Urinary tract infections at an Australian sexual health service: bacterial etiologies, antibiotic susceptibilities, and antimicrobial prescribing patterns.

Urinary tract infections (UTIs) are one of the most common infections. Management of UTIs often involves empiric antibiotics, which can contribute to antibiotic overuse. We aimed to investigate the causative organisms, prevalence of antimicrobial resistance, and empiric prescribing practices to improve antibiotic use for UTIs. We conducted a retrospective audit of UTIs in premenopausal nonpregnant persons with a vagina aged 18-51 years attending the Melbourne Sexual Health Centre from 2 January 2018 to 24 January 2023. We calculated the proportion of culture samples with pathogen(s) isolated, and their antimicrobial resistance profiles with 95% confidence intervals (CIs). We assessed adherence to first-line Australian Therapeutic guideline recommendations for acute uncomplicated lower UTIs (trimethoprim, nitrofurantoin, and cefalexin) during our study period. We included 1,680 acute UTI episodes (n = 1,569 patients). Midstream urine culture was performed in 1,503 episodes, with 911 (60.6%, 95% CI: 58.1-63.1) classified as laboratory-defined UTIs. The most common isolate was Escherichia coli (n = 615/948; 64.9%, 95% CI: 61.7-67.9). Of the first-line Australian Therapeutic Guideline recommended antibiotics, E. coli isolates were most commonly resistant to trimethoprim (n = 195/612; 31.9%, 95% CI: 28.2-35.7). Empiric antibiotics were prescribed for 1,533 (91.3%, 95% CI: 89.8-92.6) episodes. Most prescriptions (n = 1,465/1,533; 95.6%, 95% CI: 94.4-96.5) adhered to first-line recommendations, and trimethoprim accounted for 842 (54.9%, 95% CI: 52.4-57.4) prescriptions. At Australia's largest sexual health service, E. coli caused two-thirds of UTIs, with one-third of E. coli isolates demonstrating trimethoprim resistance. Empiric antibiotics were commonly prescribed and compliant with national recommendations; trimethoprim accounted for >50% of empiric prescriptions. Trimethoprim resistance indicates changes to empiric recommendations could be needed.IMPORTANCEEscherichia coli was the most common uropathogen isolated in women with uncomplicated urinary tract infection (UTI) over the past 5 years. One-third of these infections were resistant to trimethoprim, an antibiotic recommended as first-line presumptive therapy for UTIs in Australia and prescribed in over 50% of these E. coli urinary tract infections. These data demonstrate higher than previously reported levels of trimethoprim resistance in community-acquired E. coli UTIs in Australia, and the need for changes to empiric antimicrobial recommendations.