Clusters of imipenem-resistant Acinetobacter baumannii clones producing different carbapenemases in an intensive care unit.
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.
Tsakris
A
A
Department of Microbiology, Medical School, University of Athens, Athens, Greece. atsakris@med.uoa.gr
Ikonomidis
A
A
Poulou
A
A
Spanakis
N
N
Vrizas
D
D
Diomidous
M
M
Pournaras
S
S
Markou
F
F
D000151:Acinetobacter Infections / Q000453:epidemiology*; D040981:Acinetobacter baumannii / Q000201:enzymology / Q000235:genetics*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D016000:Cluster Analysis; D003428:Cross Infection / Q000453:epidemiology; D004269:DNA, Bacterial / Q000032:analysis; D004196:Disease Outbreaks; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D005260:Female; D005798:Genes, Bacterial; D006115:Greece / Q000453:epidemiology; D006769:Hospitals, General; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D015994:Incidence; D007362:Intensive Care Units; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009894:Opportunistic Infections / Q000453:epidemiology; D018571:Sentinel Surveillance; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000235:genetics*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D015378:Imipenem; D001618:beta-Lactamases; C063912:carbapenemase