Comparative in-vitro activity of moxifloxacin, minocycline and azithromycin against Chlamydia spp.

The in-vitro activity of moxifloxacin, a new 8-methoxyquinolone, was compar ed with minocycline and azithromycin against 40 strains of Chlamydia tracho matis, Chlamydia pneumoniae and Chlamydia psittaci. Both the MIC and the MB C of moxifloxacin ranged from 0.03 to 0.125 mg/L, MICs of minocycline range d from 0.015 to 0.06 mg/L and MBCs between 0.03 and 0.25 mg/L. MICs of azit hromycin ranged from 0.03 to 0.125 mg/L and the MBCs between 0.06 and 0.5 m g/L, MBC values of moxifloxacin were the same as MICs in 32 (80%) of 40 str ains tested, whereas those of minocycline and azithromycin were two to four times higher than their MICs. These data confirm those previously obtained indicating that quinolones kill chlamydial strains at concentrations equiv alent to their MICs.