(83 days)
Not Found
No
The device is a culture medium that relies on a chemical color change reaction for detection, not computational analysis.
No
The device is described as a selective and differential medium for the detection of Group B Streptococcus, aiding in the qualitative determination of GBS colonization. It does not provide any treatment or therapy.
Yes
Explanation: The device is intended for the detection of Group B Streptococcus from anovaginal specimens and is used as an aid in the qualitative determination of GBS colonization, which directly contributes to a medical diagnosis.
No
The device is a selective and differential culture medium, which is a physical reagent used in a laboratory setting, not a software program.
Yes, this device is an IVD (In Vitro Diagnostic).
Here's why:
- Intended Use: The intended use clearly states that the device is a selective and differential medium intended for the detection of Group B Streptococcus (GBS) from anovaginal specimens collected from pregnant women. It is used as an aid in the qualitative determination of GBS colonization. This aligns with the definition of an IVD, which is a medical device intended for use in vitro for the examination of specimens derived from the human body to provide information for diagnostic purposes.
- Specimen Source: The device is used with specimens derived from the human body (anovaginal specimens).
- Diagnostic Purpose: The results obtained from the device (color change indicating presence of GBS) are used as an aid in the qualitative determination of GBS colonization, which is a diagnostic purpose.
- Device Description: The description details the components and mechanism of action of the medium, which is a typical description of an IVD reagent or culture medium.
- Performance Studies: The document includes performance studies comparing the device to a reference method (LIM Broth routine culture), providing data on sensitivity and specificity. This is a standard requirement for demonstrating the performance of an IVD.
Therefore, based on the provided information, the Strep B Carrot Broth™ One-Step fits the definition and characteristics of an In Vitro Diagnostic device.
N/A
Intended Use / Indications for Use
Strep B Carrot Broth™ One-Step is a selective and differential medium which is intended for the detection of Group B Streptococcus (GBS) from anovaginal specimen collected from pregnant women. The medium is used as an aid in the qualitative determination of GBS colonization in pregnant women. The color change reaction from white to orange is representative of a positive result for presence of GBS. The medium requires 24 hours of incubation but positive results can be interpreted as early as 16 hours. Due to the properties of Strep B Carrot Broth™ One-Step, non-hemolytic GBS cannot be detected by the medium's color change and require subculture for identification. Any presumptive negative indicated by lack of color change at the incubation period must be subcultured to a non-selective medium (e.g. Tryptic Soy Agar with 5% Sheep Blood) to confirm absence of GBS. Subculture must also be performed to recover isolates for conducting susceptibility testing as recommended for penicillin-allergic women.
Product codes (comma separated list FDA assigned to the subject device)
POZ
Device Description
Approximately 10-35% of women are asymptomatic carriers of group B streptococci (GBS) in the genital and gastrointestinal tracts. Group B Streptococi (GBS) remains a leading cause of serious illness and death in newborn populations and, therefore, the detection of Group B Streptococci in the vaginal-anorectal area is critical to the prevention of neonatal GBS disease. The Centers for Disease Control and Prevention (CDC) recommends the screening of all pregnant women for vaginal and rectal Group B Streptococci colonization between 35 and 37 weeks of gestation using an enrichment broth followed by subculture.
Strep B Carrot Broth™ One-Step is a selective and differential medium with selective components designed to enrich for Group B Streptococci. The production of a light orange, or red-orange pigment is a unique characteristic of hemolytic GBS due to reaction with substrates such as starch, peptone, serum, and folate pathway inhibitors. GBS detection with Strep B Carrot Broth™ One-Step is only possible with beta-hemolytic Group B Streptococci colonies, providing evidence of a direct genetic linkage between pigment production in this media and hemolysin production. Non-hemolytic GBS can be recovered from Strep B Carrot Broth™ One-Step upon subculture to 5% sheep blood agar plates.
