In vitro activity of sitafloxacin compared with several fluoroquinolones against Streptococcus anginosus and Streptococcus constellatus

The in vitro activities of sitafloxacin and seven other fluoroquinolones a (ciprofloxacin, tosufloxacin, sparfloxacin, levofloxacin, T-3811ME, moxifloxacin and trovafloxacin) were examined by the microdilution method against 79 clinical isolated 'Streptococcus milleri' group (SMG) microorganisms. No statistically significant differences were found between the minimum inhibitory concentrations (MIC50 and MIC90) against Streplococcus anginosus and Streptococcus constellatus. Sitafloxacin was the most active agent of the eight fluoroquinolones, tested against SMG, with a MIC90 of 0.06 mu g/mL, which was 8 times more active than ciprofloxacin and 16 times more active than levofloxacin. Although none of the SMG strains showed high resistance to ally Of the fluoroquinolones tested, three agents (trovafloxacin, sitafloxacin and T-3811ME) had low MICs against 23 SMG strains against which levofloxacin had a MIC > 1 mu g/mL. In conclusion several fluoroquinolones have low MICs against SMG, but sitafloxacin has the lowest. (c) 2005 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.