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J Antimicrob Chemother. 2008 Dec;62(6):1265-8. doi: 10.1093/jac/dkn400. Epub 2008 Sep 26.

Detection of Pseudomonas aeruginosa isolates producing VEB-type extended-spectrum beta-lactamases in the United Kingdom.

Author information

1
Centre for Infections, Health Protection Agency, 61 Colindale Avenue, London NW9 5EQ, UK.

Abstract

OBJECTIVES:

The aim of this study was to investigate the presence of VEB enzymes among Pseudomonas spp. referred to the UK's national reference laboratory and with phenotypic evidence of extended-spectrum beta-lactamase (ESBL) production.

METHODS:

Antibiograms were analysed for Pseudomonas spp. referred from November 2003 to November 2007. Isolates with >/=4-fold ceftazidime/clavulanate synergy were screened for bla(VEB) alleles. Genes encoding metallo-beta-lactamases (bla(MBL)) were sought in isolates with positive imipenem/EDTA synergy tests. Selected PCR products were sequenced. PFGE of SpeI-digested genomic DNA was used to compare isolates.

RESULTS:

Forty-nine (3.7%) of 1338 Pseudomonas spp. were considered potential ESBL producers; 40 were recovered for molecular testing. bla(VEB) alleles were detected in 32 Pseudomonas aeruginosa isolates, comprising diverse PFGE types, from 12 UK hospitals and 1 in India. One UK centre referred 15 isolates with VEB-1 enzyme; these were serotype O15, representing a single PFGE-defined strain that also produced VIM-10 metallo-carbapenemase. This strain was resistant to all beta-lactams, aminoglycosides and ciprofloxacin, remaining susceptible only to colistin (MICs </=1 mg/L). Two other P. aeruginosa isolates co-producing both VEB and VIM enzymes were received from two other UK hospitals; one isolate represented inter-hospital spread of the O15 strain and the second was distinct.

CONCLUSIONS:

VEB enzymes have not been reported previously in the UK, but were produced by 80% of Pseudomonas spp. with phenotypic evidence of ESBL production. They co-existed with VIM carbapenemases in two strains, with one responsible for a major hospital outbreak. The incidence of ESBLs may be underestimated in Pseudomonas because ESBL phenotypes can be masked by other beta-lactam resistance mechanisms.

PMID:
18819973
DOI:
10.1093/jac/dkn400
[Indexed for MEDLINE]

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