A person who has a sore throat may have an infection called streptococcal pharyngitis, a condition more commonly known as strep throat. A rapid strep test is often used to uncover the presence of a strep throat infection. Also called a rapid antigen detection test, a rapid strep test can only find one kind of strep – group A streptococcal. The group A strain is more likely to result in serious throat infections then other types of strep, making early detection important.
Doctors usually order a rapid antigen strep test when a person exhibits symptoms like a sore throat, headache, weakness, or fever. An inflamed throat with white or yellow spots and a swollen, sensitive neck are other potential symptoms of the infection. If someone has been in close contact with a person who has been diagnosed with strep throat, he or she may also need to take a rapid strep test.
Traditionally, strep throat tests were conducted by taking a throat culture, which requires two or three days to process. Through rapid strep testing, however, the group A strep bacteria can be detected within minutes. Rapid strep tests typically look for the existence of the group A streptococcus carbohydrate antigen in a person's throat.
No preparation is needed for a rapid strep test, although gargling and eating right before the test can impact the results. Typically, during the test, a mucus sample is collected from the back of a person’s throat using a cotton swab. The mucus sample is then tested for the group A strep bacteria. Some people may experience sensitivity during the collection process, usually in the form of a choking or gagging sensation in the back of their throats.
A rapid strep test can be skewed if it is conducted before a sufficient bacteria sample is available in the throat. A test can also be influenced if it is performed when a person has already had the infection for some time and the strep bacteria has been mostly removed by the immune system. In addition, a test may be inaccurate if an individual has already been partly treated with antibiotics.
If the results of a strep throat rapid test are positive, then further testing is typically unnecessary. In this case, the infected individual is usually given antibiotics to treat the infection. Even if the test results are negative, a person may still have strep throat. If this happens, a throat culture may be required to completely rule out a strep infection. A negative throat culture generally means that the sore throat is the result of a viral infection.