Multidrug-Resistant Bloodstream Infections Before and After COVID-19: A Temporal Assessment of Outcomes and Resistance Across Two Eras in a Non-COVID Intensive Care Unit-The MATURATE ICU Study.

The COVID-19 pandemic redirected infection control and antimicrobial stewardship towards SARS-CoV-2, potentially increasing multidrug-resistant (MDR) bloodstream infections (BSIs). We compared MDR BSI epidemiology and outcomes in a non-COVID intensive care unit (ICU) before and after the pandemic. The MATURATE ICU study retrospectively included adults with MDR BSIs admitted to a non-COVID ICU during the pre-COVID-19 (1 January 2017-1 January 2020) and post-COVID-19 (1 January 2022-1 January 2025) eras. Clinical, microbiological and outcome data were compared. Survival analyses and multivariable logistic regression identified predictors of ICU mortality. Overall, 146 patients were included (74 pre-COVID-19 and 72 post-COVID-19). Pre-COVID-19 patients were older and had higher comorbidity burden and severity indices (all p ≤ 0.023). ICU stay after the first positive blood culture was longer in the post-COVID-19 period (p = 0.003). New organ dysfunction, acute kidney injury, and septic shock were more frequent pre-COVID-19, whereas cardiovascular events were more frequent post-COVID-19. ICU mortality was higher pre-COVID-19 (p < 0.001). Competing-risk analysis, treating ICU discharge alive as a competing event, demonstrated a significantly lower cumulative incidence of ICU death in the post-COVID-19 era (adjusted sHR 0.20, 95% CI 0.11-0.35; p < 0.001). In multivariable analysis, post-COVID-19 era independently predicted lower 28-day ICU mortality (adjusted OR = 0.11, 95% CI 0.04-0.28, p < 0.001), whereas higher CCI (adjusted OR = 1.31, 95% CI 1.04-1.69, p = 0.027) and SOFA (adjusted OR = 1.22, 95% CI 1.07-1.40, p = 0.003) independently predicted increased mortality. Despite the persistently high burden of antimicrobial resistance, improved post-COVID-19 survival suggests that, advances in ICU care and healthcare system recovery may have contributed to better outcomes.