title: Conventional and molecular epidemiology of trimethoprim-sulfamethoxazole resistance among urinary Escherichia coli isolates.
abstract: BACKGROUND
  Antibiotic resistance is increasing in Escherichia coli, the most common cause of urinary tract infections, but its epidemiology has not been well described. We evaluated the epidemiology of trimethoprim-sulfamethoxazole-resistant E. coli in a large, public health care system in Denver, Colorado.
  
  
  METHODS
  Outpatients with E. coli urinary tract infections during the first 6 months of 1998 were evaluated retrospectively. A prospective study was then performed to confirm the rate of trimethoprim-sulfamethoxazole resistance. We used several strain-typing methods (pulsed-field gel electrophoresis, ribotyping, serotyping) to evaluate the molecular epidemiology of the resistance.
  
  
  RESULTS
  The rate of trimethoprim-sulfamethoxazole resistance was similar in the retrospective (24% [161/681]) and prospective (23% [30/130]) phases of the study (P = 0.89). Almost all trimethoprim-sulfamethoxazole-resistant strains (98%) were resistant to at least one other antibiotic. Risk factors for infection with a resistant strain included age < or =3 years, Hispanic ethnicity, recent travel outside the United States, and a prior urinary tract infection. However, rates of resistance were >15% among nearly all of the subgroups. Most strains had high-level resistance (>1000 microg/mL) to trimethoprim-sulfamethoxazole. Of the 23 resistant isolates evaluated, 10 (43%) belonged to the clone A group. There was no correlation between conventional epidemiologic characteristics and the molecular mechanism of resistance or strain type.
  
  
  CONCLUSIONS
  Resistance to trimethoprim-sulfamethoxazole among E. coli isolates among patients in a Denver public health care system is common, with high rates of resistance even among patients without risk factors.
authors.affiliation: Department of Public Health, Denver Health and Hospital Authority, Colorado 80204, USA. bburman@dhha.org
authors.forename: William J
authors.initials: WJ
authors.lastname: Burman
authors.forename: Peter E
authors.initials: PE
authors.lastname: Breese
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Murray
authors.forename: Kavindra V
authors.initials: KV
authors.lastname: Singh
authors.forename: Holly A
authors.initials: HA
authors.lastname: Batal
authors.forename: Thomas D
authors.initials: TD
authors.lastname: MacKenzie
authors.forename: John W
authors.initials: JW
authors.lastname: Ogle
authors.forename: Michael L
authors.initials: ML
authors.lastname: Wilson
authors.forename: Randall R
authors.initials: RR
authors.lastname: Reves
authors.forename: Philip S
authors.initials: PS
authors.lastname: Mehler
mesh_terms: D000293:Adolescent; D000328:Adult; D000892:Anti-Infective Agents, Urinary / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D003120:Colorado / Q000453:epidemiology; D017714:Community-Acquired Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D004927:Escherichia coli Infections / Q000188:drug therapy* / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000627:therapeutic use*; D014552:Urinary Tract Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D000892:Anti-Infective Agents, Urinary; D015662:Trimethoprim, Sulfamethoxazole Drug Combination