(33 days)
Antimicrobial Susceptibility Test Disks are used for semi-quantitative in vitro susceptibility testing by standardized agar diffusion test procedures. Telithromycin 15ug BBL™ is intended for use in determining the susceptibility to telithromycin of a wide range of bacteria, as described in the "Indications for Use" section. Zone sizes used for interpretation of tests, including control organism limits, were determined by the antimicrobic manufacturer and received FDA approval under NDA Number 21-144.
Use of Telithromycin 15ug, BBL™ Sensi-Disc™ for in vitro agar diffusion susceptibility testing is indicated when there is a need to determine the susceptibility of bacteria to telithromycin. The concentration of 15ug has been shown to be active in vitro against most strains of microorganisms listed below, as described in the FDA approved drug insert for this antimicrobic.
Active In Vitro and in clinical infections against:
Aerobic gram-positive microorganisms Staphylococcus aureus (methicillin and erythromycin susceptible isolates only)
Streptococcus pneumoniae (including multi-drug resistant isolates)
Aerobic gram-negative microorganisms
Haemophilus influenzae
Active In Vitro Against:
Aerobic gram-positive microorganisms Streptococcus pyogenes (erythromycin susceptible isolates only Streptococci (Lancefield groups C and G) Viridans group streptococci
Telithromycin 15ug BBL™ Sensi-Disc™ is prepared by impregnating high quality paper with accurately determined amounts of Telithromycin supplied by the drug manufacturer. Each Telithromycin disk is clearly marked on both sides with the agent and drug content. Telithromycin cartridges each contain 50 impregnated disks that are packed as either a single cartridge in a single box, or in a package containing ten cartridges. Telithromycin disks are used for semi-quantitative in vitro susceptibility evaluations by the agar diffusion test method.
Agar diffusion susceptibility methods employing dried filter paper disks impregnated with specific concentrations of antimicrobial agents were developed in the 1940s. In order to eliminate or minimize variability in the testing, Bauer et al. developed a standardized procedure in which Mueller Hinton Agar was selected as the test medium.
Various regulatory agencies and standards-writing organizations subsequently published standardized reference procedures based on the Bauer-Kirby method. Among the earliest and most widely accepted of these standardized procedures were those published by the U.S. Food and Drug Administration (FDA) and the World Health Organization (WHO). The procedure was adopted as a consensus standard by the Clinical and Laboratory Standards Institute (CLSI) [Formerly National Committee for Clinical Laboratory Standards (NCCLS)] and is periodically updated.
Here's an analysis of the provided 510(k) submission for the Telithromycin 15µg BBL™ Sensi-Disc™ Antimicrobial Susceptibility Test Disks, focusing on the acceptance criteria and study details. It's important to note that this document is a 510(k) summary, which often refers to data presented in a separate "drug package insert" or "Susceptibility Tests: Diffusion Techniques" (Appendix 1), which is not included here. Therefore, some specific details about the study's quantitative results and ground truth establishment for the Telithromycin disc itself are referenced as being in that external document.
1. Table of Acceptance Criteria and Reported Device Performance
The provided 510(k) summary does not explicitly state numerical acceptance criteria in a dedicated table format for the Telithromycin 15µg disc specifically. Instead, it refers to established standards and previous FDA approvals for the interpretation of zone sizes. The "reported device performance" is implicitly that the Telithromycin 15µg BBL™ Sensi-Disc™ is able to produce zone sizes that are comparable to those used for interpretation in the FDA-approved drug insert and CLSI/NCCLS documents.
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Zone sizes used for interpretation of tests, including control organism limits, were determined by the antimicrobic manufacturer and received FDA approval under NDA Number 21-144. (Implied: The device produces zone sizes that allow for accurate interpretation according to these pre-approved standards.) | "Zone sizes used for interpretation of tests, including control organism limits, were determined by the antimicrobic manufacturer and received FDA approval under NDA Number 21-144." "The concentration of 15ug has been shown to be active in vitro against most strains of microorganisms listed today, as described in the FDA approved drug insert for this antimicrobic." (Implied: The device performs in accordance with these established interpretive criteria). |
| Categorical interpretation (susceptible (S), intermediate (I), or resistant (R)) for the organism being tested with the antimicrobial agent is made by comparing zone diameters to those found in the respective organism tables of CLSI/NCCLS Document M2 ("Performance Standards for Antimicrobial Disk Susceptibility Tests) and of CLSI/NCCLS Document M100 ("Performance Standards for Antimicrobial Susceptibility Testing"). | The device enables users to "determine categorical interpretations (S/I/R) using the measured zone diameters against CLSI/NCCLS Approved Standards M2 and M100." (Implied: The device generates zone diameters suitable for this interpretation). |
2. Sample Size Used for the Test Set and Data Provenance
The 510(k) summary for the Telithromycin 15µg BBL™ Sensi-Disc™ does not explicitly state the sample size used for the test set or the data provenance (e.g., country of origin, retrospective/prospective). It refers to evaluation data within the "Telithromycin drug package insert, 'Susceptibility Tests: Diffusion Techniques' (Appendix 1)," which is not provided. This external document would contain the specific study details for the new Telithromycin disc's performance.
