An outbreak of hospital-acquired Klebsiella pneumoniae bacteraemia, including strains producing extended-spectrum -lactamase C. Peña*, M. Pujol*, C. Ardanuy†, A. Ricart‡, R. Pallarés*, J. Liñares†, J. Ariza* and F. Gudiol* *Infectious Disease Service, †Microbiology Service and ‡Intensive Care Service, Hospital de Bellvitge, Universidad de Barcelona, Barcelona, Spain Summary: This study describes the clinical outcome of an outbreak of extended-spectrum -lactamase producing Klebsiella pneumoniae (ESBL-KP) bacteraemia. Ninety-two episodes of hospital-acquired K. pneumoniae bacteraemia were studied, 49 ESBL-KP and 43 non-ESBL-KP, from May 1993 to June 1995. Of these, 44 (90%) episodes of ESBL-KP vs. 20 (46%) episodes of non-ESBL-KP occurred in inten- sive care unit (ICU) patients. The incidence of K. pneumoniae bacteraemia (mainly due to ESBL-KP) increased in the ICU during the outbreak. A significant association was found between intravascular catheter-related bacteraemia and isolation of ESBL-KP [27 (56%) in the ESBL-KP group vs. 13 (30%) in the non-ESBL-KP group; P0.01]. The worst prognostic features were identified as age 65 years (P0.02), septic shock (P0.001) and secondary bacteraemia (P0.04). High rates of resistance to -lactam/-lactamase inhibitors observed in our ESBL-KP isolates, as well as variable activity of aminogly- cosides, restricts the empirical use of these antibiotics. Carbapenems should be the treatment of choice since they are uniformly active against these strains. Our study shows that ESBL-KP bacteraemia occurring in an epidemic ICU setting is mainly catheter-related. We did not find ESBL strains to be associated with a significantly poor outcome. © 2001 The Hospital Infection Society Keywords: Klebsiella pneumoniae; extended spectrum -lactamase; bacteraemia. Journal of Hospital Infection (2001) 47: 53–59 doi:10.1053/jhin.2000.0862, available online at http://www.idealibrary.com on Introduction Klebsiella spp. account for between 5% and 10% of hospital-acquired bloodstream infections and their role as hospital-acquired pathogens has been widely recognized. 1 Their importance has increased over the last few years following the appearance of extended-spectrum -lactamase-producing strains, since the therapeutic options currently available for these organisms are severely limited. 2–4 Numerous reports have characterized these -lactamases and analysed molecular epidemiologi- cal aspects of outbreaks. 3–7 However, information regarding clinical characteristics and outcome of these infections are limited, 8 and no reports have specifically focused on patients with ESBL-KP bacteraemia. A recent, outbreak of ESBL-KP occurring over a two-year period in our hospital allowed us to describe the clinical epidemiology and outcome of ESBL-KP bacteraemia, and also to determine the relevance of ESBL strains in the mortality of patients with hospital-acquired K. pneumoniae bacteraemia. Received 15 March 2000; revised manuscript accepted 7 September 2000. Author for correspondence: Dr C. Peña, Infectious Disease Service, Hospital de Bellvitge, University of Barcelona, E-08907 L’Hospitalet de Llobregat, Barcelona, Spain. Fax: 34-93-2607637; E-mail: cpena@csub.scs.es 0195-6701/01/01005307 $35.00 © 2001 The Hospital Infection Society