Outcome of Bloodstream Infections Caused by Antibiotic-Resistant Bacteria: A 7-Year Retrospective Study at the University Hospital of Palermo, Italy.

BACKGROUND

Bloodstream infections (BSIs) are both a primary cause and a severe complication of hospitalization. This retrospective study aims to analyze the epidemiology of BSIs at the University Hospital of Palermo from 2018 to 2024.

METHODS

We conducted a single-center, retrospective, observational study at the University Hospital Paolo Giaccone in Palermo, analyzing microbiological data from blood cultures collected between 1 January 2018 and 31 December 2024.

RESULTS

A total of 6345 blood culture isolates from 2967 patients were analyzed. Bacteremia-related mortality per 1000 patients rose from 5.1% in 2018 to 10.5% in 2024. The most isolated pathogens were non- staphylococci (39.7%), followed by (12.1%) and (7.47%). and were more prevalent in ICUs. The number of , , , and isolates per 1000 admitted patients increased significantly over time. Oxacillin resistance in peaked at 49.0% in 2020 before declining, while among non- staphylococci, it remained consistently high (>80%). Carbapenem-resistant peaked at 80% in 2022 before decreasing in 2024. Resistance to ceftazidime-avibactam and meropenem-vaborbactam was observed in 11.3% and 11.8% of , respectively. Multivariable analysis identified and BSIs as independent predictors of in-hospital mortality. Additionally, female sex, pneumonia, and central nervous system infections were significant risk factors for mortality.

CONCLUSIONS

We observed an increasing trend in overall bacteremia-related mortality from 2018 to 2024. Microbiological data highlight the predominance of non- staphylococci, , and as leading pathogens of BSI, with emerging as a significant threat, particularly in ICUs. Rising antimicrobial resistance, especially among , underscores the urgent need for robust antimicrobial stewardship programs. and were associated with higher mortality.