Throat Swab: Collection and Transport

COMMON PATHOGENS FOUND IN THROAT SWAB:

BACTERIA	GRAM POSITIVE: Streptococcus pyogenes, Corynebacterium diphtheria, Corynebacterium ulcerans
	GRAM NEGATIVE: Vincent’s organisms (Borrelia vincenti and gram negative anaerobic fusiform bacilli)
VIRUSES	Respiratory viruses, Enteroviruses, Herpes simplex virus type 1
FUNGI	Candida albicans and other yeasts

 

NOTES ON PATHOGENS FOUND IN THROAT SWAB

• Steptococcus pyogenes is the commonest cause of streptococcal pharyngitis (sore throat) especially in young children & is also associated with rheumatic heart disease. 

• Corynebacterium diphtheriae cause a serious disease, diphtheria, producing a powerful and often fatal exotoxin. 

• C. albicans infection of the mouth (oral thrush) is often found with HIV disease. It also affects the patients who have been treated with antibiotics over a long period and patient with diabetes. 

• Infection with Vincent’s organisms causes Vincent’s angina, an ulcerative tonsillitis with tissue necrosis.

 

COLLECTION AND TRANSPORT OF 

THROAT SWAB

In a hospital with a microbiology laboratory:

For 8 hours before swabbing, the patient must not be treated with antibiotics or antiseptic mouth—washes.

1. In a good light and using the handle of a spoon to depress the tongue, examine the inside of the mouth. Look for - inflammation (Presence of any membrane, exudates or pus).

In diphtheria - greyish—yellow membrane

In streptococcal sore throat - tonsils are inflamed & covered with yellow spots.

In infectious mononucleosis — tonsils may be covered with white exudates.

In C. albicans inflection - Patches of white exudates.

2. Swab the affected area using a sterile cotton or alginate wool swab. Taking care not to contaminate the swab with saliva, return it to its sterile container.

3. Within 2 hours of collection, deliver the swab with a request form to the laboratory.

 

In a health centre for dispatch to a microbiology laboratory:

If there is delay in transport of throat swab, then transfer the swab in tubes containing 3-5 gm of desiccated silica gel (Here, C. diphtheriae, S. pyogenes & S. aureus remain viable for at least 3 days).