Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology


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Carbapenem Resistance Mechanisms and Molecular Epidemiology of Acinetobacter spp. from Four Hospitals in Seoul and Gyeonggi Province in 2006

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2010 March, Volume 13, Issue 1, pages 27-33.

Carbapenem Resistance Mechanisms and Molecular Epidemiology of Acinetobacter spp. from Four Hospitals in Seoul and Gyeonggi Province in 2006

Kyoung Ho Roh1, Chang-Ki Kim2, Jong Hwa Yum3, Dongeun Yong4,5, Seok Hoon Jeong4,5, Chae Seung Lim1, Chang Kyu Lee1, Yunjung Cho1, Kyungwon Lee4,5, Yunsop Chong4,5
1Department of Laboratory Medicine, Korea University College of Medicine, 2Korean Institute of Tuberculosis, Seoul, 3Department of Clinical Laboratory Science, Dongeui University, Busan, 4Department of Laboratory Medicine and 5Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Korea


Background: Increasing numbers of Acinetobacter spp. resistant to multiple drugs, including carbapenem, has been a serious problem. The aims of this study were to determine carbapenem resistance patterns and mechanisms, as well as to study the molecular epidemiology of Acinetobacter spp.

Methods: Clinical isolates of Acinetobacter spp. were collected from May to November in 2006. Antimicrobial susceptibility testing was performed using CLSI disk diffusion and agar dilution methods. Metallo-β- lactamase- and OXA carbapenemase-producing isolates were detected by PCR. Carbapenem resistance and hydrolytic activities were compared according to OXA type and presence of ISAba1. Pulsed-field gel electrophoresis (PFGE) was performed to determine the epidemiologic features.

Results: The imipenem non-susceptible rates were variable from 10% to 67%. Among 151 isolates carrying blaOXA-51-like, 75 isolates carried both blaOXA-51-like and ISAba1, and 25 isolates had both blaOXA-51-like, blaOXA-23-like, and ISAba1. Carbapenem MICs of both blaOXA-51-like and ISAba1-carrying isolates were higher than those with blaOXA-51-like only. Carbapenem MICs of blaOXA-23-like-carrying isolates were higher than those with both blaOXA-51-like and ISAba1. Both blaOXA-51-like and ISAba1-carrying isolates and blaOXA-51-like, blaOXA-23-like, and ISAba1-carrying isolates demonstrated higher hydrolysis activities in oxacillin and carbapenems. Most of the tested isolates were susceptible to tigecycline, and all of them were susceptible to colistin. Pulsed-field gel electrophoresis suggested that there had been several outbreaks of bblaOXA-23-like and blaOXA-51-like-positive strains.

Conclusion: Carbapenem non-susceptible Acinetobacter isolates and OXA carbapenemase-producing isolates were prevalent. Dissemination of blaOXA-harboring isolates may make it difficult to treat infections due to carbapenem-resistant Acinetobacter spp. Further surveillance studies are required to prevent the spread of carbapenem resistance. (Korean J Clin Microbiol 2010;13:27-33)


OXA carbapenemase, Carbapenem, Acinetobacter, Outbreak