Stepwise implementation of an antimicrobial stewardship program in an open medical intensive care unit: Evaluation of antibiotic utilization and clinical outcomes.

OBJECTIVES

Appropriate antibiotic use is crucial in intensive care units (ICUs) where patients are highly vulnerable to infection and antimicrobial resistance. This study evaluated the effect of a stepwise antimicrobial stewardship program (ASP) on antibiotic utilization and clinical outcomes in an open medical ICU.

METHODS

The ASP was implemented in two sequential stages. From July 2023, infectious disease specialists reviewed electronic records three times weekly for patients receiving meropenem or imipenem and suggested recommendations (record-based ASP). From September 2024, physician assistants (PA) joined these rounds, extending stewardship to all antibiotic users (round-based ASP). Study periods were pre-ASP (June 2022-June 2023, Period 1), record-based ASP (August 2023-August 2024, Period 2), and round-based ASP (October 2024-June 2025, Period 3). Outcomes included antibiotic utilization (days of therapy [DOT] per 1000 patient-days), multidrug-resistant organism isolation, and ICU mortality.

RESULTS

Total antibiotic use decreased from 1462.6 DOT/1000 patient-days in Period 1 to 1335.4 (Incidence rate ratio, IRR 0.91, 95% CI: 0.89-0.94) in Period 2 and 1088.5 (0.82, 95% CI: 0.79-0.85) in Period 3. Meropenem/imipenem use declined from 228.2 to 176.0 (0.77, 95% CI: 0.71-0.84) and 132.6 (0.75, 95% CI: 0.68-0.84), and antipseudomonal β-lactam use from 655.5 to 592.2 (0.90, 95% CI: 0.86-0.95) and 448.8 (0.76, 95% CI: 0.72-0.80). Acinetobacter baumannii isolation and patient mortality also decreased between Periods 2 and 3.

CONCLUSION

Stepwise ASP implementation significantly reduced antibiotic consumption and multidrug-resistant organism isolation. PA-supported stewardship rounds were feasible and associated with improved outcomes in an open ICU setting.