1,4 Department of Clinical Pharmacology, MGM Healthcare, Chennai
2Department of Pharmacy Practice, JSS College of Pharmacy, Ooty
3Department of Infectious diseases, MGM Healthcare, Chennai
Antimicrobial resistance (AMR) is a major global public health concern, largely attributed to inappropriate and excessive use of antibiotics in hospital settings. Antimicrobial stewardship programs optimize antibiotic usage, reduces resistance and improves therapeutic and clinical outcomes however data from Quaternary care hospitals especially in South India is limited. This Prospective study was conducted in such a hospital where the impact of AMS program was evaluated by measuring Antibiotic consumption expressed in Defined Daily Dose (DDD) per 1000 bed-days and Duration of Therapy (DOT) along with cumulative Antibiogram data to optimize empirical antibiotic therapy and comparisons were made between pre- and post-AMS implementation in the hospital setting. AMS interventions, training sessions and role of clinical pharmacists were also included. Data were collected from hospital and patient records and were analyzed using Microsoft Excel. The results were presented using Graphs and tabular representations. Following AMS implementation total antibiotic consumption showed an improvement in DDD per 1000 bed-days, also DOT showed a limited duration of exposure to antibiotics. This study showed the importance of stewardship efforts and supported that a coordinated AMS program can improve antibiotic utilization and can help support better clinical outcomes in Quaternary hospital setting..
Antimicrobial stewardship is designed for optimal selection, dose, route, and duration of antimicrobial therapy with an aim of best clinical outcomes while reducing costs of healthcare, resistance and toxicity.[1] Antimicrobial resistance is a global concern especially in low and middle-income countries like India where over usage of antibiotics, inappropriate prescription are very common.[2][3] Hospitals are where consumption of antibiotics are high which makes them targets for intervention.[4] Antimicrobial Stewardship programs aims at optimizing antimicrobial usage in order to improve patient outcomes, minimize adverse effects, reduce resistance and improve cost effective therapies. This study evaluates the impact of an AMS team on clinical outcomes, antibiotic utilization patterns in a quaternary care hospital in South India. One of the most emerging challenges in global public health sector is Antimicrobial Resistance (AMR).[1] It was identified that AMR is highly associated with high risk of morbidity, mortality, increased hospital stays and high healthcare costs. Tertiary and Quaternary care hospitals in a hospital setting significantly contributes to the development of resistance due to inappropriate prescribing practices, lack of de-escalation, prolonged duration of therapy.[1] The implementation of AMS programs has been shown to reduce resistance rates and lower healthcare costs. Additionally antibiograms serve as a vital tool in the selection of empirical therapy and helps with the antibiotics policies of institutions.[5] Clinical pharmacists play a pivotal role in AMS by reviewing prescriptions, optimizing doses based on renal and hepatic function, facilitating de-escalation, monitoring drug–drug interactions, and educating prescribers.[6] This study was to evaluate the impact of an AMS program in a quaternary care hospital in South India by comparing outcomes before and after the implementation of the AMS program.
MATERIALS AND METHODS
Study Design and Population:
A Prospective study was conducted in a Quaternary care hospital in South India. The study compared two distinct periods which is a pre-AMS (January – December 2024) which is before implementing the AMS program, and a post-AMS period (January – December 2025) following the implementation of a structured AMS program. All hospitalized patients who received at least one systemic antimicrobial agent during the study period were included.
Study objective:
The primary objective of this study was to compare antimicrobial utilization patterns expressed as Defined Daily Dose (DDD) and Days of Therapy (DOT) between pre-AMS and post-AMS implementation periods in a quaternary care hospital. Secondary objective included evaluation of changes in antimicrobial susceptibility patterns using antibiograms, assessing antimicrobial process indicators and describing the role of clinical pharmacist led intervention following implementation of the AMS program.
AMS Team Composition and Interventions
The AMS team consisted of infectious disease physicians, microbiologists, clinical pharmacists, infection control nurses, and hospital administrators. Key interventions included prescription audits, development and dissemination of antibiotic guidelines, dose optimization, renal dose adjustments, de-escalation based on culture results, and restriction of selected broad-spectrum antibiotics. Regular educational and training sessions were conducted for clinicians and nursing staff.
Antibiotic Utilization Metrics and Microbiological Analysis
Antibiotic consumption was quantified using Defined Daily Dose (DDD) per 1000 patient-days as per WHO methodology and Days of Therapy (DOT) per 1000 patient-days to assess duration of antibiotic exposure. Cumulative antibiograms were prepared by the microbiology department using standardized susceptibility testing methods. Antibiotic susceptibility percentages for common pathogens were compared between the two study periods.
Data Analysis
Data were collected from Hospital records, microbiology reports, and AMS documentation. Analysis was performed using Microsoft Excel. Results were expressed as mean values, percentages, and comparative trends.
RESULTS
The results of this study show a significant improvement in Antimicrobial utilization patterns and antimicrobial stewardship related process indicators following the implantation of the Antimicrobial Stewardship program (AMS). Comparative analysis of the pre- and post-AMS periods showed favorable changes in antibiotic consumption expressed as Defined Daily Dose (DDD), improved susceptibility patterns on antibiogram and increased adherence to stewardship indicators. In addition, increased clinical pharmacist led interventions were observed after AMS implementation, showing strengthened antimicrobial governance within the institution.
Antibiotic Utilization Trends
A significant improvement in overall antibiotic consumption was observed following AMS implementation.
Figure 1: Comparison of total antibiotic consumption (DDD per 1000 patient-days) before AMS implementation.
