Antimicrobial susceptibility of clinical isolates of Enterobacteriaceae producing complex β-lactamase patterns including extended-spectrum enzymes

Bernardetta Segatore, Domenico Setacci, Mariagrazia Perilli, Luigi Franchino, Nicola Franceschini, Alessio Agnifili, Gian Maria Rossolini, Gianfranco Amicosante

Research output: Contribution to journalArticlepeer-review

Abstract

The antimicrobial susceptibility of 103 clinical isolates of Enterobacteriaceae to 11 antibiotics, was investigated, using a conventional inoculum size (5×105 CFU) and a higher inoculum size (5×108 CFU). All the isolates produced complex β-lactamase patterns, including an extended-spectrum β-lactamase (ESBL) of the TEM- or SHV-type plus other enzymes (a TEM-type or an SHV-type non-ESBL and/or a class C enzyme). The following repertoire of ESBLs was produced by the isolates: TEM-15, TEM-19, TEM-26, TEM-52, TEM-72, TEM-87, TEM-92, SHV-2a, SHV-5 and SHV-12, as assessed by sequencing. Production of the other enzymes was showed by analytical isoelectric focusing. Overall, meropenem was the most active agent and less influenced by inoculum size, while other β-lactams showed a lower activity and a significant inoculum size effect. In conclusion, from its in vitro performance, meropenem could be considered as the last resource drug against strains producing complex β-lactamase patterns including an ESBL.

Original languageEnglish
Pages (from-to)480-486
Number of pages7
JournalInternational Journal of Antimicrobial Agents
Volume23
Issue number5
DOIs
Publication statusPublished - May 2004

Keywords

  • β-Lactam antibiotics
  • ESBL
  • Resistance

ASJC Scopus subject areas

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

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