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.

Device Description

The Bio-Rad MRSASelect is a selective and differential chromogenic culture medium for the qualitative detection of MRSA from anterior nares specimens. The selectivity of this medium is based on the presence of an antibiotic/antifungal mixture and an optimized salt concentration and that inhibits the growth of yeast 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.

AI/ML Overview

Here's an analysis of the Bio-Rad MRSASelect Culture Media device, based on the provided 510(k) submission information:

1. Table of Acceptance Criteria and Reported Device Performance

The submission does not explicitly state pre-defined acceptance criteria for the performance metrics (sensitivity, specificity, PPV, NPV). However, the device performance is compared against two different "ground truth" methods: Routine Culture and CHROMagar. We can infer that the reported performance metrics were deemed acceptable by the FDA for substantial equivalence.

Metric	Acceptance Criteria (Inferred)	Reported Performance (vs. Routine Culture)	Reported Performance (vs. CHROMagar)
Sensitivity	Not explicitly stated	96%	94%
Specificity	Not explicitly stated	98%	99%
PPV (Positive Predictive Value)	Not explicitly stated	87%	92%
NPV (Negative Predictive Value)	Not explicitly stated	99%	99%
Agreement	Not explicitly stated	98% (agreement to routine culture)	99% (agreement to CHROMagar)

2. Sample Size Used for the Test Set and Data Provenance

Sample Size: A total of 3013 anterior nares samples were evaluated.
Data Provenance:
- Country of Origin: Not explicitly stated, but the study was conducted at "three geographically diverse hospitals." This suggests the data is likely from the country where these hospitals are located, which could be France (where Bio-Rad is headquartered) or potentially the US given the submission to the FDA.
- Retrospective or Prospective: Prospective. The study mentions "fresh surveillance specimens of the anterior nares samples," indicating real-time collection for the study.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

The submission does not specify the number of experts or their qualifications involved in establishing the ground truth. It refers to "Routine Culture which was defined as isolation on Staphylococci on Trypticase Soy Agar with 5% blood, with identification confirmed by Coagulase and Oxacillin susceptibility." While these are standard laboratory procedures, the expertise for their interpretation is implied to be within usual clinical laboratory practice, but no specific expert qualifications are provided.

4. Adjudication Method for the Test Set

The submission does not describe an adjudication method for the test set. The results are presented as direct comparisons between the MRSASelect medium and the reference methods (Routine Culture and CHROMagar). This typically implies a direct comparison of results without a separate ad-hoc adjudication process for discordant results, though standard lab protocols for resolving discrepancies or verifying results would be assumed.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, If So, What Was the Effect Size of How Much Human Readers Improve with AI vs Without AI Assistance

This document describes a diagnostic culture medium, not an AI-powered device. Therefore, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study focusing on human reader improvement with/without AI assistance is not applicable and was not performed.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

Again, this is a culture medium, not an algorithm. The "standalone" performance described here is the performance of the culture medium itself, interpreted by laboratory personnel, in detecting MRSA. There is no AI algorithm involved.

7. The Type of Ground Truth Used

Two types of ground truth were used:

Routine Culture: Defined as "isolation on Staphylococci on Trypticase Soy Agar with 5% blood, with identification confirmed by Coagulase and Oxacillin susceptibility." This is a gold standard for bacterial identification and susceptibility testing in microbiology.
BD BBL™ CHROMagar™ MRSA: This is a predicate device, which itself functions as a selective and differential chromogenic medium for MRSA detection. While a predicate, it is used here as a comparative reference, implying its results are also considered a reliable truth for comparison.

8. The Sample Size for the Training Set

The submission does not explicitly mention a "training set" as this is a traditional diagnostic assay (culture medium) and not a machine learning model. Therefore, the concept of a separate training set for algorithm development is not applicable here. The entire 3013 samples represent the validation/test set for the device's performance.

9. How the Ground Truth for the Training Set Was Established

As no training set (in the machine learning sense) was used, this question is not applicable. The existing knowledge and established methods of microbiology (e.g., specific enzyme activities, antibiotic resistance, chromogenic reactions) form the basis for how the culture medium is designed to detect MRSA.

Summary

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Bio-Rad MRSASelect Culture Media 510(k) Submission -- K070361 Request for Additional Information

SEP 1 3 2007

510(k) SUMMARY

Date of Summary	September 4, 2007
Product Name	Bio-Rad MRSASelectA selective medium for the detection and direct identificationof methicillin-resistant Staphylococcus aureus.
Sponsor	Bio-Rad3 Boulevard Raymond Poincaré92430 Marnes-la-CoquetteFrance
Correspondent	MDC Associates, LLCFran White, Regulatory Consultant163 Cabot StreetBeverly, MA 01915

Substantially Equivalent Device

MRSASelect is substantially equivalent to BBL CHROMagar MRSA (510(k) number: K042812)

Product Attribute	Bio-Rad MRSASelect™	BBL CHROMagar MRSA	SubstantiallyEquivalent?
Intended use	MRSASelect is a selectiveand differentialchromogenic medium forthe qualitative detection ofnasal colonization ofmethicillin-resistantStaphylococcus aureus(MRSA) to aid in theprevention and control ofMRSA infections inhealthcare settings.	CHROMagar is a selectiveand differentialchromogenic medium forthe qualitative detection ofnasal or colonization ofmethicillin-resistantStaphylococcus aureus(MRSA) to aid in theprevention and control ofMRSA infections inhealthcare settings.	√
Sample	Nasal swabs	Nasal swabs	√
Testmethodology	Selective Media	Selective Media	√

Manufacturer: Becton Dickinson & Company Product: BBL CHROMagar MRSA

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Bio-Rad MRSASelect Culture Media 510(k) Submission - K070361 Request for Additional Information

PRODUCT DESCRIPTION:

Methicillin-resistant Staphylococcus aureus is a major cause of nosocomial and life threatening infections which have been associated with significantly higher rates of mortality and morbidity. The Bio-Rad MRSASelect is a selective and differential chromogenic culture medium for the qualitative detection of MRSA from anterior nares specimens.

