Effect of pH on in vitro antimicrobial susceptibility of the Bacteroides fragilis group.
We studied the effect of pH (7.1, 6.3, and 5.8) on the in vitro susceptibilities of 59 isolates of Bacteroides fragilis and 60 isolates of other B. fragilis group species to trovafloxacin, ciprofloxacin, clindamycin, ampicillin-sulbactam, piperacillin-tazobactam, imipenem, and meropenem. For each agent tested the geometric mean MIC was highest at pH 5.8, intermediate at pH 6.3, and lowest at pH 7.1. The magnitude of the pH effect varied greatly among different antibiotics. These data show that an acidic pH decreases the in vitro susceptibilities of the B. fragilis group to several antibiotics.
Falagas
M E
ME
Department of Pathology (Clinical Microbiology), New England Medical Center and Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
McDermott
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Snydman
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D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001441:Bacteroides fragilis / Q000187:drug effects* / Q000378:metabolism; D002939:Ciprofloxacin / Q000494:pharmacology; D002981:Clindamycin / Q000494:pharmacology; D004359:Drug Therapy, Combination / Q000494:pharmacology; D024841:Fluoroquinolones; D006863:Hydrogen-Ion Concentration; D015378:Imipenem / Q000494:pharmacology; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D009287:Naphthyridines / Q000494:pharmacology; D010397:Penicillanic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D010878:Piperacillin / Q000494:pharmacology; D000077725:Piperacillin, Tazobactam Drug Combination; D013407:Sulbactam / Q000494:pharmacology; D013845:Thienamycins / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D009287:Naphthyridines; D013845:Thienamycins; D000077725:Piperacillin, Tazobactam Drug Combination; D002981:Clindamycin; D002939:Ciprofloxacin; C035444:sultamicillin; D015378:Imipenem; D000667:Ampicillin; D010397:Penicillanic Acid; C080163:trovafloxacin; D000077731:Meropenem; D013407:Sulbactam; D010878:Piperacillin