(262 days)
No
The device description and performance studies focus on a chromogenic culture medium and its ability to selectively grow and identify MRSA based on color change. There is no mention of AI, ML, image processing, or any computational analysis of the results. The interpretation is based on visual observation of colony color.
No
The device is a diagnostic tool used to detect MRSA colonization or infection, not to treat it. Its intended use explicitly states it is "not intended to diagnose MRSA infection nor to guide or monitor treatment of infection" but rather "to aid in the prevention and control of MRSA infections" by identifying the presence of MRSA.
Yes
Explanation: The "Intended Use / Indications for Use" section explicitly states that the device is for "qualitative detection of nasal colonization of methicillin-resistant Staphylococcus aureus (MRSA) to aid in the prevention and control of MRSA infections" and "to aid in the identification and diagnosis of MRSA from patients with skin and soft-tissue infections."
No
The device description clearly states it is a "selective and differential chromogenic medium," which is a physical substance used in laboratory testing, not a software-only product.
Yes, this device is an IVD (In Vitro Diagnostic).
Here's why:
- Intended Use: The intended use explicitly states the qualitative detection of MRSA from human specimens (nasal colonization and skin/soft tissue wound specimens) to aid in the prevention, control, identification, and diagnosis of MRSA. This is a classic definition of an in vitro diagnostic device, which is used to examine specimens taken from the human body to provide information for diagnostic purposes.
- Device Description: The description details a selective and differential chromogenic medium used to detect and identify MRSA based on its enzymatic activity. This medium is used in vitro (outside the body) with patient specimens.
- Performance Studies: The document includes performance data (sensitivity, specificity, etc.) based on testing human specimens (wound and anterior nares samples) against a reference method. This type of testing is characteristic of IVD devices undergoing regulatory review.
- Predicate Devices: The mention of predicate devices (K081212 and K100589) which are also IVDs for MRSA detection further supports that this device falls under the IVD category.
Therefore, based on the provided information, the MRSASelect™II is clearly an In Vitro Diagnostic device.
N/A
Intended Use / Indications for Use
MRSASelect™II is a selective and differential chromogenic medium for:
A) The qualitative detection of nasal colonization of methicillin-resistant Staphylococcus aureus (MRSA) to aid in the prevention and control of MRSA infections in healthcare settings. The test can be performed on anterior nares specimens from patients to screen for MRSA colonization. MRSASelect™II is not intended to diagnose MRSA infection nor to guide or monitor treatment of infection. A negative result does not preclude MRSA nasal colonization. Concomitant cultures are necessary to recover organisms for identification, antimicrobial susceptibility testing, or epidemiological typing. Results can be interpreted after 18 to 28 hours incubation.
B) The qualitative detection of methicillin-resistant Staphylococcus aureus (MRSA) from skin and soft tissue wound specimens. The MRSASelect™II is indicated for use in conjunction with other laboratory tests and clinical data available to aid in the identification and diagnosis of MRSA from patients with skin and soft-tissue infections. Concomitant cultures and antimicrobial susceptibility testing are necessary for all skin and soft-tissue wound specimens. MRSASelect™II is not intended to guide, or monitor treatment for MRSA infection, or provide results of susceptibility to methicillin. Results can be interpreted after 18 to 28 hours incubation.
Product codes
JSO
Device Description
MRSASelect™I is a selective medium for the detection and direct identification of MRSA. The selectivity of this medium is based on the presence of an antibiotic/antifungal mixture and an optimized salt concentration that inhibits the growth of yeasts and the majority of Gram negative and Gram positive bacteria, with the exception of methicillin-resistant staphylococci. Identification is based on the cleavage of a chromogenic substrate by a specific enzymatic activity of Staphylococcus aureus, leading to a strong pink coloration of the Staphylococcus aureus colonies. Plates may be read within 18-28 hours incubation:
- Methicillin-resistant Staphylococcus aureus produces pink colonies on MRSASelect™II;
- . Coagulase negative methicillin-resistant staphylococci may not grow or may grow as colorless or white colonies;
- Methicillin-susceptible staphylococci (MSS) are inhibited.
