In-vitro Antimycoplasmal Activity of Triclosan in Combination with Fluoroquinolones against Five mycoplasma Species

Mycoplasmosis caused by mycoplasma has immensely reduced the performance of commercial animal husbandry, along with prevalence and increase of drug resistance in mycoplasma, thus new agents and therapies are urgently needed. Triclosan is a broad spectrum antimicrobial agent with a favorable safety profile. In the present study, we tested the antimycoplasmal activity of triclosan alone, as well as the in-vitro interaction of triclosan and the fluoroquinolones, gatifloxacin (GAT), moxifloxacin (MXF), levofloxacin (LVX), sparfloxacin (SPX), ciprofloxacin (CIP), enrofloxacin (EFX), and norfloxacin (NOR), against five mycoplasma species. This study demonstrated that triclosan had antimycoplasmal activity against both fluoroquinolones-sensitive species and a fluoroquinolones-resistant species isolated from clinic, with minimum inhibitory concentrations (MICs) of 16.0-64.0 μg/mL and 64.0 μg/ mL, respectively. A synergistic antimycoplasmal effect between triclosan and GAT, MFX or EFX against the five mycoplasma species was observed, with modulation factors (MFs) of 4-8, 4-16, 8-32, respectively, and fractional inhibitory concentration indexes (FICIs) of 0.375- 0.500, 0.350-0.500, 0.281-0.375, respectively. The combination of triclosan with LVX, SPX, CIP or NOR displayed either synergistic activity or indifference against the same mycoplasma species with MFs of 2-64, 4-16, 2-16, 2-64, respectively, while FICI values range from 0.516- 0.750, 0.500-0.625, 0.306-0.750, and 0.615-0.750, respectively. No antagonism was observed for any drug combination against any of the species tested. To the best of our knowledge, this is the first report that triclosan has synergistic activity with fluoroquinolones against mycoplasma species.