Molecular epidemiology of an outbreak of imipenem-resistant Acinetobacter baumannii carrying the ISAba1-bla OXA-51-like Genes in a Korean hospital

Abstract

Between January 2004 and December 2004, an outbreak of imipenem-resistant Acinetobacter baumannii (IRAB) in 2 intensive care units (ICU) of Chosun University Hospital, Korea affected 77 patients. A case-control study revealed that the time spent in the hospital and mechanical ventilation practices were risk factors. IRAB was isolated from the hands of 4% (5/124) of healthcare workers, and 27.3% (21/77) of the samples obtained from the ICU environment. A pulsed-field gel electrophoresis analysis showed that 82.1% (23/28) of clinical IRAB isolates and 85.7% (6/7) of environmental IRAB isolates were type A. The ISAba1F/OXA-51-likeR PCR showed that 93.7% (30/32) of IRAB strains had the ISAba1 gene upstream of the bla OXA-51-like gene. Two ISAba1F/OXA-51-likeR PCR-negative IRAB strains were bla IMP-1 positive. All of the IRAB strains tested by PCR were negative for bla VIM, bla SIM, bla GIM-1, bla SPM-1, bla GES, bla OXA-23-like, bla OXA-24-like, and bla OXA-58-like carbapenemase genes. After implementing an infection control strategy, a steady reduction in the attack rate of IRAB infection was observed.