Comparison of In Vitro Activities of Gatifloxacin and Ciprofloxacin against Four Taxa of Rapidly Growing Mycobacteria

By using current NCCLS broth microdilution methods, we found that gatifloxacin inhibited 90% of the isolates of the Mycobacterium fortuitum group at ≤0.12 μg/ml and 90% of the Mycobacterium chelonae isolates at ≤4 μg/ml. Gatifloxacin was generally fourfold more active than ciprofloxacin. We recommend that both gatifloxacin and ciprofloxacin be tested routinely against rapidly growing mycobacteria.