Activities of Gemifloxacin (SB 265805, LB20304) Compared to Those of Other Oral Antimicrobial Agents against Unusual Anaerobes

The activities of gemifloxacin (SB 265805, LB20304) and comparator agents were determined by an agar dilution method against 419 clinical strains of less-commonly identified species of anaerobes. Gemifloxacin was generally more active than trovafloxacin against gram-positive strains by one to two dilutions. Peptostreptococci (Peptostreptococcus asaccharolyticus ,Peptostreptococcus magnus ,Peptostreptococcus micros , andPeptostreptococcus prevotii ) andPorphyromonas spp. (Porphyromonas asaccharolytica ,Porphyromonas canoris ,Porphyromonas gingivalis , andPorphyromonas macacae ) were all susceptible to ≤0.25 μg of gemifloxacin per ml. The MICs of gemifloxacin at which 90% of the following strains were inhibited (MIC90 s) were ≤2 μg/ml:Actinomyces israelii ,Actinomyces odontolyticus ,Clostridium innocuum ,Clostridium clostridioforme ,Anaerobiospirillum spp.,Bacteroides tectum ,Bacteroides ureolyticus ,Bacteroides gracilis (nowCampylobacter gracilis ),Prevotella intermedia ,Prevotella heparinolytica , and thePrevotella oris-buccae group.Fusobacterium naviforme andFusobacterium necrophorum were also susceptible to ≤2 μg of gemifloxacin per ml, whileFusobacterium varium strains exhibited a bimodal pattern; the otherFusobacterium species, such asFusobacterium ulcerans andFusobacterium russii , as well asVeillonella spp., thePrevotella melaninogenica group,Prevotella bivia ,Clostridium difficile , andBilophila wadsworthia were relatively resistant to gemifloxacin (MIC90 s, ≥4 μg/ml).