title: Prediction of piperacillin-tazobactam susceptibility among Enterobacteriaceae, Pseudomonas aeruginosa, and other bacteria using ticarcillin-clavulanic acid, ceftazidime, and other broad-spectrum antimicrobial in vitro test results.
abstract: The ability of various in vitro beta-lactam susceptibility test results to predict the susceptibility of piperacillin-tazobactam (a new beta-lactam-beta-lactamase inhibitor combination) was assessed using more than 46,000 recent clinical isolates. The organisms were tested by reference-quality National Committee for Clinical Laboratory Standards (NCCLS) broth microdilution procedures and interpreted by the currently published NCCLS criteria. The recommended antimicrobial tests that would accurately predict the piperacillin-tazobactam in vitro efficacy had an overall very major, false-susceptible rate of only 0.6% (< or = 1.5% is acceptable). The following drug tests can be used to judge piperacillin-tazobactam activity and spectrum (low patient risk) conservatively: for Enterobacteriaceae use ticarcillin-clavulanic acid results (0.6% very major error); for Pseudomonas aeruginosa use piperacillin (0.1%) results; for enterococci use ampicillin or ampicillin-sulbactam (1.8%) results; for Haemophilus influenzae and Moraxella catarrhalis use cefotaxime or cefuroxime or ceftriaxone (1.5%); and for staphylococci use oxacillin by NCCLS recommendations. When the piperacillin-tazobactam testing reagents become available, the direct testing of this combination should be applied to relevant clinical isolates. The piperacillin-tazobactam break points should be reassessed as indicated by the cited minimum inhibitory concentration population analysis to improve predictive accuracy; H. influenzae susceptibility modified to < or = 2/4 micrograms/ml and Enterococcus species susceptibility tested at < or = 16/4 micrograms.
authors.affiliation: Department of Pathology, University of Iowa College of Medicine, Iowa City 52242.
authors.forename: R N
authors.initials: RN
authors.lastname: Jones
authors.forename: L D
authors.initials: LD
authors.lastname: Sutton
authors.forename: H F
authors.initials: HF
authors.lastname: Cantrell
authors.forename: R B
authors.initials: RB
authors.lastname: Lankford
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002442:Ceftazidime / Q000494:pharmacology; D002969:Clavulanic Acids / Q000494:pharmacology; D004755:Enterobacteriaceae / Q000187:drug effects*; D013293:Enterococcus faecalis / Q000187:drug effects; D006193:Haemophilus influenzae / Q000187:drug effects; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000592:standards; D001936:Moraxella catarrhalis / Q000187:drug effects; D010397:Penicillanic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D010878:Piperacillin / Q000494:pharmacology; D011237:Predictive Value of Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D013210:Staphylococcus / Q000187:drug effects; D000078142:Tazobactam; D013982:Ticarcillin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D002969:Clavulanic Acids; D010397:Penicillanic Acid; D002442:Ceftazidime; D013982:Ticarcillin; D000078142:Tazobactam; D010878:Piperacillin