Clusters of imipenem-resistant Acinetobacter baumannii clones producing different carbapenemases in an intensive care unit

Clin Microbiol Infect. 2008 Jun;14(6):588-94. doi: 10.1111/j.1469-0691.2008.01996.x. Epub 2008 Apr 5.


During a 2-year period (April 2005-March 2007), 31 intensive care unit (ICU) patients in a Greek hospital were infected or colonised with imipenem-resistant isolates of Acinetobacter baumannii. Twelve patients died, with imipenem-resistant A. baumannii infection contributing to the death of seven patients. The 31 representative A. baumannii isolates were multidrug-resistant and clustered in four distinct clones, each of which contained different carbapenemase genes: clone I was predominant and contained bla(VIM-1), bla(OXA-58) and the intrinsic bla(OXA-66) gene; clone II contained bla(VIM-4), bla(OXA-58) and the intrinsic bla(OXA-69) gene; clone III contained bla(OXA-58) and the intrinsic bla(OXA-69) gene; and clone IV contained only the intrinsic bla(OXA-66) gene. ISAba1 was not associated with the intrinsic bla(OXA-51-like) alleles, whereas ISAba3 was found upstream and downstream of bla(OXA-58) in isolates of clone I, and upstream of bla(OXA-58) in isolates of clone III, but was not detected in isolates of clone II. PCR, curing and hybridisation experiments indicated that the bla(VIM) alleles were chromosomally located, whereas the bla(OXA-58) alleles were plasmid-located. This study provides the first description of the clonal spread of multidrug-resistant A. baumannii isolates carrying bla(VIM-1) and bla(VIM-4) metallo-beta-lactamase genes, and revealed that distinct carbapenem-resistant A. baumannii clusters bearing different carbapenemase genes may emerge and cause severe infections, even in a well-defined regional hospital setting.

MeSH terms

  • Acinetobacter Infections / epidemiology*
  • Acinetobacter baumannii / enzymology
  • Acinetobacter baumannii / genetics*
  • Adult
  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents / pharmacology
  • Bacterial Proteins / genetics*
  • Cluster Analysis
  • Cross Infection / epidemiology
  • DNA, Bacterial / analysis
  • Disease Outbreaks
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Female
  • Genes, Bacterial
  • Greece / epidemiology
  • Hospitals, General
  • Humans
  • Imipenem / pharmacology*
  • Incidence
  • Intensive Care Units*
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • Opportunistic Infections / epidemiology
  • Sentinel Surveillance
  • Sequence Analysis, DNA
  • beta-Lactamases / genetics*


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • DNA, Bacterial
  • Imipenem
  • beta-Lactamases
  • carbapenemase