Strep Throat - Diagnosis

The first steps in diagnosing strep throat are a patient history and physical examination. The doctor will ask if the patient has been around other people with the infection. He or she will also examine the patient's throat and chest. The doctor will also try to eliminate other potential causes of the symptoms, such as bronchitis (see bronchitis entry) or sinus infection.

Two kinds of tests are available for strep throat. Both involve taking a throat culture, which is done by using a cotton swab to remove a sample of tissue from the sore area in the throat. The sample can then be used for a rapid strep test or a culture.

The rapid test shows whether streptococcal bacteria are present in the throat. The results are available in about twenty minutes. The advantage of the test is the speed with which a diagnosis can be made. Its disadvantage is its high rate of error. The results are wrong in about 20 percent of all cases.

For this reason, the throat culture is often used for a second test. In this test, the sample obtained from the throat is allowed to grow in a warm, moist place for a period of twenty-four to forty-eight hours. During this period, the bacteria reproduce and grow. They reach a size where they can be studied under a microscope to see what types of bacteria are present. This test produces a much higher rate of accuracy in determining whether a patient has strep throat.