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J Antimicrob Chemother. 2014 Oct;69(10):2629-33. doi: 10.1093/jac/dku179. Epub 2014 May 30.

Characterization of plasmids carrying the blaOXA-24/40 carbapenemase gene and the genes encoding the AbkA/AbkB proteins of a toxin/antitoxin system.

Author information

1
Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain.
2
Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña-INIBIC, La Coruña, Spain.
3
Microbiology Service, Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain.
4
Clinical Unit for Infectious Diseases and Microbiology, Hospital Universitario Virgen Macarena, and University of Seville, Seville, Spain.
5
Microbiology Service, Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain Department of Molecular Biology, University of Cantabria, Santander, Spain.
6
Clinical Unit for Infectious Diseases, Microbiology and Preventive Medicine-IBiS, University Hospital Virgen del Rocío, Seville, Spain.
7
Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain Department of Clinical Microbiology, Hospital Clínic, School of Medicine, University of Barcelona, Barcelona, Spain.
8
Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña-INIBIC, La Coruña, Spain ma.del.mar.tomas.carmona@sergas.es.

Abstract

BACKGROUND:

Carbapenem-resistant Acinetobacter baumannii (CRAb) is a major source of nosocomial infections in Spain associated with the production of OXA-58-like or OXA-24/40-like β-lactamase enzymes. We analysed the plasmids carrying the bla(OXA-24/40)-like gene in CRAb isolates obtained a decade apart.

METHODS:

The presence of β-lactamases was screened for by PCR (metallo-β-lactamases, carbapenem-hydrolysing class D β-lactamases, GES and KPC) in 101 CRAb isolates obtained in two multicentre studies (GEIH/REIPI-Ab-2000 and GEIH/REIPI-Ab-2010; n = 493 Acinetobacter spp). We analysed the distribution and characterization of the plasmids carrying the bla(OXA-24/40)-like gene and sequenced two plasmids, AbATCC223p (2000) and AbATCC329p (2010) from A. baumannii ATCC 17978 transformants.

RESULTS:

Acquisition of the bla(OXA-24/40)-like gene was the main mechanism underlying resistance to carbapenems (48.7% in 2000 compared with 51.6% in 2010). This gene was mainly isolated in ST2 A. baumannii strains in both studies, although some novel STs (ST79 and ST80) appeared in 2010. The gene was located in plasmids (8-12 kbp) associated with the repAci2 or repAci2/repGR12 types. The sequences of AbATCC223p (8840 bp) and AbATCC329p (8842 bp) plasmids were similar, particularly regarding the presence of the genes encoding the AbkA/AbkB proteins associated with the toxin/antitoxin system. Moreover, the abkA/abkB gene sequences (>96% identity) were also located in plasmids harbouring the bla(OXA-58)-like gene.

CONCLUSIONS:

The action of OXA-24/40 and OXA-58 β-lactamase-like enzymes represents the main mechanism underlying resistance to carbapenems in Spain in the last decade. AbkA/AbkB proteins in the toxin/antitoxin system may be involved in the successful dissemination of plasmids carrying the bla(OXA-24/40)-like gene, and probably also the bla(OXA-58)-like gene, thus contributing to the plasmid stability.

KEYWORDS:

A. baumannii; Acinetobacter baumannii; blaOXA-24/40-like

PMID:
24879663
DOI:
10.1093/jac/dku179
[Indexed for MEDLINE]

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