Clinical and microbiological distinctions between community-acquired pneumonia and hospital-acquired pneumonia: A retrospective analysis of hospitalized patients at king Hussein medical center

Objective: To differentiate community-acquired pneumonia (CAP) from hospital-acquired pneumonia (HAP) among hospitalized patients at King Hussein Medical Center, Jordan.
Methods: Retrospective cohort study of 450 adults (225 CAP, 225 HAP) hospitalized with pneumonia (January 2022–December 2025). Demographic, clinical, microbiological, and outcome data were analyzed. Multivariate logistic regression identified independent predictors of HAP.
Results: Mean age 68.2±14.6 years; 58.4% male. HAP patients were older (72.4±12.8 vs. 64.0±15.2 years, p<0.001), had higher Charlson scores (4.2±1.8 vs. 2.6±1.4, p<0.001), and greater severity (CURB-65≥3: 28.0% vs. 12.4%, p<0.001). Microbiological confirmation: 68.4% (308/450). CAP pathogens: S. pneumoniae (28.0%), H. influenzae (14.7%), M. pneumoniae (10.7%). HAP pathogens: K. pneumoniae (25.3%), A. baumannii (18.7%), P. aeruginosa (16.0%), MRSA (9.3%). MDR organisms more common in HAP (44.0% vs. 12.0%, p<0.001). Procalcitonin distinguished bacterial CAP (AUC 0.84; 95% CI: 0.79–0.89). HAP associated with longer hospitalization (median 18 vs. 9 days, p<0.001), higher ICU admission (32.0% vs. 12.9%, p<0.001), and increased 30-day mortality (24.4% vs. 10.2%, p<0.001). Independent HAP predictors: prior antibiotics (OR=4.82), mechanical ventilation (OR=3.45), chronic lung disease (OR=2.15).
Conclusion: CAP and HAP are distinct entities with different microbiology, resistance, and outcomes. Empirical antibiotic strategies must account for local epidemiology. Procalcitonin aids bacterial CAP diagnosis.