Mentions image processing
Not Found
Mentions AI, DNN, or ML
Not Found
Input Imaging Modality
Not Found
Anatomical Site
Nasal, skin and soft tissue wound
Indicated Patient Age Range
Not Found
Intended User / Care Setting
healthcare settings
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
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: The performance of MRSASelect™II was evaluated at three (3) geographically diverse locations within the United States from 2013 to 2016. A total of 3,252 prospective valid wound and anterior nares specimens were included in the final data set and analyzed for product performance. All samples yielded valid results and were included in the final analysis. Performance of MRSASelect™II was evaluated against the established reference method; for wound samples a culture enrichment broth method (Tryptic Soy Broth (TSB) with 6.5% NaCl) was used. Positive TSB cultures were subcultured on Blood Agar Plates (BAP). Identification of suspected Staphylococcus aureus colonies on BAP was confirmed using Gram stain, slide agglutination test for detection of Staphylococcus aureus, tube coagulase, and mecAmediated oxacillin resistance testing using 30 μg cefoxitin disk. Similarly, for anterior nares samples, a culture enrichment broth method was used. Positive TSB cultures were subcultured on BAP. ldentification of suspected Staphylococcus aureus colonies on BAP was confirmed followed by confirmation using Gram stain, slide agglutination test for detection of Staphylococcus aureus, tube coagulase and PBP2a testing.
Summary of Performance Studies (study type, sample size, AUC, MRMC, standalone performance, key results)
Assay precision was tested at three clinical sites and measured site-to-site reproducibility and lot-to-lot reproducibility using a blinded panel of eleven (11) organism suspensions. Ten ATCC® strains were used for the panel preparation. The panel members consisted of MRSA, MSSA and S. epidermidis. Results demonstrate that MRSASelect™II is reproducible across sites and lots.
Analytical Sensitivity (Recovery Study): The percent recovery LoD was defined as the lowest dilution at which growth is observed (> 1 CFU) on MRSASelect™II with corresponding growth observed in parallel on Blood Agar Plate. The LoD of the MRSASelect™Il was determined using ATCC® 43300™ and NRS 660, two (2) well characterized MRSA strains from culture collections. The data confirm that the minimum concentration of MRSA reliably detected by MRSASelect™II is 800 CFU/mL in nasal or wounds matrix.
Analytical Sensitivity (Inclusivity): A total of 54 characterized collection strains of MRSA (including USA300-0114, USA100, 200, 500, 600, 700, 800, and 1000) were inoculated onto MRSASelect™MI plates using saline suspensions at the concentration of 80-240 CFU/mL. Isolates tested included known clinically associated strains from the Network on Antimicrobial Resistance in Staphylococcus aureus (NARSA) and ATCC® collections.
A total of 53/54 isolates grew as pink colonies at a concentration of 80-240 CFU/mL on MRSASelect™I after 18 hours. After 24 and 28 hours incubation all 54 isolates grew as pink colonies.
Analytical Specificity (Cross Reactivity): A total of 109 strains from various species were evaluated at a minimum concentration of 10^6 CFU/mL on MRSASelect™I. Cross-reactivity was defined as growth of distinct pink colonies on MRSASelect™Il at 18, 24 and 28 hours incubation. A total of 107 out of the 109 strains were inhibited or recovered as nonpink colonies on MRSASelect™II. Two strains of MSSA produced colonies with pink coloration on MRSASelect™I. An appropriate limitation has been added to the IFU. Some MRSE (Methicillin Resistant Staphylococcus epidermidis) strains grew as white colonies within 18-28 hours on MRSASelect™. In addition, the following organisms grew as faint pink colonies when clustered together: Corynebacterium imitans, Corynebacterium jeikeium, Aerococcus viridans, Staphylococcus cohnii and Staphylococus sciuri. An appropriate limitation has been added to the IFU.
Interference Study: A total of twenty (20) medicinal substances commonly used in anterior nares and on skin and soft-tissue wound specimens were evaluated for potential interference of the chromogenic reaction of the MRSASelect™I. No interference was observed with 12/20 of them. One (1) substance (Ocean Premium Saline Nasal Spray®) reduced the quantity of growth of MRSA on MRSASelect™I and BAP without complete inhibition. Seven (7) substances (Neosynephrine®, Dristan 12h®, Ayr Saline®, Walgreens First Aid Antiseptic Spray®, Tecnu First Aid Antiseptic Pain Relieving Gel, Bactine, inhibited growth on MRSASelect™Il and BAP. Appropriate limitations have been added to the IFU.