Mentions image processing
Not Found
Mentions AI, DNN, or ML
Not Found
Input Imaging Modality
Not Found
Anatomical Site
Anovaginal, vaginal-anorectal area, genital and gastrointestinal tracts
Indicated Patient Age Range
Not Found
Intended User / Care Setting
Not Found
Description of the training set, sample size, data source, and annotation protocol
Not Found
Description of the test set, sample size, data source, and annotation protocol
Performance of Strep B Carrot Broth™ One-Step was evaluated at four geographically diverse hospitals with routine GBS specimen in the form of an anovaginal swab. The detection of Group B Streptococi by orange color development in Strep B Carrot Broth™ One-Step was compared to routine culture, defined as the selective enrichment of specimen in LIM Broth, followed by subculture to Blood Agar and confirmed by biochemical testing. Additionally, the recovery of Group B Streptocci by a Strep B Carrot Broth™ One-Step subsequently subcultured to Blood Agar was also compared to LIM broth routine culture. Organisms that grew on Blood Agar were confirmed to be Group B Streptococci using gram-stain, catalase test, and latex agglutination.
A total of 884 specimens were tested against routine culture, 113 specimens did not meet enrollment criteria, and were therefore excluded from the analysis. Of the remaining 771 valid samples tested, a total of 143 specimens were confirmed positive for Group B Streptococci by orange color development in Strep B Carrot Broth™ One-Step after 24 hours of incubation at 35-37ºC with concordant results obtained from the LIM reference method.
Summary of Performance Studies (study type, sample size, AUC, MRMC, standalone performance, key results)
Performance of Strep B Carrot Broth™ One-Step was evaluated at four geographically diverse hospitals with routine GBS specimen in the form of an anovaginal swab.
Sample Size: 771 valid samples (from a total of 884 specimens tested)
Key results:
Overall Sensitivity: 87.7% (95% CI: 81.8-91.9)
Overall Specificity: 98.7% (95% CI: 97.4-99.3)
When considering non-hemolytic GBS as true negatives, the overall Sensitivity and Specificity values observed when comparing the recovery of beta-hemolytic GBS by the LIM reference method to the Strep B Carrot Broth™ One-Step color reaction were 90.4% (141/156) [95% CI: 84.7-94.1] and 98.4% (605/615) [95% CI: 97.0-99.1], respectively.
When comparing the number of Group B Streptococci positive specimens recovered by the LIM reference method to the number identified by Strep B Carrot Broth™ One-Step color change in conjunction with the subculture of presumptive negatives to the Blood Agar:
Overall Sensitivity: 98.8% (95% CI: 95.6-99.7)
Overall Specificity: 98.2% (95% CI: 96.8-99.0)
RECOVERY RATE: The determined Limit of Detection (LoD) for Strep B Carrot Broth™ One-Step was 10^3 CFU/mL of the fluid from a flocked anovaginal swab specimen (30 CFU/tube when using a 30μL inoculum) for S. agalactiae ATCC 12386 and S. aqalactiae ATCC 12403.
ANALYTICAL REACTIVITY: Fifty-four ATCC reference and clinical Group B Streptococci strains representing seven of the nine known serotypes were recovered in Strep B Carrot Broth™ One-Step when inoculated at the limit of detection of 100 CFU/mL. All beta-hemolytic strains produced the expected orange color. Non-hemolytic strains showed no orange color but were successfully recovered upon subculture to Blood Agar.
ANALYTICAL SPECIFICITY: Seventy-eight non-target organisms were tested. All produced a negative color reaction in Strep B Carrot Broth™ One-Step, and 45/78 (57.7%) were recoverable when subcultured after enrichment.
MICROBIAL INTERFERENCE: Strep B Carrot Broth™ One-Step was able to produce the expected color reaction with target organisms and allowed the recovery of both GBS strains in the presence of high concentrations (1.5 x 10^6 CFU/mL) of all but one of the non-target organisms (E. faecalis ATCC 29212). S. agalactiae ATCC 12386 produced the expected color reaction when E. faecalis ATCC 29212 was 10^5 CFU/mL or lower. S. agalactiae ATCC 13813 (non-hemolytic) was recovered upon subculture when E. faecalis ATCC 29212 was 10^6 CFU/mL or lower.
INTERFERENCE: No interference was observed with any tested endogenous or exogenous substance at the highest clinically relevant concentration in the GBS-negative specimen matrix.
INCUBATION STUDY: All hemolytic organisms tested produced some kind of orange color reaction by 16 hours and a definitive orange color reaction by 20 hours. All organisms, including the non-hemolytic strain tested, were recovered upon subculture of Strep B Carrot Broth™ One-Step at 12 hours. The incubation range for Strep B Carrot Broth™ was set from 16-24 hours.
