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Journal of Clinical Microbiology, August 2008, p. 2605-2612, Vol. 46, No. 8
0095-1137/08/$08.00+0 doi:10.1128/JCM.00640-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Sezione di Microbiologia del Di.S.C.A.T., University of Genoa, Genoa, Italy
Received 4 April 2008/ Returned for modification 16 May 2008/ Accepted 12 June 2008
A total of 148 E. coli strains displaying reduced susceptibility to ciprofloxacin (MIC
2 µg/ml) and causing uncomplicated urinary tract infections in eight European countries during 2003 to 2006 were studied. Their phylogenetic groups, biochemical profiles, and antibiotic susceptibilities were determined. Determination of the O:H serotype, pulsed-field gel electrophoresis (PFGE), randomly amplified polymorphic DNA (RAPD) PCR, and multilocus sequence typing provided additional discrimination. The majority (82.4%) of the microorganisms (122/148) carried resistance to two or more additional drugs, with the pattern ciprofloxacin-trimethoprim-sufamethoxazole-tetracycline-ampicillin being the most represented (73 strains out of 148; 49.3%). Extended-spectrum beta-lactamase production was detected in 12/148 strains (8.1%), with CTX-M-15 being the most-common enzyme. Six strains out of the whole collection studied (4.0%) contained a qnrB-like gene. Overall, 55 different PFGE or RAPD PCR profiles could be distinguished, indicating a substantial heterogeneity. However, about one-third (51/148) of the strains belonged to two clonal groups: O15:K52:H1 (phylogenetic group B2, lactose-nonfermenting variant, ciprofloxacin MIC of 16 µg/ml) and O25:H4 sequence type 131 (ST-131) (phylogenetic group D, ciprofloxacin MIC of
32 µg/ml). With the exception of Poland, strains of these two groups were isolated in samples from all participating countries but more frequently in samples from Spain and Italy. In some representative strains of the two main clonal groups, alterations in GyrA and ParC were the basic mechanism of fluoroquinolone resistance. In some members of the O25:H4 ST-131 group, displaying a ciprofloxacin MIC of >32 µg/ml, additional OmpF loss or pump efflux overexpression was found. In the Mediterranean area, strains belonging to these two clonal groups played a major role in determining the high rate of fluoroquinolone-resistant E. coli strains observed in the community.
Published ahead of print on 25 June 2008.
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