | |
Staphylococcus aureus, mecA | Enterococcus faecalis | 1 | 0 | ||
Staphylococcus aureus, mecA | Enterococcus faecalis | Streptococcus agalactiae | 1 | 1 | Staphylococcus aureus, mecA, |
Enterococcus faecalis, | |||||
Staphylococcus epidermidis* | |||||
Staphylococcus aureus, mecA | Enterococcus faecium, vanA | Candida glabrata | 1 | 1 | Staphylococcus aureus, mecA |
Stenotrophomonas rhizophila | Pseudomonas fulva | 1 | 1 | ||
Staphylococcus epidermidis, mecA | Enterococcus faecalis | 4 | 2 | Staphylococcus epidermidis (2), | |
mecA (2) | |||||
Staphylococcus epidermidis, mecA | Staphylococcus epidermidis | 1 | 0 | NA | |
Staphylococcus epidermidis, mecA | Staphylococcus hominis | 4 | 0 | NA | |
Staphylococcus epidermidis | Staphylococcus hominis | 2 | 1 | Staphylococcus epidermidis | |
Staphylococcus epidermidis | Staphylococcus hominis | Staphylococcus capitis | 1 | 1 | Staphylococcus epidermidis |
Staphylococcus epidermidis | Staphylococcus hominis, mecA | 1 | 1 | mecA* | |
Staphylococcus epidermidis, mecA | Staphylococcus haemolyticus | 1 | 0 | NA | |
Staphylococcus epidermidis | Staphylococcus haemolyticus | 1 | 0 | NA | |
Staphylococcus epidermidis, mecA | Staphylococcus haemolyticus, mecA | 1 | 0 | NA | |
Staphylococcus epidermidis | Staphylococcus haemolyticus, mecA | 1 | 1 | mecA* | |
Staphylococcus epidermidis, mecA | Staphylococcus capitus | 1 | 0 | Staphylococcus epidermidis, mecA | |
Staphylococcus epidermidis | Staphylococcus capitus | 1 | 1 | NA | |
Staphylococcus epidermidis, mecA | Staphylococcus capitus, mecA | 1 | 1 | Staphylococcus epidermidis, mecA | |
Staphylococcus epidermidis, mecA | Staphylococcus lugdunensis | 1 | 0 | NA | |
Staphylococcus epidermidis, mecA | Staphylococcus warneri, mecA | 1 | 0 | NA | |
Staphylococcus epidermidis, mecA | Staphylococcus species, mecA | 1 | 0 | NA | |
Staphylococcus epidermidis, mecA | Aerococcus viridans | 1 | 0 | NA | |
Staphylococcus epidermidis | Bacillus circulans | 1 | 0 | NA | |
Staphylococcus epidermidis | Streptococcus agalactiae | 1 | 0 | NA | |
Staphylococcus epidermidis | Streptococcus oralis | 1 | 0 | NA | |
Staphylococcus epidermidis | Low Disc: Strep. mitis/oralis | 1 | 1 | Staphylococcus epidermidis | |
Staphylococcus aureus, mecA | Streptococcus mitis | 1 | 0 | NA | |
Staphylococcus aureus, mecA | Unidentified Organism | 1 | 1 | Staphylococcus aureus, mecA | |
Enterococcus faecalis | Staphylococcus simulans | Aerococcus viridans | 1 | 1 | Enterococcus faecalis |
Enterococcus faecalis | Staphylococcus haemolyticus, mecA | 1 | 0 | NA | |
Enterococcus faecalis | Klebsiella pneumoniae | 1 | 0 | NA | |
Staphylococcus hominis, mecA | Staphylococcus hominis | 4 | 3 | Staphylococcus epidermidis (2)**, | |
Enterococcus faecalis* | |||||
Staphylococcus hominis, mecA | Staphylococcus capitis | 2 | 1 | Staphylococcus epidermidis* | |
Staphylococcus hominis | Staphylococcus lentus | 1 | 0 | NA | |
Staphylococcus hominis | Staphylococcus species | 2 | 0 | NA | |
Staphylococcus hominis | Aerococcus viridans | 1 | 0 | NA | |
Multiple Detections by Culture, Biochemicals & AST | |||||
Target 1 | Target 2 | Target 3 | Frequency | No. w/ Discrepant Targets | Discrepant Target |
Staphylococcus haemolyticus | Staphylococcus capitis | 1 | 1 | Staphylococcus epidermidis* | |
Staphylococcus capitis | Low Disc: Streptococcus mitis/oralis | 1 | 0 | NA | |
Staphylococcus capitis | Staphylococcus warneri | 1 | 1 | Staphylococcus epidermidis* | |
Staphylococcus lentus, mecA | Low Disc: Strep. mitis/oralis | 1 | 0 | NA | |
Staphylococcus cohnii ssp urealyticus, mecA | Staphylococcus cohnii ssp cohnii, mecA | 1 | 0 | NA | |
Streptococcus sanguinis | Streptococcus gordonii | 1 | 0 | NA |
36
*false positive result
Expected Values:
913 prospectively collected fresh and frozen blood culture specimens were obtained from four geographically dispersed clinical sites. The number and percentage of positive cases (positivity rate) determined by the iC-GPC Assay stratified by U.S. state for each of the organisms and resistance markers detected by the assay are presented below. Overall, the iC-GPC Assay detected at least one organism in 66.9% (611/913) prospectively collected specimens and at least one resistance marker in 33.4% (305/913) prospectively collected specimens.
