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Strep A Test Procedures

Strep throat is a condition caused by bacteria named group A streptococcus. These bacteria are highly contagious and can cause numerous symptoms in an infected patient, such as sore throat, trouble swallowing, fever, headache and nausea. If you think you may have strep throat, tell your doctor about your symptoms. She will perform a strep A test to see if you are suffering from this bacterial infection.

  1. Clinical Observation

    • Your physician will first perform a brief clinical evaluation to look for outward signs of strep throat. He will check for a fever. Then he may feel for inflammation in the lymph nodes on the side of your neck to see if your immune system is working hard to fight an infection. Your physician will use a tongue depressor to see the back of your throat and your tonsils. Any redness or pus in these areas may indicate strep throat.

      While the presence of these symptoms likely will lead to a diagnosis of an infection of some kind, these physical tests cannot determine whether the infection is viral or bacterial in nature. To further clarify, your doctor will choose a laboratory test for identifying the streptococcus bacteria.

    Throat Swab

    • Before your physician can tell you definitively whether you're infected with strep throat, she needs a sample of the secretions from the back of your throat. Using a thin, sterilized cotton swab, she will rub the back of the throat for a few seconds. You may feel a normal gagging response. The sample is then brought to another room to have tests performed.

    Lab Tests

    • The first test is called a rapid strep test since the results are ready within a few minutes. This tests for the presence of antigens, foreign substances that stimulate an immune response. If these are present (i.e. the test is positive), then strep throat is confirmed and the patient can begin treatment. If no antigens are found, this does not rule out an infection. The rapid test may be quick, but it is only a cursory glance--false negatives may occur.

      If the results are negative, the sample should be sent for further testing. This more comprehensive test is called a throat culture. A lab technician studies the sample over a few days, monitoring the presence and potential growth of bacteria. The results of this test take one or two days to return, but they are much more reliable than a rapid test.

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