Epidemiology of the Acinetobacter-derived Cephalosporinase, Carbapenem-Hydrolysing Oxacillinase and metallo-β-lactamase Genes, and of Common Insertion Sequences, in Epidemic Clones of Acinetobacter Baumannii From Spain

J Antimicrob Chemother. 2013 Mar;68(3):550-3. doi: 10.1093/jac/dks448. Epub 2012 Nov 9.

Abstract

Objectives: To study the distribution, diversity and activity of Acinetobacter-derived cephalosporinase (ADC)-, carbapenem-hydrolysing oxacillinase (CHO)- and metallo-β-lactamase (MBL)-encoding genes, and of the most common insertion sequences (ISs), in the genome of nosocomial, epidemic, multidrug-resistant Acinetobacter baumannii (MDRAB) clones from Spain.

Methods: The studied population included 59 MDRAB strains previously genotyped by PFGE and multilocus sequence typing. The search for the ADC (bla(ADC)), CHO (bla(OXA-51-like), bla(OXA-23-like), bla(OXA-40-like) and bla(OXA-58-like)) and MBL (bla(IMP), bla(VIM), bla(SIM-1), bla(GIM-1), bla(SPM-1) and bla(NDM-1)) genes, and for the ISs (ISAba1, ISAba2, ISAba3, ISAba4 and IS18) was done by PCR assays. The phenotypic presence of MBL enzymes was examined using imipenem/imipenem + EDTA strips.

Results: The most prevalent IS, ISAba1 (93.2%), was detected upstream of bla(ADC) and bla(OXA-51-like). These genes showed ample diversity (10 and 8 alleles, respectively). Four ADC sequences (ADC-1-like(P240S), ADC-2-like(N260H/T264N), ADC-11-like(Q163K) and ADC-11-like(G342R)) are described here for the first time. bla(OXA-58-like) was carried by 20.3% of strains, in association with ISAba2, ISAba3 or IS18. bla(OXA-40-like) was the most prevalent acquired CHO gene (57.6%), and was associated with none of the studied ISs. Neither bla(OXA-23-like) nor ISAba4 was detected in any strain. Some 67.8% of strains with MBL activity showed no corresponding gene in PCR; these results were more common in strains with a highly active CHO, such as OXA-40.

Conclusions: All the studied genes and their related ISs showed a clonal distribution. Imipenem resistance was probably provided by OXA-40 for the most part, while MBL- and OXA-23-encoding genes were absent in the studied population.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter Infections / epidemiology*
  • Acinetobacter Infections / microbiology
  • Acinetobacter baumannii / enzymology*
  • Acinetobacter baumannii / genetics
  • Acinetobacter baumannii / isolation & purification
  • Cluster Analysis
  • Cross Infection / epidemiology
  • Cross Infection / microbiology
  • DNA Transposable Elements*
  • DNA, Bacterial / genetics
  • Drug Resistance, Multiple, Bacterial
  • Genetic Variation*
  • Genotype
  • Humans
  • Microbial Sensitivity Tests
  • Molecular Epidemiology
  • Molecular Typing
  • Polymerase Chain Reaction
  • Spain / epidemiology
  • beta-Lactamases / genetics*

Substances

  • DNA Transposable Elements
  • DNA, Bacterial
  • beta-Lactamases