Method Description

The Binax NOW Streptococcus pneumoniae test is an immunochromatographic membrane assay used to detect pneumococcal soluble antigen in human urine and cerebrospinal fluid. Rabbit anti-S pneumoniae and anti-species antibodies are conjugated to visualizing particles that are dried onto an inert fibrous support. The resulting conjugate pad and the striped membrane are combined to construct the test strip.

To perform the test, a swab is dipped into the specimen, removed, and then inserted into the test device. Reagent A, a buffer solution is added from a dropper bottle. The device is then closed, bringing the sample into contact with the test strip. Pneumococcal antigen present in the sample reacts to bind anti-S pneumonia-conjugated antibody. The resulting antigen-conjugate complexes are captured by immobilized anti-S pneumoniae-conjugated antibody. The resulting antigen-conjugate complexes are captured by immobilized anti-S pneumoniae antibody, forming the sample line. Immobilized control antibody captures anti-species conjugate forming the control line.

Test results are interpreted by the presence or absence of visually detectable pink-to-purple colored lines. A positive test result, read in 15 minutes depending on the concentration of antigen present in the sample, will include the detection of both a sample and control line. A negative test result, read in 15 minutes, will produce only a control line, indicating that S pneumoniae antigen was not detected in the sample. Failure of the control line to appear, whether the sample line is present or not, indicates an invalid assay.(Package insert: BinaxNOW Streptococcus pneumoniae Antigen Card. Abbott Diagnostics; 01/2020)