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Mueller Hinton Agar is a standard basal medium intended for in vitro antimicrobial disk diffusion susceptibility testing of isolated colonies of common, rapidly growing bacteria by the Bauer-Kirby method as standardized by the Clinical and Laboratory Standards Institute (CLSI). This product has not been evaluated for gradient diffusion testing.

Mueller Hinton Agar is a standard basal medium intended for in vitro antimicrobial disk diffusion susceptibility testing of isolated colonies of common, rapidly growing bacteria by the Bauer-Kirby method standardized by the Clinical and Laboratory Standards Institute (CLSI). This product has not been evaluated for gradient diffusion testing.

The Bauer-Kirby procedure is based on the diffusion through an agar gel of antimicrobial substances which are impregnated on sterile paper disks. This method employs disks with a sinqle concentration of antimicrobial agent and zone sizes are correlated with minimum inhibitory concentrations. In the test procedure, a standardized suspension of the organism is swabbed over the entire surface of the agar medium. Sterile paper disks impregnated with specified amounts of antibiotic or other antimicrobial agents are then placed on the surface of the inoculated agar medium. The agar medium is incubated at 35+ 2°C for 16-18 hours. The organism will grow as a solid "lawn". The antimicrobial will diffuse outward (in a circle). If the antimicrobial agent has activity against the organism, a circular zone of growth inhibition will result. The zone of inhibition around the paper disk is measured. A determination as to whether the organism is susceptible, intermediate or resistant to the antimicrobial agent is determined by comparing the size of the zone of inhibition to the zone diameter interpretive criteria in the CLSI M100 Standard.

Here's an analysis of the provided information regarding the Mueller Hinton Agar device, structured according to your request:

Acceptance Criteria and Device Performance Study

1. Table of Acceptance Criteria and Reported Device Performance

2. Sample size used for the test set and the data provenance

• Test Set Sample Size: The sample size varies per organism-antimicrobial combination.
  • For most organism-antimicrobial combinations, a total of 72 results were generated (3 sites x 3 separate days x 2 duplicate tests x 2 lots of Mueller Hinton Agar x 2 different manufacturers of antimicrobial disks).
  • For Ceftaroline, High Level Gentamicin, and High Level Streptomycin, a total of 36 results were generated (only one manufacturer of antimicrobial disks available).
  • The total number of individual test results presented are:
    • Escherichia coli ATCC 25922: 972
    • Staphylococcus aureus ATCC 25923: 648
    • Pseudomonas aeruginosa ATCC 27853: 468
    • Enterococcus faecalis ATCC 29212: 72
    • Enterococcus faecalis ATCC 51299: 144
    • Escherichia coli ATCC 35218: 360
• Data Provenance: The study was a "multi-site reproducibility study" conducted with "CLSI recommended quality control organisms from American Type Culture Collection (ATCC)". The document implies it was a prospective study specifically designed for the 510(k) submission. The country of origin for the data is not explicitly stated, but given the submission to the FDA and reference to CLSI standards, it is highly likely to be the USA.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts

This type of study (in vitro diagnostic for microbial susceptibility) does not typically involve human experts establishing a "ground truth" for each individual test result in the same way an imaging study would. The ground truth (acceptable range) is established by:

• Antimicrobial-specific FDA drug label: These labels are based on extensive clinical trials and regulatory review, involving many experts in microbiology, pharmacology, and clinical medicine.
• CLSI Standards M100-S24 or M02-A11: These standards are developed by consensus of numerous international experts in clinical microbiology, including microbiologists, infectious disease physicians, and laboratory scientists.
• Therefore, the "ground truth" is derived from a consensus of a large, unnamed group of highly qualified experts in the field of clinical microbiology and infectious diseases, codified in widely accepted standards.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set

Not applicable. This study measures the zone of inhibition, which is a quantitative measurement compared against predefined interpretive criteria (acceptable range). There is no subjective interpretation requiring adjudication by multiple readers for individual test results.

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

Not applicable. This is an in vitro diagnostic device for antimicrobial susceptibility testing, not an AI-based diagnostic platform for human readers.

6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done

Yes, this was a standalone performance study of the Mueller Hinton Agar medium itself. The performance was evaluated based on the quantitative measurement of inhibition zones, with the interpretation of these zones determined by established CLSI standards and FDA drug labels, not by a human interpreting a visual output from an AI algorithm.

7. The type of ground truth used (expert concensus, pathology, outcomes data, etc)

The ground truth used is expert consensus and regulatory/scientific standards. Specifically, the acceptable ranges for zone of inhibition measurements are derived from:

• Antimicrobial-specific FDA drug labels.
• CLSI Standards M100-S24 (Performance Standards for Antimicrobial Susceptibility Testing) or M02-A11 (Performance Standards for Antimicrobial Disk Susceptibility Tests). These standards represent the consensus of experts in clinical microbiology.

8. The sample size for the training set

Not applicable. This is not an AI/machine learning device that requires a training set. The study evaluated the intrinsic performance of the agar medium itself.

9. How the ground truth for the training set was established

Not applicable, as there is no training set for this type of device.