Co-Infection/Mixed Infection: The effect of mixed cultures on the performance of MRSASelect™II was assessed by inoculating MRSA in the presence of an increasing concentration of methicillin-resistant S. epidermidis or K. pneumoniae. No impact on the growth of the MRSA was observed due to co-infection.
Validation of Transport Media: The effect of three (3) different transport media on the growth of MRSA on MRSASelect™Il was evaluated. The following transport media were used LQ STUART and LQ AMIES with or without charcoal. The use of these transport media did not decrease the recovery of MRSA on MRSASelect™M. An appropriate limitation has been added to the IFU.
Clinical Performance Characteristics: The performance of MRSASelect™II was evaluated at three (3) geographically diverse locations within the United States from 2013 to 2016. A total of 3,252 prospective valid wound and anterior nares specimens were included in the final data set and analyzed for product performance.
For Wound Samples (N=842): Sensitivity 96.7%, Specificity 95.4%, Positive Predictive Value 82.1%, Negative Predictive Value 99.2%. The overall prevalence of MRSA as determined broth culture reference method was 18% (152/842).
For Anterior Nares Samples (N=2,410): Sensitivity 91.0%, Specificity 98.3%, Positive Predictive Value 86.2%, Negative Predictive Value 98.9%. The overall prevalence of MRSA as determined by the enriched broth culture reference method was 10.6% (255/2410).
Key Metrics (Sensitivity, Specificity, PPV, NPV, etc.)
Wound Samples:
Sensitivity (%): 96.7% (95% C.I. 96.0% - 97.5%)
Specificity (%): 95.4% (95% C.I. 94.5% - 96.2%)
Positive Predictive Value: 82.1% (95% C.I. 80.5% - 83.7%)
Negative Predictive Value: 99.2% (95% C.I. 98.9% - 99.6%)
Anterior Nares Samples:
Sensitivity (%): 91.0% (95% C.I. 86.8% - 93.9%)
Specificity (%): 98.3% (95% C.I. 97.6% - 98.8%)
Pos. Predictive Value: 86.2% (95% C.I. 81.6% - 89.9%)
Neg. Predictive Value: 98.9% (95% C.I. 98.4% - 99.3%)
Predicate Device(s)
Reference Device(s)
Not Found
Predetermined Change Control Plan (PCCP) - All Relevant Information
Not Found
§ 866.1700 Culture medium for antimicrobial susceptibility tests.
(a)
Identification. A culture medium for antimicrobial susceptibility tests is a device intended for medical purposes that consists of any medium capable of supporting the growth of many of the bacterial pathogens that are subject to antimicrobial susceptibility tests. The medium should be free of components known to be antagonistic to the common agents for which susceptibility tests are performed in the treatment of disease.(b)
Classification. Class II (performance standards).
0
Image /page/0/Picture/0 description: The image contains the logos of the Department of Health & Human Services and the Food and Drug Administration (FDA). The Department of Health & Human Services logo is on the left, and the FDA logo is on the right. The FDA logo includes the text "FDA U.S. FOOD & DRUG ADMINISTRATION" in blue.
December 28, 2017
Bio-Rad % Fran White President MDC Associates, LLC 180 Cabot Street Beverly, Massachusetts 01915
Re: K171061
Trade/Device Name: MRSASelect II Regulation Number: 21 CFR 866.1700 Regulation Name: Culture medium for antimicrobial susceptibility tests Regulatory Class: Class II Product Code: JSO Dated: November 30, 2017 Received: December 1, 2017
Dear Fran 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, 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 Part 801 and Part 809); medical device 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
1
Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.
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.
For comprehensive regulatory information about mediation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/) and CDRH Learn (http://www.fda.gov/Training/CDRHLearn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (http://www.fda.gov/DICE) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).
Sincerely,
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) K171061
Device Name MRSASelect™II
Indications for Use (Describe)
MRSASelect™II is a selective and differential chromogenic medium for:
A) The qualitative detection of nasal colonization of methicillin-resistant Staphylococcus aureus (MRSA) to aid in the prevention and control of MRSA infections in healthcare settings. The test can be performed on anterior nares specimens from patients to screen for MRSA colonization. MRSASelect™II is not intended to diagnose MRSA infection nor to guide or monitor treatment of infection. A negative result does not preclude MRSA nasal colonization. Concomitant cultures are necessary to recover organisms for identification, antimicrobial susceptibility testing, or epidemiological typing. Results can be interpreted after 18 to 28 hours incubation.
