I.    INTEDED USE:

The SP^TM Brand Rapid Test Strep A Dipstick is a rapid chromatographic immunoassay for the qualitative detection of group A antigen from  throat swab specimen to aid in the diagnosis of Group A Streptococcal infection.

Streptococcus pyogenes is a non-motile gram-positive cocci, which contains the Lancefield  group A antigen 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 GroupA Streptococci infection involve the isolation and identification of viable organisms using techniques that require 24- 48 hours or longer.

The SP^TM Brand Rapid Test Strep A Dipstick is a rapid test to qualitatively detect the presence of Strep A antigen in throat swab specimens, providing results within 5 minutes. The test utilizes antibodies specific for whole cell Lancefield Group A Streptococcus to selectively detect Strep A antigen in a throat swab specimen.

II.   PRINCIPLE: 

The SP™ Brand Rapid Test Strep A Dipstick is a qualitative, lateral flow immunoassay for the detection of Strep A carbohydrate antigen in a throat swab.  In this test, antibody specific to Strep A carbohydrate antigen is coated on the test line region of the dipstick.  During testing, the extracted throat swab specimen reacts with an antibody to Strep A that is coated onto particles.  The mixture migrates up the membrane to react with the antibody to Strep A on the membrane and generate a red line in the test region.  The presence of this red line in the test region indicates a positive result, while its absence indicates a negative result.  To serve as a procedural control, a red line will always appear in the control region if the test has been performed properly.  If a red control line does not appear, the test result is not valid.

III.  MATERIALS:

1. TEST PACK containing: one test strip, one plastic workstation, one extraction tube.
2. SWABS: sterile polyester throat swabs
3. REAGENTS:  Reagent A  (2M Sodium Nitrite),  Reagent B  (0.4M Acetic Acid)
4. CONTROL: Positive Control,  Negative control

IV.   SPECIMEN: 

1. Collect the throat swab specimen with a sterile swab.  Transport swabs containing modified Stuart’s or Amies medium can also be used with this product.  Swab the posterior pharynx, tonsils, and other inflamed areas.  Avoid touching the tongue, cheeks, and teeth with the swab.
2. Testing should ideally be performed immediately after the specimens have been collected.  Swab specimens may be stored at room temperature for up to four hours prior to testing.

V.    PROCEDURE

	PROCEDURE:
1	Remove the test strip from the sealed foil pouch and use it as soon as possible.  Best results will be obtained if the test is performed immediately after opening the foil pouch.
2	Hold the Reagent A bottle upright and add 4 full drops (approximately 240 uL) to an extraction test tube.  Reagent A is red in color.  Hold the Reagent B bottle upright and add 4 full drops (approximately 160uL) to the tube.  Reagent B is colorless.  The addition of Reagent B to Reagent A changes the color of the solution from red to pale yellow.  Tap the bottom of the tube gently to mix the liquid.   (See illustration.)
3	Immediately add the throat swab into the tube of pale yellow solution.  Rotate the swab 10 times in the tube.  Leave the swab in the tube for 1 minute.  Then 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.)
4	With arrows pointing down, place the test strip into the tube of solution and then start the timer.  IF the procedure is followed correctly, the liquid should be at or just below the maximum line (MAX) on the test strip. (See illustration.)
5	Leave the strip in the tube and read the results at 5 minutes.

VI.   PROCEDURAL NOTES:

1. Very low concentrations of Strep A might result in a weak line appearing in the test region (T) after an extended period of time; therefore do not read the result after 10 minutes.
2. To avoid cross contamination, do not allow the tip of the reagent bottles to come in contact with throat swabs or Extraction Tubes.
3. ALL NEGATIVE TESTS ARE CULTURED.

VII.  INTERPRETATION OF RESULTS:

POSITIVE:  Two distinct red lines appear.  One line should be in the control region and another line should be in the test region.  A positive result indicates that Strep A was detected in the sample. 

NOTE:  The intensity of the red color in the test line region will vary depending on the concentration of Strep A present in the sample.  Therefore, any shade of red in the test region should be considered positive.

