Title: Stewardship Antibiotica VErona.

Design: Hospital-wide multifaceted Antimicrobial Stewardship Intervention. Monocentric, quasi-experimental, non-randomized, Interrupted Time Series, open-label study.

Primary Objective: Improving the quality of care through decreasing the rate of inappropriate antibiotic prescription and the rates of infections caused by antibiotic-resistant organisms. Measuring the effect of the Antimicrobial Stewardship Interventions (ASI) implementation on:

• variation in antibiotic consumption.

• prevalence of Carbapenem-Resistant Enterobacteriaceae (CRE) bacteremia and C.difficile infections.

• patient-safety metrics.

Secondary Objective: Analyzing the individual and socio-contextual determinants influencing prescribing behaviours, barriers and facilitators for ASI implementation.

"Firstline" App: In February 2023, the Firstline mobile App was launched and made accessible to all the healthcare professional at the University Hospitals of Verona, following its two years of development, and successful pilot phase.

The app, through guidance of appropriateness of various treatments, aims to reduce the use of antibiotics. During the pilot phase, the app was adopted within the COVID wards, the Paediatric area and in the two Emergency Departments of the hospitals.

The pilot phase, which ended in December 2022, produced highly positive results. In the COVID departments, there was a 37% reduction in antibiotic consumption and a drop from 31% to 58% in infections from multi-drug resistant bacteria and invasive Candida. In the paediatric departments, there was a reduction in antibiotic consumption of 44%. The pilot phase targeted a total of 350 users, reaching up to 100 accesses per day and 3000 accesses per year for the most consulted guidelines . Overall, there was a 30% reduction in unnecessary antibiotic use and a net improvement in prescribing appropriateness.

The novelty and the effectiveness of this app lie in the fact that it contains easy to access guidelines, diagnostic algorithms, and updated surveillance of antibiotic susceptibility data.