Search Results

Antimicrobial Susceptibility Test Discs are used for semi-quantitative in vitro susceptibility testing by standardized agar diffusion test procedures. Levofloxacin Sensi-Discs® are intended for use in determining the susceptibility of gram-positive and gram-negative bacteria, including Enteroccus faecalis, Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Enterobacter cloacae, Escherichia coli, Haemophilus influenzae, Haemophilus parainfluenzae, Klebsiella pneumoniae, Moraxella catarrhalis, Proteus mirabilis, and Pseudomonas aeruginosa species to Levofloxacin. Zone sizes used for interpretation of tests, including control organism limits, were determined by the antimicrobic manufacturer, Ortho Pharmaceutical Corporation/McNeil Pharmaceutical, and received FDA approval under NDA No. 20-634.

Use of BBL® Levofloxacin Sensi-Discs® for in vitro agar diffusion susceptibility testing is indicated when there is a need to determine the susceptibility of bacteria to Levofloxacin. Levofloxacin has been shown to be active against most strains of microorganisms listed below, both in vitro and in clinical infections, as described in the Ortho Pharmaceutical Corporation/McNeil Pharmaceutical package insert for this antimicrobic.

Levofloxacin Susceptibility Test Discs are prepared by impregnating high quality paper with accurately determined amounts of Levofloxacin supplied by the manufacturers, Ortho Pharmaceutical Corporation, Raritan, New Jersey, or McNeil Pharmaceutical, Raritan, New Jersey. Each Levofloxacin disc is clearly marked on both sides with the agent and content. Levofloxacin discs are furnished in cartridges of 50 discs each. Levofloxacin cartridges are packed as either a single cartridge in a single box, or in a package containing ten cartridges.

Agar diffusion methods employing dried filter paper discs impregnated with specific concentrations of antimicrobial agents were developed in the 1940's. 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.

Discs containing a wide variety of antimicrobial agents are applied to the surface of Mueller Hinton Agar plates [or Haemophilus Test Medium Agar for H. influenzae or Mueller Hinton Agar with 5% Sheep Blood for S. pneumoniae) inoculated with pure cultures of clinical isolates. Following incubation, the plates are examined and the zones of inhibition surrounding the discs are measured and compared with established zone size ranges for individual antimicrobial agents in order to determine the agent(s) most suitable for use in antimicrobial therapy. The determination as to whether the organism in question is susceptible (S), intermediate (I), or resistant (R) to an antimicrobial agent is made by comparing zone sizes to those found in the respective organism tables of National Committee for Clinical Laboratory Standards (NCCLS) Document M2-A5 ("Performance Standards for Antimicrobial Disk Susceptibility tests - Fifth Edition, Approved Standard", 12/93) and of NCCLS Document M100-S6 ("Performance Standards for Antimicrobial Susceptibility Testing", Sixth Informational Supplement, 12/95).

Here's an analysis of the provided text regarding the acceptance criteria and study data for the Levofloxacin Sensi-Disc:

This document is a 510(k) summary for an antimicrobial susceptibility test disc. It describes the device's intended use and how its performance is determined by comparing zone sizes to established standards, rather than a standalone device performance study in the way a medical imaging AI might be evaluated.

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for antimicrobial susceptibility test discs are defined by the comparability of the zone sizes produced by the device to established standards. The reported device performance is inherently tied to meeting these interpretative criteria.

Explanation of "Reported Performance": The document indicates that the zone sizes for interpretation and control organism limits were determined by the antimicrobic manufacturer and received FDA approval under NDA No. 20-634. This means the performance information is being referenced from the drug's regulatory submission, which established the clinical efficacy and appropriate breakpoints for Levofloxacin. The device's performance is essentially its ability to consistently produce zones that are interpretable using these established breakpoints. The document does not provide raw performance data (e.g., sensitivity, specificity for individual bacterial strains) for the disc itself in this submission summary. It relies on the pre-established standards.

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

The document refers to "Performance Data: See attached Ortho Pharmaceutical Corporation/McNeil Pharmaceutical product insert section on Susceptibility Testing Diffusion Techniques for Levaquin™ (Levofloxacin)."

