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Tentative interpretive standards for disk susceptibility tests with moxalactam (LY127935)
Antimicrobial Agents and Chemotherapy
|November 1, 1980
Summary
New beta-lactam antibiotic moxalactam susceptibility testing requires further clinical evaluation. Tentative zone standards for disk diffusion tests are proposed, establishing categories for susceptible, intermediate, and resistant bacterial strains.
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Moxalactam is a novel beta-lactam antibiotic.
- Susceptibility testing is crucial for guiding antibiotic therapy.
Purpose of the Study:
- To propose tentative zone standards for agar diffusion susceptibility tests of moxalactam.
- To define preliminary breakpoints for categorizing bacterial susceptibility to moxalactam.
Main Methods:
- Agar diffusion susceptibility tests using 30-microgram moxalactam disks.
- Correlation of zone diameters with minimal inhibitory concentrations (MICs).
Main Results:
- Proposed categories: susceptible (MIC ≤ 8 µg/ml), intermediate (MIC 16–32 µg/ml, zones 15–22 mm), and resistant (MIC ≥ 64 µg/ml).
- 30-µg disk tests adequately categorized isolates but had limitations in differentiating very low MICs (< 2 µg/ml) from low MICs (8 µg/ml).
Conclusions:
- Tentative zone standards are proposed for moxalactam disk diffusion testing.
- Clinical experience is needed to finalize MIC breakpoints.
- Disk diffusion tests provide a satisfactory method for categorizing moxalactam susceptibility into proposed clinical categories.