B) The qualitative detection of methicillin-resistant Staphylococcus aureus (MRSA) from skin and soft tissue wound specimens. The MRSASelect™II is indicated for use in conjunction with other laboratory tests and clinical data available to aid in the identification and diagnosis of MRSA from patients with skin and soft-tissue infections. Concomitant cultures and antimicrobial susceptibility testing are necessary for all skin and soft-tissue wound specimens. MRSASelect™I is not intended to guide, or monitor treatment for MRSA infection, or provide results of susceptibility to methicillin. Results can be interpreted after 18 to 28 hours incubation.
| 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
| Date of Summary | December 12, 2017 | ||
|---|---|---|---|
| Product Name | MRSASelect™II | ||
| Sponsor | Bio-Rad Laboratories | ||
| 3 Boulevard Raymond Poincaré | |||
| 92430 Marnes-la-Coquette | |||
| France | |||
| Correspondent | MDC Associates, LLC | ||
| Fran White, Regulatory Consultant | |||
| 180 Cabot Street | |||
| Beverly, MA 01915 | |||
| Phone: (978) 927-3808 | |||
| Fax: (978) 927-1308 | |||
| Email: fran@mdcassoc.com | |||
| Device Identification | |||
| Trade or Proprietary Name: | MRSASelect™II | ||
| Common or Usual Name: | Culture Media, Antimicrobial Susceptibility Test, Excluding Mueller | ||
| Hinton Agar | |||
| Product Code: | ાડભ | ||
| Regulation Section: | 21 CFR 866.1700 | ||
| Product Classification: | Class II |
Intended Use
MRSASelect™II is a selective and differential chromogenic medium for:
A) The qualitative detection of nasal colonization of methicillin-resistant Staphylococcus aureus (MRSA) to aid in the prevention and control of MRSA infections in healthcare settings. The test can be performed on anterior nares specimens from patients to screen for MRSA colonization. MRSASelect™I is not intended to diagnose MRSA infection nor to guide or monitor treatment of infection. A negative result does not preclude MRSA nasal colonization. Concomitant cultures are necessary to recover organisms for identification, antimicrobial susceptibility testing, or epidemiological typing. Results can be interpreted after 18 to 28 hours incubation.
B) The qualitative detection of methicillin-resistant Staphylococcus aureus (MRSA) from skin and soft tissue wound specimens. The MRSASelect™II is indicated for use in conjunction with other laboratory tests and clinical data available to aid in the identification and diagnosis of MRSA from patients with skin and soft-tissue infections. Concomitant cultures and antimicrobial susceptibility testing are necessary for all skin and soft-tissue wound specimens. MRSASelect™II is not intended to guide, or monitor treatment for MRSA infection, or provide results of susceptibility to methicillin. Results can be interpreted after 18 to 28 hours incubation.
4
Device Description
MRSASelect™I is a selective medium for the detection and direct identification of MRSA. The selectivity of this medium is based on the presence of an antibiotic/antifungal mixture and an optimized salt concentration that inhibits the growth of yeasts and the majority of Gram negative and Gram positive bacteria, with the exception of methicillin-resistant staphylococci. Identification is based on the cleavage of a chromogenic substrate by a specific enzymatic activity of Staphylococcus aureus, leading to a strong pink coloration of the Staphylococcus aureus colonies. Plates may be read within 18-28 hours incubation:
- Methicillin-resistant Staphylococcus aureus produces pink colonies on MRSASelect™II;
- . Coagulase negative methicillin-resistant staphylococci may not grow or may grow as colorless or white colonies;
- Methicillin-susceptible staphylococci (MSS) are inhibited.
Substantial Equivalency
The MRSASelect™I is substantially equivalent to the Bio-Rad MRSASelect™ Extended Incubation (K081212) and MRSASelect™ Wound Specimen (K100589) products. Table 1 on the following page compares the characteristics of the Bio-Rad MRSASelect™I (New Device) and the Bio-Rad MRSASelect™ Extended Incubation (K081212) and MRSASelect™ (K100589) products (Predicate Devices). The differences noted do not impact the intended use and do not raise questions as the safety and effectiveness of the test (new) device.
