Background:
Antibiotic resistance is being a crucial issue in our hospitals, and its control, which is one of the most challenging task for the future, passes through an appropriate use of antibiotics. To evaluate the prescriptive appropriateness of antimicrobials, we recently created a new indicator which takes into account the rate of infections together with antimicrobial consumption and the median time of treatment of each event.

Methods:
The “Estimated Prescriptive Appropriateness Rate” (EPA-SCORE) “ has been calculated for each group of bacteria, as the rate between the observed consumption of an antibiotic ( DDD/1000days of hospitalization) and the expected one as if the same antibiotic had been used for 10 days exclusively for the observed infections where it was indicated, according to the following formula: _EPASCORE=__DDD(__observed/e__xpected)__*(__1/__N. of infections)_ Data from January 2020 and June 2022 were collected while restrictive and persuasive strategies of Antimicrobial Stewardship were implemented. Changes in EPA-SCORE were evaluated through the years.

Results:
In our hospital, in the first semester of 2022 prevalence of ESBL+ Gram negative-infections was 0.90 cases/1000 doh/year. The observed consumption of drugs indicated for those infections was 86.9 DDD/1000 doh, whilst the expected one for the registered number of infections was 9.01 DDD/1000doh, with an EPASCORE of 10.37%. Regarding multi-drug-resistant gram negative-infections, prevalence was 1.48/1000doh/year; observed antibiotic consumption for them (whose prescription policy was restricted to ID specialists) was 43DDD/1000doh, whilts the expected DDD was 29.6 DDD/1000doh (EPASCORE 67.7%) Comparing data between the first semester of 2020 and the same period of 2022, a significant increase in EPASCORE was detected (+4.2% and +7.1% for ESBL+ and MDR Gram-negative infections in 2022 respectively)

Conclusion:
Our date demonstrate that the EPASCORE could represent a feasible indicator of appropriateness of antimicrobial prescription, and restrictive strategies of antimicrobial stewardship can help to improve its outcome.