Performance in detection and reporting β-lactam resistance phenotypes in Enterobacteriaceae: a nationwide proficiency study in Italian laboratories

Francesco Luzzaro, Giovanni Gesu, Andrea Endimiani, Giuseppe Ortisi, Sergio Malandrin, Laura Pagani, Gian Maria Rossolini

Research output: Contribution to journalArticlepeer-review

Abstract

We evaluated the ability of 60 Italian clinical microbiology laboratories in detecting and reporting β-lactam resistance phenotypes in Enterobacteriaceae. Laboratories received 5 well-characterized isolates producing extended-spectrum β-lactamases (ESBLs), 2 hyperproducers of chromosomal enzymes, and 3 quality control strains. The performances in antimicrobial susceptibility testing (AST) were different depending on the species and type of ESBL produced. High rates of very major errors (up to 56%) were observed for ESBL producers when testing cephalosporins and aztreonam, especially in the case of CTX-M-1-producing Escherichia coli and TEM-52-producing Proteus mirabilis. Isolates hyperproducing chromosomal enzymes were erroneously reported as ESBL producers in approximately 20% of cases. Detection of ESBLs is still a problem for clinical microbiology laboratories. Overall, performances in AST appear to be better with Klebsiella spp. producing well-known enzymes (e.g., SHV type) than with strains producing emerging enzymes (e.g., CTX-M type) or organisms not well recognized as ESBL producers (e.g., P. mirabilis).

Original languageEnglish
Pages (from-to)311-318
Number of pages8
JournalDiagnostic Microbiology and Infectious Disease
Volume55
Issue number4
DOIs
Publication statusPublished - Aug 2006

Keywords

  • β-Lactamases
  • Antimicrobial resistance
  • AST
  • Enterobacteria
  • ESBL

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Immunology
  • Microbiology
  • Parasitology
  • Virology
  • Immunology and Allergy
  • Infectious Diseases

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