Figure 2: Comparison of total antibiotic consumption (DDD per 1000 patient-days) after AMS implementation.
Antibiogram Analysis:
Improved antimicrobial susceptibility was observed Enterobacterales and Pseudomonas species following AMS implementation.
Table 1: Antibiogram
Fig 3: cumulative antibiogram of year 2024
Fig 4: cumulative antibiogram of year 2025
AMS Process Indicators
The number of prescription audits increased from 120 to 340 annually. Twenty-five structured AMS training sessions were conducted during the post-implementation period. Clinical pharmacist-led interventions increased by approximately 40%, indicating enhanced multidisciplinary collaboration.
Figure 5: AMS process indicators
DISCUSSION
The present study demonstrates that the implementation of a coordinated Antimicrobial stewardship program (AMS) in a quaternary hospital led to improvements in antibiotic utilization patterns and stewardship related process indicators. Antibiotic utilization following AMS implementation as shown by improvements in Defined Daily Dose (DDD) per 1000 bed-days and Duration of Therapy (DOT) highlights the effectiveness of structured stewardship interventions in Quaternary care hospital setting. Similar findings have been reported in previous AMS studies conducted in tertiary and quaternary care hospitals, where stewardship interventions resulted in improved antimicrobial utilization. (Davey et al., 2017; Barlam et al., 2016). Studies by Karanika et al. and Schuts et al. reported improvements in antibiotic consumption following AMS implementation, showing the role of stewardship programs. [7][10] Duration of Therapy (DOT) analysis in the study indicated limited duration of antibiotic exposure following AMS implementation. Duration of Therapy (DOT) analysis in the present study indicated limited duration Excessive duration of antibiotic treatment is a major contributor to drug reactions, resistance and increased healthcare costs. Previous studies have discussed that stewardship guided duration optimization reduces unnecessary antibiotic days effectiveness (Tamma et al., 2017; Yahav et al., 2019) The DOT trends in this study further support the role of AMS in minimizing prolonged and inappropriate antimicrobial therapy. [8][9] Cumulative antibiogram analysis before and after implementation of AMS revealed improvement in antimicrobial susceptibility patterns among key pathogens. Though antimicrobial resistance is influenced by various factors, antibiograms remains a cornerstone of effective antimicrobial stewardship by guiding empirical therapy. Similar improvements in susceptibility trends following AMS implementation have been reported in studies by McGregor et al. and Paskovaty et al., where rational antibiotic use was associated with stabilization or improvement of resistance patterns. [11][12] The observed improvements in stewardship-related process indicators, including empirical therapy optimization, de-escalation rates, documentation of indication, and adherence to prescribing guidelines, reflect the strengthening of antimicrobial governance within the institution. These findings are consistent with reports by Schuts et al. and Baur et al., which highlight that AMS programs significantly improve process measures related to antimicrobial prescribing quality. Process indicators serve as essential surrogate markers of stewardship effectiveness, particularly in settings where direct clinical outcomes may be influenced by multiple confounding factors. [13] Clinical pharmacists played a pivotal role in the implementation and sustainability of the AMS program in this study. Pharmacist-led interventions such as prescription review, dose optimization, monitoring for adverse drug events, and facilitation of de-escalation contributed to improved antimicrobial use. The role of clinical pharmacists in AMS has been well documented in previous studies, including those by Bond and Raehl and Karanika et al., which demonstrated improved antimicrobial appropriateness and reduced resistance rates following pharmacist involvement in stewardship activities. [14[15] Despite the positive findings, this study has certain limitations. Being a single-center study, the findings may not be generalizable to all hospital settings. Additionally, clinical outcomes such as mortality and length of hospital stay were not evaluated in detail, and resistance trends may be influenced by factors beyond stewardship interventions. Nevertheless, similar limitations have been acknowledged in previous AMS studies, and the present findings contribute valuable data from a quaternary care setting in South India, where published AMS data remain limited.Overall, the findings of this study reinforce existing evidence that coordinated AMS programs are effective in optimizing antibiotic utilization, improving stewardship-related process indicators, and supporting rational antimicrobial use. Sustained stewardship efforts, regular surveillance using antibiograms, and active involvement of multidisciplinary teams are essential to combat antimicrobial resistance and ensure safe and effective antimicrobial therapy in quaternary care hospitals.
CONCLUSION
The implementation of a coordinated AMS program led to a significant reduction in antibiotic consumption, improved antimicrobial susceptibility patterns, and strengthened antimicrobial governance compared to the pre-implementation period. These findings underscore the importance of multidisciplinary AMS programs in promoting rational antibiotic use, enhancing patient safety, and addressing the growing challenge of antimicrobial resistance in hospital settings.
SCOPE FOR IMPROVEMENT
Although improvements were observed following AMS implementation, there remains scope for optimization, especially in ensuring complete documentation of antibiotic indications, which is essential for monitoring prescribing appropriateness and strengthening stewardship interventions.
ACKNOWLEGMENT
The authors acknowledge the Antimicrobial Stewardship Committee, Department of Clinical Pharmacy, and Microbiology Department for their support and assistance in data collection and analysis.
REFERENCES
A. Sivaranjani, J. Anto Musy Bosco, R. Madhumitha, Mukesh Joshi, Impact of a Coordinated Antimicrobial Stewardship (AMS) Program on Antibiotic Utilization and Clinical Outcomes in a Quaternary Care Hospital, Chennai, India - A Prospective Study, Int. J. of Pharm. Sci., 2026, Vol 4, Issue 2, 2985-2992. https://doi.org/10.5281/zenodo.18696566
10.5281/zenodo.18696566
