Occurrence of OXA-58 and an OXA-58 variant in Acinetobacter baumannii isolates from blood cultures in a university hospital in Athens, Greece

Abstract number: 1733_366

Galani I., Sakka V., Galani L., Souli M., Chryssouli Z., Giamarellou H.

Objectives: Imipenem (IMP)-resistant A. baumannii isolates, collected from blood cultures of hospitalised patients in the University General Hospital ``Attikon'', between September 2004 – May 2005, were studied for their clonality and carbapenemase content.

Methods: Susceptibility to antimicrobials was determined using a broth microdilution method and E-test. Bacterial clones were identified by PFGE with ApaI. Metallo-b-lactamases were detected by the IMP-EDTA disc synergy test and by PCR with primers specific for blaVIM. Multiplex PCR with primers amplifying blaOXA-23-like, blaOXA-24-like, blaOXA-51-like and blaOXA-58-like, was performed according to Woodford et al (Int J Antimicrob Agents 2006; 27:351–353). Sequencing of cloned PCR products was performed by MWG-THE Genomic Company. Sequence similarity searches were carried out with the BLAST programme found at the website of the NCBI.

Results: Twenty-seven non-repetitive IMP-resistant isolates, 70.2% of all A. baumannii strains isolated from blood cultures, were tested. All isolates presented a multi-resistance pattern, with all being susceptible to colistin (MICs: 0.125–0.75) and 33% being susceptible also to ampicillin/sulbactam. A. baumannii isolates were distributed into seven genotypes by PFGE profiles, with 12, 4, 4, 3, 2, 1, and 1 strains in each group. The three genotype-groups of 12 and 4 isolates were further divided into 2 subgroups. None of the isolates was positive for metallo-b-lactamase production by IMP-EDTA synergy test or PCR. Multiplex PCR for OXA-type carbapenemases revealed the presence of blaOXA-51-like, which is believed to be intrinsic to A. baumannii and blaOXA-58-like in all isolates. Sequencing of blaOXA-58 PCR amplicon revealed the presence of the blaOXA-58 in most of the isolates but also the existence of a novel variant of OXA-58 in which an A to G substitution revealed a Thr to Ala amino acid change.

Conclusions: Several clones of IMP-resistant A. baumannii producing both blaOXA-58 and naturally occurring blaOXA-51-like have emerged as important bloodstream pathogens in our hospital. This observation emphasizes the importance of both the restriction of carbapenem usage as well as of the strict implementation of hand hygiene techniques for the containment of this emerging threat.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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