STANDARDIZED BACTEC METHOD TO MEASURE CLARITHROMYCIN SUSCEPTIBILITY OF MYCOBACTERIUM GENAVENSE

A standardized clarithromycin susceptibility test for Mycobacterium ge navense is reported. The BACTEC radiometric broth dilution test method recommended for Mycobacterium avium complex was modified to develop a reliable and reproducible procedure, Test development involved optimi zation of medium pH and inoculum densities for antibiotic vials as wel l as growth control vials, MIC control organisms included Mycobacteriu m simiae, Mycobacterium avium, and Mycobacterium xenopi, Growth contro l vials required two to three inoculum dilutions, which varied for eac h species, Clarithromycin MICs and MBCs for 12 isolates and 1 colonial variant of M. genavense ranged from less than or equal to 0.06 to 0.2 5 mu g/ml.