Antimicrobial effects of a new carboxyquinolone drug, Q-35, on five serogroups of Leptospira interrogans.

New carboxyquinolone drugs, including the recently developed Q-35, were evaluated for their in vitro potency against five serogroups of Leptospira interrogans. Q-35, ofloxacin, ciprofloxacin, and tosufloxacin showed MICs (0.05 to 0.20 microgram/ml) comparable to those of tetracycline. However, MBCs of these drugs varied between 10- and 100-fold above the MIC for most strains tested. Q-35 was shown to be active against L. interrogans in vitro as judged by the MICs obtained.