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The first incidence of PER-1 ESBL-producing Pseudomonas aeruginosa in Poland and identification of a novel OXA beta-lactamase variant

Abstract number: 1134_01_386

Empel J., Filczak K., Mrowka A., Hryniewicz W., Gniadkowski M.

Objectives:  

To analyse an outbreak caused by ESBL-producing P. aeruginosa in one of Warsaw hospitals.

Methods:  

Thirty-eight ESBL-producing P. aeruginosa isolates were collected between September 2003 and May 2004 from patients in different wards of a Warsaw hospital. The ESBL production was confirmed by the double-disc test. MICs of 14 antibiotics were determined by the NCCLS agar dilution method. Molecular typing was performed by the PFGE analysis of the XbaI-digested bacterial DNA. Beta-lactamases of the isolates were visualised by isoelectric focusing (IEF) of whole-cell extracts. Genes coding for the enzymes were identified by PCR and sequencing of the resulting amplicons.

Results:  

The susceptibility testing revealed that the P. aeruginosa isolates were multiresistant, demonstrating resistance to beta-lactams, aminoglycosides and ciprofloxacin. Their patterns of resistance to beta-lactams were typical for ESBL producers except for the fact that all but 5 isolates were susceptible to piperacillin. The PFGE analysis classified the isolates into two different types; 35 isolates represented PFGE type A and the remaining 3 isolates belonged to type B. The PFGE type A isolates were characterised by beta-lactamase IEF patterns consisting of enzymes with pIs of 5.3, 7.7 and 8.2 (33 isolates), or 5.3 and 8.2 (2 isolates). The PFGE type B isolates produced beta-lactamases with pIs of 5.3, 6.5, 7.7 and 8.2. Of the enzymes observed in the all isolates, the one with the pI of 8.2 corresponded to the species-specific AmpC cephalosporinase, whereas that with the pI of 5.3 was identified as the PER-1 ESBL. The pI 7.7 and 6.5 IEF bands were assigned to OXA-2 and OXA-74 beta-lactamases, respectively. OXA-74, produced exclusively by the PFGE type B isolates, is a novel variant of OXA-10-related oxacillinases. Although no other bands were observed in the IEF analysis, PCR amplicons specific for the blaOXA-50 gene, which naturally occurs in P. aeruginosa, were generated for the all isolates.

Conclusions:  

PER-1-producing P. aeruginosa was identified for the first time in Poland. It caused a highly clonal outbreak in one of Warsaw hospitals. It is possible that a blaPER-1 gene-containing determinant was transmitted between two separate clones of the organism observed during the outbreak.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
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