Antimicrobial Resistance and Clinical Outcome Among Hospitalized Bacterial Pneumonia: A Retrospective Cohort Study in Indonesian Tertiary Hospital

Background: Pneumonia is a common cause of hospitalization and a significant contributor to worldwide morbidity and mortality. Effective definitive antimicrobial therapy for pneumonia relies on accurate identification of bacterial pathogens and their resistance patterns. Therefore, this study aims to evaluate the distribution bacterial pathogens and their antimicrobial resistance patterns, as well as clinical factors associated with outcomes among hospitalized pneumonia patients. Methods: This retrospective cohort study was conducted at Dr. Hasan Sadikin General Hospital, Indonesia, and included adult patients hospitalized with pneumonia between January and December 2024. Clinical, demographic, microbiological, and outcome data were extracted from electronic medical records and the laboratory system. Bacterial distribution, antimicrobial patterns, and clinical outcomes were analyzed descriptively and compared across pneumonia types. Multivariable regression analyses were performed to identify factors associated with in-hospital mortality and length of hospital stay. Results: A total of 662 hospitalized pneumonia patients were included with Gram-negative bacteria (i.e., Klebsiella pneumonia, Acinetobacter baumannii, and Pseudomonas aeruginosa) identified as the most common pathogens. Carbapenem-resistant Acinetobacter baumannii (CR-Ab) and Klebsiella pneumoniae (CR-Kp) were the most frequently identified resistant pathogens, particularly in hospital-acquired (HAP) and ventilator-associated pneumonia (VAP). HAP and VAP were independently associated with higher in-hospital mortality and longer hospital stay compared to community-acquired pneumonia (CAP). In addition, CR-Ab and difficult-to-treat Pseudomonas aeruginosa (DTR-Psa) were associated with prolonged hospitalization. Conclusions: Type of pneumonia, bacterial pathogens and resistance patterns were associated with in-hospital mortality and length of hospital stay. These findings highlight the importance of ongoing microbiological surveillance, antimicrobial stewardship, and infection prevention strategies to optimize pneumonia management and clinical outcomes.