In vitro activity of 6 fluoroquinolones against Mycoplasma hominis

Objective: To test the activity of fluoroquinolones against Mycoplasma hominis (Mh) for the guidance of rational use of antibiotics. Methods: Susceptibility of 103 clinical isolates of Mh to 6 fluoroquinolones were determined by broth microdilution method. Results: Among the 6 fluoroquinolones tested, sparfloxacin and gatifloxacin were the most active against Mh, the MIC 50s being 0.0325?mg /L and 0.25?mg /L, respectively; and MIC 90s being 1?mg /L for both drugs; the MIC 50 and MIC 90 of levofloxacin being 1?mg /L and 4?mg /L; while the MIC 50 and MIC 90 of ofloxacin and ciprofloxacin were 2?mg /L and 8?mg /L, respectively. Norfloxacin was the least active one with MIC 50 and MIC 90 32?mg /L and 64?mg /L respectively. Conclusions: New fluoroquinolone such as sparfloxacin, and gatifloxacin are more active against Mh than the older fluoroquinolones; Mh has varying degree of resistance to commonly used fluoroquinolones.