Microbiology Test

Test : Group A Streptococcus screen


Indications : The test is ordered when a person has strep throat symptoms such as -

• Fever
• Tender or swollen glands in the neck
• White or yellow spots on the tonsils

A throat sample is taken from the area of the tonsils using a cotton swab. This procedure takes about 7 minutes. The sample is then taken to the laboratory where it will be transferred to a culture dish containing a special medium that promotes the growth of streptococcus bacilli.

No preparation is required prior to the test. It is important to inform the doctor about any medicine that you may be taking, including antibiotics.

Physiology : Group A streptococcal screen is a laboratory test that is done to detect group A streptococcus, a type of gram –positive bacteria, that causes “strep throat” infection. Streptococcus pyogenes is a commonly found organism in temperate regions where, during winter and spring, it causes acute pharyngitis and infections of the upper respiratory tract in 5-10% of adults and 15-30% of the children. Group A streptococcus infection could lead to rheumatic fever, glomerulonephritis and also skin infections like cellulitis, impetigo and erysipelas.

Interpretation :

Normal
No strep bacterial growth will be seen in the culture dish. This indicates that you don’t have strep throat.

Abnormal
If the culture tests positive then it indicates the presence of streptococcus in the throat sample.

Sample : Throat swab

Test Method : Agglutination reaction, Counter immnoelectrophoresis

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