INTENDED USE:

SUMMARY OF TECHNOLOGY:

MRSASelect 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 and that inhibits the growth of yeast 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.

At 24 hours incubation time methicillin-resistant Staphylococcus aureus produce small pink colonies on MRSASelect. Coagulase negative methicillin-resistant staphylococci that do not metabolize the chromogenic substrate appear as colorless or white colonies (possibly light pink). Methicillin sensitive staphylococci (MSS) are inhibited.

PERFORMANCE DATA:

Performance of MRSASelect was evaluated at three geographically diverse hospitals with fresh surveillance specimens of the anterior nares samples. A total of 3013 nares samples were evaluated. MRSASelect was compared to routine culture which was defined as isolation on Staphylococci on Trypticase Soy Agar with 5% blood, with identification confirmed by Coagulase and Oxacillin susceptibility and BD BBL™ CHROMagar™ MRSA. Culture results and MRSASelect results were reported at 24 hours, BD ChromAgar was read at 48 hours in accordance with manufacturers instructions. Product performance is summarized below:

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Comparison with Routine Culture

			Routine Culture
			pos	neg	total
MRSA Select24 hours	pos	227	33	260		sen	96%
	neg	10	1502	1512		spec	98%
			237	1535	1772		ppv	87%
							npv	99%

Comparison with CHROMagar

			CHROMagar
			pos	neg	total
MRSA Select24 hours	pos	297	24	321	sen	94%
	neg	18	2674	2692	spec	99%
		315	2698	3013	ppv	92%
					npv	99%

Interference Study

Commonly used medicinal substances and commonly used transport devices were evaluated for potential interference of the chromogenic reaction of the MRSASelect medium. No interference was noted. Commonly used nasal sprays at concentrations may inhibit growth that is unrelated to medium performance.

STATEMENT OF SAFETY AND EFFICACY:

MRSASelect was tested and compared to routine culture, identification and susceptibility methods, and BD CHROMagar. MRSASelect, when testing 3013 surveillance samples, demonstrated, at 24 incubation, 98% agreement to routine culture, identification and susceptibility and 99% as compared to CHROMagar.

Bio-Rad confirms that any/all data provided in this submission may be released upon request.

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DEPARTMENT OF HEALTH & HUMAN SERVICES

Image /page/3/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo consists of a stylized eagle with three stripes representing the three branches of government. The eagle is positioned to the right of a circular text that reads "DEPARTMENT OF HEALTH & HUMAN SERVICES USA".

SEP 1 3 2007

Food and Drug Administration 2098 Gaither Road Rockville MD 20850

Public Health Service

Bio-Rad c/o Ms. Fran White Regulatory Consultant MDC Associates, LLC 163 Cabot Street Beverly, MA 01915

Re: K070361

Trade/Device Name: MRSASelect Regulation Number: 21 CFR 866.1700 Regulation Name: Culture Medium for Antimicrobial Susceptibility Test Regulatory Class: Class II Product Code: JSO Dated: September 5, 2007 Received: September 6, 2007

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, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to such additional controls. Existing major regulations affecting your device can be found in Title 21, Code of Federal Regulations (CFR), Parts 800 to 895. 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 af 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); and good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820). This letter will allow your o begin marketing your device as described in your Section 510(k) premarket notification. The

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Page 2 -

This letter will allow you to begin marketing your device as described in your Section 510(k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.

If you desire specific advice for your device on our labeling regulation (21 CFR Part 801), please contact the Office of In Vitro Diagnostic Device Evaluation and Safety at 240-276-0450. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21CFR Part 807.97). For questions regarding postmarket surveillance, please contact CDRH's Office of Surveillance and Biometric's (OSB's) Division of Postmarket Surveillance at 240-276-3474. For questions regarding the reporting of device adverse events (Medical Device Reporting (MDR)), please contact the Division of Surveillance Systems at 240-276-3464. You may obtain other general information on your responsibilities under the Act from the Division of Small Manufacturers, International and Consumer Assistance at its toll-free number (800) 638-2041 or (240) 276-3150 or at its Internet address http://www.fda.gov/cdrh/industry/support/index.html.

Sincerely vours.

Sally attaym

Sally A. Hojvat, M.Sc., Ph.D. Director Division of Microbiology Devices Office of In Vitro Diagnostic Device Evaluation and Safety Center for Devices and Radiological Health

Enclosure

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Bio-Rad MRSASelect Culture Media 510(k) Submission - K070361 Request for Additional Information

Indications for Use

510(k) Number (if known): K070361

Device Name: MRSASelect

Indications for Use:

Prescription Use X (Part 21 CFR 801 Subpart D)

AND/OR

Over-The-Counter Use (21 CFR 801 Subpart C)

(PLEASE DO NOT WRITE BELOW THIS LINE-CONTINUE ON ANOTHER PAGE OF NEEDED)

Concurrence of CDRH, Office of Device Evaluation (ODE)

Division Sign-Off

l of 1

Office of In Vitro Diagnostic Device Evaluation and Safety

510(k) K07036/

Regulation Number and Section

§ 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).