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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°C +/- 1°C, 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 Ampicillin, at concentrations of 0.12 to 64 ug/ml for the Long Dilution Sequence and 2 - 8 µg/ml for the Breakpoint Dilution Sequence, to the test panel.

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

Enterococcus species

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 and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of rapidly growing aerobic 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.

Here's a summary of the acceptance criteria and study information for the MicroScan® Synergies plus™ Gram-Positive MIC/Combo Panels with Ampicillin, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

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

• Sample Size:
  • Efficacy Isolates: 293 isolates
  • Challenge Strains: 72 isolates
  • Note: 16 isolates (13 efficacy, 3 challenge) were excluded due to read times >16 hours.
• Data Provenance: The document does not specify the country of origin. It indicates that the evaluation was "external," meaning outside of the manufacturer's internal development testing. The data appears to be prospective as it's an evaluation of the panel's performance against a reference standard to demonstrate substantial equivalence.

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

The document does not explicitly state the number of experts or their qualifications for establishing the ground truth for the test set. However, the ground truth for the challenge strains was "Expected Results determined prior to the evaluation," and the comparison for efficacy isolates was against a "frozen Reference panel" which implies a highly standardized and validated method, likely established by expert consensus or a reference laboratory.

4. Adjudication Method for the Test Set

The document does not explicitly state an adjudication method. The comparison was primarily against a "frozen Reference Panel" and "Expected Results," which serve as the standard. Discrepancies between the device and the reference would be analyzed, but a specific user-based adjudication process (like 2+1) is not described.

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 conducted. This study focuses on the standalone performance of the automated system compared to a reference standard, not on human reader performance with or without AI assistance.

6. If a Standalone Study Was Done

Yes, a standalone study (algorithm only, without human-in-the-loop performance) was performed. The entire evaluation compares the MicroScan® Synergies plus™ Gram-Positive MIC/Combo Panels with Ampicillin, read by the WalkAway® SI System, directly against a frozen Reference Panel and expected results.

7. The Type of Ground Truth Used

The ground truth used was:

• Reference Standard: A "frozen Reference Panel" for the efficacy isolates. These panels are typically highly standardized and validated MIC determinations, often established by a reference laboratory following CLSI (Clinical and Laboratory Standards Institute) guidelines.
• Expected Results: For the "Challenge strains." These are likely strains with known antimicrobial susceptibility profiles, serving as a form of "expert consensus" or established standard.

8. The Sample Size for the Training Set

The document does not provide information regarding the sample size for a training set. This submission is for the addition of a new antimicrobial (Ampicillin) to an existing, previously cleared system. It's likely that the core technology and algorithm for reading the panels were trained and validated in prior submissions. The current submission focuses on validating the performance of Ampicillin within that established framework.

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

Since information about a specific training set or its size is not provided for this submission, there is no information on how its ground truth was established. For AST systems, the ground truth would typically be established using validated methods such as macrobroth or microbroth dilution reference methods performed by expert microbiologists or reference laboratories.

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