Rapid-VIDITEST Strep A Blister One step Strep A Blister for the detection of Group A Streptococcal antigen from throat swabs or culture. Instruction manual Producer: VIDIA spol. s r.o., Nad Safinou II 365, Vestec, 252 42 Jesenice, Czech Republic, Tel.: +420 261 090 565, www.vidia.cz INTENDED USE: The Rapid-VIDITEST Strep A Blister is a one step coloured chromatographic immunoassay for the qualitative detection of Group A Streptococcal antigen. It can be used with throat swabs or confirmation of presumptive Group A Streptococcal colonies recovered from culture. INTRODUCTION: Group A Streptococcal (Strep) infections are caused by Group A Streptococcus, a bacterium responsible for a variety of health problems. These infections can range from mild skin infection or sore throat to severe, life-threatening conditions such as toxic shock syndrome (multi-organ failures) and necrotizing fasciitis (soft tissue disease), commonly known as flesh eating disease. Most people are familiar with strep throat, which along with minor skin infection, is the most common form of the disease. Health experts estimate that more than 10 million mild infections (throat and skin) like these occur every year. Conventional identification procedures for Group A Streptococcus from throat swabs involve the isolation and subsequent identification of viable pathogens by techniques that require 24 to 48 hours or longer. The Rapid-VIDITEST Strep A Blister detects either viable or nonviable organisms directly from a throat swab, providing results within 5 minutes. PRINCIPLE OF THE TEST: The Rapid-VIDITEST Strep A Blister is a qualitative immunochromatographic assay for the determination of Group A Streptococcal antigen. The membrane is pre-coated with mouse monoclonal antibodies, on the test band region, to recognize this antigen. During testing, the sample is allowed to react with the coloured conjugate (anti-group A Streptococcal antibodies-red microspheres) which was pre-dried on the test. The mixture then moves upward on the membrane by capillary action. As the sample flows through the test membrane, the coloured particles migrate. In the case of a positive result the specific antibodies present on the membrane will capture the coloured conjugate (result region). The mixture continues to move across the membrane to the immobilized antibody placed in the control band region, a blue coloured band always appears. The presence of this blue band serves as: 1) verification that sufficient volume is added, 2) that proper flow is obtained and 3) as an internal control for the reagents. - 1 -
STORAGE AND STABILITY: Store as packaged in the sealed pouch at 15-30ºC. The test is stable through the expiration date printed on the sealed pouch. The test must remain in the sealed pouch until use. Do not freeze. MATERIALS PROVIDED: - Blister tests - Reagent A (2M Sodium Nitrite) and Reagent B (0.15M Acetic Acid) - Testing tubes - Sterile swabs - Disposable pipettes - Instructions for use MATERIALS REQUIRED BUT NO PROVIDED: - Disposable gloves - Timer SPECIMEN COLLECTION AND PREPARATION: Collect specimens with a sterile swab from the tonsils and/or the back of the throat. Take care to avoid the teeth, gums, tongue or cheek surfaces. Process the swab as soon as possible after collecting the specimen. If your lab requires a culture result as well as the Rapid-VIDITEST Strep A Blister result, streak the culture plate with the swab before starting the Rapid-VIDITEST Strep A Blister procedure. The extraction reagents will cause the specimen to become nonviable. The swabs can be stored at room temperature or in the refrigerator (2-4ºC) for up to 24 hours prior to testing. The swabs and the test kit must be brought to room temperature before testing. CULTURE CONFIRMATION: The Rapid-VIDITEST Strep A Blister can also be used to confirm the identification of Group A Streptococcus on blood agar plates. The plates must be less than 72 hours old. Lightly touch 1-3 suspect colonies (showing characteristic beta hemolysis) using a sterile swab. Do not sweep the plate. Follow the instructions in the test procedure section to test the swab. TEST PROCEDURE: Allow the tests, swabs and controls to reach to room temperature (15-30ºC) prior to testing. Do not open the package until ready to perform the assay. Only bring to room temperature the number of tests required to assay before opening it. 1. Add 5 drops (1) Reagent A (pink) and 5 drops (2) Reagent B in a testing tube (the solution should turn light yellow). 2. Immediately put the swab into the tube. 3. Mix the solution by rotating the swab forcefully against the side of the tube at least 10 times. Best results are obtained when the specimen is vigorously extracted in the solution (3). 4. Let stand for 1 minute. 5. Extract as much liquid as possible from the swab, pressing the sides of the tube. 6. Discard the swab. - 2 -
