Impact of Antimicrobial-Resistant Bacterial Pneumonia on In-Hospital Mortality and Length of Hospital Stay: A Retrospective Cohort Study in Spain

This nationwide study in Spain analyzed over 116,000 hospitalizations for bacterial pneumonia (2017–2022) to assess the impact of antimicrobial resistance (AMR) on patient outcomes. About 5.1% of cases involved resistant bacteria, most commonly Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli. Patients with resistant infections were older, had more comorbidities, and were more frequently admitted to intensive care. AMR was linked to significantly higher in-hospital mortality (18.5% vs. 10.1%) and longer hospital stays (median 14 vs. 8 days), with adjusted analyses confirming a 47% higher risk of death and a 46% longer stay. The findings underscore that antimicrobial resistance substantially worsens clinical outcomes, highlighting the need for stronger AMR surveillance, resource allocation, and stewardship programs, alongside the use of rapid diagnostics to improve patient care.