SPECIMEN STABILITY: Strep B Carrot Broth™ One-Step was able to recover 8/8 (100%) of GBS strains and produce an orange coloration from Healthlink swabs in Liquid Amies, Stuart's liquid, Amies Gel, and Stuart's Gel when stored at 2-8°C for up to 96 hours. 100% of GBS strains also produced the expected orange color reaction from the flocked swab TransPRO™ Liquid Amies stored at 2-8°C for up to 120 hours. All transport systems tested saw a decline in recovery of GBS after 24 hours of room temperature storage.
REPRODUCIBILITY: Agreement of >95% with known test results was seen for reproducibility panel. Strains in the reproducibility panel produced the expected color results with Strep B Carrot Broth™ One-Step >95% of the time at 24 hours. All non-hemolytic GBS isolates tested (100%) were recovered upon subculture to TSA with 5% Sheep's Blood.
Key Metrics (Sensitivity, Specificity, PPV, NPV, etc.)
Sensitivity, Specificity. (See Summary of Performance Studies for values.)
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.
LIM Broth, K871447
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
§ 866.2360 Selective culture medium.
(a)
Identification. A selective culture medium is a device that consists primarily of liquid or solid biological materials intended for medical purposes to cultivate and identify certain pathogenic microorganisms. The device contains one or more components that suppress the growth of certain microorganisms while either promoting or not affecting the growth of other microorganisms. The device aids in the diagnosis of disease caused by pathogenic microorganisms and also provides epidemiological information on these diseases.(b)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 866.9.
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Image /page/0/Picture/1 description: The image is a black and white logo for the U.S. Department of Health & Human Services. The logo consists of a circular border with the text "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" written around it. Inside the circle is a stylized image of three human profiles facing to the right, with a design that resembles a caduceus or a flowing ribbon.
Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002
May 22, 2017
HARDY DIAGNOSTICS CHRISTOPHER MASSEY DIRECTOR OF RESEARCH & DEVELOPMENT 1430 WEST MCCOY LANE SANTA MARIA CA 93455
Re: K170586
Trade/Device Name: Strep B Carrot Broth One-Step Regulation Number: 21 CFR 866.2360 Regulation Name: Selective culture medium Regulatory Class: II Product Code: POZ Dated: January 20, 2017 Received: February 28, 2017
Dear Mr. Massey:
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. listing 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 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.
1
If you desire specific advice for your device on our labeling regulations (21 CFR Parts 801 and 809), 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" (21 CFR 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 yours,
Ribhi Shawar -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) K170586
Device Name Strep B Carrot Broth™ One-Step
Indications for Use (Describe)
Strep B Carrot Broth™ One-Step is a selective and differential medium which is intended for the detection of Group B Streptococcus (GBS) from anovaginal specimen collected from pregnant women. The medium is used as an aid in the qualitative determination of GBS colonization in pregnant women. The color change reaction from white to orange is representative of a positive result for presence of GBS. The medium requires 24 hours of incubation but positive results can be interpreted as early as 16 hours. Due to the properties of Strep B Carrot Broth™ One-Step, non-hemolytic GBS cannot be detected by the medium's color change and require subculture for identification. Any presumptive negative indicated by lack of color change at the incubation period must be subcultured to a non-selective medium (e.g. Tryptic Soy Agar with 5% Sheep Blood) to confirm absence of GBS. Subculture must also be performed to recover isolates for conducting susceptibility testing as recommended for penicillin-allergic women.
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)
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3
510(k) Summary - K170586
I. SUBMITTER
Chris Massey Director of Research & Development Hardy Diagnostics 1430 W. McCoy Lane Santa Maria, CA 93455 Phone: 805-346-2766 x 5620 E-mail: MasseyC@hardydiagnostics.com
II. DEVICE
Name of Device: Strep B Carrot Broth™ One-Step Classification Name: Selective Culture Medium Regulatory Class: I Product Code: PQZ
III. PREDICATE DEVICE
LIM Broth, K871447
IV. DEVICE DESCRIPTION
Approximately 10-35% of women are asymptomatic carriers of group B streptococci (GBS) in the genital and gastrointestinal tracts. Group B Streptococi (GBS) remains a leading cause of serious illness and death in newborn populations and, therefore, the detection of Group B Streptococci in the vaginal-anorectal area is critical to the prevention of neonatal GBS disease. The Centers for Disease Control and Prevention (CDC) recommends the screening of all pregnant women for vaginal and rectal Group B Streptococci colonization between 35 and 37 weeks of gestation using an enrichment broth followed by subculture.
