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

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pISSN 2288-0585 eISSN 2288-6850

Epidemiologic Investigation of an Outbreak of Serratia marcescens Urinary Tract Infection in an Intensive Care Unit Using Pulsed-Field Gel Electrophoresis

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2005 June Volume 8, Issue 1, pages 34-40.


https://doi.org/10.5145/ACM.2005.08.1.34

Epidemiologic Investigation of an Outbreak of Serratia marcescens Urinary Tract Infection in an Intensive Care Unit Using Pulsed-Field Gel Electrophoresis

Eun Ha Koh1,3, Sunjoo Kim1,3*, and In-Gyu Bae2
Department of Laboratory Medicine1, School of Medicine, and Institute of Health Sciences2, Gyeongsang National University, Jinju, Korea

Abstract

Background: Serratia marcescensis a well-known cause of nosocomial infections. We investigated an outbreak of S. marcescens infections in a surgical intensive care unit (SICU) and identified the source of the outbreak using pulsed-field gel electrophoresis (PFGE). 

Methods: A total of 39 isolates of S. marcescens were included in this study: 28 isolates from the patients in the SICU and epidemiologically-unrelated 11 isolates from the patients in the general wards from May through August, 2003 at Gyeongsang National University Hospital. Twenty-six of the 28 isolates in the SICU were from the urine collected from indwelling urinary catheters. Fifty-six environmental samples, such as the hands of healthcare workers and urinals were cultured to identify the source of infection. Antimicrobial susceptibility tests by Vitek GNS card (bioMerieux) and PFGE were performed to identify the clonality of the isolates. 

Results: Twenty of the 28 S. marcescens isolated from the patients in the SICU showed the identical PFGE fingerprint pattern and two isoates had a closely-related pattern with the outbreak strain. The isolates from urine in the SICU were resistant to almost all the antibiotics tested except imipenem and cotrimoxazole. Nine of the 11 isolates from the general wards had PFGE patterns and antimicrobial susceptibility results different from those of the outbreak clone. Five samples from used-urinals and one from disinfected-urinal of 56 environmental samples grew S. marcescens that were resistant to the all antibiotics tested except imipenem and cotrimoxazole. 

Conclusion: The outbreak of urinary tract infections in SICU was due to a clonal spread of a single strain of S. marcescens that was multiple resistant to antibiotics except imipenem and cotrimoxazole. The source of outbreak appeared to be inadequately disinfected urinals. (Korean J Clin Microbiol 2005;8(1):34-40)

Keywords

Pulsed-field gel electrophoresis, Serratia marcescens, Nosocomial infection, Urinary tract infection, Epidemiology