title: Characterization of plasmids carrying the blaOXA-24/40 carbapenemase gene and the genes encoding the AbkA/AbkB proteins of a toxin/antitoxin system.
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.
authors.affiliation: Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain.
authors.forename: Noraida
authors.initials: N
authors.lastname: Mosqueda
authors.affiliation: Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña-INIBIC, La Coruña, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Gato
authors.affiliation: Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain.
authors.forename: Ignasi
authors.initials: I
authors.lastname: Roca
authors.affiliation: Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña-INIBIC, La Coruña, Spain.
authors.forename: María
authors.initials: M
authors.lastname: López
authors.affiliation: Microbiology Service, Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain.
authors.forename: Carlos Ruíz
authors.initials: CR
authors.lastname: de Alegría
authors.affiliation: Clinical Unit for Infectious Diseases and Microbiology, Hospital Universitario Virgen Macarena, and University of Seville, Seville, Spain.
authors.forename: Felipe
authors.initials: F
authors.lastname: Fernández Cuenca
authors.affiliation: Microbiology Service, Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain Department of Molecular Biology, University of Cantabria, Santander, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Martínez-Martínez
authors.affiliation: Clinical Unit for Infectious Diseases, Microbiology and Preventive Medicine-IBiS, University Hospital Virgen del Rocío, Seville, Spain.
authors.forename: Jerónimo
authors.initials: J
authors.lastname: Pachón
authors.affiliation: Clinical Unit for Infectious Diseases, Microbiology and Preventive Medicine-IBiS, University Hospital Virgen del Rocío, Seville, Spain.
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Cisneros
authors.affiliation: Clinical Unit for Infectious Diseases and Microbiology, Hospital Universitario Virgen Macarena, and University of Seville, Seville, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Rodríguez-Baño
authors.affiliation: Clinical Unit for Infectious Diseases and Microbiology, Hospital Universitario Virgen Macarena, and University of Seville, Seville, Spain.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pascual
authors.affiliation: 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.
authors.forename: Jordi
authors.initials: J
authors.lastname: Vila
authors.affiliation: Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña-INIBIC, La Coruña, Spain.
authors.forename: Germán
authors.initials: G
authors.lastname: Bou
authors.affiliation: Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña-INIBIC, La Coruña, Spain ma.del.mar.tomas.carmona@sergas.es.
authors.forename: María
authors.initials: M
authors.lastname: Tomás
mesh_terms: D000151:Acinetobacter Infections / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000992:Antitoxins / Q000235:genetics*; D001427:Bacterial Toxins / Q000235:genetics*; D005843:Geography; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010957:Plasmids / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D000992:Antitoxins; D001427:Bacterial Toxins; D001618:beta-Lactamases; C410345:beta-lactamase OXA-24; C488541:beta-lactamase OXA-40, Acinetobacter baumannii
keywords: A. baumannii; Acinetobacter baumannii; blaOXA-24/40-like