Accu-Tell^® Strep A Rapid Test Cassette (Throat Swab)

Product Description

CATALOG

KEY POINTS

Detection for: Strep A antigens in throat swab specimens

Specimen volume: Refer to the test procedure

Reading time: 5 minutes

Relative Sensitivity: 94.4% (88.7%-97.7%)*   

Relative Specificity: 97.3% (95.1%-98.6%)*

Accuracy: 96.6% (94.6%-98.0%)*

INTRODUCTION

Streptococcus pyogenes is non-motile gram-positive cocci, which contains the Lancefield group A antigens that can cause serious infections such as pharyngitis, respiratory infection, impetigo, endocarditis, meningitis, puerperal sepsis, and arthritis. Left untreated, these infections can lead to serious complications, including rheumatic fever and peritonsillar abscess. Traditional identification procedures for Group A Streptococci infection involve the isolation and identification of viable organisms using techniques that require 24 to 48 hours or longer.

INTENDED USE

ACCU-TELL^® Strep A Rapid Test Cassette (Throat Swab) is a rapid chromatographic immunoassay for the qualitative detection of Strep A antigens from throat swab specimens to aid in the diagnosis of Group A Streptococcal infection.

TEST PROCEDURE

1. Remove the test cassette or test strip from the sealed foil pouch and use it within one hour. Best results will be obtained if the test is performed immediately after opening the foil pouch.

1.) Hold the Extraction Reagent 1 bottle vertically and add 4 full drops (approximately 240 μL) of Extraction Reagent 1 to an extraction tube. Extraction Reagent 1 is red in color. Hold the Extraction Reagent 2 bottle vertically and add 4 full drops (approximately 160μL) to the tube. Extraction Reagent 2 is colorless. Mix the solution by gently swirling the extraction tube. The addition of Extraction Reagent 2 to Extraction Reagent 1 changes the color of the solution from red to yellow. See illustration 1.

2.) Immediately add the swab into the extraction tube, agitate the swab vigorously 15 times. Leave the swab in the extraction test tube for 1 minute. See illustration 2.

3.) Press the swab against the side of the tube and squeeze the bottom of the tube while removing the swab so that most of the liquid stays in the tube. Discard the swab. See illustration 3

4.) Fit the dropper tip on top of the extraction tube. Place the test cassette on a clean and level surface. Add three drops of the solution (approx.100μL) to the sample well and then start the timer. Read the result at 5 minutes. Do not interpret the result after 10 minutes. See illustration 4 and illustration 5.

2.  Wait for the colored line(s) to appear. Read the result at 5 minutes. Do not interpret the result after 10 minutes.

PERFORMANCE CHARACTERISTICS

Sensitivity and Specificity

Using three medical centers for evaluation, a total of 525 throat swabs were collected from patients exhibiting symptoms of pharyngitis. Each swab was rolled onto a sheep blood agar plate, and then tested by ACCU-TELL^® Strep A Rapid Test Strip/Cassette (Throat Swab). The plates were further streaked for isolation, and then incubated at 37℃ with 5-10% CO₂ and a Bacitracin disk for 18-24 hours. The negative culture plates were incubated for an additional 18-24 hours. Possible GAS colonies were subcultured and confirmed with a commercially available latex agglutination grouping kit. Of the 525 total specimens, 401 were confirmed to be negative and 124 were confirmed to be positive by culture. During this study, one Strep F specimens yielded positive results with the Test. One of these specimens was re-cultured, then re-tested and yielded a negative result. Three additional different Strep F strains were cultured and tested for cross-reactivity and also yielded negative results.

Relative Sensitivity: 94.4% (88.7%-97.7%)*   

Relative Specificity: 97.3% (95.1%-98.6%)*

Accuracy: 96.6% (94.6%-98.0%)*

* 95% Confidence Intervals

Cross Reactivity

The following organisms were tested at 1.0 x 10⁷ organisms per test and were all found to be negative when tested with ACCU-TELL^® Strep A Rapid Test Cassette (Throat Swab). No mucoid-producing strains were tested.

LIMITATIONS

1. ACCU-TELL^® Strep A Rapid Test Cassette (Throat Swab) is for in vitro diagnostic use only. The test should be used for the detection of Strep A antigen in throat swab specimens only. Neither the quantitative value nor the rate of increase in Strep A antigen concentration can be determined by this qualitative test.

2. This test will only indicate the presence of Strep A antigen in the specimen from both viable and non-viable Group A Streptococcus bacteria.

A negative result should be confirmed by culture. A negative result may be obtained if the concentration of the Strep A antigen present in the throat swab is not adequate or is below the detectable level of the test.

3. Excess blood or mucus on the swab specimen may interfere with test performance and may yield a false positive result. Avoid touching the tongue, cheeks, and teeth5 and any bleeding areas of the mouth with the swab when collecting specimens.

4. As with all diagnostic tests, all results must be interpreted together with other clinical information available to the physician.

Note: The above information is for reference use only. Please refer to the product insert provided with the products before use.