Regional Escherichia coli antibiotic resistance among outpatients in Washington state from 2013-2019

Escherichia coli is a predominant pathogen of urinary tract infections (UTIs) in the United States. Understanding regional patterns of uropathogenic E. coli antimicrobial resistance (AMR) may help further antibiotic stewardship by creating region-specific antibiograms. We analyzed regional patterns of uropathogenic E. coli AMR among outpatients in Washington state. Deidentified results from antibiotic susceptibility tests performed by Quest Diagnostics on Washington state outpatient isolates from 2013 through 2019 were analyzed. Only the first E. coli isolate from each patient was included in the analyses. We conducted logistic regressions with robust standard errors for five antibiotics, with isolates classified as “susceptible” or “non-susceptible” for each antibiotic and adjusted for sex, year of isolate collection, and age group (0-18, 19-50, >50). The state’s nine Public Health Emergency Preparedness Regions (PHEPRs), served as the exposures for the analysis. We included 40,217 isolates in the study (93% female, mean age 47 years). Compared to the Central PHEPR (containing Seattle), most other regions had significantly lower adjusted prevalence ratios (aPR) of AMR; no regions had significantly higher aPR of resistance for any of the five antibiotics. Differences in resistance between the Central and other regions varied by antibiotic. Regional AMR differences were largest for ceftriaxone (low aPRs in other regions compared to Central) and smallest for ampicillin. The regional variation of AMR calls for more specific outpatient antibiograms to enable healthcare providers to take a precision medicine approach to antibiotic prescribing and stewardship. Importantly, this will improve health outcomes and mitigate emerging resistance among outpatients with uropathogenic E. coli UTIs.