title: Clonal groups and the spread of resistance to trimethoprim-sulfamethoxazole in uropathogenic Escherichia coli.
abstract: BACKGROUND
  Antibiotic resistance is increasingly complicating the management of urinary tract infection. We investigated the extent to which a group of Escherichia coli called clonal group A (CGA), which is associated with resistance to trimethoprim-sulfamethoxazole (TMP-SMZ), accounted for TMP-SMZ resistance among a prospectively collected set of uropathogenic and rectal E. coli isolates from a university population in Michigan.
  
  
  METHODS
  Resistant and susceptible uropathogenic E. coli isolates (45 each) and 79 randomly selected rectal E. coli isolates were evaluated for CGA status by use of 2 definitions of this group-- the enterobacterial repetitive intergenic consensus sequence 2 (ERIC2)-polymerase chain reaction (PCR) pattern A fingerprint and the C288T single nucleotide polymorphism (SNP) in the fumC gene. We compared virulence gene profiles and molecular mechanisms of resistance to TMP-SMZ between isolates classified as CGA by both approaches to better characterize the relationship between isolates.
  
  
  RESULTS
  Of the 45 isolates that exhibited ERIC2-PCR pattern A, one-half (23 of 45) were resistant to TMP-SMZ, and 16 contained the C288T SNP. The pattern A isolates were diverse, exhibiting multiple mechanisms of resistance to TMP-SMZ and various combinations of virulence factors. C288T SNP isolates showed less variation, with 15 of 16 resistant to TMP-SMZ and a 1.8-kb class I integron bearing the dfrA17 gene present in 14 of 15 resistant isolates. Twelve of 16 exhibited the same combination of virulence genes. Pulsed-field gel electrophoresis patterns for these 12 isolates were unique.
  
  
  CONCLUSIONS
  CGA, as defined by the fumC C288T SNP, appears to be distantly clonal but is not an outbreak-related group. The widespread group has likely evolved through lateral transfer of genes conferring virulence and antibiotic resistance.
authors.affiliation: Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: France
authors.forename: Kiersten M
authors.initials: KM
authors.lastname: Kugeler
authors.forename: Alison
authors.initials: A
authors.lastname: Freeman
authors.forename: Christy Ann
authors.initials: CA
authors.lastname: Zalewski
authors.forename: Matthew
authors.initials: M
authors.lastname: Blahna
authors.forename: Lixin
authors.initials: L
authors.lastname: Zhang
authors.forename: Carl F
authors.initials: CF
authors.lastname: Marrs
authors.forename: Betsy
authors.initials: B
authors.lastname: Foxman
mesh_terms: D000293:Adolescent; D000328:Adult; D016172:DNA Fingerprinting; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000145:classification* / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity; D005260:Female; D006801:Humans; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology*; D014552:Urinary Tract Infections / Q000188:drug therapy / Q000382:microbiology*; D014774:Virulence
chemical_list: D015662:Trimethoprim, Sulfamethoxazole Drug Combination