Strep B Carrot Broth™ One-Step is a selective and differential medium with selective components designed to enrich for Group B Streptococci. The production of a light orange, or red-orange pigment is a unique characteristic of hemolytic GBS due to reaction with substrates such as starch, peptone, serum, and folate pathway inhibitors. GBS detection with Strep B Carrot Broth™ One-Step is only possible with β-hemolytic Group B Streptococci colonies, providing evidence of a direct genetic linkage between pigment production in this media and hemolysin production. Non-hemolytic GBS can be recovered from Strep B Carrot Broth™ One-Step upon subculture to 5% sheep blood agar plates.
V. INDICATIONS FOR USE
Strep B Carrot Broth™ One-Step is a selective and differential medium which is intended for the detection of Group B Streptococcus (GBS) from anovaginal specimen collected from pregnant women. The medium is used as an aid in the qualitative determination of GBS colonization in pregnant women. The color change reaction from white to orange is representative of a positive result for presence of GBS. The medium requires 24 hours of incubation but positive results can be interpreted as early as 16 hours. Due to the properties of Strep B Carrot Broth™ One-Step, non-hemolytic GBS cannot be detected by the medium's color change and require subculture for identification. Any presumptive negative indicated by lack of color change at the incubation period must be subcultured to a non-selective medium (e.g. Tryptic Soy Agar with 5% Sheep Blood) to confirm absence of GBS. Subculture must also be performed to recover isolates for conducting susceptibility testing as recommended for penicillin-allergic women.
4
| Attribute | Device | Comparator | Substantially
Equivalent? |
|----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------|
| Name | Strep B Carrot Broth One-Step | LIM Broth | Yes |
| 510(k) Details | 510(k) number K170586
Product Code PQZ
21 CFR 866.2360
"Culture media, selective and differential"
Class I
Panel 83 Microbiology | 510(k) number K871447
Product Code JSD
21 CFR 866.2360
"Culture Media, Selective Broth"
Class I
Panel 83 Microbiology | Yes |
| Intended Use | Strep B Carrot BrothTM One-Step is a selective
and differential medium which is intended for
the detection of Group B Streptococcus (GBS)
from anovaginal specimen collected from
pregnant women. The medium is used as an
aid in the qualitative determination of GBS
colonization in pregnant women. The color
change reaction from white to orange is
representative of a positive result for presence
of GBS. The medium requires 24 hours of
incubation but positive results can be
interpreted as early as 16 hours. Due to the
properties of Strep B Carrot BrothTM One-Step,
non-hemolytic GBS cannot be detected by the
medium's color change and require subculture
for identification. Any presumptive negative
indicated by lack of color change at the end of
the incubation period must be subcultured to
a non-selective medium (e.g. Tryptic Soy Agar
with 5% Sheep Blood) to confirm absence of
GBS. Subculture must also be performed to
recover isolates for conducting susceptibility
testing as recommended for penicillin-allergic
women. | Remel Todd Hewitt Broth w/ CNA (Lim
Broth) is a liquid medium recommended for
use in qualitative procedures for the
isolation of Group B Streptococcus (GBS)
from clinical specimens containing mixed
bacterial flora. | Yes |
| Methodology | Enrichment Broth, Chromogenic | Enrichment Broth | Yes |
| Inoculation | Direct | Direct | Yes |
| Sample Type | Vaginal/rectal swab | Vaginal/rectal swab | Yes |
| Interpretation | Manual/visual and subculture negatives | Manual/visual and subculture | Yes |
VI. COMPARISON OF TECHNOLOGICAL CHARACTERISTICS WITH THE PREDICATE DEVICE
5
VII. PERFORMANCE DATA
Performance of Strep B Carrot Broth™ One-Step was evaluated at four geographically diverse hospitals with routine GBS specimen in the form of an anovaginal swab. The detection of Group B Streptococi by orange color development in Strep B Carrot Broth™ One-Step was compared to routine culture, defined as the selective enrichment of specimen in LIM Broth, followed by subculture to Blood Agar and confirmed by biochemical testing. Additionally, the recovery of Group B Streptocci by a Strep B Carrot Broth™ One-Step subsequently subcultured to Blood Agar was also compared to LIM broth routine culture. Organisms that grew on Blood Agar were confirmed to be Group B Streptococci using gram-stain, catalase test, and latex agglutination.
