Nosocomial bloodstream infections caused by Escherichia coli and Klebsiella pneumoniae resistant to third-generation cephalosporins, Finland, 1999-2013: Trends, patient characteristics and mortality.

Background: Few systematically collected multi-centre surveillance data on nosocomial bloodstream infections (BSI) caused by extended-spectrum β-lactamase (ESBL) producing Escherichia coli or Klebsiella pneumoniae have been published.
Aim: To evaluate trends, patient characteristics and mortality of such infections, nosocomial BSI data reported by the 4-17 hospitals participating in the prospective laboratory-based surveillance during 1999-2013 were analysed.
Methods: Data were collected by local infection control nurses, patient-days were obtained from the hospital's administrative database, and dates of deaths from the population registry. Resistance to third-generation cephalosporins was further examined in the national reference laboratory.
Findings: A total of 16 028 nosocomial BSIs were identified; 2217 (14%) were caused by E. coli and 661 (4%) by K. pneumoniae; 207 (7%) were non-susceptible to third-generation cephalosporins, with an increasing trend from 0% in 1999 to 17% in 2013. Patient characteristics did not differ significantly between BSIs caused by third-generation susceptible and resistant E. coli and K. pneumonia, but the case fatality tended to be higher. Most (88%) of the isolates reported as non-susceptible to third-generation cephalosporins had ESBL phenotype, CTX-M (79%) being the most common enzyme.
Conclusion: A sharp increase in nosocomial BSIs caused by ESBL producing bacteria was observed. Identification of patients for screening pose a challenge, emphasising the role of infection control guidelines and antibiotic policy in prevention.