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INTENDED USE: Mueller Hinton II Broth (Cation-Adjusted) with Lysed Horse Blood (MHLHB) is intended for use in broth dilution antimicrobial susceptibility testing of Streptococcus pneumoniae with 11 antimicrobial agents; i.e., cefaclor, cefotaxime, ceftriaxone, cefuroxime, chloramphenicol, ervthromvcin, imipenem, penicillin, tetracycline, trimethoprim/ sulfamethoxazole, and vancomycin, according to the protocol described in the Approved Standard M7-A3, "Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically - Third Edition", dated 12/93, published by the National Committee for Clinical Laboratory Standards (NCCLS).

INDICATIONS FOR USE; Use of BBL® Mueller Hinton II Broth (Cation-Adjusted) with Lysed Horse Blood is indicated when Streptococcus pneumoniae has been isolated in pure culture in the clinical laboratory, and a determination is desired as to whether the organism is susceptible, intermediate, or resistant to selected antimicrobial agents. In cases such as these, broth dilution antimicrobial susceptibility testing may be performed on BBL® Mueller Hinton II Broth (Cation-Adjusted) with Lysed Horse Blood, using cefaclor, cefotaxime, ceftrixone, cefuroxime, chloramphenicol, erythromycin, imipenem, penicillin, tetracycline, trimethoprim/sulfamethoxazole, and vancomycin.

Mueller Hinton II Broth (Cation-Adjusted) with Lysed Horse Blood (MHLHB) is an Antimicrobial Susceptibility Culture Medium used for broth dilution antimicrobial susceptibility testing. It is a liquid medium used in tubes (macrodilution) or microtiter trays. The test involves inoculating serial dilutions of the drug in the medium and examining for the presence of growth after incubation to determine the minimal inhibitory concentration (MIC).

The application describes the acceptance criteria and study proving the device meets said criteria for the "Mueller Hinton II Broth (Cation-Adjusted) with Lysed Horse Blood" (MHLHB) for antimicrobial susceptibility testing of Streptococcus pneumoniae.

1. Table of Acceptance Criteria and Reported Device Performance:

2. Sample Sizes and Data Provenance:

• Test Set Sample Size:
  • Quality Control Testing: 20 tests with Streptococcus pneumoniae ATCC 49619 using microtiter panels containing 11 antimicrobics, performed over 10 test days. This represents 220 individual MIC determinations (20 tests * 11 antimicrobics).
  • Reproducibility Studies: Streptococcus pneumoniae ATCC 49619 and 9 additional well-characterized S. pneumoniae strains. Performed 3 times per day for 3 days at two field sites for each of the 11 antimicrobics. The exact total number of MIC determinations for the reproducibility studies is not explicitly stated but can be calculated as: (1 quality control strain + 9 additional strains) * 11 antimicrobics * 3 tests/day * 3 days * 2 sites = 10 * 11 * 9 * 2 = 1980 individual MIC determinations.
• Data Provenance: "In-house" testing was performed for the quality control strain. Reproducibility studies were conducted at "two field sites." The data appears to be prospective, generated specifically for this validation study. The country of origin is not explicitly stated but can be inferred to be the US given the submission to the FDA and reliance on NCCLS standards.

3. Number of Experts and Qualifications:

• Not Applicable. This device is a culture medium for antimicrobial susceptibility testing, which generates quantitative Minimal Inhibitory Concentration (MIC) values. The ground truth (reference method) is based on a standardized laboratory procedure (NCCLS M7-A3) rather than expert interpretation of images or clinical data. Therefore, experts for establishing ground truth in the traditional sense (e.g., radiologists) are not used.

4. Adjudication Method:

• Not Applicable. Adjudication methods like 2+1 or 3+1 are typically used when there's subjective interpretation by multiple human experts. In this study, the "ground truth" and "reference method" are objective laboratory procedures (NCCLS M7-A3) for determining MICs. Discrepancies would be resolved through re-testing or troubleshooting the laboratory procedure, not through expert consensus.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:

• No. An MRMC study is not applicable as this is a laboratory diagnostic product (culture medium) and not an AI-assisted diagnostic tool that aids human readers in interpreting clinical data. The study focuses on the accuracy and reproducibility of the medium itself compared to a reference standard.

6. Standalone Performance Study (Algorithm Only):

• Yes, effectively. While not an algorithm in the software sense, the "device" (MHLHB medium) is tested in a standalone fashion. Its performance (MIC determination) is evaluated directly against the NCCLS reference method without human interpretive intervention beyond performing the standardized laboratory procedure. The study determines the inherent accuracy and reproducibility of the MHLHB medium in yielding MIC values.

7. Type of Ground Truth Used:

• Reference Method (Standardized Laboratory Procedure). The ground truth for both quality control and reproducibility studies is established by the "NCCLS reference method" as described in NCCLS Document M7-A3, "Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically - Third Edition," and interpretive criteria from NCCLS Supplement M100-S6. This involves performing broth dilution antimicrobial susceptibility testing according to the stipulated protocol, which yields the Minimal Inhibitory Concentration (MIC).

8. Sample Size for the Training Set:

• Not Applicable / Not explicitly stated. This document describes a validation study for a medical device (culture medium), not a machine learning model. Therefore, there isn't a "training set" in the context of AI/ML. The device's formulation and manufacturing process would have been optimized through internal development, but this document focuses on its performance validation against established standards.

9. How the Ground Truth for the Training Set was Established:

• Not Applicable. As there is no "training set" in the AI/ML sense, this question is not relevant to the described device validation.

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