Over the past two decades, nosocomial infections caused by extended-spectrum beta-lactamase (ESBL)-producingOver the past two decades, nosocomial infections caused by extended-spectrum beta-lactamase (ESBL)-producing Klebsiella spp. have become a major problem all around the world (CDC 1998, Archibald 2004, Martins et al. 2005). This situation is of concern because there are limited antimicrobial options to treat patients infected with these pathogens (Bratu et al. 2005), and also because this kind of resistance can spread to a wide variety of Gramnegative bacilli, either Enterobacteriaceae (Knothe et al. 1983, Chanawong et al. 2001, Petroni et al. 2002, Calatayud 2005 or non-fermentative microorganisms (Poirel et al. 2003, Quinteros et al. 2003.Several risk factors for ESBL-producing Klebsiella spp. infections have been described, the most frequent being antimicrobial exposure, especially to third-generation cephalosporins (Naumovski et al. 1992, Lautenbach et al. 2001, Bermejo et al. 2003, and exposure to invasive procedures such as central venous catheters, mechanical ventilation, urinary catheterization and intraabdominal surgery (Piroth et al. 1998, Lautenbach et al. 2001, Menashe et al. 2001). It has also been demonstrated that this kind of infection increases length of stay among hospitalized patients (Cofsky et al. 2002, Stone et al. 2003, producing a significant economic impact (Stone et al. 2003).The literature is conflictive about the effect on mortality caused by ESBL-producing Klebsiella spp. compared to non-ESBL-producing Klebsiella spp., with some studies reporting a negative impact (Paterson et al. 1997, Kim et al. 2002, Bermejo et al. 2003, Martínez et al. 2005 and others finding no impact (Menashe et al. 2001, Kang et al. 2004.The purpose of the present study was to assess the risk factors and clinical impact associated with ESBL-producing strains, compared to non-ESBL-producing strains among in-patients at a university hospital with documented infection caused by Klebsiella spp.
MATERIALS AND METHODSThe University Hospital of the Faculty of Medicine of Ribeirão Preto (HC-FMRP) is a general hospital located in Ribeirão Preto city, at the state of São Paulo. It has 847-bes, distributed in 29 wards with several clinical and surgical specialties. It has six intensive-care units, being their areas of activities: neonatology, pediatry, general care of adults, cardiology, thoracic surgery, and neurosurgery.The research project was submitted to the local Ethics Committee and was approved. 2003). We considered the E-test to be positive when it showed at least a 4-fold decrease in the MIC for the combination side, compared to the cephalosporin alone side (NCCLS 2000). Strains were considered to be ESBL-producers when they tested positive in at least one detection test. K. pneumoniae ATCC 700603 was used as a positive control and E. coli ATCC 25922 as a negative control for the ESBL detection tests.Clinical data were collected from the medical records and also from physical examination of the patients...