Extended-spectrum beta-lactamases in isolates of Enterobacteriaceae from inpatients and outpatients in Northern Italy

Abstract number: 902_p754

Luzzaro F.


Extended-spectrum beta-lactamases (ESBL) are important resistance traits for nosocomial isolates of Enterobacteriaceae and their spread in the community generates increasing concern. This study was performed to investigate the prevalence of ESBL producers in Enterobacteria isolated from both inpatients and outpatients in three different geographic areas of Northern Italy.


2600 consecutive nonreplicate isolates of Enterobacteriaceae were collected at three Clinical Microbiology Laboratories (Novara, Varese, and Verona; 1850 isolates from inpatients and 750 from outpatients) from June to November 2003. ESBL production was screened for by MIC analysis and confirmed by the double-disk synergy test. ESBL determinants of the TEM-, SHV-, CTX-M-, and PER-type were investigated by molecular analysis (colony-blot hybridisation, PCR and DNA sequencing).


The average prevalence of ESBL producers was 7.5% among isolates from inpatients (range 4.8–8.5% in different hospitals) and 2.5% among outpatient isolates (range 0.8–5.6% in different geographic areas). Approximately 70% of the ESBL-producing strains belonged to just three species: Proteus mirabilis (n = 45), Escherichia coli (n = 34), and Klebsiella pneumoniae (n = 31). Most ESBLs were of the TEM- or SHV-type, the TEM-52 and SHV-12 enzymes showing the highest prevalence. CTX-M type enzymes appeared to emerge, with most of these resistance traits detected in E. coli isolates. Enzymes of the PER-type were not found.


ESBL producers are widespread in different hospitals of Northern Italy and are also present in the community, though at lower rates. A variety of ESBL has been detected in several different species of Enterobacteriaceae and their expression is usually associated with multi-drug resistance. Thus, surveillance of ESBL dissemination appears to be important also for community acquired isolates.


Supported by an educational grant from Wyeth-Lederle SpA, Italy.


Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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