Comparative in vitro activity of gemifloxacin.

Gemifloxacin is a new quinolone and, like moxifloxacin, trovafloxacin, grepafloxacin and clinafloxacin, is more potent in vitro than ciprofloxacin or ofloxacin against Gram-positive aerobes. Gemifloxacin was the most potent of the quinolones tested against streptococci and most ciprofloxacin-resistant pneumococci were susceptible to gemifloxacin. Gemifloxacin, like moxifloxacin, trovafloxacin, grepafloxacin and clinafloxacin, was more potent than ciprofloxacin or ofloxacin against all staphylococci and many ciprofloxacin-resistant isolates were susceptible to these quinolones. Against Gram-negative aerobes gemifloxacin was as potent as or slightly less potent than ciprofloxacin, and isolates resistant to ciprofloxacin were also resistant to gemifloxacin and to moxifloxacin, trovafloxacin and grepafloxacin. Gemifloxacin was also the most potent quinolone against Gram-positive anaerobes and fusobacteria but trovafloxacin was the most potent agent tested against other Gram-negative anaerobes.