Evolution of Antimicrobial Resistance of Uropathogen Escherichia coli in an Emergency Hospital from Bucharest

Escherichia coli is the leading uropathogen and a sentinel organism for antimicrobial resistance (AMR), yet urine culture over-ordering is an increasingly recognized, modifiable driver of unnecessary antimicrobial use. We evaluated both urinary E. coli resistance and urine culture utilization over a five-year period encompassing the COVID-19 pandemic in a Romanian tertiary hospital. In this retrospective single-center study (Central Military University Emergency Hospital "Dr. Carol Davila", Bucharest; January 2019-December 2023), adult inpatient urine culture utilization was expressed per 1000 occupied bed-days (OBD) and modelled using quasi-Poisson and cluster-robust negative-binomial regression, while resistance was assessed from the first isolate per patient using linear probability and logistic regression. Among 95,840 cultures (16.3% positive), 7957 yielded E. coli (56.5% of positives; 76.5% female; mean age 64.1 years). OBD-adjusted utilization rose by 4.4% annually (IRR 1.044; p < 0.001), driven mainly by medical wards. Resistance was largely stable, with significant declines for nitrofurantoin and amoxicillin-clavulanic acid; aminopenicillins, trimethoprim-sulfamethoxazole, and fluoroquinolones exceeded the 20% empirical-use threshold, whereas nitrofurantoin and fosfomycin remained low. Rising bed-day-normalized utilization identifies medical wards as priority diagnostic-stewardship targets, while stable resistance supports nitrofurantoin and fosfomycin as preferred empirical agents, arguing for combined stewardship and activity-adjusted surveillance.