| SIMILARITIES | |||
|---|---|---|---|
| Product | |||
| Attribute | Primary Predicate Device | ||
| Bio-Rad MRSASelect™ | |||
| Extended Incubation | |||
| (K081212) | Predicate Device | ||
| Bio-Rad MRSASelect™ | |||
| Wound Specimen | |||
| (K100589) | New Device | ||
| Bio-Rad MRSASelect™II | |||
| Combined Nasal and Wound Culture Media | |||
| Specimens | |||
| Regulation | 21 CFR 866.1700 | 21 CFR 866.1700 | 21 CFR 866.1700 |
| Product Code | JSO | JSO | JSO |
| Device Class | Class II | Class II | Class II |
| Intended Use | MRSASelect™ is a selective | ||
| and differential chromogenic | |||
| medium for the qualitative | |||
| detection of nasal | |||
| colonization of methicillin- | |||
| resistant Staphylococcus | |||
| aureus (MRSA) to aid in the | |||
| prevention and control of | |||
| MRSA infections in healthcare | |||
| settings. The test can be | |||
| performed on anterior nares | |||
| specimens from patients and | |||
| healthcare workers to screen | |||
| for MRSA colonization | |||
| MRSASelect™ is not intended | |||
| to diagnose MRSA infection | |||
| nor to guide or monitor | |||
| treatment of infection. | |||
| Results can be interpreted | MRSASelect™ is a selective | ||
| and differential chromogenic | |||
| medium for the qualitative | |||
| detection of methicillin- | |||
| resistant S. aureus (MRSA) | |||
| from skin and soft-tissue | |||
| wound specimens. The | |||
| MRSASelect™ is indicated for | |||
| use in conjunction with other | |||
| laboratory tests and clinical | |||
| data available to aid in the | |||
| identification and diagnosis | |||
| of MRSA from patients with | |||
| skin and soft-tissue | |||
| infections. Concomitant | |||
| cultures and susceptibility | |||
| testing are necessary for all | |||
| skin and soft-tissue wound | |||
| specimens. MRSASelect™ is | MRSASelect™II is a selective and differential | ||
| chromogenic medium for: | |||
| A) The qualitative detection of nasal | |||
| colonization of methicillin-resistant | |||
| Staphylococcus aureus (MRSA) to aid in the | |||
| prevention and control of MRSA infections in | |||
| healthcare settings. The test can be performed | |||
| on anterior nares specimens from patients to | |||
| screen for MRSA colonization. MRSASelect™II is | |||
| not intended to diagnose MRSA infection nor to | |||
| guide or monitor treatment of infection. A | |||
| negative result does not preclude MRSA nasal | |||
| colonization. Concomitant cultures are | |||
| necessary to recover organisms for | |||
| identification, antimicrobial susceptibility | |||
| testing, or epidemiological typing. Results can | |||
| be interpreted after 18 to 28 hours incubation. | |||
| B) The qualitative detection of methicillin- |
Table 1: Comparison of New Device with Predicate Devices
5
| SIMILARITIES | |||
|---|---|---|---|
| Product | |||
| Attribute | Primary Predicate Device | ||
| Bio-Rad MRSASelect™ | |||
| Extended Incubation | |||
| (K081212) | Predicate Device | ||
| Bio-Rad MRSASelect™ | |||
| Wound Specimen | |||
| (K100589) | New Device | ||
| Bio-Rad MRSASelect™II | |||
| Combined Nasal and Wound Culture Media | |||
| Specimens | |||
| after 18–28 hours incubation. | not intended nor to guide, or | ||
| monitor treatment for MRSA | |||
| infection, or provides results | |||
| of susceptibility to | |||
| methicillin. Results can be | |||
| interpreted after 18 to 28 | |||
| hours incubation. | resistant Staphylococcus aureus (MRSA) from | ||
| skin and soft tissue wound specimens. The | |||
| MRSASelect™II is indicated for use in | |||
| conjunction with other laboratory tests and | |||
| clinical data available to aid in the identification | |||
| and diagnosis of MRSA from patients with skin | |||
| and soft-tissue infections. Concomitant cultures | |||
| and antimicrobial susceptibility testing are | |||
| necessary for all skin and soft-tissue wound | |||
| specimens. MRSASelect™II is not intended to | |||
| guide, or monitor treatment for MRSA infection, | |||
| or provide results of susceptibility to methicillin. | |||
| Results can be interpreted after 18 to 28 hours | |||
| incubation. | |||
| Product | |||
| Format | Chromogenic agar | Chromogenic agar | Chromogenic agar |
| Read Time | 18–28 hours incubation | 18–28 hours incubation | 18–28 hours incubation |
| DIFFERENCES | |||
| Product | |||
| Attribute | Primary Predicate Device | ||
| Bio-Rad MRSASelect™ | |||
| Extended Incubation | |||
| (K081212) | Predicate Device | ||
| Bio-Rad MRSASelect™ | |||
| Wound Specimen | |||
| (K100589) | New Device | ||
| Bio-Rad MRSASelect™II | |||
| Combined Nasal and Wound Culture Media | |||
| Specimens | |||
| Specimen | |||
| Type | Anterior nares | Skin and soft-tissue wound | Anterior nares and skin and soft-tissue wound |
| Inoculum | Direct and Indirect (saline) | Direct | Direct |
Performance Characteristics: Analytical Performance
Precision/Reproducibility
Assay precision was tested at three clinical sites and measured site-to-site reproducibility and lot-to-lot reproducibility using a blinded panel of eleven (11) organism suspensions. Ten ATCC® strains were used for the panel preparation. The panel members consisted of MRSA, MSSA and S. epidermidis. Results demonstrate that MRSASelect™II is reproducible across sites and lots.
