Targeting Overtreatment of Asymptomatic Bacteriuria in the Emergency Department: Results from a Quasi-Experimental Clinical Pharmacist-Led Program Based on Education and Audit

<b>Background:</b> Asymptomatic bacteriuria (ASB) is frequently overtreated in emergency departments (EDs), contributing to antimicrobial resistance without improving clinical outcomes. The rapid pace of clinical decision-making and high patient turnover in the ED further predispose clinicians to unnecessary antibiotic prescribing. <b>Methods:</b> A quasi-experimental study was conducted in the ED of a tertiary hospital in Barcelona, Spain, from January 2024 to September 2025. The intervention included targeted education for ED staff and daily audit-feedback on antibiotic prescriptions for suspected ASB. The outcomes were the following variables, compared between study periods: cases of ASB with unnecessary antibiotic treatment per month, antimicrobial consumption, urine culture (UC) requests, 30-day return visits to the ED for urinary tract infection, and 30-day all-cause mortality for safety assessment. <b>Results:</b> A total of 93 patients with suspected ASB in the pre-intervention period and 102 patients in the intervention period were included. The median cases of ASB with unnecessary antibiotic treatment per month decrease from 19 (IQR 16-26) in the pre-intervention period to 9 (IQR 9-13) in the intervention period (<i>p</i> = 0.018). Antimicrobial consumption declined: meropenem and imipenem decreased from 5.5 to 3.0 DDD/1000 admissions, ertapenem from 5.6 to 3.1, and ceftriaxone from 35.0 to 24.1. UC requests fell by 16.1%. Clinical safety outcomes did not differ significantly between periods: 30-day return visit to the ED for UTI with the same isolate dropped from 8.6% to 1.9% (<i>p</i> = 0.076), overall UTI return visits to the ED dropped from 11.8% to 5.9% (<i>p</i> = 0.225), and 30-day mortality remained stable (8.6% vs. 4.9%, <i>p</i> = 0.455). <b>Conclusions:</b> These findings support the use of combined educational and audit-feedback strategies as effective and safe Antimicrobial Stewardship interventions in high-intensity clinical environments such as the ED, as they reduce inappropriate antibiotic use and unnecessary UC requests without compromising patient safety.