Prevalence of Acinetobacter baumannii Multidrug Resistance in University Hospital Environment

<b>Background:</b><i>Acinetobacter baumannii</i> is a significant pathogen and a major contributor to healthcare-associated infections, particularly in intensive care units. Its high potential for developing multiple drug resistance (MDR) makes it a challenging pathogen to manage. This study investigates the prevalence and resistance patterns of MDR <i>A. baumannii</i> isolates over a six-year period at a university hospital in Southern Italy. <b>Objective:</b> The aims of this study are to evaluate recent trends in the prevalence of MDR <i>A. baumannii</i>, analyze resistance patterns, and assess the impact of the antimicrobial diagnostic stewardship program implemented in 2018. <b>Methods:</b> This retrospective cohort study was conducted at the University Hospital of Campania "Luigi Vanvitelli" from 2018 to 2023. A total of 191 <i>A. baumannii</i> isolates from blood, urine, and wound samples were analyzed. Antimicrobial susceptibility testing was performed following EUCAST guidelines. The prevalence of MDR strains was assessed across three periods: pre-pandemic (2018-2019), during the pandemic (2020-2021), and post-pandemic (2022-2023) <b>Results:</b> Among the 191 isolates, 89.5% were classified as MDR. The highest number of isolates occurred in 2020, with blood cultures and urine samples increasing by 40.9% and 62.5%, respectively, while wound isolates decreased by 34.2%. The implementation of antimicrobial diagnostic stewardship programs correlated with a reduction in carbapenem resistance in 2020 and 2022. However, resistance to meropenem and colistin persisted. A 60.4% decline in total isolation from 2020 to 2023 suggests effective infection control measures. <b>Conclusions:</b> MDR <i>A. baumannii</i> remains a significant threat to healthcare. Although there have been slight reductions in resistance following antimicrobial stewardship interventions, persistent resistance to last-line antibiotics underscores the urgent need for alternative treatments, enhanced surveillance, and stricter infection control strategies.