Extended-spectrum b-lactamases and plasmid-mediated AmpC enzymes among Enterobactercloacae strains isolated from cardiovascular prosthetic devices associated infections

Abstract number: 1734_46

Cernat R., Balotescu C., Lazar V., Banu O., Ivanescu D., Bucur M.

Objective: The purpose of this study was to establish the frequency of resistance to broad-spectrum cephalosporins of E. cloacae strains isolated from patients with cardiovascular prosthetic implants hospitalised in a Romanian institution and to characterise the types of ESBL produced.

Material and Methods: During 2003–2006, 120 E. cloacae strains were recovered. ESBL-producing enzymes were screened by double-disk synergy test or positive ceftazidime and cefotaxime clavulanic combination discs tests. MICs of 18 antibiotics were performed by microdilution broth method against ESBL-positive strains. Isoeletrofocusing (IEF) and PCR with specific primers were used to confirm and type b-lactamase genes in ESBL producers: blaTEM, blaOXA, blaSHV, blaCTX-M and ampC. When IEF and PCR indicated concordant results, final identification of ESBL enzymes was obtained by sequence analysis. PFG with XbaI-digested genomic DNA established the diversity of ESBL-positive clones.

Results: 46 of 120 (38.3%) strains were confirmed as ESBL producers and showed a multiresistance phenotype. All strains had the ubiquitary blaCTX-M, blaTEM genes plus AmpC gene. Sequencing of blaCTX-M, blaTEM amplicons identified that all the strains encode the TEM-1A enzyme, 20 the CTX-M-15 and 5 the CTX-M-3; these enzymes were characterised with pIs of 5.4 and between 8.0 and 9.0 respectively. PFGE profiles of these strains indicated that only five clones were related.

Conclusion: This study illustrates a high frequency of polyclonal dissemination of resistance to broad-spectrum b-lactams in a hospital in Romania through CTX-M ESBL, most probably facilitated by mobile elements such as gene cassettes for which preliminary results indicated to be carried by the class 1 integrons. Our results suggest that in Romania also the therapeutic options may be dramatically diminished if CTX-M enzymes continue spreading among Enterobacteriaceae implicated in the aetiology of bacterial infections occurred in hospitalised patients with cardiovascular prosthetic devices.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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