A total of 884 specimens were tested against routine culture, 113 specimens did not meet enrollment criteria, and were therefore excluded from the analysis. Of the remaining 771 valid samples tested, a total of 143 specimens were confirmed positive for Group B Streptococci by orange color development in Strep B Carrot Broth™ One-Step after 24 hours of incubation at 35-37ºC with concordant results obtained from the LIM reference method. Those results are shown in Table 1.
All discrepant isolates were frozen in CryoSavers™ with Brucella Broth and returned to Hardy Diagnostics for testing. The identity of each isolate was confirmed (β Group B Streptococci, NH Group B Streptococci, or non-Group B Streptococci). Once the identity was confirmed, positive organisms (β Group B Streptococci or NH Group B Streptococi) were tested at LoD (10 CFU/mL) in donated negative-vaginal rectal matrix for their recovery from the LIM reference method, color development in Carrot Broth™ One-Step, and recovery from the Carrot Broth™ One-Step to Blood Agar System.
| Site | TP | FP1 | FN2 | TN | Sensitivity | 95% CI | Specificity | 95% CI | ||
|---|---|---|---|---|---|---|---|---|---|---|
| CCP | 47 | 1 | 4 | 141 | 92.2 | 81.5 | 96.9 | 99.3 | 96.1 | 99.9 |
| NY | 35 | 4 | 8 | 136 | 81.4 | 67.4 | 90.3 | 97.1 | 92.9 | 98.9 |
| CC | 26 | 0 | 2 | 83 | 92.9 | 77.4 | 98.0 | 100.0 | 95.6 | 100.0 |
| MCW | 35 | 3 | 6 | 240 | 85.4 | 71.6 | 93.1 | 98.8 | 96.4 | 99.6 |
| Overall | 143 | 8 | 20 | 600 | 87.7 | 81.8 | 91.9 | 98.7 | 97.4 | 99.3 |
Table 1. LIM Broth vs. Strep B Carrot Broth™ One-Step Color reaction
' There were 8 False Positives observed. All isolates were re-tested and confirmed at Hardy Diagnostics using the discrepant analysis protocol described above. Of these, six isolates were originally negative by LIM reference method, showed a positive color reaction in Strep B Carrot Broth™ One-Step, and were confirmed to be ß-hemolytic when subcultured on Blood Agar. One was not able to be confirmed because no GBS isolate was frozen and the remaining specimen had f-hemolytic colonies present on the blood agar plates; however, Proteus swarmed the technician from isolating the ß-hemolytic colonies for identification.
" There were 20 False Negatives observed. All isolates were re-tested and confirmed at Hardy Diagnostics using the discrepant analysis protocol described above. Fourteen of the B Group B Streptococci isolates recovered from LIM, but originally gave a negative Strep B Carrot Broth™ One-Step color reaction, were confirmed as B Group B Streptococci and subsequently confirmed to have a positive Strep B Carrot Broth™ One-Step color reaction at LoD. Two isolates were identified as very weak B Group B Streptococci and did not produce the expected color reaction in Strep B Carrot Broth™ One-Step. Four isolates were confirmed as non-hemolytic Group B Streptococi with a negative color reaction in Strep B Carrot Broth™ One-Step.
3 Considering that non-hemolytic GBS cannot be detected by the medium's color change and require subculture for identification, there were 5 specimens that were found to be non-hemolytic. Considering those results as true negatives, the overall Sensitivity and Specificity values observed when comparing the recovery of β-hemolytic GBS by the LIM reference method to the Strep B Carrot Broth™ One-Step color reaction were 90.4% (141/156) 195% CI: 84.7-94.1] and 98.4% (605/615) [95% CI: 97.0-99.1], respectively.
