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A throat culture is a test to find germs (such as bacteria or a fungus that can cause an infection. A sample of cells from the back of your throat is added to a substance that promotes the growth of germs. If no germs grow, the culture is negative. If germs that can cause infection grow, the culture is positive. The type of germ may be identified using a microscope or chemical tests. Sometimes other tests are done to find the right medicine for treating the infection. This is called sensitivity testing.
Examples of infections that may be found during a throat culture include:
If bacteria grows in the culture, other tests may be done to check which antibiotic will treat the infection best. This is called susceptibility or sensitivity testing.
Most sore throats are caused by an infection with a virus, such as a cold or flu. Throat cultures are not done for viral infections because it is very hard to grow viruses and it is expensive.
Instead of a regular throat culture, you may get a different type of test (called a molecular test) that looks for DNA (the genetic information inside cells). A molecular test checks for the most common type of bacteria that causes a throat infection. Both types of tests are done by swabbing the back of your throat.
A throat culture may be done to:
You do not need to do anything before you have this test. Tell your doctor if you have recently taken any antibiotics.
You will be asked to tilt your head back and open your mouth as wide as possible. Your doctor will press your tongue down with a flat stick (tongue depressor) and then examine your mouth and throat. A clean swab will be rubbed over the back of your throat, around your tonsils, and over any red areas or sores to collect a sample.
The sample may also be collected using a throat washout. For this test, you will gargle a small amount of salt water and then spit the fluid into a clean cup. This method gives a larger sample than a throat swab and may make the culture more reliable.
If your child needs a throat culture, you may hold your child on your lap while the sample is taken. This can prevent your child from moving around too much.
You may feel like gagging when the swab touches the back of your throat. If your throat is sore, the swabbing may be slightly painful.
Generally there is no chance of problems with collecting a sample for a throat culture. Your doctor can talk to you about any specific risks of the test.
A throat culture is a test to find a bacterial or fungal infection in the throat. Throat culture test results for bacterial infections are ready in 1 to 2 days, depending on which bacteria are being tested for. Test results for a fungus may take about 7 days.
Rapid strep test
Another type of test is called a rapid strep test. You can't get this test through an Alberta Health Services lab or service. You may be able to buy this test at your local pharmacy. You’ll get the results of a rapid strep test within 10 to 15 minutes. If you get a negative test result, it could mean you don't have a bacterial throat infection. But sometimes the results of these tests are wrong. If your symptoms don't go away, make an appointment to see your healthcare provider. They may want to send you for a throat culture or a molecular test to check for a throat infection.
Normal (negative results):
No strep bacteria are detected. A throat culture may be recommended if your symptoms don't go away.
Abnormal (positive results):
Strep bacteria are detected. This means you have strep throat. Antibiotics can be started immediately.
No infection (bacteria or fungi) grows in the culture.
A negative throat culture may mean that the cause of your infection is a virus, rather than bacteria or fungus.
Some viruses that cause throat infections include:
Bacteria grows in the culture. Some bacterial throat infections include:
Fungus grows in the culture. The most common fungal throat infection is thrush, caused by the fungus Candida albicans.
Reasons you may not be able to have the test or why the results may not be helpful include:
Adaptation Date: 5/4/2021
Adapted By: Alberta Health Services
Adaptation Reviewed By: Alberta Health Services
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