IVATECT STREPTO A (20 Tests)
Reference : IVN 25410
Insert version : 03-2003
For Qualitative Detection of Group A Streptococcal Antigen from
Throat Swabs or Confirmation of Presumptive Group A
Streptococcal Colonies from Culture
I-SUMMARY AND EXPLANATION
Among the beta-hemolytic streptococci causing infections in humans, the A, B, C
and G groups figure most prominently (5).
Group A streptococci continue to be a focus of interest not only because of their
causal role in acute streptococcal pharyngitis and other pyogenic infections but also
because of their association with post streptococcal sequelae, specifically acute
rheumatic fever and acute glomerulonephritis (1,2).
In order to properly treat the disease using antibiotic therapy, it is important to use an
accurate diagnostic method to identify the pathologic agent.
For the screening of group A streptococcal infection several methods are currently
used including susceptibility of the organism to a bacitracin disc placed on a sheep
blood agar plate, latex agglutination and enzyme immunoassay (3,4).
II-PRINCIPLE
The IVATECT STREPTO A test is a rapid qualitative one step assay for the
detection of Streptococcus group A antigen from Throat swabs specimens.
The method employs a unique combination of monoclonal-dye conjugate and
polyclonal solid phase antibodies to selectively identify streptococcus A with a high
degree of sensitivity.
As the test samples flows through the absorbent pad, the labelled antibody-dye
conjugate binds to the Strep-A antigen forming an antibody antigen complex. This
complex binds to the Anti-Strep-A antibody in the test zone producing a pink-rose
color band. In the absence of Strep-A, there is no line in the test zone. The reaction
mixture continues flowing through the solid phase. Unbound conjugate binds to the
reagents in the control zone producing a pink-rose color band, demonstrating that
the reagents are functioning correctly.
VIII-INTERPRETATION OF RESULTS
B
B- Positive :
In addition to the control band, a
clearly distinguishable band will
appear near to the “bottom”
indicating presence of Strep A in the
sample.
C- Inconclusive :
The test is inconclusive in the absence of distinct band at the top and bottom areas
of the reaction strip. It is recommended that in this case the test should be repeated.
IX-PERFORMANCE DATA
1. ACCURACY
A study was performed using a total of 375 patients. Samples were collected on
duplicate throat swabs from patients complaining of a save throat.
One of the swabs was tested using the IVATECT STREPTO A and the other swab
was cultured on sheep blood agar plates containing a bacitracin disc. After 24 hours
of incubation, all samples showing a zone of inhibition around the bacitracin disc
were considered as positive.
III- IVATECT STREPTO A COMPONENTS
Each kit contains everything needed to perform 20 tests :
- 20 Strep A Strip tests
- 1 bottle of extraction solution 1 (6.5 ml)
- 1 bottle of extraction solution 2 (6.5 ml)
- Swabs are available optionnaly
A
A- Negative :
Only 1 couloured band near to the
“top” (control band) will appear.
IVATECT STREPTO A
CULTURE +
-
+
-
36
2
1
336
IV-STORAGE AND STABILITY
SENSITIVITY
36/38
94,7 %
Strep A has to be stored at room temperature (4°C to 30°C) in the sealed pouch. Do
not freeze the test kit.
SPECIFICITY
336/337
99,7 %
AGREEMENT
372/375
99,2 %
V-PRECAUTIONS
1.
2.
3.
4.
This test is designed for “IN VITRO” diagnostic use only
Extraction reagents are caustic and may cause irritation to skin, eyes and
mucus membranes. Wash off immediatly if extraction reagent came in
contact with skin.
Read carefully instruction notice using this test.
Do not use beyond expiry date which appears in the package label.
2. SPECIFICITY
Different strains of bacteria were tested using the IVATECT STREPTO A in order to
determinate if they may cause non specific reaction.
The following panel of organisms was obtained from the Center for Disease Control
(CDC) and the American type Culture Collection (ATCC).
SPECIES
VI-SPECIMEN COLLECTION
To obtain the best results, specimens should be collected using standard throat
swabs collection methods. Plastic shafted swabs with rayon or dacron tips may be
used.
Do not use swabs with cotton or calcium alginate tips, with wooden shafts or
impregnated with charcoal or transport media containing agar or gelatin.
Patient samples are best performed immediatly following specimen collection. If
immediate testing is not possible, the patient samples should be placed in a dry
plastic tube and stored refrigerated at 2-8°C.
VII-ASSAY PROCEDURE
1.
2.
3.
4.
5.
Remove the strip test from the aluminium pouch.
Place the specimen swab in a plastic tube (12 x 55 mm or comparable).
Add 6 drops of extraction reagent 1 (300 µl) and 6 drops of extraction
reagent 2 (300 µl). Twirl swab to mix the extraction reagents thoroughly.
Incubate at room temperature for 2 mn minimum and 5 mn maximum.
At the end of the incubation time, squeeze the swab firmly against the
side of the tube in order to remove as such as possible liquid from the
swab. Discard the swab.
Dip the reaction strip into the tube containing the extract solution. Do not
dip over the blue mark. The reaction strip can be left vertically until the
end of the reaction time.
Read results of the test between 5 to 10 mn after dipping.
Streptococcus group A
Streptococcus group B
Streptococcus group C
Ungrouped Streptococcus
S. mutans
S. epidermidis
STRAIN
RESULT
CDC-799
CDC-1073
CDC-660
CDC-763
ATCC-27351
ATCC-155
Positive
Negative
Negative
Negative
Negative
Negative
X-LIMITATION OF THE TEST
1- IVATECT STREPTO A is a screening test for the presence of Group A
streptococci.
2-As it is true with any diagnostic procedure, the physician should evaluate data
obtained by the use of this kit in light of other clinical information, including culture, if
results are inconsistent with clinical presentation.
3-This test will not differenciate between colonized and infected individuals.
4-Pharyngitis can be caused by organisms other than Group A streptococci
XI-BIBLIOGRAPHY
1. Appleton, R.S., B.E. Victoria, D.Tamer, and E.M. Ayoub, J.Lab clin. Med, 105 :
114-119,1985.
2. Ayoub, E.M. and L.W. Wannamaker, Pediatrics, 29 : 527-538, 1962.
3. Bisuo, A.L. and I Ofek, J.dis; Child, 127 : 676-681,1974.
4. Levinson, M.L. and P.F. Franck, J.Bacteriol, 69 : 284-287, 1955.
Manufactured by :
IVAgen S.A.
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FRANCE