In vitro activities of three of the newer quinolones against anaerobic bacteria.

The antimicrobial activities of three new quinolone compounds, sparfloxacin, temafloxacin, and WIN 57273, against anaerobic bacteria were determined in three separate studies. The Wadsworth agar dilution technique using brucella-laked blood agar was used throughout. The activities of other antimicrobial agents, including ciprofloxacin, imipenem, chloramphenicol, metronidazole, cefotetan, cefoxitin, and amoxicillin-clavulanic acid, were also determined. The breakpoints of the new quinolones were 2 micrograms/ml for sparfloxacin and WIN 57273 and 4 micrograms/ml for temafloxacin. WIN 57273 displayed very good activity against anaerobes, inhibiting all strains of Bacteroides fragilis group species at 2 micrograms/ml. Only two strains of Fusobacterium species were resistant (MIC, 4 micrograms/ml). Sparfloxacin inhibited 78% of B. fragilis strains and 44% of other B. fragilis group isolates at 2 micrograms/ml. At 2 micrograms/ml, the percentages of other anaerobic species susceptible were as follows: B. gracilis, 70%; other Bacteroides species, 61%; Clostridium species, 50%; Fusobacterium species, 70%; Peptostreptococcus species, 91%; non-spore-forming gram-positive rods, 71%. Temafloxacin inhibited 91% of B. fragilis strains and 87% of other B. fragilis group species at 4 micrograms/ml. All strains of other Bacteroides species, 78% of Fusobacterium species, 80% of Clostridium species, and 90% of Peptostreptococcus species were inhibited at 4 micrograms of temafloxacin per ml.