Resident OXA-51-like carbapenemases in Acinetobacter baumannii: a useful marker for genotyping?

Abstract number: 1733_503

Giani T., D'Andrea M.M., Migliavacca R., Spalla M., Nucleo E., Fina G., Luzzaro F., Pagani L., Rossolini G.M.

Objectives: Multi drug resistant (MDR) Acinetobacter baumannii is a problem of a great concern in nosocomial settings. Hospital outbreaks have been described worldwide and this organism has become endemic in some areas. Comparison of isolates obtained from different investigators is not straightforward, mostly because requires the interchange of isolates between laboratories and the standardisation of the genotyping techniques used. Recently resident blaOXA-51 type determinants have been proposed as a convenient marker for species identification, in alternative to previous molecular approaches. The aim of this study was to investigate the correlation between OXA-51-like carbapenemases and genotypes in a collection of A. baumannii isolates from Italian hospitals.

Methods:A. baumannii analyzed in this work included 151 clinical isolates, collected from 14 different Italian hospitals. Identification and susceptibility testing were carried out following standard procedures. Genotyping was carried out by RAPD, REP-PCR and PFGE analysis. OXA-51-like determinants were investigated by PCR, followed by direct amplicon sequencing.

Results: Genotyping analysis defined 5 major clusters of MDR A. baumannii, with consistent results using the various typing methods. Each cluster was characterised by a specific resident blaOXA-51-type carbapenemase, namely OXA-66, OXA-69, OXA-90, OXA-98 and OXA-100. The last three are new variants which differ from OXA-51 by 4, 7 and 6 amino acids respectively.

Conclusions: Consistent relationship between the blaOXA-51-like variants and genotyping results was found. Present results suggest that OXA-51 typing could be a useful marker for genotyping of A. baumannii clinical isolates.

This work was funded in part by the research grant ``MIUR-PRIN 2005061894_004''.

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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