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

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pISSN 2288-0585 eISSN 2288-6850

Characterization of the Multidrug-Resistant Acinetobacter species Causing a Nosocomial Outbreak at Intensive Care Units in a Korean Teaching Hospital: Suggesting the Correlations with the Clinical and Environmental Samples, Including Respiratory Tract-related Instruments

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2014 June, Volume 17, Issue 2, pages 29-34.

https://doi.org/10.5145/ACM.2014.17.2.29

Characterization of the Multidrug-Resistant Acinetobacter species Causing a Nosocomial Outbreak at Intensive Care Units in a Korean Teaching Hospital: Suggesting the Correlations with the Clinical and Environmental Samples, Including Respiratory Tract-related Instruments

Hae-Sun Chung1,2, Yangsoon Lee2, Eun Suk Park3, Dong Suk Lee3, Eun Jin Ha3, Myungsook Kim2, Dongeun Yong2, Seok Hoon Jeong2, Kyungwon Lee2,3, Yunsop Chong2
1Department of Laboratory Medicine, Ewha Womans University School of Medicine, 2Department of Laboratory Medicine and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, 3Department of Infection Control, Severance Hospital, Seoul, Korea

Abstract

Background: Acinetobacter spp. is an important nosocomial pathogen for which increasing resistance to multiple antimicrobial agents has been observed. Prevalence of multidrug-resistant (MDR) Acinetobacter spp. in the intensive care unit (ICU) at a teaching hospital in Korea started to increase in 2008. The aim of this study was to determine the source of pathogen spread and to characterize the emerging strains at an early stage of outbreak.

Methods: Samples from respiratory instruments and fomites in the ICUs, as well as from the healthcare workers, were cultured to identify the sources of MDR Acinetobacter spp. Antimicrobial susceptibility was determined by the CLSI disk diffusion method. Pulsed field gel electrophoresis (PFGE) was performed for clinical and environmental isolates in order to determine clonality. Carbapenemase genes were detected by multiplex PCR. Infection control measures including peer-monitoring of hand washing, environmental cleaning and standard precautions were enforced.

Results: Among the samples from the ICU tools (105) and healthcare worker’s hands (44), 31 (30%) and 2 (5%) respective samples yielded MDR Acinetobacter spp. Among the environmental samples, 90% were from respiratory-related equipment. The majority of clinical and environmental MDR Acinetobacter spp. (44/55) belonged to the pulsotype A. baumannii and carried both blaOXA-51-like and blaOXA-23-like genes. Even though infection-control measures were enforced, prevalence of MDR Acinetobacter spp. continues to increase.

Conclusion: An outbreak of MDR Acinetobacter spp. in a Korean hospital was caused by A. baumannii carrying the blaOXA-23-gene and was correlated with contaminated respiratory-related instruments in the ICUs. More intensive measures for nosocomial infection control are needed for successful prevention of Acinetobacter spread in hospitals. (Ann Clin Microbiol 2014;17:29-34)

Keywords

Acinetobacter, Beta-lactamase OXA-23, Infection control, Disease outbreaks