Colds and the Flu - Diagnosis

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How Is Strep Throat Diagnosed? Most cold-related sore throats are caused by viruses and require no treatment. They usually do not last more than a day. When the sore throat persists and is very painful the doctor will want to rule out or confirm the presence of the Streptococcus bacteria.

• The doctor will look for redness and pus-filled patches on the tonsils and back of the throat.
• The doctor will feel the sides of the neck for swollen lymph nodes. If the lymph nodes are not swollen, it is less likely to be a strep throat.
• A cotton swab is used to take a sample of pus in the throat for a throat culture.

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A throat culture is the most effective and least expensive test for confirming the presence of strep throat. It takes 24 - 48 hours to obtain a result.

Rapid Antigen-Detection Test for Strep Throat. A faster test, called the Rapid Strep Antigen Test, uses chemicals to detect the presence of bacteria in a few minutes. A positive result nearly always means that streptococcal bacteria are present in the throat. The test, however, fails to detect 5 - 10% of cases, so a culture may still be necessary to catch any missed infections, particularly in children.

How Serious is Strep Throat? The use of antibiotics has removed the threat of most complications from streptococcus infection in the throat. However, untreated strep throat could lead to the following complications:

• Abscess in the tonsils
• Scarlet fever
• Rheumatic fever (rare in the U.S.)

Review Date: 01/29/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).