Activity of five quinolones, three macrolides and telithromycin against 12 Haemophilus influenzae strains with different resistance phenotypes

ABSTRACTGemifloxacin MICs for 12 Haemophilus influenzae strains with different resistance phenotypes were 0.001–0.015 mg/L. Gemifloxacin was bactericidal against all 12 strains after 24 h at 2 × MIC. Ciprofloxacin, levofloxacin, gatifloxacin and moxifloxacin had MICs of 0.008–0.03 mg/L and similar kill kinetics. Macrolides and telithromycin had unimodal MICs (1.0–8.0 mg/L), except for two strains without efflux systems (0.0125–0.5 mg/L) and two with efflux systems and ribosomal protein mutations (> 64.0 mg/L), and were bactericidal against eight to ten strains tested at 2 × MIC after 24 h