Laboratory: Clinical Microbiology
Test Name:
STREPTOCOCCUS PYOGENES (GROUP A STREPTOCOCCUS), ANTIGEN, THROAT SWAB (WESTMAN AND THE PAS LABORATORIES ONLY)
Test Code: None
Clinical Information:
Test Indications:
Pediatric patient - Classic signs and symptoms include: abrupt onset sore throat, fever, headache abdominal pain, nausea, and vomiting.  In addition, exudative tonsillopharyngitis with enlarged erythematous tonsils, enlarged tender anterior cervical lymph nodes, palatal petechiae, and inflamed uvula may be present. 
Children < 3yrs may not present with well defined episodes of pharyngitis, instead they may have protracted symptoms of nasal congestion and discharge, low-grade fever and tender cervical adenopathy.
Adults - Classic signs and symptoms include:  acute-onset sore throat, fever, pharyngeal edema, patchy tonsillar exudates, and prominent, tender, anterior cervical lymphadenopathy.

Recommendations:
Also submit a second swab in transport media for culture, as Group A Streptococcus (GAS) rapid antigen test is a qualitative test for the detection of Group A Streptococcus only.
Collection Devices:
Preferred Device: Throat swab in an empty sleeve.
Alternate Device: Throat swab in transport media.
Use sterile rayon swabs.
Specimen Required: Adult and Pediatric: ask the patient to open their mouth, depress the tongue with sterile/clean tongue depressor and then, using a sterile rayon swab, sample the tonsillar fossae and posterior pharyngeal wall, taking care to avoid the teeth, gums, tongue or check surfaces.
This is a qualitative test and the results of the test depends on the quality of the sample obtained.  Negative results can occur from inadequate specimen collection or antigen level which is below the detection limit of the test.
Do not use swabs with cotton tips, wooden shafts or calcium alginate swabs.
Do not use a transport media that is semisolid or contains charcoal.
Transport at ambient temperature.
Referral:

Throat swab, using a sterile rayon swab, which may be submited in transport media or in a sleeve.
Transport swab at ambient temperature.  Process as soon as possible after collection.
Testing Laboratory (MB): Westman Laboratory and The Pas lab
Requisition:
Reference Values:
Positive:  Group A Streptococcus antigen detected.
Negative:  No group A Streptococcus antigen detected.
Method of Analysis: A color immunochromatographic assay.
Availability:
Daily
See Also:
More Information: