Laboratory N300 Microscope

The Strep A Test-Strip is an immunological one-step membrane-test for quick and qualitative determination of streptococci-antigens Group A directly from the throat-swab.

• for throat-swabs
• high sensitivity and specificity
• results after few minutes
• qualitative determination of streptococci A-antigens
• simple test-strip method
• complete package: 20 test-strips, 1 bottle each reagent A and B, 20 swabs, 20 extraction-vessels

Beta-hemolytic streptococci Group A are the main reason for upper respiratory-tract infections, like tonsillitis, pharyngitis and scarlatina (scarlet fever). It has been proven that early diagnosis and treatment of streptococci Group A in conditional pharyngitis helps reduce the depth of the symptoms and further complications, like rheumatic fever and post-streptococci-glomerulonephritis (1). Conventional proof-methods of this illness are based on isolation and following identification of the organisms (1, 2), which, as a rule, takes 24 – 48 hours. The development of new immunological techniques (3, 4) for proof of streptococci Group A directly from the throat-swab allows the doctor quick diagnosis and immediate treatment.

Test principle
The Strep A test-strip uses the immunological “sandwich-assay” technology for the proof of streptococci Group A. The test contains nitro-cellulose membrane-strips, coated with rabbit anti-strep A anti-bodies in the region of the test-line, and goat anti-rabbit anti-bodies in the region of the control-line. The end of the membrane has a pillow with colored, polyclonal rabbit anti-strep A anti-body colloidal-gold conjugate. During the test, strep A antigen is extracted from the throat-swab through use of the extraction-reagents 1 and 2. The test-strip is then dipped into the extraction-vessel. Here, the strep a antigen reacts with the colored anti-body gold-conjugate by building the strep A antigen anti-body compounds. Via influence of capillary forces, the sample mixture flows on the membrane to the immobilized rabbit anti-strep A anti-bodies in the test-line region.In case of strep A antigen in the sample, the colored line of the “sandwich” compounds appears in the shape of a solid-phase anti-strep A anti-body/ strep A antigen/anti-strep A gold-conjugate compound. With a negative result, no line appears in the test-line region.

Independent of the presence of the strep-A antigen, the sample mixture always reacts with a colored line with the goat anti-rabbit anti-bodies when passing the control-line region. The presence of the colored control-line serves:

1) as proof that sufficient sample volume was applied,

2) as proof that the sample flowed across the membrane properly and

3) as reagent-control.