Occurrence of extended spectrum beta-lactamases among isolates of Enterobacteriaceae from urinary tract infections in southern Italy

The present investigation was undertaken to assess the prevalence of extended-spectrum beta-lactamases (ES beta Ls) among urinary tract infection (UTI) isolates. During 4 months in 2004, a total of 650 Enterobacteriaceae strains from UTIs was collected by Five clinical microbiology laboratories located in southern Italy and the beta-lactamase production was investigated. A total of 50 of the 650 isolates were double-disk positive and suspected of producing an ES beta L; Escherichia coli (36.0%) and Klebsiella pneumoniae (32.0%) were the most common species among all ES beta L producers. Characterization of ES beta L determinants was carried out by the colony blot hybridization method, and polymerase chain reaction (PCR) and DNA sequencing in order to identify the presence of bla(TEM), bla(SHV), bla(PER), and bla(CTX-M) determinants. The ES beta L variants found in this study were the following: TEM-15, TEM-24, TEM-52, TEM-134, SHV-12, CTX-M-1, CTX-M-3, CTXM-15, and PER-1. As expected, the majority of the isolates were found to be susceptible to imipenem (94%), cefepime (54%) and piperacillin-tazobactam (54%). The results of this survey show the prevalence of ES beta L enzymes among enterobacterial pathogens causing UTIs in southern Italy.