Etiology and Factors Contributing to Mortality in Healthcare-associated Pneumonia: A Single-center Study

Factors contributing to mortality in healthcare-associated pneumonia (HCAP) have not been investigated fully. We reviewed the etiology and identified prognostic factors of HCAP in hospitalized patients. We conducted a retrospective study of 500 Japanese patients with HCAP to assess these factors, with special emphasis on microbial etiology. Patients with HCAP were older (73.4±11.4 years), more predominantly male (74.4%), and had more smoking history and comorbidity than did community-acquired pneumonia (CAP) patients. Microbes were identified in 52.8% of HCAP patients. The most frequent causative microbial agents were Streptococcus pneumoniae (n = 108, 21.6%), influenza virus (n = 47, 9.4%), and Pseudomonas aeruginosa (n = 40, 8.0%). Multiple drug-resistant (MDR) pathogens were more frequent in HCAP patients (9.8%) than CAP patients. Overall, 47 HCAP patients (9.4%) died, with mortality being higher in HCAP than CAP patients. The three leading causes of non-survival from HCAP were S. pneumoniae, influenza virus, and P. aeruginosa. MDR pathogens accounted for 21.3% of non-survivors. Multivariate analysis revealed disease severity on admission and treatment failure of initial antibiotics as independent factors for 30-day mortality. Among patients with treatment failure of initial antibiotics, 29.9% had received appropriate antibiotics. The most frequent pathogens in HCAP were S. pneumoniae, influenza virus, and P. aeruginosa, in both survivors and non-survivors. Disease severity on admission and treatment failure of initial antibiotics were independent factors for mortality. MDR pathogens are important therapeutic targets to mitigate negative results, and treatment strategies other than antibiotic selection are also required