Increased Odds of Antibiotic Resistance in E. coli Isolates from Recurrent Urinary Tract Infections

This study included deidentified antibiotic susceptibility results from outpatient urinary Escherichia coli isolates from Washington state which were tested at a large clinical laboratory during 2013–2019. Isolates were categorized as representing the first, second, third, or fourth-or-greater occurrence of infection in data from individual patients. We used logistic regression with the outcome of resistance, adjusting for year of antimicrobial susceptibility test, patient sex, patient age, and facility type. In cases of subsequent infection, we found a significant risk of resistance to levofloxacin, ciprofloxacin, ceftriaxone, trimethoprim-sulfa, nitrofurantoin, ampicillin, gentamicin, and amoxicillin-clavulanate. Our findings suggest that Escherichia coli isolates from recurrent urinary tract infections have a higher rate of resistance to most tested antibiotics than isolates from the first urinary tract infection in a given year. However, susceptibility frequencies did not differ significantly between antibiograms constructed using only the first occurrence in a patient and those constructed using all subsequent occurrences. These findings suggest that the traditional approach of including only the first occurrence of urinary Escherichia coli in a patient may underestimate levels of antibiotic resistance in a community. Such underestimation could negatively affect empiric therapeutic choices, health outcomes, and treatment costs.