Molecular Epidemiology of an Outbreak of Imipenem-Resistant <i>Acinetobacter baumannii</i> Carrying the IS<i>Aba1-bla</i><sub>OXA-51-like</sub> 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; 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 blaOXA-51-like gene. Two ISAba1F/OXA-51-likeR PCR-negative IRAB strains were blaIMP-1 positive. All of the IRAB strains tested by PCR were negative for blaVIM, blaSIM, blaGIM-1, blaSPM-1, blaGES, blaOXA-23-like, blaOXA-24-like, and blaOXA-58-like carbapenemase genes. After implementing an infection control strategy, a steady reduction in the attack rate of IRAB infection was observed.