Multiple antibiotic-resistant Klebsiella and Escherichia coli in nursing homes

JAMA. 1999 Feb 10;281(6):517-23. doi: 10.1001/jama.281.6.517.


Context: Infections caused by ceftazidime sodium-resistant gram-negative bacteria that harbor extended-spectrum beta-lactamases (ESBLs) are increasing in frequency in hospitals in the United States.

Objectives: To report a citywide nursing home-centered outbreak of infections caused by ESBL-producing gram-negative bacilli and to describe the clinical and molecular epidemiology of the outbreak.

Design: Hospital-based case-control study and a nursing home point-prevalence survey. Molecular epidemiological techniques were applied to resistant strains.

Settings: A 400-bed tertiary care hospital and a community nursing home.

Patients: Patients who were infected and/or colonized with ceftazidime-resistant Escherichia coli, Klebsiella pneumoniae, or both and controls who were admitted from nursing homes between November 1990 and July 1992.

Main outcome measures: Clinical and epidemiological factors associated with colonization or infection by ceftazidime-resistant E coli or K pneumoniae; molecular genetic characteristics of plasmid-mediated ceftazidime resistance.

Results: Between November 1990 and October 1992, 55 hospital patients infected or colonized with ceftazidime-resistant E coli, K pneumoniae, or both were identified. Of the 35 admitted from 8 nursing homes, 31 harbored the resistant strain on admission. All strains were resistant to ceftazidime, gentamicin, and tobramycin; 96% were resistant to trimethoprim-sulfamethoxazole and 41% to ciprofloxacin hydrochloride. In a case-control study, 24 nursing home patients colonized with resistant strains on hospital admission were compared with 16 nursing home patients who were not colonized on hospital admission; independent risk factors for colonization included poor functional level, presence of a gastrostomy tube or decubitus ulcers, and prior receipt of ciprofloxacin and/or trimethoprim-sulfamethoxazole. In a nursing home point-prevalence survey, 18 of 39 patients were colonized with ceftazidime-resistant E coli; prior receipt of ciprofloxacin or trimethoprim-sulfamethoxazole and presence of a gastrostomy tube were independent predictors of resistance. Plasmid studies on isolates from 20 hospital and nursing home patients revealed that 17 had a common 54-kilobase plasmid, which conferred ceftazidime resistance via the ESBL TEM-10, and mediated resistance to trimethoprim-sulfamethoxazole, gentamicin, and tobramycin; all 20 isolates harbored this ESBL. Molecular fingerprinting showed 7 different strain types of resistant K pneumoniae and E coli distributed among the nursing homes.

Conclusions: Nursing home patients may be an important reservoir of ESBL-containing multiple antibiotic-resistant E coli and K pneumoniae. Widespread dissemination of a predominant antibiotic resistance plasmid has occurred. Use of broad-spectrum oral antibiotics and probably poor infection control practices may facilitate spread of this plasmid-mediated resistance. Nursing homes should monitor and control antibiotic use and regularly survey antibiotic resistance patterns among pathogens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Case-Control Studies
  • Ceftazidime / pharmacology
  • Cephalosporin Resistance
  • Cephalosporins / pharmacology
  • Cross Infection / drug therapy
  • Cross Infection / epidemiology*
  • Cross Infection / microbiology
  • DNA Fingerprinting
  • DNA, Bacterial / genetics
  • Drug Resistance, Microbial*
  • Drug Resistance, Multiple*
  • Electrophoresis, Gel, Pulsed-Field
  • Escherichia coli / drug effects
  • Escherichia coli / genetics*
  • Escherichia coli Infections / drug therapy
  • Escherichia coli Infections / epidemiology*
  • Escherichia coli Infections / microbiology
  • Female
  • Homes for the Aged
  • Humans
  • Klebsiella / drug effects
  • Klebsiella / genetics*
  • Klebsiella Infections / drug therapy
  • Klebsiella Infections / epidemiology*
  • Klebsiella Infections / microbiology
  • Male
  • Multivariate Analysis
  • Nursing Homes*
  • Plasmids / genetics


  • Cephalosporins
  • DNA, Bacterial
  • Ceftazidime