Comparative in vitro activity of gemifloxacin to other fluoroquinolones and non-quinolone agents against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis in the United States in 1999-2000.

This study was undertaken to assess the in vitro activity of gemifloxacin, five other fluoroquinolone antimicrobial agents (ciprofloxacin, gatifloxacin, levofloxacin, moxifloxacin and ofloxacin) and other non-quinolone comparator agents (ampicillin, erythromycin, clindamycin, doxycycline, penicillin and trimethoprim/sulphamethoxazole) against Streptococcus pneumoniae collected in the United States. Susceptibility testing of 550 S. pneumoniae, 290 Haemophilus influenzae and 205 Moraxella catarrhalis showed that 38.2% of pneumococci were penicillin nonsusceptible, while 26.2 and 95.6% of H. influenzae and M. catarrhalis, respectively, produced beta-lactamase. Overall new fluoroquinolones were the most active agents. The in vitro activity (based on MIC90 in mg/l) of the six fluoroquinolones was gemifloxacin>moxifloxacin>gatifloxacin>levofloxacin>ciprofloxacin and ofloxacin.