Proposed quality control and interpretive criteria for disk diffusion susceptibility testing with enoxacin

Area of Science:

• Microbiology
• Clinical Microbiology
• Antimicrobial Susceptibility Testing

Background:

• Accurate antimicrobial susceptibility testing is crucial for guiding effective treatment decisions.
• Standardized methods are needed to ensure reliable interpretation of results.
• Enoxacin is an important antibiotic, necessitating validated testing protocols.

Purpose of the Study:

• To establish reference control values for enoxacin disk diffusion and microbroth dilution tests.
• To correlate inhibitory zone diameters with Minimum Inhibitory Concentrations (MICs) for enoxacin.
• To propose interpretive criteria for categorizing the susceptibility of gram-negative clinical isolates to enoxacin.

Main Methods:

• Standardized disk diffusion tests using 10-micrograms enoxacin disks were performed.
• Microbroth dilution methods were used to determine MICs.
• Regression analysis correlated zone diameters with MICs for approximately 400 gram-negative clinical isolates.

Main Results:

• Control values were established using reference strains: Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Staphylococcus aureus ATCC 25923/29213.
• Linear regression and error rate-bounded analyses were conducted on clinical isolates.
• Proposed criteria were developed for the categorical interpretation of enoxacin susceptibility.

Conclusions:

• The study provides validated criteria for interpreting enoxacin disk diffusion tests against gram-negative bacteria.
• These criteria facilitate accurate susceptibility reporting, aiding in appropriate antibiotic selection.
• The findings support the use of disk diffusion as a reliable method for enoxacin susceptibility testing in clinical laboratories.