a) Using the blister Test single pack as a Card test: 7. Cut the blister to obtain a test single pack, hold the non sealed side and open it peeling off the upper foil. Don t remove the test from the blister cavity and use it as soon as possible. 8. Place the test on a flat surface. Use a separate pipette and device for each sample or control. Dispense exactly 4 drops or 125 µl from the testing tube, on the white end of the test (4a). 9. Read the result at 10 minutes. b) Using the blister Test single pack as a Strip test: By immersion: 7. Cut the blister to obtain a test single pack, hold the non sealed side and open it peeling off the upper foil. 8. Place the test vertically with the white end submerged into the sample taking care of not surpassing the limit of immersion indicated with the arrows (4b). 9. Read the result at 10 minutes. INTERPRETATION OF RESULTS (please refer to the illustration below): - 3 -
NEGATIVE: Only one blue band (control line) appears in the white central zone of the test (control region). POSITIVE: In addition to the blue control band, a red band (test line) also appears in the white central zone of the test (result region). INVALID: A total absence of the control coloured band (blue) regardless the appearance or not of the result line (red). Insufficient specimen volume, incorrect procedural techniques or deterioration of the reagents are the most likely reasons for control line failure. Review the procedure and repeat the test with a new test. If the problem persists, discontinue using the test kit and contact your local distributor. NOTES ON THE INTERPREATION OF RESULTS: The intensity of the red coloured band in the result region will vary depending on the concentration of antigens present in the specimen. However, neither the quantitative value, nor the rate of increase in antigens can be determined by this qualitative test. QUALITY CONTROL: Internal procedural controls are included in the test. - A blue line appearing in the control region is the internal procedural control. It confirms sufficient specimen volume and correct procedural technique. - The color of the liquid changes from pink to light yellow as you add Reagent B to Reagent A. This is an internal extraction reagent control. The color change means that you mixed the extraction reagent control, that you mixed the extraction reagent properly and that the reagents are functioning properly. External quality control testing. LIMITATIONS: 1. The test must be carried out within 2 hours of opening the sealed pack. 2. This test provides a presumptive diagnosis for Group A Streptococcus infections. A confirmed infection diagnosis should only be made by a physician after all clinical and laboratory findings have been evaluated. 3. The Rapid-VIDITEST Strep A Blister should be used only with throat swabs or colonies taken directly from a plate. The use of swab specimens taken from other sites or the use of other samples such as saliva, sputum or urine has not been established. The quality of the test depends on the quality of the sample; proper throat swab specimens must be obtained. 4. This test does not differentiate between carriers and acute infection. Pharyngitis may be caused by organisms other than Group A Streptococcus. 5. A negative result may be obtained if the specimen is inadequate or antigen concentration is below the sensitivity of the test. Therefore, it is recommended that all negative Rapid-VIDITEST Strep A Blister test results undergo confirmatory testing using a culture method. EXPECTED VALUES: Although strep throat can occur at any age and at any time of the year, it mainly affects school-age children during the winter and spring. - 4 -
PERFORMANCE: Sensitivity Different inactivated Group A Streptococcus cultures dilutions were tested directly in the sample diluent or spiked in a negative specimens in accordance with the kit instructions. Detection limit: 1,9x 10 4 CFU/mL. The detection of Group A Streptococcus with Rapid-VIDITEST Strep A Blister test showed >99% of sensitivity compared with other commercial rapid tests. Specificity The detection of Group A Streptococcus with Rapid-VIDITEST Strep A Blister test showed >99% of specificity compared with other commercial rapid tests. PRECAUTIONS: - Rapid-VIDITEST Strep A Blister is intended for professional in vitro diagnostic use. - Do not use after expiration date. - Do not use test devices if the aluminium has been damaged during storage. - All the specimens should be considered potentially hazardous and handled in the same manner as an infectious agent. A new swab must be used for each sample to avoid contamination errors. - The tests should be discarded in a proper biohazard container after testing. REFERENCES: 1. Dos Santos, Ana Gabriele P., Berezin, Fitan N.; Comparative analysis of clinical and laboratory methods for diagnosing Streptococcal sore throat. J. Pediatr. (Rio J.) 2005; 81 (1): 23-8 2. Borbeau, Paul P. and Heither, Barbara J.; Use of swab without Transport media for the Gen-Probe Group A Strep Direct Test. Journal of Clinical Microbiology, July 2004, p. 3207-3211 3. Petts, D.N.; Evaluation of a modified nitrous acid extraction latex agglutination kit for grouping beta-hemolytic Streptococci and Enterococci. Journal of Clinical Microbiology, Apr. 1995, p.1016-1018. 4. Sheeler, Robert P. et al., Accuracy of Rapid Strep testing in patients who have had recent Streptococcal Pharyngitis. JABFP, July-August 2002, Vol 15 No 4, p. 261-265. SYMBOLS FOR IVD COMPONENTS AND REAGENTS: In vitro diagnostic device Use by Batch code Manufacturer - 5 -