Strep A, also known as group A strep, is a type of bacteria that causes strep throat and other infections. Strep throat is an infection that affects the throat and tonsils. The infection is spread from person to person through coughing or sneezing. While you can get strep throat at any age, it’s most common in children 5 to 15 years old.

Strep throat can be easily treated with antibiotics. But left untreated, strep throat can lead to serious complications. These include rheumatic fever, a disease that can damage the heart and joints, and glomerulonephritis, a type of kidney disease.

Strep A tests check for strep A infections. There are two types of strep A tests:

• Rapid strep test. This test looks for antigens to strep A. Antigens are substances that cause an immune response. A rapid strep test can provide results in 10–20 minutes. If a rapid test is negative, but your provider thinks you or your child has strep throat, he or she may order a throat culture.
• Throat culture. This test looks for strep A bacteria. It provides a more accurate diagnosis than a rapid test, but it can take 24–48 hours to get results.

What is it used for?

A strep A test is most often used to find out if a sore throat and other symptoms are being caused by strep throat or by a viral infection. Strep throat needs to be treated with antibiotics to prevent complications. Most sore throats are caused by viruses. Antibiotics don’t work on viral infections.