Open Access Highly Accessed Research article

Nosocomial bloodstream infections caused by Klebsiella pneumoniae: impact of extended-spectrum β-lactamase (ESBL) production on clinical outcome in a hospital with high ESBL prevalence

Alexandre R Marra1*, Sérgio B Wey1, Adauto Castelo1, Ana Cristina Gales12, Ruy Guilherme R Cal3, José R do Carmo Filho2, Michael B Edmond4 and Carlos Alberto P Pereira1

Author Affiliations

1 Division of Infectious Diseases, Universidade Federal de São Paulo, Brasil (UNIFESP-EPM)/Hospital São Paulo (HSP), Brasil

2 Clinical Microbiology Laboratory, Universidade Federal de São Paulo, Brasil (UNIFESP-EPM)/Hospital São Paulo (HSP), Brasil

3 Intensive Care Unit, Hospital Israelita Albert Einstein, São Paulo, Brasil

4 Department of Internal Medicine, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia, USA

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BMC Infectious Diseases 2006, 6:24  doi:10.1186/1471-2334-6-24

Published: 14 February 2006



The frequency of ESBL producing Klebsiella pneumoniae bloodstream infections (BSI) is high in Brazilian hospitals, however little is known regarding what role, if any, resistance plays in the expected outcome in hospitals with a high prevalence of these pathogens.


From 1996 to 2001, hospital acquired K. pneumoniae BSI were evaluated retrospectively. Each patient was included only once at the time of BSI. ESBL producing strains were identified using the E-test method. The association of variables with the mortality related to bacteremia was included in a stepwise logistic regression model.


One hundred and eight hospital acquired K. pneumoniae BSI met criteria for inclusion. Fifty two percent were due to ESBL producing strains. The overall in-hospital mortality was 40.8%. Variables independently predicting death by multivariate analysis were the following: mechanical ventilation (p = 0.001), number of comorbidities (p = 0.003), antimicrobials prescribed before bacteremia (p = 0.01) and fatal underlying disease (p = 0.025).


Bacteremia due to ESBL producing K. pneumoniae strains was not an independent predictor for death in patients with BSI. An increased mortality in hospital-acquired BSI by K. pneumoniae was related to the requirement for mechanical ventilation, more than two comorbidities, the previous use of two or more antibiotics, and the presence of a rapidly fatal disease.