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When comparing the number of Group B Streptococci positive specimens recovered by the LIM reference method to the number identified by Strep B Carrot Broth™ One-Step color change in conjunction with the subculture of presumptive negatives to the Blood Agar, an additional 18 specimens showed concordant positive results for a total of 161 true positive results. The LIM reference method included the identification of both ß-hemolytic and non-hemolytic GBS from samples by culture. Those results are shown in Table 2.
| Site | TP | FP1 | FN2 | TN | Sensitivity | 95% CI | Specificity | 95% CI | ||
|---|---|---|---|---|---|---|---|---|---|---|
| CCP | 50 | 0 | 1 | 142 | 98.0 | 89.7 | 99.7 | 100.0 | 97.4 | 100.0 |
| NY | 43 | 6 | 0 | 134 | 100.0 | 91.8 | 100.0 | 95.7 | 91.0 | 98.0 |
| CC | 28 | 0 | 0 | 83 | 100.0 | 87.9 | 100.0 | 100.0 | 95.6 | 100.0 |
| MCW | 40 | 5 | 1 | 238 | 97.6 | 87.4 | 99.6 | 97.9 | 95.3 | 99.1 |
| Overall | 161 | 11 | 2 | 597 | 98.8 | 95.6 | 99.7 | 98.2 | 96.8 | 99.0 |
Table 2. LIM Reference Method vs. Strep B Carrot Broth™ One-Step (color), plus Subculture of Presumptive Negatives to Blood Agar with Biochemical Testing
There were eleven False Positives observed. All isolates were re-tested and confirmed at Hardy Diagnostics using the discrepant analysis protocol described above. All isolates recovered from the Strep B Carrot Broth to Blood Agar system were confirmed to be ß Group B Streptococci.
2 There were two False Negatives observed. Both isolates were re-tested and confirmed at Hardy Diagnostics using the discrepant analysis protocol described above. Both of the B Group B Streptococci isolates recovered from LIM were confirmed as B Group B Streptococci.
RECOVERY RATE
To determine the recovery [Limit of Detection (LoD)] of Strep B Carrot Broth™ One-Step, the media was challenged with two beta-hemolytic ATCC strains of Group B Streptococci at 10-fold decreasing concentrations and evaluated for color change. The lowest concentration at which a positive reaction was seen, indicated by an orange color, was determined to be the LoD. The determined by testing Strep B Carrot Broth™ One-Step with 20 replicate dilutions of the determined LoD concentrations. Strep B Carrot Broth™ One-Step was able to recover both S. agalactiae ATCC 12386 and S. aqalactiae ATCC 12403 at a LoD of 103 CFU/mL of the fluid from a flocked anovaginal swab specimen (30 CFU/tube when using a 30μL inoculum). Variable recovery was seen at lower concentrations. Blood agar plates were used to determine the concentrations of organisms present in each dilution.
ANALYTICAL REACTIVITY
Fifty-four ATCC reference and clinical Group B Streptococci strains representing seven of the nine known serotypes were recovered in Strep B Carrot Broth™ One-Step when inoculated at the limit of detection of 100 CFU/mL. The GBS serotypes included in this study were serotypes la, Ib, II, III, IV, V, and VI. Serotypes VII and VIII are rare and were not available for testing. Four strains that were non-typable against the nine known serotypes were also included. All the beta-hemolytic strains of Group B Streptococi produced the expected orange color in Strep B Carrot Broth™ One-Step. The non-hemolytic strains showed no orange color in Strep B Carrot Broth™ One-Step but were successfully recovered upon subculture to Blood Agar.
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ANALYTICAL SPECIFICITY
Seventy-eight non-target organisms that are phylogenetically-related to Group B Streptococci or potentially encountered in an anovaginal swab were tested in Strep B Carrot Broth™ One-Step at a concentration of 10° CFU/mL. All organisms tested are listed in Table 3 below. After 24 hours of incubation, all Carrot Broth tubes were evaluated for color reaction. In order to determine if Strep B Carrot Broth™ One-Step supported the growth of non-target organisms in the absence of a color reaction, all negative tubes were subcultured to an appropriate medium for the non-target organisms tested produced a negative color reaction in Strep B Carrot Broth™ One-Step and 45/78 (57.7%) of the organisms were recoverable when subcultured after enrichment.
