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Beta Hemolytic Streptococcus Culture (Throat)

Does this test have other names?

Strep test, throat culture, Streptococcal screen

What is this test?

This test looks for the bacteria that cause strep throat. This condition causes a severe sore throat and makes it painful to swallow. It's important to find and treat strep throat as soon as possible because it can progress to more serious illnesses, such as rheumatic fever.

The bacteria most likely to cause strep throat and bacterial sore throats in general are called Group A beta-hemolytic Streptococcus pyogenes (GABHS).

This test is a highly reliable way to diagnose strep throat because it has a sensitivity of 90% to 95%. But it's not used as commonly as the rapid antigen test because throat culture results are often not available until 24 to 48 hours later.

Why do I need this test?

You may need this test if you have symptoms of strep throat, including:

  • Sore throat. The soreness can begin suddenly and cause severe pain when you swallow.

  • Fever. Temperatures in adults are often 101°F (38.3°C) or higher.

  • Chills

  • Headache, nausea, and vomiting

  • Mild neck stiffness

  • Appetite loss

  • Swollen or enlarged lymph nodes in the neck

  • Swollen, red tonsils, at times with streaks of pus or white patches.

  • Rash or body aches

  • Small red spots on the roof of the mouth or in the back on the soft or hard palate

You may also have this test if your tonsils are painfully enlarged and your breath smells very bad.

Strep throat is treated with antibiotics. Starting antibiotics right away eases symptoms and can reduce the time you are contagious from 1 week to 1 day. Treatment also prevents rheumatic fever if taken within 10 days after symptoms begin.

What other tests might I have along with this test?

You may also need these tests:

  • Rapid antigen test

  • Clinical prognostic score for GABHS, a score that helps prevent overuse of antibiotics for sore throats 

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

Normal results are negative, meaning you don't have strep throat. If your test result is positive, you almost certainly have strep throat caused by GABHS. If your sore throat lasts longer than a week, you likely have a different illness.

If your test is positive, it's important to stay home from work or school until you have been taking your antibiotics for 24 hours. This is so the infection won’t be spread to others. You should start feeling better in 1 to 2 days after starting the antibiotics.

Finish the entire prescription even though you are feeling better.

How is this test done?

The test is done with a sample from your throat. Your healthcare provider will take the sample by swabbing both of your tonsils.

Does this test pose any risks?

The swabbing may cause a slight discomfort.

What might affect my test results?

Taking antibiotics can affect your results.

How do I get ready for this test?

You don't need to prepare for this test. Tell your healthcare provider about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.  

Online Medical Reviewer: Chad Haldeman-Englert MD
Online Medical Reviewer: Raymond Turley Jr PA-C
Online Medical Reviewer: Tara Novick BSN MSN
Date Last Reviewed: 9/1/2022
© 2000-2024 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.