The present investigation was undertaken to assess the prevalence of extended-spectrum
β
-lactamases
(ES
β
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
β
-lactamase production was investigated. A total of 50 of the 650 isolates were double-disk positive
and suspected of producing an ES
β
L;
Escherichia coli
(36.0%) and
Klebsiella pneumoniae
(32.0%) were the
most common species among all ES
β
L producers. Characterization of ES
β
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
blaTEM
,
blaSHV
,
blaPER
, and
blaCTX-M
determinants. The ES
β
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, CTX-M-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
β
L
enzymes among enterobacterial pathogens causing UTIs in southern Italy.