| Organism | ||
|---|---|---|
| Acinetobacter baumannii | Enterococcus durans | Proteus mirabilis |
| Aeromonas hydrophila | Enterococcus faecalis | Providencia alcalifaciens |
| Aspergillus brasiliensis | Enterococcus faecium | Pseudomonas aeruginosa |
| Bacillus cereus | Enterococcus flavescens | Pseudomonas fluorescens |
| Bacillus subtilis | Enterococcus hirae | Saccharomyces cerevisiae |
| Bacteroides fragilis | Enterococcus raffinosus | Salmonella enterica (typhii) |
| Bifidobacterium breve | Enterococcus saccharolyticus | Salmonella enterica arizonae |
| Campylobacter coli | Escherichia coli | Serratia marcescens |
| Campylobacter jejuni | Gardnerella vaginalis | Shigella boydii |
| Candida albicans | Geotrichum candidum | Shigella flexneri |
| Candida glabrata | Hafnia alvei | Shigella sonnei |
| Candida parapsilosis | Klebsiella oxytoca | Staphylococcus aureus |
| Candida tropicalis | Klebsiella pneumoniae | Staphylococcus epidermidis |
| Citrobacter brakkii | Lactobacillus acidophilus | Staphylococcus saprophyticus |
| Citrobacter freundii | Lactobacillus gasseri | Stenotroph. maltophilia |
| Citrobacter koseri | Lactobacillus leichmannii | Streptococcus mutans |
| Clostridium difficile | Lactococcus lactis | Streptococcus anginosus |
| Clostridium novyi | Legionella pneumophila | Streptococcus bovis |
| Clostridium perfringens | Listeria monocytogenes | Streptococcus dysgalactiae |
| Clostridium sporogenes | Micrococcus luteus | Streptococcus mitis |
| Corynebacterium jekeium | Moraxella catarrhalis | Streptococcus pneumoniae |
| Enterobacter aerogenes | Morganella morganii | Streptococcus pyogenes |
| Enterobacter cloacae | Neisseria gonorrhoeae | Streptococcus salivarius |
| Enterococcus casseliflavus | Pediococcus acidilacti | Streptococcus uberis |
| Enterococcus cecorum | Peptostreptococcus anaerobius | Vibrio parahaemolyticus |
| Enterococcus dispar | Plesiomonas shigelloides | Yersinia enterocolitica |
Table 3. List of non-target organisms tested in Analytical Specificity
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MICROBIAL INTERFERENCE
Strep B Carrot Broth™ One-Step was challenged to determine if target organisms at low concentration could be recovered in the presence of non-target organisms at a high concentration. All organisms that were recovered upon subculture from Strep B Carrot Broth™ One-Step in the Analytical Specificity study were used in this Microbial Interference study. Non-target organisms at a high concentration (1.5 x 10° CFU/mL) were mixed with each target organism at the LoD concentration and inoculated into Strep B Carrot Broth™ One-Step. If the target organism was not recovered, the concentration of the non-target organism was lowered 10-fold until the target organism was recovered.
Strep B Carrot Broth™ One-Step was able to produce the expected color reaction with target organisms and allowed the recovery of both GBS strains in the presence of high concentrations (1.5 x 10 CFU/mL) of all but one of the non-target organisms used in this study. The only organism found to affect recovery was E. faecalis ATCC 29212. S. agalactiae ATCC 12386 produced the expected color reaction when the concentration of E. faecalis ATCC 29212 was 105 CFU/mL or lower. S. agalactiae ATCC 13813, a non-hemolytic strain, was recovered upon subculture when the concentration of E. faecalis ATCC 29212 was 10° CFU/mL or lower.
9
INTERFERENCE
Commonly used or encountered endogenous and exogenous substances that may be present in anovaginal swabs were evaluated for potential interference of growth or chromogenic reaction in Strep B Carrot Broth™One-Step. The substances tested are listed in the table below. No interference was observed with any substance at the highest clinically relevant concentration in the GBS-negative specimen matrix.
