title: Epidemic clonal groups of Escherichia coli as a cause of antimicrobial-resistant urinary tract infections in Canada, 2002 to 2004.
abstract: The extent to which clonal spread contributes to emerging antimicrobial resistance in Escherichia coli is incompletely defined. To address this question within a recent, nationally representative strain collection, three established drug-resistant E. coli clonal groups (i.e., clonal group A, E. coli O15:K52:H1, and sequence type 131 [ST131]) were sought among 199 E. coli urine isolates recovered from across Canada from 2002 to 2004, with stratification by resistance to trimethoprim-sulfamethoxazole (TS) and fluoroquinolones (FQs). The isolates' clonal backgrounds, virulence genotypes, and macrorestriction profiles were assessed. The three clonal groups were found to account for 37.2% of isolates overall, but accounted for 0% of TS-susceptible (TS-S) and FQ-susceptible (FQ-S) isolates, 20% of TS-resistant (TS-R) and FQ-S isolates, 60% of TS-S and FQ-R isolates, and 68% of TS-R and FQ-R isolates (P < 0.001). E. coli ST131, the most prevalent clonal group, accounted for 23.1% of isolates overall and for 44% of the FQ-R isolates. Nearly all ST131 isolates were FQ-R (96%) but, notably, cephalosporin susceptible (98%). Although the distinctive virulence profiles of the FQ-R clonal group isolates were less extensive than those of the susceptible isolates, they were significantly more extensive than those of the other FQ-R isolates. These findings indicate that among the E. coli urine isolates studied, resistance to TS and FQs has a prominent clonal component, with the O15:K52:H1 clonal group and especially E. coli ST131 being the major contributors. These clonal groups appear to be more virulent than comparably resistant isolates, possibly contributing to their success as emerging multi-drug-resistant pathogens.
authors.affiliation: Infectious Diseases (111F), Minneapolis VA Medical Center, 1 Veterans Drive, Minneapolis, MN 55417, USA. johns007@umn.edu
authors.forename: James R
authors.initials: JR
authors.lastname: Johnson
authors.forename: Megan
authors.initials: M
authors.lastname: Menard
authors.forename: Brian
authors.initials: B
authors.lastname: Johnston
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kuskowski
authors.forename: Kim
authors.initials: K
authors.lastname: Nichol
authors.forename: George G
authors.initials: GG
authors.lastname: Zhanel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000890:Anti-Infective Agents / Q000494:pharmacology / Q000627:therapeutic use; D002170:Canada / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000502:physiology*; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D014552:Urinary Tract Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D055815:Young Adult
chemical_list: D000890:Anti-Infective Agents