Viral and bacterial aetiology of community-acquired pneumonia in adults

Background Modern molecular techniques reveal new information on the role of respiratory viruses in community-acquired pneumonia. In this study, we tried to determine the prevalence of respiratory viruses and bacteria in patients with community-acquired pneumonia who were admitted to the hospital. Methods Between April 2008 and April 2009, 408 adult patients (aged between 20 and 94years) with community-acquired pneumonia were tested for the presence of respiratory pathogens using bacterial cultures, real-time PCR for viruses and bacteria, urinary antigen testing for Legionella and Pneumococci and serology for the presence of viral and bacterial pathogens. Results Pathogens were identified in 263 (64·5%) of the 408 patients. The most common single organisms in these 263 patients were Streptococcus pneumoniae (22·8%), Coxiella burnetii (6·8%) and influenza A virus (3·8%). Of the 263 patients detected with pathogens, 117 (44·5%) patients were positive for one or more viral pathogens. Of these 117 patients, 52 (44·4%) had no bacterial pathogen. Multiple virus infections (≥2) were found in 16 patients. Conclusion In conclusion, respiratory viruses are frequently found in patients with CAP and may therefore play an important role in the aetiology of this disease.