International prospective study of Klebsiella pneumoniae bacteremia: implications of extended-spectrum beta-lactamase production in nosocomial Infections

Ann Intern Med. 2004 Jan 6;140(1):26-32. doi: 10.7326/0003-4819-140-1-200401060-00008.


Background: Commonly encountered nosocomially acquired gram-negative bacteria, especially Klebsiella pneumoniae, produce extended-spectrum beta-lactamases (ESBLs) as an antibiotic resistance mechanism.

Objective: To determine whether microbiology laboratories should report the presence of ESBLs and to establish the infection-control implications of ESBL-producing organisms.

Design: Prospective observational study.

Setting: 12 hospitals in South Africa, Taiwan, Australia, Argentina, the United States, Belgium, and Turkey.

Patients: 440 patients with 455 consecutive episodes of K. pneumoniae bacteremia between 1 January 1996 and 31 December 1997; of these, 253 episodes were nosocomially acquired.

Measurements: The K. pneumoniae isolates were examined for the presence of ESBLs. Pulsed-field gel electrophoresis was used to analyze the molecular epidemiology of nosocomial bacteremia with ESBL-producing K. pneumoniae.

Results: Overall, 30.8% (78 of 253) episodes of nosocomial bacteremia and 43.5% (30 of 69) episodes acquired in intensive care units were due to ESBL-producing organisms. After adjustment for potentially confounding variables, previous administration of beta-lactam antibiotics containing an oxyimino group (cefuroxime, cefotaxime, ceftriaxone, ceftazidime, or aztreonam) was associated with bacteremia due to ESBL-producing strains (risk ratio, 3.9 [95% CI, 1.1 to 13.8]). In 7 of 10 hospitals with more than 1 ESBL-producing isolate, multiple strains with the same genotypic pattern were observed, indicating patient-to-patient spread of the organism.

Conclusions: Production of ESBLs by Klebsiella pneumoniae is a widespread nosocomial problem. Appropriate infection control and antibiotic management strategies are needed to stem the spread of this emerging form of resistance.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteremia / epidemiology
  • Bacteremia / microbiology*
  • Bacteremia / prevention & control
  • Cross Infection / epidemiology
  • Cross Infection / microbiology*
  • Cross Infection / prevention & control
  • Humans
  • Intensive Care Units
  • Klebsiella Infections / epidemiology
  • Klebsiella Infections / microbiology*
  • Klebsiella Infections / prevention & control
  • Klebsiella pneumoniae / enzymology*
  • Klebsiella pneumoniae / genetics
  • Prospective Studies
  • Risk Factors
  • beta-Lactam Resistance*
  • beta-Lactamases / biosynthesis*


  • beta-Lactamases