Analytical Sensitivity (Recovery Study)
The percent recovery LoD was defined as the lowest dilution at which growth is observed (> 1 CFU) on MRSASelect™II with corresponding growth observed in parallel on Blood Agar Plate. The LoD of the MRSASelect™Il was determined using ATCC® 43300™ and NRS 660, two (2) well characterized MRSA strains from culture collections. The data confirm that the minimum concentration of MRSA reliably detected by MRSASelect™II is 800 CFU/mL in nasal or wounds matrix.
Analytical Sensitivity (Inclusivity)
A total of 54 characterized collection strains of MRSA (including USA300-0114, USA100, 200, 500, 600, 700, 800, and 1000) were inoculated onto MRSASelect™MI plates using saline suspensions at the
6
concentration of 80-240 CFU/mL. Isolates tested included known clinically associated strains from the Network on Antimicrobial Resistance in Staphylococcus aureus (NARSA) and ATCC® collections.
Table 2: Analytical Sensitivity
| MRSASelect™ II | |||
|---|---|---|---|
| Reading times | 18 hours | 24 hours | 28 hours |
| Sensitivity | 53/54 | ||
| (98.1%) | 54/54 | ||
| (100%) | 54/54 | ||
| (100%) |
A total of 53/54 isolates grew as pink colonies at a concentration of 80-240 CFU/mL on MRSASelect™I after 18 hours. After 24 and 28 hours incubation all 54 isolates grew as pink colonies.
Analytical Specificity (Cross Reactivity)
A total of 109 strains from various species were evaluated at a minimum concentration of 10° CFU/mL on MRSASelect™I. Cross-reactivity was defined as growth of distinct pink colonies on MRSASelect™Il at 18, 24 and 28 hours incubation. A total of 107 out of the 109 strains were inhibited or recovered as nonpink colonies on MRSASelect™II. Two strains of MSSA produced colonies with pink coloration on MRSASelect™I. An appropriate limitation has been added to the IFU. Some MRSE (Methicillin Resistant Staphylococcus epidermidis) strains grew as white colonies within 18-28 hours on MRSASelect™. In addition, the following organisms grew as faint pink colonies when clustered together: Corynebacterium imitans, Corynebacterium jeikeium, Aerococcus viridans, Staphylococcus cohnii and Staphylococus sciuri. An appropriate limitation has been added to the IFU.
Interference Study
A total of twenty (20) medicinal substances commonly used in anterior nares and on skin and soft-tissue wound specimens were evaluated for potential interference of the chromogenic reaction of the MRSASelect™I. No interference was observed with 12/20 of them. One (1) substance (Ocean Premium Saline Nasal Spray®) reduced the quantity of growth of MRSA on MRSASelect™I and BAP without complete inhibition. Seven (7) substances (Neosynephrine®, Dristan 12h®, Ayr Saline®, Walgreens First Aid Antiseptic Spray®, Tecnu First Aid Antiseptic Pain Relieving Gel, Bactine, inhibited growth on MRSASelect™Il and BAP. Appropriate limitations have been added to the IFU.