• Sample Size for Test Set: Not explicitly stated in the provided text for the disc device itself. The sample size for establishing the reference zone sizes and control limits would be from the original drug (Levofloxacin) development data, which is not detailed here.
• Data Provenance: The standards (NCCLS documents) are international consensus standards. The data referenced for "Performance Data" comes from the antimicrobic manufacturer (Ortho Pharmaceutical Corporation/McNeil Pharmaceutical), which would likely involve data from clinical trials and laboratory studies conducted during the drug's development. The specific country of origin and retrospective/prospective nature of that underlying data are not provided in this specific device summary.

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

• Number of Experts: Not specified.
• Qualifications of Experts: Not specified.

The "ground truth" here is the established interpretive criteria for Levofloxacin susceptibility, which was determined by the drug manufacturer and subsequently approved by the FDA (under NDA No. 20-634). This would have involved experts in microbiology, infectious diseases, and clinical trials. The NCCLS documents referenced are consensus standards developed by committees of experts in clinical microbiology.

4. Adjudication Method for the Test Set

Not applicable in the context of this device. The device's performance is not evaluated by expert adjudication of its output against a 'ground truth' in the way one might evaluate an AI's classification. Instead, the output (zone size) is a direct measurement which is then interpreted by comparing it to pre-defined numerical thresholds established by expert committees and regulatory bodies (NCCLS, FDA).

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, If So, What Was the Effect Size of How Much Human Readers Improve with AI vs Without AI Assistance

Not applicable. This is an antimicrobial susceptibility test disc, not an AI-assisted diagnostic tool for human image interpretation or similar. There's no "human reader" in the sense of interpreting complex images or data that an AI might assist. The interpretation of zone sizes is a standardized, objective measurement against established breakpoints.

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

Not applicable. This device is a physical disc used in a laboratory procedure. Its "standalone" performance is its ability to diffuse the antimicrobial agent consistently and produce measurable zones of inhibition. This process is inherently "algorithm-only" in that the interpretation rules (NCCLS breakpoints) are fixed, but the measurement of the zone is typically done by a human, or increasingly, by automated zone readers which apply those fixed rules. The document does not describe a performance study of the disc itself (e.g., reproducibility studies, comparison to reference method) but rather references the interpretative criteria derived from the drug's NDA.

7. The Type of Ground Truth Used (Expert Consensus, Pathology, Outcomes Data, etc.)

The "ground truth" in this context is based on expert consensus (through NCCLS standards) and clinical outcomes data / pharmacokinetic-pharmacodynamic (PK/PD) correlations (from the original drug development and FDA approval). The drug manufacturer established the "correct" interpretive zone sizes (Susceptible, Intermediate, Resistant) based on:
* In vitro activity studies.
* Correlation between in vitro results and in vivo clinical outcomes data in patients treated with Levofloxacin.
* Pharmacokinetic and pharmacodynamic considerations.
* This "ground truth" was approved by the FDA as part of the drug's NDA.

8. The Sample Size for the Training Set

Not applicable in the typical AI/ML sense. There is no "training set" for the disc device itself. The process of establishing interpretative zone sizes for the drug Levofloxacin involved extensive testing of numerous isolates, which could be considered analogous to a training set for the drug's breakpoints. This data would be part of the drug's original NDA, but specifics are not provided here for the disc device.

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

As above, not applicable for a traditional "training set" as in AI/ML. For the underlying establishment of Levofloxacin's susceptibility breakpoints (which serve as the interpretative "ground truth" for the disc), the process involved:

• Extensive in vitro testing: Numerous bacterial isolates exposed to varying concentrations of Levofloxacin to determine Minimum Inhibitory Concentrations (MICs).
• Correlation with in vivo efficacy: Data from clinical trials demonstrating the effectiveness of Levofloxacin in treating infections caused by specific organisms at certain MIC levels.
• Pharmacokinetic/Pharmacodynamic (PK/PD) modeling: Understanding how the drug behaves in the human body and how drug concentrations relate to bacterial killing.
• Expert Review and Consensus: These data were then reviewed by regulatory bodies (e.g., FDA) and expert committees (e.g., NCCLS) to define the specific zone size breakpoints for Susceptible, Intermediate, and Resistant categories. This comprehensive evaluation established the reliable "ground truth" for interpreting the device's output.

Ask a specific question about this device