COMPARATIVE ANTIMYCOBACTERIAL ACTIVITIES OF THE NEWLY SYNTHESIZED QUINOLONE AM-1155, SPARFLOXACIN, AND OFLOXACIN

AM-1155 is a newly synthesized 6-fluoro-8-methoxy quinolone. We assess ed its in vitro antimycobacterial activity using sparfloxacin (SPFX) a nd ofloxacin (OFLX) as comparison drugs, The MICs of these agents for various mycobacterial strains were determined by the agar dilution met hod with 7H11 medium. AM-1155 had lower MICs for 50 and 90% of tested strains of Mycobacterium kansasii, M. marinum, and M. fortuitum-M. che lonae complex than SPFX and OFLX, and the values for M. tuberculosis, M. scrofulaceum, and the M. avium-M. intracellulare complex were simil ar to those of SPFX and considerably lower than those of OFLX. In addi tion, the antimicrobial activity of AM-1155 against M. tuberculosis an d M. intracellulare phagocytosed into murine peritoneal macrophages wa s compared with that of OFLX. AM-1155 (1 mug/ml) inhibited the intrace llular growth of both M. tuberculosis and M. intracellulare, whereas O FLX at the same concentration failed to show any such effect. Moreover , AM-1155 (10 mug/ml) exhibited a steady bactericidal action against M . tuberculosis, whereas OFLX at the same concentration had only a weak effect. AM-1155 (10 mug/ml) also inhibited the growth of M. intracell ulare more effectively than OFLX.