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The MicroScan® MICroSTREP plus® Panel is used to determine quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of aerobic streptococci including Streptococcus pneumoniae. After inoculation, panels are incubated for 20 -24 hours at 35°C +/- 1°C in a non-CO2 incubator, and read visually. Alternatively, the panels can be incubated in and read by the MicroScan® WalkAway System, according to the Package insert.

This particular submission is for the addition of the antimicrobial agent Linezolid, at concentrations of 0.12 to 16 ug/mL, to the test panel.

The organisms which may be used for Linezolid susceptibility testing in this panel are:

Streptococcus pneumoniae including multi-drug resistant strains

Streptococcus pyogenes

Streptococcus agalactiae

Viridans group streptococci

MicroScan MICroSTREP plus panels are designed for use in determining quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of . aerobic streptococci, including Streptococcus pneumoniae.

The antimicrobial susceptibility tests are miniaturizations of the broth dilution susceptibility test that have been diluted in water and dehydrated. Various antimicrobial agents are diluted in water, buffer or minute concentrations of broth to concentrations bridging the range of clinical interest. Panels are rehydrated with 115 µl Mueller-Hinton broth supplemented with 2-5% lysed horse blood (LHB), after inoculation of the broth with a standardized suspension of the organism. After incubation in a non-CO2 incubator for 20-24 hours, the minimum inhibitory concentration (MIC) for the test organism is manually read by observing the lowest antimicrobial concentration showing inhibition of growth. Alternatively, the panel can be incubated in and read by the MicroScan® WalkAway System.

Here's an analysis of the acceptance criteria and study detailed in the provided documents, structured according to your request:

1. Table of Acceptance Criteria and Reported Device Performance

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

The document mentions "fresh and stock Efficacy isolates and stock Challenge strains" for the external evaluation. However, it does not explicitly state the specific number of isolates or strains used for either the efficacy or challenge testing.

• Data Provenance: The study was an "external evaluation," implying it was conducted outside of the manufacturer's immediate control but within a regulated framework, comparing the device to a CLSI frozen Reference panel. The document does not specify the country of origin but implies a standard reference method commonly used in the US (CLSI). It is a retrospective evaluation as it uses established isolates.

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

• The document states that "Challenge strains were compared to Expected Results determined prior to the evaluation." This implies that the "Expected Results" serve as the ground truth for the challenge strains.
• The number of experts and their specific qualifications are not mentioned in the provided text. The ground truth for the reference panel itself is implicitly a consensus from standard methodologies (CLSI).

4. Adjudication Method for the Test Set

• The document implies a direct comparison of the MicroScan MICroSTREP plus Panel's performance against a CLSI frozen Reference panel.
• For challenge strains, performance was compared to "Expected Results."
• No specific multi-reader adjudication method (e.g., 2+1, 3+1) is described for the test set. The comparison is against established reference values.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

• No, an MRMC comparative effectiveness study involving human readers is not described in these documents. The study focuses on the performance of the automated/semi-automated AST system against a reference method. The document mentions reproducibility testing with different read methods (manual and WalkAway™ instrument), but this refers to the device's consistency, not the improvement of human readers with AI assistance.

6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done

• Yes, a standalone performance study was done. The device itself (MicroScan MICroSTREP plus Panels) is assessed for its ability to determine antimicrobial susceptibility. The "manual" read method mentioned in reproducibility testing still refers to reading the panel results, not a human interpretation divorced from the device's output. The "WalkAway™ instrument" automatically reads the panel, which is a standalone function of the device system.

7. The Type of Ground Truth Used

• The primary ground truth used is a CLSI frozen Reference Panel. For challenge strains, "Expected Results" determined prior to the evaluation were used, which would also be based on established reference methods. This falls under expert consensus derived from standardized laboratory procedures.

8. The Sample Size for the Training Set

• The document does not provide information on the sample size used for the training set. The focus is on the performance evaluation of the device as submitted. This type of device (AST panel) typically relies on biochemical principles and established MIC ranges, rather than deep learning models that require distinct training sets in the same way an AI image analysis algorithm would.

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

• Given that the document does not mention a distinct "training set" in the context of machine learning, the question of how its ground truth was established is not applicable. The device's development would be based on established microbiological principles for determining MICs, where the "ground truth" is defined by standard reference methods like those outlined by CLSI.

