Comparison of four antimicrobial susceptibility testing methods to determine the in vitro activities of piperacillin and piperacillin-tazobactam against clinical isolates of Enterobacteriaceae and Pseudomonas aeruginosa

J Clin Microbiol. 2003 Jul;41(7):3339-43. doi: 10.1128/JCM.41.7.3339-3343.2003.

Abstract

Susceptibility to piperacillin was similar to that to piperacillin-tazobactam (<1% difference) for 6,938 isolates of Enterobacter aerogenes and 13,954 isolates of Enterobacter cloacae tested using a Vitek system; for the same species, in contrast, susceptibility rates to piperacillin-tazobactam were 5.9 to 13.9% higher than to piperacillin using disk diffusion, MicroScan, and Vitek 2 testing. Unprecedented phenotypes (piperacillin susceptible and piperacillin-tazobactam intermediate; piperacillin intermediate and piperacillin-tazobactam resistant; piperacillin susceptible and piperacillin-tazobactam resistant) accounted for 6.1% of the results for E. aerogenes isolates and 6.0% of the results for E. cloacae isolates tested with the Vitek system.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Drug Resistance, Bacterial
  • Drug Therapy, Combination / pharmacology*
  • Enterobacteriaceae / classification
  • Enterobacteriaceae / drug effects*
  • Humans
  • Microbial Sensitivity Tests / methods
  • Penicillanic Acid / analogs & derivatives
  • Penicillanic Acid / pharmacology*
  • Penicillins / pharmacology*
  • Piperacillin / pharmacology*
  • Piperacillin, Tazobactam Drug Combination
  • Population Surveillance
  • Pseudomonas aeruginosa / drug effects*

Substances

  • Penicillins
  • Piperacillin, Tazobactam Drug Combination
  • Penicillanic Acid
  • Piperacillin