Introduction:
antimicrobial stewardship policies are crucial in the fight against hospital-acquired infections (hais) and antimicrobial resistances. A new stewardship program was introduced in irccs policlinico san donato in 2022, consisting in a motivated request form for antimicrobial intravenous medications. The aim of this study is to analyse the daily defined dose (ddd) for every intravenous antimicrobial during the last four years and estimate the pharmacoeconomic impact of the stewardship policies in our hospital.

Methods:
The retrospective observation on antimicrobial consumption took place in the period january – october for the years 2019-2021 and a comparative analysis with 2022 was performed. The motivated request form was introduced for all the units and required as mandatory for prescription, along with an infectious disease counseling and microbiological tests. In the second half of 2022 the electronic health record was introduced in the hospital, enabling control on prescriptions. The total costs were calculated per operative unit linked to the requests of antimicrobials and ddd were calculated for each antimicrobial.

Results:
Considering the ddd/100 days of hospital stay no reduction was observed in 2022 with 52,22 ddd/100d administered but concerning the prescription pattern we could observe during 2022 a significant drop in consumption of broad-spectrum antibiotics such as ceftriaxone or amoxicillin. A significant drop in total pharmaceutical expenditure was observed too, with a median reduction of 25% of total costs.

Conclusion:
New stewardship policies not only led to more appropriate antibiotic usage in every unit but they led to a reduction in total pharmaceuticals costs. the stricter controls on the antimicrobials requests led to a virtuous mechanism of more appropriate antimicrobial choice and length of treatment. In the long run this can result in a drop both in terms of direct costs (medications, nurse working-time) and indirect costs (shorter hospital stayings and less infectious complications).