IN-VITRO ANTIMYCOBACTERIAL ACTIVITY OF A NEW QUINOLONE, LEVOFLOXACIN (DR-3355)

Objective: To examine in vitro antimycobacterial activity of levofloxa cin. Design: Minimum inhibitary concentrations (MICs) of levofloxacin for various mycobacterial species were determined by the agar dilution method using 7H11 medium and compared with those of ofloxacin. Antimi crobial activity of levofloxacin against Mycobacterium tuberculosis an d M. intracellulare phagocytosed in murine peritoneal macrophages was measured in terms of reducing cell-associated bacterial colony forming units (CFUs). Results: MICs of levofloxacin against M. tuberculosis, M. kansasii, M. marinum, M. scrofulaceum, M. avium, M. intracellulare, M. fortuitum, and M. chelonae were 2 to 4 times lower than those of o floxacin. Levofloxacin exhibited higher efficacy in reducing bacterial CFUs in macrophages than ofloxacin. Conclusion: Levofloxacin possesse d more potent in vitro antimycobacterial activities as compared to tha t of ofloxacin.