Long-Term Impact of Antimicrobial Stewardship Strategies on Antibiotic Prescribing and Gram-Negative Bacilli Susceptibility: A 17-Year Experience

Background/objectives: Studies evaluating the longitudinal impact (beyond a decade) of Antibiotic stewardship programs (ASP) strategies on the volume/quality of antibiotic prescriptions, as well as impact on antimicrobial resistance are lacking. Since 2008, the ASP at Singapore General Hospital had implemented various strategies in the following phases: 1) initiation; 2) expansion; 3) optimisation; and 4) innovation. In this study, we aim to evaluate the impact of ASP on the volume/quality of antibiotic prescribing and susceptibility trends of clinically significant Gram-negative bacilli (GNB). Methods: We conducted a single-center, retrospective observational study from 2011 to 2024. Antibiotic consumption, appropriateness and susceptibility trends of 6 GNBs to 7 commonly used antibiotics were analysed using Kendall tau test. Results: We demonstrated sustained improvement in appropriateness of 7 broad-spectrum IV antibiotics, accompanied by significant reductions in IV ciprofloxacin, cefepime and, ertapenem use (p < 0.05). Hospital-wide susceptibility of 6 GNBs to all evaluated antibiotics improved significantly (p < 0.05), except for E. coli susceptibility to ertapenem and Enterobacterales susceptibility to ciprofloxacin. Conclusion: An evolving multi-pronged antibiotic stewardship approach improved antibiotic prescribing and GNB susceptibility towards majority of the antibiotics. In a rapidly evolving healthcare landscape, ASPs must remain agile, continually refining priorities and employing innovative strategies.