Multicenter evaluation of the new etest gradient diffusion method for piperacillin-tazobactam susceptibility testing of enterobacterales, pseudomonas aeruginosa, and acinetobacter baumannii complex

Sergio García-Fernández, Yohann Bala, Tom Armstrong, María García-Castillo, Carey Ann D. Burnham, Meghan A. Wallace, Dwight Hardy, Gilles Zambardi, Rafael Cantón

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Piperacillin-tazobactam (P/T) is a β-lactam-β-lactamase inhibitor combination frequently used in the hospital setting. Etest is a gradient diffusion method that represents an alternative to broth microdilution (BMD) for performing antimicrobial susceptibility testing. We conducted a multicenter evaluation of the performance of the new P/T Etest compared to that of BMD following U.S. Food and Drug Administration (FDA) and International Standards Organization (ISO) standard ISO 20776-2 criteria using Clinical and Laboratory Standards Institute (CLSI)-FDA and European Committee on Antimicrobial Susceptibility Testing (EUCAST) interpretive breakpoints, respectively. A total of 977 isolates (775 Enterobacterales isolates, 119 Pseudomonas aeruginosa isolates, and 83 Acinetobacter baumannii complex isolates) were tested. Overall essential agreement (EA) was 96.4% and 96.6% for Enterobacterales when FDA and ISO 20776-2 criteria, respectively, were followed. EA was 98.3% for P. aeruginosa and 91.6% for the A. baumannii complex when both the FDA and ISO criteria were followed. Applying CLSI-FDA breakpoints, categorical agreement (CA) reached 93.0%, 93.3%, and 89.2% for the Enterobacterales, P. aeruginosa, and the A. baumannii complex, respectively. Two very major errors (VMEs; 1.1%) were found among the Enterobacterales (for 2 Klebsiella pneumoniae isolates). No additional major errors (MEs) or VMEs were found. Applying EUCAST breakpoints, CA was 94.8% and 95.8% for Enterobacterales and P. aeruginosa, respectively (no breakpoints are currently available for the A. baumannii complex). No VMEs were observed among the Enterobacterales, but 2 (0.4%) MEs were found. Among the P. aeruginosa isolates, 2 (6.9%) VMEs and 3 (3.3%) MEs were observed. These errors resulted when P/T Etest MICs were 1 doubling dilution apart from the BMD MICs. In conclusion, the new P/T Etest represents an accurate tool for performing antimicrobial susceptibility testing of Enterobacterales, P. aeruginosa, and A. baumannii complex isolates with limited category errors.

Original languageEnglish
Article numbere01042-19
JournalJournal of clinical microbiology
Volume58
Issue number2
DOIs
StatePublished - Jan 1 2020

Keywords

  • Acinetobacter baumannii complex
  • Antimicrobial susceptibility testing
  • Enterobacterales
  • Etest
  • Gradient diffusion
  • Piperacillin-tazobactam
  • Pseudomonas aeruginosa

Fingerprint Dive into the research topics of 'Multicenter evaluation of the new etest gradient diffusion method for piperacillin-tazobactam susceptibility testing of enterobacterales, pseudomonas aeruginosa, and acinetobacter baumannii complex'. Together they form a unique fingerprint.

  • Cite this