However, the general practice for such devices involves testing against a range of clinically relevant bacterial isolates. The document lists target microorganisms such as:
- Staphylococcus aureus (methicillin and erythromycin susceptible isolates only)
- Streptococcus pneumoniae (including multi-drug resistant isolates)
- Haemophilus influenzae
- Streptococcus pyogenes (erythromycin susceptible isolates only)
- Streptococci (Lancefield groups C and G)
- Viridans group streptococci
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The 510(k) document does not specify the number or qualifications of experts used to establish the ground truth for the test set.
For antimicrobial susceptibility testing, the "ground truth" (or reference method) is typically established by broth microdilution or agar dilution Minimum Inhibitory Concentration (MIC) testing, performed and read according to CLSI (Clinical and Laboratory Standards Institute) methodologies. The interpretation of these MIC values into susceptible, intermediate, or resistant categories is based on CLSI breakpoints and FDA-approved breakpoints for the specific antimicrobial-organism combination. While expert microbiologists perform and interpret these reference tests, the concept of "experts establishing ground truth" in the same way as, for instance, radiologists interpreting images, is not directly applicable in this context. The ground truth is defined by standardized laboratory methods and established breakpoints.
4. Adjudication Method for the Test Set
The concept of "adjudication method" (like 2+1, 3+1 for imaging studies) is not applicable to this type of in vitro diagnostic device for antimicrobial susceptibility testing. The outcome (zone size and subsequent S/I/R categorization) is determined by objective measurement and comparison to predefined breakpoints, not subjective expert opinion requiring adjudication.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
A Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not performed, nor is it relevant, for this type of device. The device is a diagnostic tool for measuring susceptibility, not an AI-assisted diagnostic aid for human interpretation of complex medical images where reader performance could be compared with and without AI.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Performance
This device is not an algorithm. It is a physical Sensi-Disc™. The "performance" in this context refers to the output of the device itself (the zone of inhibition) when used as per standardized procedures. The measurement of the zone of inhibition (and subsequent interpretation) requires human involvement to measure the zone and compare it to interpretive criteria. Therefore, the concept of "standalone performance" for an algorithm is not directly applicable. The device's performance is intrinsically linked to the standardized laboratory procedure and human measurement/interpretation.
However, the "study that proves the device meets the acceptance criteria" refers to the evaluation of the disc's ability to produce consistent and accurate zones of inhibition that correlate with the interpretive categories of the Telithromycin drug (S/I/R). This would be a "standalone" evaluation of the disc's biological performance in conjunction with the standardized methodology.
7. Type of Ground Truth Used
The ground truth used for evaluating antimicrobial susceptibility test devices is the Minimum Inhibitory Concentration (MIC) determined by a reference dilution method (e.g., broth microdilution or agar dilution). This is considered the gold standard for antimicrobial susceptibility testing. This MIC data is then correlated with the zone diameters produced by the Sensi-Disc™. The interpretation of both MIC and zone diameters into susceptible (S), intermediate (I), or resistant (R) categories uses established breakpoints set by CLSI and FDA, often derived from pharmacokinetic/pharmacodynamic (PK/PD) data, clinical outcome data, and microbiological distributions.
8. Sample Size for the Training Set
The 510(k) summary does not provide information on a "training set" sample size. For an antimicrobial susceptibility disc, the concept of a training set for an AI algorithm is not applicable. The development of the disc itself involves manufacturing processes and quality control, but not a data-driven training of a model. The interpretive zone breakpoints (the "rules" for the device's output) for Telithromycin were established by the drug manufacturer and FDA based on extensive clinical, microbiological, and pharmacokinetic data supporting the New Drug Application (NDA) for Telithromycin.
9. How the Ground Truth for the Training Set Was Established
As there is no "training set" in the AI sense, this question is not directly applicable. However, the "ground truth" (i.e., the interpretive breakpoints) for Telithromycin was established through:
- Extensive research and clinical trials for the Telithromycin drug itself (NDA Number 21-144). This would have involved determining the MIC distributions for various organisms, correlating MICs with clinical outcomes, and establishing pharmacokinetic/pharmacodynamic relationships.
- CLSI (Clinical and Laboratory Standards Institute) methodologies, which provide standardized frameworks for determining MICs and interpreting susceptibility.
- FDA review and approval of these breakpoints as part of the drug's labeling.
The Telithromycin 15µg BBL™ Sensi-Disc™ is then validated to ensure that the zone diameters it produces reliably correlate with these established MIC-derived interpretive categories.
§ 866.1620 Antimicrobial susceptibility test disc.
(a)
Identification. An antimicrobial susceptibility test disc is a device that consists of antimicrobic-impregnated paper discs used to measure by a disc-agar diffusion technique or a disc-broth elution technique the in vitro susceptibility of most clinically important bacterial pathogens to antimicrobial agents. In the disc-agar diffusion technique, bacterial susceptibility is ascertained by directly measuring the magnitude of a zone of bacterial inhibition around the disc on an agar surface. The disc-broth elution technique is associated with an automated rapid susceptibility test system and employs a fluid medium in which susceptibility is ascertained by photometrically measuring changes in bacterial growth resulting when antimicrobial material is eluted from the disc into the fluid medium. Test results are used to determine the antimicrobial agent of choice in the treatment of bacterial diseases.(b)
Classification. Class II (performance standards).