Testing may involve traditional culture on sheep blood agar (GABHS) or Thayer-Martin medium (gonorrhea), rapid antigen testing (GABHS), or nucleic acid amplification testing (gonorrhea, COVID-19).
(See also Streptococcal Infections.)
Indications
In patients with tonsillopharyngitis, a throat swab may need to be tested primarily to diagnose:
Gonococcal pharyngitis may be suspected in patients with known or possible exposure to gonorrhea (eg, recent oral-genital contact).
Criteria suggestive of need for testing for GABHS pharyngitis include the presence of ≥ 2 of the following:
Threshold for GABHS testing may be lower in patients at increased risk because of diabetes or immunocompromise.
Throat swabs are also sometimes tested if COVID-19 is suspected.
Contraindications
Complications
Equipment
Use swabs supplied with the specific test kit being used or by the facility's laboratory. If none are supplied, use a swab with a plastic or wire shaft and a rayon, Dacron, or calcium alginate tip. Avoid swabs with wooden shafts and/or cotton tips because these materials may interfere with certain tests.
Relevant Anatomy
Positioning
Step-by-Step Description of Procedure
-
Explain the procedure to the patient, including that they may gag briefly.
-
Wear gloves and eye protection, and if COVID-19 is under consideration, gown, N95 respirator, and face shield.
-
Position the patient and light source to illuminate the posterior oropharynx.
-
Have the patient open the mouth and relax the tongue by saying "aaaah."
-
Press the tongue down using a tongue depressor.
-
Gently rub the swab against both tonsils and the posterior pharynx.
-
Place the swab in the culture medium, transport medium, or sterile test tube.
