Evidence of Interhospital Transmission of Extended-Spectrum Beta-Lactam-Resistant Klebsiella Pneumoniae in the United States, 1986 to 1993. The National Nosocomial Infections Surveillance System

Infect Control Hosp Epidemiol. 1997 Jul;18(7):492-8. doi: 10.1086/647654.


Background: In addition to single-hospital outbreaks, interhospital transmission of extended-spectrum beta-lactam-resistant (ESBLR) Klebsiella pneumoniae has been suspected in some reports. However, these studies lacked sufficient epidemiological information to confirm such an occurrence.

Methods: We reviewed the surveillance data reported to the National Nosocomial Infections Surveillance (NNIS) System during 1986 to 1993 for K pneumoniae isolates and their susceptibility to either ceftazidime, cefotaxime, ceftriaxone, or aztreonam. Pulsed-field gel electrophoresis (PFGE) was used to study available ESBLR K pneumoniae isolates.

Results: Among 8,319 K pneumoniae isolates associated with nosocomial infections, 727 (8.7%) were resistant or had intermediate-level resistance to at least one of these antibiotics. One hospital (hospital A) accounted for 321 isolates (44.2%) of ESBLR K pneumoniae. During 1986 to 1993, the percentage of K pneumoniae isolates that were ESBLR increased from 0 to 57.7% in hospital A, from 0 to 35.6% in NNIS hospitals 0 to 20 miles from hospital A (area B), and from 1.6 to 7.3% in NNIS hospitals more than 20 miles from hospital A, including hospitals located throughout the United States. Analysis of PFGE restriction profiles showed a genetic relationship between a cluster of isolates from hospital A and some isolates from one hospital in area B, and consecutive admission in these two hospitals was confirmed for two patients from whom isolates were available.

Conclusions: These data provide evidence of interhospital transmission of ESBLR K pneumoniae in one region of the United States and stress the interrelationship between hospitals when trying to control antimicrobial resistance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Cross Infection / drug therapy
  • Cross Infection / epidemiology*
  • Cross Infection / transmission
  • DNA, Bacterial / analysis
  • Humans
  • Klebsiella Infections / drug therapy
  • Klebsiella Infections / epidemiology*
  • Klebsiella Infections / transmission
  • Klebsiella pneumoniae / drug effects*
  • Klebsiella pneumoniae / genetics
  • Molecular Epidemiology
  • Population Surveillance*
  • Regression Analysis
  • United States / epidemiology
  • beta-Lactams


  • Anti-Bacterial Agents
  • DNA, Bacterial
  • beta-Lactams