Widespread distribution of urinary tract infections caused by a multidrug-resistant Escherichia coli clonal group

N Engl J Med. 2001 Oct 4;345(14):1007-13. doi: 10.1056/NEJMoa011265.


Background: The management of urinary tract infections is complicated by the increasing prevalence of antibiotic-resistant strains of Escherichia coli. We studied the clonal composition of E. coli isolates that were resistant to trimethoprim-sulfamethoxazole from women with community-acquired urinary tract infections.

Methods: Prospectively collected E. coli isolates from women with urinary tract infections in a university community in California were evaluated for antibiotic susceptibility, O:H serotype, DNA fingerprinting, pulsed-field gel electrophoretic pattern, and virulence factors. The prevalence and characteristics of an antibiotic-resistant clone were evaluated in this group of isolates and in those from comparison cohorts in Michigan and Minnesota.

Results: Fifty-five of the 255 E. coli isolates (22 percent) from the California cohort were resistant to trimethoprim-sulfamethoxazole as well as other antibiotics. There was a common pattern of DNA fingerprinting, suggesting that the isolates belonged to the same clonal group (clonal group A), in 28 of 55 isolates with trimethoprim-sulfamethoxazole resistance (51 percent) and in 2 of 50 randomly selected isolates that were susceptible to trimethoprim-sulfamethoxazole (4 percent, P<0.001). In addition, 11 of 29 resistant isolates (38 percent) from the Michigan cohort and 7 of 18 (39 percent) from the Minnesota cohort belonged to clonal group A. Most of the clonal group A isolates were serotype O11:H(nt) or O77:H(nt), with similar patterns of virulence factors, antibiotic susceptibility, and electrophoretic features.

Conclusions: In three geographically diverse communities, a single clonal group accounted for nearly half of community-acquired urinary tract infections in women that were caused by E. coli strains with resistance to trimethoprim-sulfamethoxazole. The widespread distribution and high prevalence of E. coli clonal group A has major public health implications.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Anti-Infective Agents, Urinary* / pharmacology
  • Anti-Infective Agents, Urinary* / therapeutic use
  • California / epidemiology
  • Cohort Studies
  • Community-Acquired Infections / epidemiology
  • Community-Acquired Infections / microbiology
  • DNA Fingerprinting
  • Drug Resistance, Multiple*
  • Escherichia coli / classification
  • Escherichia coli / drug effects*
  • Escherichia coli / genetics
  • Escherichia coli / isolation & purification
  • Escherichia coli Infections / epidemiology
  • Escherichia coli Infections / microbiology*
  • Female
  • Humans
  • Michigan / epidemiology
  • Middle Aged
  • Minnesota / epidemiology
  • Prevalence
  • Serotyping
  • Trimethoprim, Sulfamethoxazole Drug Combination* / pharmacology
  • Trimethoprim, Sulfamethoxazole Drug Combination* / therapeutic use
  • Urinary Tract Infections / epidemiology
  • Urinary Tract Infections / microbiology*
  • Virulence / genetics


  • Anti-Infective Agents, Urinary
  • Trimethoprim, Sulfamethoxazole Drug Combination