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The MicroScan® Synergies plus® Gram-Positive MIC/Combo Panel is used to determine quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of rapidly growing aerobic and facultative anaerobic gram-positive staphylococci and enterococci. After inoculation, panels are incubated for 4.5 - 18 hours at 35℃ +/- 1℃, in a WalkAway® SI, or equivalent, and read by the MicroScan® Instrumentation. Additionally, the panels may be incubated in a non-CO2 incubator and the Antimicrobial Susceptibility Testing (AST) portions can be read visually, according to the Package Insert.

This particular submission is for the addition of the antimicrobial vancomycin, at concentrations of 0.25 to 64 ug/ml, to the test panel.

The gram-positive organisms which may be used for vancomycin susceptibility testing in this panel are:

• Enterococcus spp. (e.g., Enterococcus faecalis) .
• Staphylococcus spp. ●
• Staphylococcus aureus (including methicillin-resistant strains) .
• Staphylococcus epidermidis (including methicillin-resistant ● strains)

MicroScan® Synergies plus Gram-Positive MIC/Combo Panels, utilizing both the MicroScan® Rapid Fluorogenic Identification and Dried Overnight Antimicrobial Susceptibility Testing (AST) technologies, are designed for use in determining quantitative antimicrobial agent susceptibility of colonies grown on solid media of rapidly growing and facultative anaerobic gram-positive staphylococci and enterococci.

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 Synergies plus® Pos Broth, after inoculation with a standardized suspension of the organism. After incubation in the WalkAway® SI System, or equivalent, for 4.5 -18 hours, the minimum inhibitory concentration (MIC) for the test organism is read by determining the lowest antimicrobial concentration showing inhibition of growth.

This 510(k) summary describes a device modification for an existing antimicrobial susceptibility test (AST) system. The modification involves updating the product labeling with new Staphylococcus aureus interpretive criteria for vancomycin.

Here's an analysis of the provided information:

1. Table of Acceptance Criteria and Reported Device Performance

Note: The specific numerical acceptance criteria from the FDA guidance document are not explicitly stated in the provided text. However, the document states the device demonstrated "acceptable performance" and achieved 97.6% Essential Agreement, implying this met the pre-defined criteria. Essential Agreement (EA) for AST devices typically refers to the agreement between the investigational device and the reference method within ±1 dilution.

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

• Sample Size: Not explicitly stated as a number. The text mentions "Challenge strains were compared to Expected Results determined prior to the evaluation."
• Data Provenance: The S. aureus data came from a "previously cleared vancomycin external evaluation (K060312)." This indicates the data was retrospective relative to this specific 510(k) submission, as it was collected for an earlier clearance. The country of origin is not specified, but given the submission to the US FDA and Siemens Healthcare Diagnostics' presence, it's likely primarily US-based or multi-site clinical trial data.

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

• Number of Experts: Not specified.
• Qualifications of Experts: Not specified. However, the ground truth was established by comparing the challenge strains to "Expected Results determined prior to the evaluation," and this evaluation used a CLSI frozen Reference panel. This implies the ground truth was based on a highly standardized and accepted reference method in the field of microbiology, which typically has expert consensus underlying its establishment.

4. Adjudication Method for the Test Set

• Adjudication Method: Not applicable or not specified. Ground truth was established by comparison to a CLSI frozen Reference panel, rather than human expert consensus requiring adjudication on individual cases.

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

• MRMC Study: No, this is not an MRMC study. This device is an automated in vitro diagnostic (IVD) system for antimicrobial susceptibility testing, which does not involve human readers interpreting images or data directly in a comparative effectiveness study against AI. The comparison is between the automated device and a reference laboratory method.

6. Standalone (Algorithm Only) Performance Study

• Standalone Performance: Yes. The study directly evaluates the performance of the MicroScan® Synergies plus® Gram-Positive MIC/Combo Panel (the algorithm/device) against a frozen Reference Panel. This is a standalone performance evaluation of the device without human-in-the-loop performance being the primary subject of the comparison.

7. Type of Ground Truth Used

• Type of Ground Truth: The ground truth used was a CLSI frozen Reference panel. This is a highly standardized and validated laboratory method for determining antimicrobial susceptibility, widely accepted as a "gold standard" in microbiology. The reference panel essentially provides the "true" MIC values and interpretive categories (S, I, R) for the challenge strains.

8. Sample Size for the Training Set

• Sample Size: This information is not provided in the summary. As an in vitro diagnostic device, the "training set" concept is different from AI/ML models. It would refer to the strains and data used during the development and optimization of the MicroScan® system's AST methodology.

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

• Ground Truth Establishment for Training Set: This information is not provided in the summary. Similar to point 8, the ground truth for any development/training would likely involve standard reference methods, possibly including CLSI guidelines and expert microbiology protocols, but the specifics are not detailed.

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