Detection and characterization of class A extended-spectrum-{beta}-lactamase-producing Pseudomonas aeruginosa isolates in Belgian hospitals.

Glupczynski, Gerald [UCL] Bogaerts, Pierre [UCL] Deplano, A. [Laboratoire de Bactériologie, Hôpital Universitaire Erasme, Université Libre de Bruxelles, B-1070 Bruxelles, Belgium] Berhin, C. Huang, Te-Din [UCL] Van Eldere, J. [Laboratory of Microbiology, Catholic University of Leuven, B-300 Leuven, Belgium] Rodriguez-Villalobos, Hector [Laboratoire de Bactériologie, Hôpital Universitaire Erasme, Université Libre de Bruxelles, B-1070 Bruxelles, Belgium] et al.[show all]

Objectives To investigate the presence of extended-spectrum beta-lactamases (ESBLs) among Pseudomonas aeruginosa clinical isolates referred to two Belgian reference laboratories. Methods Antibiograms were analysed for P. aeruginosa isolates referred between 2004 and 2008. Isolates resistant to ceftazidime (MIC > 8 mg/L) and with a positive double-disc synergy test between ceftazidime and clavulanate were serotyped and screened for the presence of ESBL-encoding genes. Genes encoding metallo-beta-lactamases (bla(MBL)) were sought by PCR in ESBL-producing isolates with positive imipenem/EDTA synergy tests. PFGE of SpeI-digested genomic DNA was used to compare isolates and selected strains were characterized by multilocus sequence typing. Results Forty-eight (2.2%) of 2150 P. aeruginosa isolates were confirmed as class A ESBL-producing isolates by molecular testing. bla(BEL) and bla(PER) alleles were detected, respectively, in 39 and 10 P. aeruginosa isolates originating from 16 hospitals (two isolates were simultaneously positive for BEL and PER). Fifteen of the isolates were found to co-produce ESBLs and VIM carbapenemases. These strains were pan-resistant and remained susceptible only to colistin (MICs