In vitro activity of moxifloxacin compared to other fluoroquinolones against different erythromycin-resistant phenotypes of group A beta-hemolytic streptococcus.

The aim of the present study was to evaluate the in vitro activity of moxifloxacin (BAY 12-8039) compared to ciprofloxacin, ofloxacin and sparfloxacin against 156 group A beta-hemolytic Streptococcus strains. Sixty strains were macrolide-, lincosamide- and streptogramin-B-susceptible; 16 strains exhibited a constitutive resistance phenotype; 32 strains exhibited an inducible phenotype, and 48 strains were characterized by the M-type efflux-dependent phenotype. The minimum inhibition concentrations were determined by an agar dilution method according to NCCLS-approved guidelines. Moxifloxacin showed an enhanced activity compared with the other fluoroquinolones against the different macrolide-resistant phenotypes. Copyright 2000 S. Karger AG, Basel