In vitro Activities of Nemonoxacin and Other Antimicrobial Agents Against Human Mycoplasma and Ureaplasmas Isolates and Their Defined Resistance Mechanisms

Nemonoxacin, a newly developed non-fluorinated quinolone (NFQ), selectively inhibits bacterial DNA topoisomerase activity. However, its activities against have rarely been studied to date. Herein, the activities of nemonoxacin were evaluated against clinical isolates of 50 , 20 , and 77 spp., and they were compared to fluoroquinolones, tetracyclines, and macrolides. Nemonoxacin MICs (μg/ml) ranged from 0.03 to 0.25 for , 0.25 to 8 for , and 0.06 to >16 for spp., and all of the ranges are similar to those of fluoroquinolones. The activity of nemonoxacin against was not affected by resistance to macrolides in the strains tested, but it seems to have the same resistant mechanism as fluoroquinolones. In addition, minimum bactericidal concentrations (MBC) of nemonoxacin to were within two dilutions of the MIC values, indicating a bactericidal effect on . Nemonoxacin merits further study for treating infections caused by these organisms.