Impact of infectious etiology on the outcome of Taiwanese patients hospitalized with community acquired pneumonia

Introduction: This study aimed to assess the relationships between infectious etiology, empiric treatment, and outcomes in Taiwanese patients with community acquired pneumonia (CAP). Methodology: A retrospective analysis of the data of 208 adult patients from a single medical center was performed with patients classified as having low or high disease severity based on the Pneumonia Severity Index (PSI). Patients with PSI ≤ 90 (n=120) were classified as low severity and patients with PSI > 90 (n=88) were classified as high severity. Results: The low-risk group had significantly higher rates of infection with Chlamydia pneumoniae (C. pneumoniae) and Mycoplasma pneumoniae (M. pneumoniae), whereas the high-risk group had significantly higher rates of infection with Klebsiella pneumoniae (K. pneumoniae) and Pseudomonas aeruginosa (P. aeruginosa) (p < 0.05). Empiric treatment in both groups was in accordance with the 2007 guidelines issued by the Infectious Diseases Society of America/American Thoracic Society (IDSA/ATS). Twenty-nine of 208 patients (13.9%) died, one in the low-risk group and 28 in the high-risk group. The highest rates of mortality were in patients infected with P. aeruginosa or K. pneumoniae. Conclusions: In the present study, we demonstrated that the patients with different severity had different microbiologic etiology. In general, P. aeruginosa and K. pneumoniae were the most commonly isolated organisms in high-risk patients who died from CAP. We showed that use of the IIDSA/ATS guidelines for treatment of CAP in Taiwan resulted in a better outcome in the low PSI group.