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The MicroScan® MICroSTREP plus® Panel is used to determine quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of aerobic streptococci, including Streptococcus pneumoniae. After inoculation, panels are incubated for 20 - 24 hours at 35°C +/- 1°C in a non-CO2 incubator, and read visually. Alternatively, the panels can be incubated in and read by the MicroScan® WalkAway System, according to the Package Insert.

This particular submission is for the addition of the antimicrobial Moxifloxacin at concentrations of 0.03 to 8 ug/ml to the test panel.

The organisms which may be used for Moxifloxacin susceptibility testing in this panel are:

Streptococcus pneumoniae (including penicillin resistant strains) Streptococcus pyogenes Streptoccocus agalactiae Streptococcus constellatus Streptococcus anginosus Viridans group streptococci

MicroScan MICroSTREP plus panels are designed for use in determining quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of aerobic streptococci, including Streptococcus pneumoniae.

The antimicrobial susceptibility tests are miniaturizations of the broth dilution susceptibility test that have been diluted in water and dehydrated. Various antimicrobial agents are diluted in water, buffer or minute concentrations of broth to concentrations bridging the range of clinical interest. Panels are rehydrated with 115 µl Mueller-Hinton broth supplemented with 2-5% lysed horse blood (LHB), after inoculation of the broth with a standardized suspension of the organism. After incubation in a non-CO2 incubator for 20-24 hours, the minimum inhibitory concentration (MIC) for the test organism is manually read by observing the lowest antimicrobial concentration showing inhibition of growth. Alternatively, the panel can be incubated in and read by the MicroScan® WalkAway System.

Here's a breakdown of the acceptance criteria and study information for the MicroScan® MICroSTREP plus® Panels with Moxifloxacin, based on the provided 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

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

• Test Set Sample Size: Not explicitly stated as a single number of isolates. However, the study mentions:
  • "fresh and stock Efficacy isolates"
  • "stock Challenge strains"
  • The overall Essential Agreement of 97.3% for Moxifloxacin suggests a substantial number of isolates were tested to achieve this agreement rate across different concentrations.
• Data Provenance: Not explicitly stated (e.g., country of origin). The data is retrospective, as it compares the performance of the device to an established CLSI frozen Reference Panel.

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

• The ground truth for the test set was not established by individual experts in this context. Instead, it was established by a CLSI frozen Reference Panel. This panel itself represents a consensus standard for antimicrobial susceptibility testing, implying that its development and validation involved a panel of experts in microbiology and antimicrobial susceptibility. No specific number or qualifications of experts are given for the initial establishment of the CLSI reference method.

4. Adjudication Method for the Test Set

• No explicit adjudication method (like 2+1 or 3+1) is described. The comparison was directly between the MicroScan MICroSTREP plus Panel and the CLSI frozen Reference Panel. For challenge strains, the method was comparison to "Expected Results determined prior to the evaluation," which implies pre-defined reference values.

5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study was Done

• No, a Multi Reader Multi Case (MRMC) comparative effectiveness study was not done. This study focuses on the agreement between the device and a reference method, not on human reader performance with or without AI assistance. While the panel can be read manually or by the MicroScan® WalkAway System, the study primarily evaluates the device's accuracy against the CLSI reference.

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

• Yes, a standalone study was done. The "MicroScan® MICroSTREP plus® Panel" itself is the "algorithm/device" being tested. Its performance (Essential Agreement) was compared directly to the CLSI frozen Reference Panel, representing its standalone accuracy. While it can be read manually, the core evaluation confirms the performance of the panel itself.

7. The Type of Ground Truth Used

• The primary ground truth used was a CLSI frozen Reference Panel. For "Challenge strains," the ground truth was "Expected Results determined prior to the evaluation," which would have been established using a recognized reference method, likely aligned with CLSI standards. This is a form of expert consensus standard in microbiology.

8. The Sample Size for the Training Set

• The document does not provide information on a "training set" in the context of machine learning or AI development. This device is an antimicrobial susceptibility test panel, which operates based on biochemical reactions and defined dilutions, not a machine learning algorithm that requires a separate training set. Its "development" would involve optimizing dilutions and components to match reference methods.

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

• As there is no explicit "training set" described for a machine learning model, this question is not applicable to the information provided. The "ground truth" for the device's development would be established through established microbiological reference methods (like CLSI standards), but this is not a separate training set as understood in AI/ML contexts.

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