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Journal of Clinical Microbiology, August 2007, p. 2365-2369, Vol. 45, No. 8
0095-1137/07/$08.00+0 doi:10.1128/JCM.02546-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Infectious Diseases Service,1 Microbiology Service,2 Pharmacy Service, Hospital Universitari de Bellvitge, Feixa Llarga, sn., L'Hospitalet de Llobregat, 08907 Barcelona, Spain3
Received 20 December 2006/ Returned for modification 16 April 2007/ Accepted 11 June 2007
Enterobacter cloacae has been associated with several outbreaks, usually involving strains that overproduce chromosomal ß-lactamase or, uncommonly, strains expressing extended-spectrum ß-lactamases (ESBL). Only sporadic cases of ESBL-producing E. cloacae have been identified in our hospital in recent years. We describe the epidemiology and clinical and microbiological characteristics of an outbreak caused by ESBL-producing E. cloacae in a cardiothoracic intensive care unit (CT-ICU). Prospective surveillance of patients with infection or colonization by ESBL-producing E. cloacae among patients admitted to the CT-ICU was performed during the outbreak. Production of ESBL was determined by decreased susceptibility to expanded-spectrum cephalosporins and a positive double-disk test result. Clone relatedness was determined by pulsed-field gel electrophoresis (PFGE). From July to September 2005, seven patients in the CT-ICU with ESBL-producing E. cloacae were identified (four males; median age, 73 years; range, 45 to 76 years); six patients had cardiac surgery. Four patients developed infections; three had primary bacteremia, one had ventilator-associated pneumonia, and one had tracheobronchitis. ESBL-producing E. cloacae showed resistance to quinolones and aminoglycosides. PFGE revealed two patterns. Five isolates belonged to clone A; two carried a single ESBL (pI 8.2 and a positive PCR result for the SHV type), and three carried two ESBLs (pIs 8.1 and 8.2 and positive PCR results for the SHV and CTX-M-9 types). Isolates belonging to clone B carried a single ESBL (pI 5.4 and a positive PCR result for the TEM type). Review of antibiotic consumption showed increased use of cefepime and quinolones during June and July 2005. The outbreak was stopped by the implementation of barrier measures and cephalosporin restriction. ESBL production could be increasingly common in nosocomial pathogens other than Escherichia coli or Klebsiella pneumoniae.
Published ahead of print on 20 June 2007.
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