| Interfering Substances | ||
|---|---|---|
| Category | Substance/Supplier | Concentration in |
| Sample Matrix1 | ||
| Anti-diarrheal | ||
| Medication | Pepto-Bismol® (Bismuth subsalicylate solution) | 1% v/v |
| Imodium A-D® (Loperamide HCI) | 2% w/v | |
| Body Oil | Neutrogena Body Oil | 2% v/v |
| Body Powder | Gold Bond Body Powder | 1% w/v |
| Contraceptive Gel | Options Gynol II® (Nonoxynol-9) | 0.59% w/v |
| Enema Solution | Physiological saline | 0.25% v/v |
| Lubricating Gel | K-Y® Jelly | 0.57% v/v |
| Oral Laxative | Milk of Magnesia | 1.78% v/v |
| Dulcolax® (Sodium picosulfate solution) | 1% w/v | |
| Polysorbate 80 | Tween®80 | 10% v/v |
| Rectal Laxative | Fleet® Glycerin Suppositories | 10% v/v |
| Topical Hemorrhoid | ||
| Ointment | Preparation-H® | 0.26% w/v |
| Vaginal Anti-Itch | ||
| Medication | Vagisil® Cream | 0.41% w/v |
| Vaginal Anti-Fungal | ||
| Medication | Monistat® (Miconazole nitrate) | |
| Lotrimin® (Clotrimazole) | 0.29% w/v | |
| 0.29% w/v | ||
| Endogenous Substances | ||
| Human Amniotic Fluid | Medfusion | 2% v/v |
| Human Feces | Central Coast Pathology | 2% v/v |
| Human Meconium | LEE Biosolutions | 2% v/v |
| Human Urine | Central Coast Pathology | 2% v/v |
| Human Whole Blood | In-house | 2% v/v |
| Mucin | Sigma, M2378 | 0.05% w/v |
Specific amounts of substance added to anovaginal specimen matrix calculated using GM=C>V=C>V> with the assumption that 1g=LmL.
INCUBATION STUDY
In order to determine a recommended incubation time range, the performance of Strep B Carrot Broth™ One-Step was evaluated using nine beta-hemolytic strains of GBS and one non-hemolytic strain of GBS at the LoD from 12 to 24 hours at 35°CThe enrichment broth was subcultured to a Tryptic Soy Agar plate with 5% sheep blood every two hours to confirm the presence of GBS. All hemolytic organisms tested produced some kind of orange color reaction by 16 hours and a definitive orange color reaction by 20 hours. All organisms, including the non-hemolytic strain tested, were recovered upon subculture of Strep B Carrot Broth™ One-Step at 12 hours. The incubation range for Strep B Carrot Broth™ was set from 16-24 hours.
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SPECIMEN STABILITY
Various types of specimen transport swabs were evaluated to determine the acceptable storage conditions required to recover GBS from Strep B Carrot Broth™ One-Step. Swabs were spiked with Group B Streptococci and a contrived matrix consisting of organisms commonly found in vaginal flora, kept at both room temperature and refrigerated conditions, and were inoculated to Carrot Broth at 0, 24, 48, 72, 96, and 120 hours. Eight different GBS strains were used in this study and were spiked into the contrived matrix near LoD. The contrived matrix containing non-target organisms consisted of E. faecalis, E. coli, C. albicans, and L. acidophilus. TransPRO™ swabs with Liquid Amies (flocked swab liquid-based transport system) and four types of Healthlink transport systems: Sponge-based Liquid Amies and Liquid Stuart's, and Gel-based: Amies Gel and Stuart's Gel were used in this study.
Strep B Carrot Broth™ One-Step was able to recover 8/8 (100%) of GBS strains and produce an orange coloration from Healthlink swabs in Liquid Amies, Stuart's liquid, Amies Gel, and Stuart's Gel when stored at 2-8°C for up to 96 hours. 100% of GBS strains also produced the expected orange color reaction from the flocked swab TransPRO™ Liquid Amies stored at 2-8°C for up to 120 hours. All transport systems tested saw a decline in recovery of GBS after 24 hours of room temperature storage.
REPRODUCIBILITY
Prior to initiating the study, a panel of 12 blinded isolates provided by Hardy Diagnostics was tested at three distinct study sites in triplicate on five work days to demonstrate reproducibility and to document proficiency in the performance of the test. Agreement of >95% with known test results was required before proceeding with the study. The testing was done with at least one operator and two readers, blinded to each other's results, per site. Strains in the reproducibility panel produced the expected color results with Strep B Carrot Broth™ One-Step >95% of the time at 24 hours. All non-hemolytic GBS isolates tested (100%) were recovered upon subculture to TSA with 5% Sheep's Blood.
CONCLUSIONS
The clinical and performance studies summarized above demonstrate the substantial equivalence of Strep B Carrot Broth™ One-Step to the predicate device.