Co-Infection/Mixed Infection
The effect of mixed cultures on the performance of MRSASelect™II was assessed by inoculating MRSA in the presence of an increasing concentration of methicillin-resistant S. epidermidis or K. pneumoniae. No impact on the growth of the MRSA was observed due to co-infection.
Validation of Transport Media
The effect of three (3) different transport media on the growth of MRSA on MRSASelect™Il was evaluated. The following transport media were used LQ STUART and LQ AMIES with or without charcoal. The use of these transport media did not decrease the recovery of MRSA on MRSASelect™M. An appropriate limitation has been added to the IFU.
Clinical Performance Characteristics
The performance of MRSASelect™II was evaluated at three (3) geographically diverse locations within the United States from 2013 to 2016. A total of 3,252 prospective valid wound and anterior nares specimens were included in the final data set and analyzed for product performance. All samples yielded
7
valid results and were included in the final analysis. Performance of MRSASelect™II was evaluated against the established reference method; for wound samples a culture enrichment broth method (Tryptic Soy Broth (TSB) with 6.5% NaCl) was used. Positive TSB cultures were subcultured on Blood Agar Plates (BAP). Identification of suspected Staphylococcus aureus colonies on BAP was confirmed using Gram stain, slide agglutination test for detection of Staphylococcus aureus, tube coagulase, and mecAmediated oxacillin resistance testing using 30 µg cefoxitin disk. Similarly, for anterior nares samples, a culture enrichment broth method was used. Positive TSB cultures were subcultured on BAP. ldentification of suspected Staphylococcus aureus colonies on BAP was confirmed followed by confirmation using Gram stain, slide agglutination test for detection of Staphylococcus aureus, tube coagulase and PBP2a testing. Performance results are shown in the Table 3 and Table 4 below:
Results
Table 3: Wound Samples
| All Sites | | | Culture Enrichment Broth
(Cefoxitin) | | |
|--------------------------------------------|-------|-------|------------------------------------------------|-------|--|
| | | POS | NEG | TOTAL | |
| MRSASelectTMII
(Primary Culture) | POS | 147 | 32a | 179 | |
| | NEG | 5b | 658 | 663 | |
| | TOTAL | 152 | 690 | 842 | |
| All Sites | | | 95% C.I. | | |
| Sensitivity (%) | | 96.7% | 96.0% | 97.5% | |
| Specificity (%) | | 95.4% | 94.5% | 96.2% | |
| Positive Predictive Value | | 82.1% | 80.5% | 83.7% | |
| Negative Predictive Value | | 99.2% | 98.9% | 99.6% | |
ª Discordant analysis was performed for 27 of the 32 specimens identified as MRSA positive by MRSA was confirmed in 17 of the 27 specimens using PBP2a test.
0 Discordant analysis was performed for 5 of the 5 specimens identified as MRSA negative by MRSA was confirmed in 3 of the 5 specimens using PBP2a test.
် The overall prevalence of MRSA as determined broth culture reference method was 18% (152/842).
| Table 4: Anterior Nares Samples | ||||
|---|---|---|---|---|
| -- | -- | --------------------------------- | -- | -- |
| | All Sites | Culture Enrichment Broth
(PBP2a)(c) | | | |
|--|------------------------------------|----------------------------------------|----------|-------|-------|
| | | POS | NEG | TOTAL | |
| | MRSASelect™II
(Primary Culture) | POS | 232 | 37(e) | 269 |
| | | NEG | 23(d) | 2,118 | 2,141 |
| | | TOTAL | 255 | 2,155 | 2,410 |
| | All Sites | | 95% C.I. | | |
| | Sensitivity (%) | 91.0% | 86.8% | 93.9% | |
| | Specificity (%) | 98.3% | 97.6% | 98.8% | |
| | Pos. Predictive Value | 86.2% | 81.6% | 89.9% | |
| | Neg. Predictive Value | 98.9% | 98.4% | 99.3% | |
c) PBP2a test performed from colonies on BAP after the enrichment step in TSB (PBP2a).
No further discordant resolution was conducted on those discrepant samples.
d) All 23 specimens resulted in no growth on MRSASe/ect™II.
e) Of the 37 false positives observed, a total of 25 isolates were determined to be non-S. aureus species (including 11 strains of coagulase-negative Staphylococcus); and 12 isolates were identified as methicillin-susceptible S. aureus.
-The overall prevalence of MRSA as determined by the enriched broth culture reference method was 10.6% (255/2410).
8
Conclusions
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.