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

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Abstract
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 , and Peptostreptococcus prevotii ) and Porphyromonas spp. ( Porphyromonas asaccharolytica , Porphyromonas canoris , Porphyromonas gingivalis , and Porphyromonas 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 (MIC 90 s) were ≤2 μg/ml: Actinomyces israelii , Actinomyces odontolyticus , Clostridium innocuum , Clostridium clostridioforme , Anaerobiospirillum spp., Bacteroides tectum , Bacteroides ureolyticus , Bacteroides gracilis (now Campylobacter gracilis ), Prevotella intermedia , Prevotella heparinolytica , and the Prevotella oris-buccae group. Fusobacterium naviforme and Fusobacterium necrophorum were also susceptible to ≤2 μg of gemifloxacin per ml, while Fusobacterium varium strains exhibited a bimodal pattern; the other Fusobacterium species, such as Fusobacterium ulcerans and Fusobacterium russii , as well as Veillonella spp., the Prevotella melaninogenica group, Prevotella bivia , Clostridium difficile , and Bilophila wadsworthia were relatively resistant to gemifloxacin (MIC 90 s, ≥4 μg/ml).