Usefulness of pneumococcal antigen detection in pleural effusion for the rapid diagnosis of infection by Streptococcus pneumoniae.

Pleural effusion is increasingly reported in children. Standard culture of blood or pleural fluid is frequently negative and molecular diagnosis by polymerase chain reaction is not available in all hospitals. The Binax NOW Streptococcus pneumoniae Antigen test (Binax, Portland, USA) is a rapid immunochromatographic test (ICT) for the detection of the C polysaccharide antigen. We evaluated the Binax NOW test on the pleural fluid of 73 children hospitalized with pleural effusion over a period of 4 years. In our sample, the sensitivity and specificity of ICT were high (88% and 71%, respectively), with a positive predictive value of 96%. Detection of the pneumococcal antigen in pleural fluid by ICT is easy and quick, and enables us to identify the pneumococcal origin of the effusion, thus, making the treatment of complicated pneumonia suitably and early.