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.


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


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.


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.


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
Location: Oxford, UK
Presentation type:
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