Modification of interpretive breakpoints for netilmicin disk susceptibility tests with Pseudomonas aeruginosa.

AUTOR(ES)

Barry, A L

RESUMO

Regression analysis of data correlating 30-micrograms netilmicin disk zone diameters with microdilution MICs, obtained by testing close-interval dilution steps, was performed with 77 selected strains of Pseudomonas aeruginosa, each tested in three independent laboratories. A zone of greater than or equal to 15 mm correlated with an MIC of less than or equal to 12 micrograms/ml (susceptible), and a zone of less than or equal to 12 mm correlated with an MIC of greater than 16 micrograms/ml (resistant). Additional disk tests were performed with 256 strains having known resistance mechanisms and 280 susceptible strains: the majority were appropriately categorized by these interpretive zone standards. The previously recommended standards of greater than or equal to 17 mm (MIC, less than or equal to 8.0 micrograms/ml) for the susceptible category inappropriately placed a significant number of truly susceptible P. aeruginosa strains in the intermediate category.

Documentos Relacionados

• Laboratory- and species-specific interpretive breakpoints for disk diffusion tests of chloramphenicol susceptibility of Haemophilus influenzae.
• Interpretive standards for disk susceptibility tests with Sch 21420 and amikacin.
• Tentative interpretive standards for disk susceptibility tests with moxalactam (LY127935).
• Single-strain regression analysis for determination of interpretive breakpoints for cefoperazone disk diffusion susceptibility testing.
• Levofloxacin disk potency and tentative interpretive criteria for susceptibility tests.