Molecular Epidemiology of Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae Isolated From Environmental and Clinical Specimens in a Cardiac Surgery Intensive Care Unit

Abstract

To investigate environmental contamination by extended-spectrum beta-lactamase-producing Enterobacteriaceae and to perform a comparative molecular analysis of clinical and environmental strains. A 17-bed cardiac surgery intensive care unit of a 480-bed university teaching hospital. Following an outbreak of extended-spectrum beta-lactamase-producing Enterobacteriaceae, an environmental survey revealed extensive contamination of the environment (particularly faucets, sink drains, and the joints of the countertops) by extended-spectrum beta-lactamase-producing Enterobacteriaceae. Environmental strains were compared with clinical strains by pulsed-field gel electrophoresis and randomly amplified polymorphic DNA. A total of 62 environmental strains belonging to 4 species of extended-spectrum beta-lactamase-producing Enterobacteriaceae were analyzed and compared with 43 clinical strains obtained from 34 patients. Comparative molecular analysis revealed 4 identical or closely related patterns (3 fromKlebsiella oxytocaand 1 fromEnterobacter cloacae)between environmental and clinical strains. Moist surfaces may serve as sources of multiply resistant Enterobacteriaceae in the intensive care unit. Identification and disinfection of such sources may therefore be helpful in prevention and control of outbreaks.