366. Antibiotic Stewardship Program Improved the Susceptibility of Commonly Seen Gram-negative Bacilli Over 12 Years at Singapore General Hospital
Authors: Yvonne Zhou Peijun , Xin Liew Yi , Chun Lim Shena Yun , Wang YiBo , Lee Winnie , Chua Nathalie , Wen Loo Li , Wei Lee Lai , Chieh Yii Daphne Yah , Koomanan Narendran , Chee Hung Kai , Le Lim Jia , San Teoh Boon , Jie Tan Jun , Trevina Lee Li Xuan , Le Gan Cherie Si , Yee Thien Siew , Zhi Cherng Benjamin Pei , Piotr Chlebicki Maciej , Jasmine Chung Shimin , Andrea Kwa Lay Hoon 
Published: January 2025

Abstract

Background
Antibiotic stewardship program (ASP) is advocated in all healthcare institutions to combat rising bacteria resistance. In 2008, ASP was established at Singapore General Hospital, with strategies focused on promoting appropriate use of anti-pseudomonal agents at first and expanding to ceftriaxone in 2015. Strategies include: 1) prospective audit feedback (PAF); 2) antibiotic guidelines; 3) digital solutions (computerized decision support system & mobile application); and 4) physician education [Figure 1]. In this study, we aim to evaluate the susceptibility rates of common gram-negative bacilli (GNB) and appropriate antibiotic use over time with ASP implementation.Figure 1:Antibiotic stewardship strategies implemented at Singapore General Hospital from 2008 to 2023

Methods
We conducted an observational study from 2011 to 2023. Kendall’s tau coefficient (τ) was used to correlate the trend of bacteria susceptibility and percentage of appropriate antibiotic use with time. Susceptibility results of E.coli (EC), Klebsiella species (excluding Klebsiella aerogenes), Pseudomonas aeruginosa (PA) and Acinetobacter baumannii (AB) towards ceftriaxone (CRO), co-amoxiclav (AMC), piperacillin-tazobactam (PT), ertapenem (ERT) and meropenem (MEM), where applicable, was established based on breakpoints by Clinical and Laboratory Standards Institute. Percentage of appropriate MEM, ERT and PT use were derived from hospital-wide PAF.Figure 2:Trends of antibiotic susceptibility of E. coli, Klebsiella spp., Ps. aeruginosa and A. baumannii at Singapore General Hospital (2011-2023)

Results
Susceptibility of EC and Klebsiella spp. towards CRO, AMC, PT, ERT and MEM have significantly increased over time (p &lt; 0.05). Susceptibility of PA and AB towards MEM have also significantly increased (p &lt; 0.05) [Figure 2, 3].
Notably, % of appropriate MEM and ERT use from 2011 to 2023 have significantly improved from 72.7% to 85.9% (τ= 0692, p &lt; 0.05) and 75.9% to 92.0% (τ= 0.72, p &lt; 0.05) respectively [Figure 4]. Percentage of appropriate PT use from 2013 to 2023 increased from 72% to 80.4% (τ= 0.055, p= 0.815).Figure 3:12- year trend of the susceptibility of Gram-negative bacilli towards commonly used broad-spectrum antibiotics from 2011 to 2023

Conclusion
ASP is pertinent in promoting appropriate antibiotic use through multi-pronged approaches. Importantly, ASP’s goal of improving susceptibility of common GNB towards several broad-spectrum antibiotics was achieved. With increasing appropriate carbapenem use reaching a saturable stage, ASP must remain adaptable and design innovative strategies to expand its reach to even narrower spectrum antibiotics.Figure 4:Percentage of appropriate use of ertapenem, meropenem, and piperacillin-tazobactam over time

Disclosures
All Authors: No reported disclosures