U.S. State | NY | WI | NM | FL | TOTAL | |
---|---|---|---|---|---|---|
Organism | TOTAL n | 300 | 269 | 248 | 96 | 913 |
POSITIVE n | 86 | 57 | 92 | 31 | 266 | |
S. aureus | % Positivity | 28.7% | 21.2% | 37.1% | 32.3% | 29.1% |
S. epidermidis | POSITIVE n | 63 | 85 | 66 | 21 | 235 |
% Positivity | 21.0% | 31.6% | 26.6% | 21.9% | 25.7% | |
POSITIVE n | 12 | 7 | 7 | 1 | 27 | |
S. pneumoniae | % Positivity | 4.0% | 2.6% | 2.8% | 1.0% | 3.0% |
POSITIVE n | 22 | 26 | 6 | 7 | 61 | |
E. faecalis | % Positivity | 7.3% | 9.7% | 2.4% | 7.3% | 6.7% |
POSITIVE n | 5 | 22 | 1 | 1 | 29 | |
E. faecium | % Positivity | 1.7% | 8.2% | 0.4% | 1.0% | 3.2% |
Resistance Marker | TOTAL n | 300 | 269 | 248 | 96 | 913 |
POSITIVE n | 77 | 91 | 81 | 36 | 285 | |
mecA | % Positivity | 25.7% | 33.8% | 32.7% | 37.5% | 31.2% |
POSITIVE n | 4 | 15 | 1 | 0 | 20 | |
vanA | % Positivity | 1.3% | 5.6% | 0.4% | 0.0% | 2.2% |
POSITIVE n | 1 | 1 | 0 | 0 | 2 | |
vanB | % Positivity | 0.3% | 0.4% | 0.0% | 0.0% | 0.2% |
Error Rates and Sample Withdrawals:
Throughout the course of the study, an initial error rate of 7.6% (83/1098) was observed. Errors included positive controls check failures, array registration errors, and processor or other system errors. When a failed control or system error was observed, the sample was retested on the iC-GPC Assay. Upon repeat testing, the error rate was reduced to 1.6% (17/1098). Samples generating reproducible iC-GPC errors were withdrawn from the study.
37
No-Calls | |||||
---|---|---|---|---|---|
Internal Positive Control Failure | Instrument Errors | Total Non-Reportable Rate | |||
Initial | |||||
#fail/#total | |||||
Percent (95% CI) | Final | ||||
#fail/#total | |||||
Percent (95% CI) | Initial | ||||
#fail/#total | |||||
Percent (95% CI) | Final | ||||
#fail/#total | |||||
Percent (95% CI) | Initial | ||||
#fail/#total | |||||
Percent (95% CI) | Final | ||||
#fail/#total | |||||
Percent (95% CI) | |||||
5.9% | 1.5% | 1.6% | 0.1% | 7.6% | 1.5% |
65/1098 | 16/1098 | 18/1098 | 1/1098 | 83/1098 | 17/1098 |
[4.7-7.5%] | [0.9-2.4%] | [1.0-2.6%] | [0.0-0.5%] | [6.1-9.3%] | [1.0-2.5%] |
The total specimens excluded from the iC-GPC Assay Method Comparison Study (n=53) are listed by site and reason for exclusion in the following table. The most common reasons for exclusion included repeat iC-GPC error, repeat comparator assay error, or specimens demonstrating mixed Gram stain results.
Withdrawn Samples | |||||
---|---|---|---|---|---|
Reason for Withdrawal | |||||
Site | Mixed Gram | ||||
Stain | Repeat | ||||
iC-GPC Error | Repeat | ||||
Comparator | |||||
Assay Error | No | ||||
Comparator | |||||
Assay ID/ | |||||
Other | TOTAL | ||||
1 | 6 | 4 | 2 | 0 | 12 |
2 | 13 | 7 | 2 | 0 | 22 |
3 | 3 | 8 | 1 | 4 | 16 |
4 | 1 | 0 | 0 | 2 | 3 |
TOTAL | 23 | 19 | 5 | 6 | 53 |
Additional specimens were excluded when iC-GPC Assay performance was compared to conventional reference methods for the following reasons: no culture identification, indeterminate culture identification, or non-specific AST results (i.e., intermediate susceptibility).