Impact of clinical pharmacist-led antimicrobial stewardship on antibiotic appropriateness, clinical outcomes, and antimicrobial consumption in hospital-acquired and ventilator-associated pneumonia: a randomized controlled trial

Background Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are major drivers of inappropriate antimicrobial use and resistance in hospitals. Clinical pharmacist-led antimicrobial stewardship programs (ASPs) are promising interventions for optimizing antimicrobial prescriptions and combating antimicrobial resistance. Methods This prospective randomized controlled trial was conducted over 18 months (from April 2023 to October 2024) at a tertiary care hospital. Adult patients with HAP or VAP were randomized to receive either pharmacist-led ASP interventions ( n = 366) or standard care ( n = 334) in a clinical trial setting. The intervention comprised daily medication reviews, culture-guided optimization, therapeutic drug monitoring, duration optimization, adverse event monitoring, and multidisciplinary communication training. The primary outcome was an appropriate antimicrobial prescription on day three. Results The intervention group demonstrated significantly higher rates of appropriate antimicrobial prescriptions (77.6% vs. 60.8%; odds ratio [OR] = 2.26, 95% confidence interval [CI]: 1.65–3.09; p < 0.001). Clinical cure rates were higher in the intervention group (84.4% vs. 74.3%; OR = 1.86, 95% CI: 1.27–2.72; p = 0.001). The mean hospital length of stay was reduced by 2.83 days (14.64 ± 5.48 vs. 17.47 ± 7.22 days; p < 0.001). Total antimicrobial treatment duration decreased by 10.9% (11.98 ± 5.80 vs. 13.45 ± 6.12 days; p < 0.001). Antimicrobial-related adverse events occurred less frequently in the intervention group (8.7% vs. 14.1%; p = 0.04). Conclusion Clinical pharmacist-led antimicrobial stewardship programs (ASPs) significantly reduced antimicrobial exposure and healthcare utilization, improving the appropriateness of antimicrobial prescriptions and clinical outcomes. These findings highlight the importance of ASPs as an evidence-based strategy to address antimicrobial resistance and optimize patient care in HAP.