Increased in vitro activity of ceftriaxone by addition of tazobactam against clinical isolates of anaerobes.
A total of 461 clinical strains of anaerobes were tested using a broth microdilution test to determine the activity of the combination of ceftriaxone and tazobactam and other antimicrobials against these isolates. Ceftriaxone was combined with tazobactam in ratios of 1:1, 2:1, 4:1, and 8:1 and twofold dilutions of ceftriaxone in constant concentrations to tazobactam of 2, 4, 8, 16, and 32 micrograms/ml. Against beta-lactamase-producing strains of the Bacteroides fragilis group, B. capillosus, and Prevotella species all combinations of ceftriaxone and tazobactam showed enhanced in vitro activity and were eight- to 2048-fold more active than ceftriaxone alone. By comparison ceftriaxone and tazobactam showed superior or equal activity to ampicillin and sulbactam, piperacillin and tazobactam, amoxicillin and clavulanate, ticarcillin and clavulanate, and metronidazole against these same strains. Against beta-lactamase nonproducing strains of Porphyromonas, Fusobacterium, Clostridium, Eubacterium, Peptostreptococcus, and Veillonella parvula the addition of tazobactam produced no appreciable enhanced ceftriaxone activity. Fixed concentrations of tazobactam at 2 and 4 micrograms/ml appear to be most suitable for susceptibility testing and are within the pharmacologic profile of this inhibitor. Pharmacologic and toxicity studies will be needed to define the role of ceftriaxone and tazobactam in infectious diseases.
Department of Medicine, Louisiana State University Medical Center, New Orleans 70112.
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KE
Aldridge
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N
Morice
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Schiro
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001421:Bacteria, Anaerobic / Q000145:classification / Q000187:drug effects*; D002443:Ceftriaxone / Q000494:pharmacology*; D004359:Drug Therapy, Combination / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D010397:Penicillanic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D000078142:Tazobactam; D065093:beta-Lactamase Inhibitors
D000900:Anti-Bacterial Agents; D065093:beta-Lactamase Inhibitors; D002443:Ceftriaxone; D010397:Penicillanic Acid; D000078142:Tazobactam