title: Activity of ticarcillin/clavulanate and piperacillin/tazobactam (YTR 830; CL-298,741) against clinical isolates and against mutants derepressed for class I beta-lactamase.
abstract: Piperacillin/tazobactam (YTR 830; CL-298,741) was tested against fresh and stock clinical isolates of Gram-negative bacilli, as well as against Gram-negative bacilli that had stably derepressed Class I beta-lactamases or that were hyperproductive of non-Class I beta-lactamases. Of 63 clinical isolates of the Enterobacteriaceae with ticarcillin (plus clavulanate) minimum inhibitory concentrations (MICs) of greater than or equal to 128 micrograms/ml, 16 had piperacillin/tazobactam MICs of less than or equal to 16/2 micrograms/ml. Of 48 clinical isolates of Pseudomonas spp. with ticarcillin (plus clavulanate) MICs of greater than or equal to 128 micrograms/ml, 35 had piperacillin/tazobactam MICs of less than or equal to 64/8 micrograms/ml. Tazobactam generally reduced piperacillin MICs by two- to greater than or equal to eightfold against stably derepressed mutants for Class I beta-lactamases.
authors.affiliation: Department of Microbiology, Cleveland Clinic Foundation, Ohio 44195.
authors.forename: C C
authors.initials: CC
authors.lastname: Knapp
authors.forename: J
authors.initials: J
authors.lastname: Sierra-Madero
authors.forename: J A
authors.initials: JA
authors.lastname: Washington
mesh_terms: D001419:Bacteria / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D002969:Clavulanic Acids / Q000494:pharmacology*; D004338:Drug Combinations; D004352:Drug Resistance, Microbial; D004359:Drug Therapy, Combination / Q000494:pharmacology; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D006801:Humans; D009154:Mutation; D010397:Penicillanic Acid / Q000494:pharmacology*; D010406:Penicillins / Q000494:pharmacology*; D010878:Piperacillin / Q000494:pharmacology*; D011549:Pseudomonas / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D000078142:Tazobactam; D013982:Ticarcillin / Q000494:pharmacology*; D065093:beta-Lactamase Inhibitors
chemical_list: D002969:Clavulanic Acids; D004338:Drug Combinations; D010406:Penicillins; D065093:beta-Lactamase Inhibitors; C043215:ticarcillin-clavulanic acid; D010397:Penicillanic Acid; D013982:Ticarcillin; D000078142:Tazobactam; D010878:Piperacillin