Longitudinal Impact of Antibiogram-Guided Antimicrobial Stewardship on Resistance Patterns and Multidrug-Resistant Organisms in a South Indian Tertiary Care Hospital

Introduction

Antimicrobial resistance (AMR) is a major global health threat driven by inappropriate antibiotic use. Antimicrobial stewardship programs (ASPs) aim to optimize prescribing and limit the spread of multidrug-resistant organisms (MDROs). This study evaluated the impact of an antibiogram-guided antimicrobial stewardship intervention on antimicrobial susceptibility patterns, MDRO prevalence, and antibiotic consumption in a tertiary care hospital in South India.

Methods

A longitudinal observational study was conducted from January 2022 to December 2024 in a tertiary care hospital. A total of 3092 clinical specimens were processed, of which 1144 yielded bacterial growth. Antimicrobial susceptibility testing was performed using the Kirby–Bauer disk diffusion method as per CLSI guidelines. A cumulative antibiogram (2022) was used to formulate and implement an institutional antibiotic policy in January 2023, supported by clinician education and prescription audits as part of the ASP. Resistance trends were compared across three periods: pre-implementation (OYB), one year post-implementation (OYA), and two years post-implementation (TYA). Statistical analysis was performed using Chi-square/Fisher’s exact test, with p <0.05 considered significant. Antibiotic consumption was assessed using DDD/1000 patients.

Results

Following implementation, modest but significant improvements in antimicrobial susceptibility were observed. Mean susceptibility of Escherichia coli increased from 65.6% to 68.5%, with significant improvement in doxycycline susceptibility (p <0.05). Pseudomonas aeruginosa showed improved ciprofloxacin susceptibility (p <0.05). The prevalence of ESBL-producing E. coli declined from 63% to 51%, and ESBL-producing Klebsiella from 60% to 52%. MRSA prevalence decreased from 24% to 22%. A significant reduction in β-lactam/β-lactamase inhibitor consumption was observed (p <0.05).

Conclusion

Antibiogram-guided antimicrobial stewardship, incorporating policy implementation, clinician education, and audit feedback, was associated with improved susceptibility patterns and reduced MDRO burden. Sustained surveillance and policy reinforcement are essential to combat AMR.