NAME AND INTENDED USE
This Group A Streptococcal Antigen Rapid Test Kit is an in vitro immunoassay for the qualitative detection of Group A Streptococcal in human throat swab specimens in just one step. It is used for the diagnosis of early infection and epidemic survey. This kit is intended only for an initial screening test and reactive samples should be confirmed by a supplemental assay such as commercial enzyme immunoassay (ELISA) or RT-PCR.
Group A Streptococcus (GAS) is the most pathogenic Streptococcus that is widely found in human and animal feces, and also in the nasopharynx of healthy people, it is an acute respiratory infection. It is an important bacterial pathogen of upper respiratory tract infection that can cause Acute Pharyngitis and Tonsillitis in the children and adults and can also cause serious invasive infections such as toxic shock syndrome.
Repeated infections can cause secondary diseases such as rheumatoid arthritis, rheumatic heart disease, and acute glomerulonephritis. Presently, relevant clinical and laboratory diagnostic methods include enzyme immunofilm method, latex coacervation method, colloidal gold immunochromatography, real-time fluorescent PCR technology and bacterial culture identification method. Among them, bacterial culture is the traditional detection method of group A hemolytic streptococcus.
PRINCIPLES OF THE ASSAY
The test kit applies colloidal gold immunochromatography to qualitatively detect the group A Streptococcus, pyogenes antigen in throat swab specimens. A rabbit anti-A-type Streptococcus polyclonal antibody labeled with colloidal gold is coated on the gold-labeled mat, and a rabbit anti-A-type Streptococcus polyclonal antibody is coated on the nitrocellulose membrane. In the case of a positive specimen, the Group A Streptococcus antigen in the specimen can be combined with a colloidal gold-labeled-rabbit anti-A-type Streptococcus polyclonal antibody to form an immune complex, due to the chromatographic complex and the sample flows forward within the nitrocellulose membrane. When the complex passes through the T line, it combines to the coated rabbit anti-A strain of Streptococcus polyclonal antibody to form an immune complex and agglutinate color. The remaining colloidal gold-labeled Rat-anti-rabA strain of Streptococcus polyclonal antibody binds to the C-line coated goat-anti-rabbit IgG antibody to agglutinate the color; if it is a negative specimen, the specimen does not contain group A beta-streptococcus antigen that causes the formation of immune complexes, can only be developed at the C line.
20x1 tests (Cassette) Group A Streptococcal test Cassette and each cassette contain a test strip with:
T-line coated rabbit-anti-A group B streptococcus polyclonal antibody. In the C-line, a goat-anti-rabbit IgG antibody is coated, and a buffer solution of 0.05 M PBS pH 7.4: 1 × 20 pieces
Extract A (2M sodium nitrite): 1 × 6 ml
Extract B (1 M acetic acid): 1 × 6 ml
Sample tube for extraction: 1.5ml × 20
Instructions: 1 copy
The components of different batches and different varieties of kits are not mixed.
SAMPLE COLLECTION AND PRESERVATION
Sample collection swab
The main sample of group A Streptococcus is swabs or other parts of the cotton swabs with pathogens. It can also be obtained from the cultured bacterial colonies.
While sampling, use a cotton swab to gently wipe the tonsil and throat wall to avoid any direct contact between the tongue and the swab. The collected samples should be sealed and refrigerated.
The bacteria to be identified should be a pure culture with a bacterial age of no more than 48 hours. The number of colonies to be tested should not be less than 105 CFU/ml and the culture medium requires a blood plate medium.
Preparation before inspection: The specimens to be tested are taken out from the refrigerated environment and should be allowed to equilibrate for 30 minutes at room temperature.
Add 5 drops of about 250 μl extract A and extract B to the tube for extraction and mix well.
Place the cotton swab containing the bacteria into the test tube with the extract, let it stand for 3 to 5 minutes at room temperature, shake the cotton swab for a few seconds, and repeatedly squeeze and rotate on the tube wall; discard the liquid on the cotton swab. Throat swabs, tube extracts can be used for testing within 60 minutes.
Inspection process: Remove the test card from the foil pouch and place it on a dry horizontal work surface, add 100 μl of extract finally formed extract in above Step 3(about 2 drops, and then add the second drop after infiltration of the first drop) into the well and judge the results within 8 to 10 minutes.
Precautions taken during the inspection process: The test kit and the sample to be tested should be placed at room temperature before being tested. Use the test card within 30 minutes after opening it.
INTERPRETATION OF RESULT
Positive: If two pink lines appear in both the C and T position
Negative: If only one pink line appears in the C position
Invalid: If the control line next to the test line is not visible within 10 minutes after the addition of the sample.
The test results of this product are interpreted by human and are subjected to visual errors or subjective judgment. Therefore, when the color of the strip is difficult to determine it clearly, it is recommended to repeat the test.
This test card is one of the auxiliary means of diagnosis and the test result is for reference only so, should not be taken as the sole basis for clinical diagnosis and treatment. The positive result should be further confirmed by other methods also, the detection result is limited by the sensitivity of the test. The negative result may be due to low antibody concentration, due to the sensitivity of product analysis. Clinical diagnosis should be combined with clinical examination, medical history and other tests.
This detection kit (colloidal gold method) cannot distinguish between the dead and live bacteria. Due to the presence of group A streptococcal antigens, patients who have recently been treated with group A streptococci or similar infections may have positive results for a period of effective treatment.
This kit does not distinguish between asymptomatic carriers and those with infection.
Pharyngitis can also be caused by bacteria other than group A streptococci. When the laboratory diagnosis does not match the clinical performance, further diagnosis including bacterial culture is required.
Use of corporate standards for testing meets the following criteria: positive coincidence rate (+/+) = 10/10; negative coincidence rate (-/-) = 10/10; precision (n = 10) results are all positive. The color rendering is uniform; minimum detection limit of the serial dilution is the internal control standard, and the positive end point should be not less than 1:8 dilution.
Use this kit to detect the samples of group B streptococcus (Strep B), group C streptococcus (Strep C), group D streptococcus (Strep D), and staphylococcus aureus (SA) at a concentration of 108 CFU/ml.
Positive samples such as Mycoplasma pneumoniae IgM/IgG, Chlamydia pneumoniae IgM/IgG and respiratory syncytial virus IgM will not be tested with this kit.
Both plate and the sample should be at room temperature 20-25°C
Failure to detect Group A streptococcus may be a result of factors such as collection of specimen at improper time in the disease or improper sampling or handling of the specimen.
Wrong result might be caused by the expired kit or inappropriate samples.
STORAGE AND STABILITY
Store at room temperature and the shelf life is of 24months.Do not use the kit beyond its expiration date.