In Vitro Activities of Six Fluoroquinolones against 250 Clinical Isolates of Mycobacterium tuberculosis Susceptible or Resistant to First-Line Antituberculosis Drugs

Two hundred fifty isolates of Mycobacterium tuberculosis were evaluated for susceptibility to ciprofloxacin, ofloxacin, levofloxacin, grepafloxacin, trovafloxacin, and gemifloxacin (SB-265805). Levofloxacin, ciprofloxacin, and grepafloxacin showed the greatest activity (MIC for 90% of strains tested [MIC(90)] 1 μg/ml), although ofloxacin also showed good activity, with an MIC(90) of 2 μg/ml. Trovafloxacin and gemifloxacin showed lower in vitro activity, with MIC(90)s of 64 and 8 μg/ml, respectively.