Throat culture

A throat culture is a test to find a bacterial or fungal infection in the throat.

A throat culture may be done to:

• Find the cause of a sore throat. Most sore throat infections are caused by a virus. A throat culture shows if the infection is viral or bacterial by ruling out a bacterial infection. This can help guide treatment.
• Check a person who may not have any symptoms of infection but who carries bacteria that can spread to others. This person is called a carrier.

• You will be asked to tilt your head back and open your mouth as wide as you can.
• Your doctor will press your tongue down with a flat stick (tongue depressor) and then examine your mouth and throat.
• A clean cotton 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. It may make the culture more reliable.

• In general, there's nothing you have to do before this test, unless your doctor tells you to.
• Tell your doctor if you have recently taken any antibiotics.

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 results are ready in 10 to 15 minutes. This test is only for bacterial infections caused by strep bacteria.

Normal (negative results)

• No strep bacteria are found. A throat culture may be recommended.

Abnormal (positive results)

• Strep bacteria are found. This means you have strep throat. Antibiotics can be started right away.

Normal (negative)

• No infection (bacteria or a fungus) grows in the culture.
• A negative throat culture may mean that the cause of your infection is a virus, rather than bacteria or fungus.

Abnormal (positive)

• Bacteria grow in the culture. Some bacterial throat infections include strep, scarlet fever, and pneumonia.
• Fungus grows in the culture. The most common fungal throat infection is thrush, caused by the fungus Candida albicans.