IN-VITRO ACTIVITY OF ROXITHROMYCIN AGAINST 16 SPECIES OF ATYPICAL MYCOBACTERIA AND EFFECT OF PH ON ITS RADIOMETRIC MICS

The antimycobacterial spectrum of roxithromycin, a semisynthetic 14-me mbered ring macrolide, was determined against 28 strains belonging to 16 species of atypical mycobacteria by measuring radiometric MICs by B ACTEC methodology at two different pH values, i.e., 6.8 and 7.4. The M ICs obtained at pH 7.4 were 1 to 2 dilutions lower or more than those obtained at pH 6.8 for some of the species. Roxithromycin possessed pr omising MICs against such potential pathogens as the Mycobacterium avi um complex, M. scrofulaceum, M. szulgai, M. malmoense, M. xenopi, M. m arinum, M. kansasii, and rare pathogens like M. chelonei subsp. chelon ei and M. chelonei subsp. abscessus but not against M. simiae. Roxithr omycin showed lower MICs against M. fortuitum var. peregrinum than M. fortuitum var. fortuitum.