Characterisation of extended-spectrum b-lactamases in clinical Escherichia coli isolates in a Spanish hospital

Abstract number: R2308

Somalo S., Vinué L., Olarte I., Undabeitia E., Ugalde E., Sáenz Y., Zarazaga M., Torres C.

Objective: To characterize the genes encoding ESBLs, their genetic environments and the phylogenetic groups of broad-spectrum cephalosporin-resistant clinical Escherichia coli isolates recovered in a Spanish hospital.

Methods: Seventy-seven broad-spectrum cephalosporin-resistant E. coli isolates recovered in the Hospital San Pedro (Logroño, Spain) during 2004–2007, presented a positive ESBL-screening test and were included in this study. Genes encoding CTX-M, SHV and TEM type b-lactamases were analysed by specific PCR-RFLP and/or PCR-sequencing. The genetic environment of blaCTX-M genes were characterised by PCR-mapping and the phylogenetic groups of ESBL-positive isolates were determined by PCR (chuA, tspE4.C2, and yjaA genes).

Results: The origin of the 77 ESBL-positive isolates were: urine (77%), blood (5%), wounds (5%), others (13%). The bla genes encoding the following ESBLs were detected in our 77 E. coli (number of isolates): blaCTX-M-14 (46), blaCTX-M-14 plus blaSHV-12 (3), blaCTX-M-67 (1), blaCTX-M-15 (2), blaCTX-M-9 (7), blaCTX-M-9 plus blaSHV-12 (1), blaSHV-12 (10), and unknown mechanisms (7). Thirty-seven of the 70 CTX-M and SHV-positive ESBL-isolates harboured a TEM b-lactamase. The surrounding regions of blaCTX-M genes detected in our isolates were as follows (number of isolates): ISEcp1-blaCTX-M-14-IS903 (38), blaCTX-M-14-IS903 (4), ISEcp1-blaCTX-M-14 (1), ISCR1-blaCTX-M-9-orf1005 (7), blaCTX-M-9-orf1005 (1), ISEcp1-blaCTX-M-67-IS903 (1), and blaCTX-M-15-orf477 (2 isolates). Forty-eight per cent of the ESBLs-positive isolates were classified into the A or B1 phylogenetic groups, and 52% into the B2 or D phylogenetic groups.

Conclusions: The ESBLs of the CTX-M-type are predominant in this hospital (80%), mainly of the CTX-M-9 group (77%), associated to SHV-12 (10%). Different genetic environments associated to ISEcp1 and ISCR1 were detected among our blaCTX-M-positive isolates.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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