Escherichia coliSequence Type 131 Is a Dominant, Antimicrobial-Resistant Clonal Group Associated with Healthcare and Elderly Hosts

OBJECTIVE: To determine prevalence, predictors, and outcomes of infection due to Escherichia coli sequence type ST131. DESIGN: Retrospective cohort. SETTING: All healthcare settings in Olmsted County, Minnesota (eg, community hospital, tertiary care center, long-term care facilities, and ambulatory clinics). PATIENTS: Ambulatory and hospitalized children and adults with extraintestinal E. coli isolates. METHODS: We analyzed 299 consecutive, nonduplicate extraintestinal E. coli isolates submitted to Olmsted County laboratories in February and March 2011. ST131 was identified using single-nucleotide polymorphism polymerase chain reaction and further evaluated through pulsed-field gel electrophoresis. Associated clinical data were abstracted through medical record review. RESULTS: Most isolates were from urine specimens (90%), outpatients (68%), and community-associated infections (61%). ST131 accounted for 27% of isolates overall and for a larger proportion of those isolates resistant to fluoroquinolones (81%), trimethoprim-sulfamethoxazole (42%), gentamicin (79%), and ceftriaxone (50%). The prevalence of ST131 increased with age (accounting for 5% of isolates from those 11-20 years of age, 26% of isolates from those 51-60 years of age, and 50% of isolates from those 91-100 years of age). ST131 accounted for a greater proportion of healthcare-associated isolates (49%) than community-associated isolates (15%) and for fully 76% of E. coli isolates from long-term care facility (LTCF) residents. Multivariable predictors of ST131 carriage included older age, LTCF residence, previous urinary tract infection, high-complexity infection, and previous use of fluoroquinolones, macrolides, and extended-spectrum cephalosporins. With multivariable adjustment, ST131-associated infection outcomes included receipt of more than 1 antibiotic (odds ratio OR, 2.54 95% confidence interval (CI), 1.25-5.17) and persistent or recurrent symptoms (OR, 2.53 95% CI, 1.08-5.96). Two globally predominant ST131 pulsotypes accounted for 45% of ST131 isolates. CONCLUSIONS: ST131 is a dominant, antimicrobial-resistant clonal group associated with healthcare settings, elderly hosts, and persistent or recurrent symptoms.