Clinical Study Concerning the Relationship between Community-Acquired Pneumonia and Viral Infection in Northern Thailand

Objective The etiological agents associated with community-acquired pneumonia (CAP) in Thailand have been studied extensively in bacterial pathogens, but not in viral pathogens. To clarify the association of viral pathogens with CAP, we conducted a comprehensive study of viral and bacterial pathogens in patients with CAP. Methods We enrolled 119 hospitalized patients with CAP in Nakornping Hospital, Chiang Mai, Thailand between 2006 and 2008. The severity of pneumonia was classified and the risk factors for death were estimated. Bacterial and fungal pathogens were determined from specimens taken from blood and sputum, and viral pathogens were identified from nasopharyngeal specimens by RT-PCR using primers specific for 7 respiratory viruses. Results Overall, 29 patients were HIV-infected and 90 patients were non-HIV-infected. The microbial pathogens most commonly isolated among HIV-infected patients were: 4 Klebsiella pneumoniae, 4 Mycobacterium tuberculosis and 3 Haemophilus influenzae. Among non-HIV infected patients, predominant microbial pathogens were: 6 Pseudomonas aeruginosa, 5 Haemophilus influenzae and 4 Klebsiella pneumoniae. As for viral pathogens for CAP, influenza virus was identified from 2 HIV-infected patients and 5 non-HIV infected patients. In addition, human rhinovirus (HRV) and respiratory syncytial virus (RSV) were identified from 2 patients each among non-HIV-infected patients. Conclusion Our study demonstrates that the most common viral agent was influenza virus (5%), followed by HRV (2%) and RSV (2%) among CAP patients in northern Thailand. The underlying chronic obstructive pulmonary disease (COPD) seems to be correlated with the severity of illness.