NEGATIVE:   One red line appears in the control region.  No apparent red or pink line appears in the test region.  A negative result indicates that Strep A is not present in the sample, or is present below the detectable level of the test.  The patient’s sample should be cultured to confirm the absence of Strep A infection.  If clinical symptoms are not consistent with results, obtain another sample for culture.

INVALID RESULT:  Control line fails to appear.  Insufficient sample volume or incorrect procedural techniques are the most likely reasons for control line failure.  Review the procedure and repeat the test with a new test strip.  If the problem persists, discontinue using the test kit immediately, and contact St. Peter’s Hospital Lab. ext# 2319, ask for Point-of-Care Testing, and/or Technical Services at 1-866-211-7853.

NOTE: ALL NEGATIVE TESTS ARE CULTURED.

VIII. ALTERNATIVE METHOD: Collect specimen and send to St. Peter’s Hospital Lab for testing.

IX.     QUALITY CONTROL: 

1.      INTERNAL PROCEDURAL CONTROLS: Internal procedural controls are included in the test.  A red line appearing in the control region is an internal positive procedural control.  It confirms sufficient sample volume and correct procedural technique.  A clear background is an internal negative background control.  If the test is working properly, the background in the result area should be white to light pink and not interfere with the ability to read the test result.

2.      EXTERNAL CONTROLS: It is recommended that a positive and negative external control be run every 30 tests, and as deemed necessary by internal laboratory procedures.  External positive and negative controls are supplies in the kit.  Both a Positive and Negative Control are tested with each new kit opened.  Record these results on the test log sheet.

Procedure for External Quality Control Testing:

1. Add 4 full drops of Reagent A and 4 full drops of Reagent B into an extraction test tube.  Tap the bottom of the tube gently to mix the liquid.
2. Add 1 full drop of positive or negative control solution into the tube, holding the bottle upright.
3. Place a clean swab into the tube.  Rotate the swab 10 times in the tube.  Leave the swab in the tube for 1 minute.  Then 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 tube.
4. Continue with Step 4 of Procedure.

If the controls do not perfume as expected, do not interpret the test results.  Repeat the test or call St. Peter’s Hospital Lab ext# 2319, ask for Point-of-Care Testing, and/or Technical Services at 1-866-211-7853.

X.    STORAGE: 

The kit can be stored at room temperature or refrigerated 2°-30°C.  The test strip must remain in the sealed pouch until use.  DO NOT FREEZE.  The test strip and the reagents are stable through the expiration date printed on the box. Do not use beyond the expiration date.

XI.   LIMITATIONS:

1. The SP™ Brand Rapid Test Strep A Dipstick is for in vitro diagnostic use only.  The test should be used for the detection of Strep A antigen in throat swab samples 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.
3. A negative result obtained from this kit 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.
4. 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 teeth and any bleeding areas of the mouth with the swab when collecting specimens.
5. As with all diagnostic tests, all results must be interpreted together with other clinical information available to the physician.

XII.   EXPECTED VALUES:

Approximately 15 % of pharyngitis in children ages 3 months to 5 years is caused by Group A beta-hemolytic Streptococcus.  In school-aged children and adults, the incidence of Strep throat infection is about 40%.  This disease usually occurs in the winter and early spring in temperate climates.

XIII.  WARNINGS AND PRECAUTIONS: 

1. Humidity and temperature can adversely affect results
2. Reagent B contains an acidic solution. If the solution contact the skin or the eye, flush with large volumes of water.
3. The positive and negative controls contain sodium azide (NaN₃ ) as a preservative.
4. Do not interchange reagent bottle caps.
5. Do not interchange external control solution bottle caps.

XIV.   DOCUMENTATION: Record the result on the result log and in Meditech. 

XV.   SPH SITES PERFORMING:

SPMG ,NMC and UC. All personnel performing this test must be enrolled in St. Peter’s Hospital competency Program

XVI.  REFERENCE: 

Package inserts from Cardinal Health, Strep A Dipstick SP™ Brand Rapid Test. PN:1155903601

PLACED INTO SERVICE: July 6, 2009

Replaces Abbott Signify Strep Kit used since July 2000.

Revised:  July 4, 2009.