Molecular characterisation of PER-1 extended-spectrum b-lactamase producing Pseudomonas aeruginosa clinical isolates from Romania

Abstract number: P1213

Straut M., Cretoiu S., Dragulescu C., Lixandru B., Petrescu A.M., Surdeanu M.

Objectives: The presence of PER-1-producing P. aeruginosa isolates in Romania has been already described since 2005. The aim of the present study was to characterise the genetic structures associated with the bla genes harboured by these strains and to establish any clonal relationships between the isolates.

Methods: Analytical isoelectric focusing was used for preliminary characterisation of the b-lactamases expressed by the isolates included in this study. PCR using blaPER-1, blaOXA-2, and blaOXA-10 specific primers, followed by DNA sequencing, was performed in order to identify b-lactamase genes present in P. aeruginosa isolates. The occurrence of class1 integrons and Tn1213 transposon was assessed by PCR. Amplicons were further analysed by RFLP (restriction fragment length polymorphism) technique using several combinations of restriction endonucleases. Clonal relationships of PER-1 producing isolates were established by pulsed-field gel electrophoresis (PFGE) analysis of macrorestriction patterns of genomic DNA.

Results: Seventy-four out of 94 ceftazidime resistant clinical isolates examined were PCR-positive for blaPER-1. In all of the studied isolates the blaPER-1 gene was located within a composite transposon Tn1213, bracketed by two different insertion sequences, ISPa12 and ISPa13 (Poirel et al, 2005, Antimicrob. Agents Chemother.: 1708–1713). Additionally, PCR experiments revealed the presence of a pair of class 1 integrons of 3350 bp and 3900 bp among the majority of isolates. The 3350 bp class 1 integron harboured blaOXA-74 gene in the first gene cassette position and the aminoglycoside resistance gene aacA4 in the second place. The blaOXA-2 gene is located within the variable region of the 3900bp integron. The PER-1 producing isolates, originating from nine Bucharest hospitals, clustered into four PFGE types with a high degree of similarity.

Conclusions: PER-1 appears to have a significant presence among the clinical isolates from Bucharest hospitals. PER-1 expression was inferred to be the major source of oxyimino-b-lactam resistance in the examined isolates although they also produced other b-lactamases. Along with some recent reports from other European countries, this work illustrates the ongoing dissemination of organisms with PER-type extended-spectrum b-lactamase.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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