Korean J Clin Microbiol.  2005 Apr;8(1):34-40.

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

• Koh EH
• Kim S
• Bae IG

Abstract

BACKGROUND
Serratia marcescens is 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 isolates 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.

Keyword

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

MeSH Terms

Anti-Bacterial Agents
Clone Cells
Cross Infection
Delivery of Health Care
Dermatoglyphics
Electrophoresis, Gel, Pulsed-Field*
Epidemiology
Hand
Humans
Imipenem
Intensive Care Units*
Critical Care*
Patients' Rooms
Serratia marcescens*
Serratia*
Trimethoprim, Sulfamethoxazole Drug Combination
Urinary Catheters
Urinary Tract Infections*
Urinary Tract*
Anti-Bacterial Agents
Imipenem