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Liofilchem Antibiotic Discs are a semi-quantitative agar diffusion method for in vitro determination of antimicrobial susceptibility of clinical isolates tested on agar media after overnight incubation.

The Ceftobiprole BPR 5 µg Disc is intended to determine susceptibility of Enterobacterales and Staphylococcus aureus to ceftobiprole, as recognized by the FDA Susceptibility Test Interpretive Criteria (STIC). Ceftobiprole at concentrations of 5 μg should be interpreted at 16-18 hours of incubation.

The Ceftobiprole BPR 5 µg Disc demonstrated acceptable performance with the following organisms:

• Enterobacterales (Escherichia coli and Klebsiella pneumoniae)
• Staphylococcus aureus (includes methicillin resistant isolates)

Not Found

Based on the provided FDA 510(k) Clearance Letter, the device in question is a "Ceftobiprole BPR 5 µg Disc." This is an Antimicrobial Susceptibility Test (AST) disc, not a medical imaging or AI-driven diagnostic device. Therefore, the acceptance criteria and study design elements typically associated with AI/ML-based devices (such as MRMC studies, multi-reader consensus, training/test sets for AI, pixel-level ground truth, etc.) are not applicable in this context.

The 510(k) letter discusses the substantial equivalence of this AST disc to legally marketed predicate devices. The "study" proving the device meets acceptance criteria for an AST disc involves demonstrating its performance in determining antimicrobial susceptibility for specific organisms, as recognized by FDA Susceptibility Test Interpretive Criteria (STIC).

Here's how to interpret the provided information in the context of an AST disc:

1. A table of acceptance criteria and the reported device performance:

For an AST disc, "acceptance criteria" typically refer to the agreement of the new device's zone diameters or interpretations (Susceptible, Intermediate, Resistant) with a reference method (e.g., broth microdilution or another FDA-cleared AST method) and demonstrating acceptable categorical agreement (CA) and essential agreement (EA) rates, as well as addressing very major errors (VME), major errors (ME), and minor errors (mE). The specific numerical targets for these metrics are not provided in this 510(k) letter but are standard for AST device clearance.

The letter states:

• Enterobacterales (Escherichia coli and Klebsiella pneumoniae)
• Staphylococcus aureus (includes methicillin resistant isolates)"

While specific percentages for CA, EA, VME, ME, mE are not in this letter, "acceptable performance" implies these standard metrics were met as per FDA guidance for AST devices. |

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

• Sample Size for Test Set: The 510(k) letter does not specify the number of isolates (sample size) used for the performance testing. For AST devices, this would typically be a pre-defined number of clinical isolates, often including a challenge set (e.g., resistant strains).
• Data Provenance: The letter doesn't directly state the country of origin or if the study was retrospective or prospective. For AST studies, the isolates are usually collected from various clinical sources to ensure representativeness. They are often cultivated and tested prospectively in a lab setting.

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

• For an AST disc, the "ground truth" is not established by human experts in the same way it is for image interpretation. Instead, the ground truth is established by a reference method, typically a CLSI-standardized broth microdilution method or another FDA-cleared AST system, using precisely controlled laboratory conditions.
• The "experts" involved would be trained microbiologists and laboratory technicians who perform these standardized susceptibility tests accurately. Their qualification lies in their adherence to CLSI (Clinical and Laboratory Standards Institute) guidelines and good laboratory practices. The number of such individuals is not specified and is less relevant than the accuracy and standardization of the reference method itself.

4. Adjudication method for the test set:

• Adjudication methods (e.g., 2+1, 3+1) are for subjective interpretations, primarily in medical imaging. For AST, the interpretations are quantitative (zone diameters) and then categorically assigned based on established breakpoints. There is no "adjudication" in the sense of multiple experts independently reviewing and then resolving discrepancies. The results from the test disc are compared directly to the results from the reference method.

5. If a multi reader multi case (MRMC) comparative effectiveness study was done:

• No, an MRMC comparative effectiveness study was not done. MRMC studies are for evaluating human reader performance, often with and without AI assistance, especially in radiology. This is not applicable to an antimicrobial susceptibility test disc, which is a laboratory diagnostic tool that provides a direct measurement for interpretation.

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

• This concept is also not applicable. The "device" is a physical disc that produces a zone of inhibition. A human (trained lab personnel) measures this zone and interprets it based on established criteria. There is no "algorithm" in the AI sense that performs a standalone diagnosis without human involvement. The interpretation is human-in-the-loop, though it's rule-based rather than expert opinion-based as in image reading.

7. The type of ground truth used:

• The ground truth for an AST disc is typically established by comparison to a CLSI-standardized reference method, such as broth microdilution or agar dilution, or an existing FDA-cleared AST system with well-defined performance characteristics. The relevant outcome data is the in vitro susceptibility phenotype of the bacterial isolate. It is not expert consensus, pathology, or direct patient outcomes in this context, but rather highly controlled laboratory measurements.

8. The sample size for the training set:

• For an AST disk like this, there isn't a "training set" in the AI/ML sense. The "training" of the device is through its precise manufacturing to consistently release the specified antimicrobial concentration and create reproducible inhibition zones. The "training data" for setting interpretive criteria (breakpoints) involves extensive in vitro testing of many strains, correlation with clinical outcomes, and pharmacokinetic/pharmacodynamic (PK/PD) studies, which often span decades of research. The 510(k) letter doesn't provide details on this broader historical "training" data.

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

• As above, for an AST disc, the concept of a "training set" and "ground truth" establishment for it, as understood in AI/ML, doesn't directly apply. The establishment of ground truth for setting the specific concentration of the disc (5 µg) and the interpretive breakpoints (STIC) is a highly complex process within clinical microbiology. It involves:
  • Extensive in vitro susceptibility testing: Using reference methods like broth microdilution against thousands of bacterial isolates to determine the minimal inhibitory concentrations (MICs).
  • Pharmacokinetic/Pharmacodynamic (PK/PD) studies: To understand drug concentrations in the body and how they relate to the MICs needed to inhibit bacterial growth.
  • Clinical Efficacy Data: Correlation between in vitro susceptibility results and patient outcomes in clinical trials (though these trials are usually for the drug itself, not the disc).
  • Expert Consensus and Regulatory Body Review: Committees (like CLSI and FDA) review all the available data to establish and officially recognize Susceptibility Test Interpretive Criteria (STIC) or breakpoints.

In summary, the information in the 510(k) letter pertains to an Antimicrobial Susceptibility Test Disc, which follows a different regulatory and validation pathway than AI/ML-driven diagnostic devices. The details requested primarily apply to AI-based systems.

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