The role of viruses in the development of pleural infection

Introduction: Several factors imply a viral role in the development of pleural infection including low yield on bacterial culture and seasonal variation. The relationship between respiratory viruses and pneumococcal pneumonia is well known but no studies have tested the association with pleural infection. Additionally, Epstein-Barr virus (EBV) has been implicated as a possible cause of ‘undiagnosed effusions’ without being validated. Methods: We analysed serum and pleural fluid (pf) from a prospective cohort of patients with effusions due to infection and biopsy-proven inflammatory pleuritis (IP). Nucleic acids were extracted from pf using the QIAsymphony DSP Virus/Pathogen Kit. Real-time PCR was performed using TaqMan array with 48 pathogen targets. Serum complement fixation testing using influenza and RSV antigen was performed alongside EBV serological tests. Results: From 193 patients including 60 empyema, 50 parapneumonic, 28 IP and 55 cardiac transudates (controls) there were no significant respiratory viral titres in pf. In patients with infective effusions, 21% had serological evidence of recent viral infection (Influenzas A&B or RSV). EBV was present at low levels in 22 pf samples (11%). There was no evidence of acute or re-activated EBV infection in the sera of patients with EBV DNA in pf. Conclusion: This is the first prospective study to test for the presence of viruses in pleural infection. We found no evidence of respiratory viruses within the effusions of either infection or control groups. However, there was serological evidence of recent flu/RSV infection in patients with pleural infection indicating a precedent illness. Results from pf EBV analysis demonstrated latent infection in 11% but no causative role.