Proposed zone standards for interpretation of fortimicin A disk diffusion tests

Area of Science:

• Microbiology
• Antimicrobial Susceptibility Testing

Background:

• Fortimicin A is an aminoglycoside antibiotic.
• Accurate susceptibility testing is crucial for effective antibiotic treatment.

Purpose of the Study:

• To evaluate the efficacy of Fortimicin A microdilution and disk diffusion tests.
• To establish reliable zone diameter standards for disk diffusion testing.

Main Methods:

• Performed microdilution and disk diffusion tests with 454 bacterial strains.
• Utilized 10-, 30-, and 50-microgram Fortimicin A disks.
• Correlated zone diameters with minimal inhibitory concentrations (MICs).

Main Results:

• 30-microgram disks demonstrated preferred performance.
• Established zone standards: ≤14 mm for resistant strains (MIC > 16 µg/ml).
• Established zone standards: ≥17 mm for susceptible strains (MIC < 16 µg/ml).

Conclusions:

• Fortimicin A disk diffusion with 30-microgram disks is a reliable method for susceptibility testing.
• The defined zone standards accurately predict bacterial susceptibility to Fortimicin A.