Seventeen Years of an Antibiotic Stewardship Programme: Trends in Antibiotic Prescribing and Gram-Negative Bacilli Susceptibility at a Quaternary Healthcare Institution

Background/objectives: Studies evaluating the longitudinal impact (beyond a decade) of antibiotic stewardship programs (ASPs) on the volume/quality of antibiotic prescriptions, as well as the impact on antibiotic resistance, are lacking. Since 2008, the ASP at Singapore General Hospital has implemented various strategies in the following phases: (1) initiation, (2) expansion, (3) optimisation, and (4) innovation. In this study, we aim to evaluate the volume/quality of antibiotic prescribing and susceptibility trends of clinically significant Gram-negative bacilli (GNBs), along with the evolution of ASP strategies over time. Methods: We conducted a single-centre, retrospective observational study from 2011 to 2024. Antibiotic consumption, appropriateness, and susceptibility trends of six GNBs to seven commonly used antibiotics were analysed using the Kendall tau test to identify potential monotonic trends based on aggregated rather than patient-level data. Results: We demonstrated sustained improvement in appropriateness of seven broad-spectrum IV antibiotics, accompanied by significant reductions in IV ciprofloxacin, cefepime, and ertapenem use (p < 0.05). Hospital-wide susceptibility of six GNBs to all evaluated antibiotics improved significantly (p < 0.05), except for E. coli’s susceptibility to ertapenem and Enterobacterales’s susceptibility to ciprofloxacin. Conclusions: With an evolving, multi-pronged stewardship approach, antibiotic prescribing and GNB susceptibility to most antibiotics have improved. In a rapidly evolving healthcare landscape, ASPs must remain agile, continually refining priorities and employing innovative strategies.