Detection of Streptococcus pneumoniae antigen in pleural fluid: usefulness of an immunofluorescence-based lateral flow assay for the diagnosis of pneumococcal pneumonia.

The performance of an immunofluorescence-based Streptococcus pneumoniae antigen detection test in pleural fluid (IF-PF) was evaluated. For proven and possible pneumococcal pneumonias global sensitivity and specificity were 92.6 (95 CI 76.6-97.9) and 80 (95 CI 62.7-90.5), respectively, with no significant differences between children and adults. Global diagnostic accuracy of IF-PF was 86% (74.2-93.7), and a substantial k index of concordance with culture/RT-PCR of 0.716 (0.535-0.896). IF-PF might be useful as a rapid complementary test for the etiologic diagnosis of pneumococcal pneumonia.