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

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.