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What is Throat Swab Culture test? 

A throat swab culture test detects the presence of a bacteria called Streptococcus pyogenes (group A streptococcus) in the throat. This bacterium is the causative agent of strep throat - a common infection that makes your throat feel itchy and sore.

Strep throat usually affects children in the age group of five to 15 years. It is the cause of about 20-30% of throat infections in school-going children. The condition is not common in infants and toddlers though if affected, their symptoms may differ from those seen in older children. Adults who are at risk of strep throat include parents of school-going children and adults in close contact with children. This infection spreads from one person to another through fluids from the nose or saliva.

Strep throat symptoms are similar to that of a sore throat but they are more severe and last longer. It usually takes about two to five days for a person to become sick after being exposed to the bacteria. Treatment with antibiotics is necessary, as the infection can lead to severe (though rare) complications like rheumatic fever (affecting the heart) and glomerulonephritis (affecting the kidney). If you get a strep throat, your doctor may advise you to stay away from healthy people until you have been on antibiotics for at least 24 hours and the fever is completely gone.

  1. Why is a Throat Swab Culture test performed?
  2. How do you prepare for a Throat Swab Culture test?
  3. How is a Throat Swab Culture test performed?
  4. What do Throat Swab Culture test results mean?

The test is performed to differentiate between viral and bacterial throat infections. It also helps the doctor decide if you need antibiotics. In case the infection is mild, you may recover without antibiotics. However, if the condition is due to strep throat, your doctor will prescribe antibiotics as they are essential for a speedy recovery and to prevent the transmission of the disease to close contacts.

Your doctor may order this test if you have the following symptoms and signs:

  • High fever starting suddenly and lasting longer than usual
  • Sore throat which lasts longer than seven days
  • Painful swallowing
  • Swollen tonsils
  • Red and white patches in the throat and on the tonsils
  • Swollen lymph nodes on the sides of the neck

Other symptoms which may be seen include:

No special preparations are needed for this test. However, it is important that the test is performed before starting antibiotics, as they will prevent the growth of the bacteria and affect the results. Inform your doctor if you are taking any prescription and non-prescription medicines or supplements. It is also best to avoid antiseptic mouthwashes before the procedure, as they may alter the results. If you have any other queries about the test, this is the time to ask your doctor.

A throat swab is collected from the back of the throat using a special cotton swab. Your doctor or nurse will explain the steps of the procedure. If your child is being tested, you may wish to place the child on your lap during the procedure.

  • You will be asked to tilt your head backwards and open your mouth as wide as possible.
  • Using a tongue depressor (flat stick), the doctor will press your tongue against the floor of your mouth. This helps get a better view of the throat 
  • He/she will then brush a cotton swab against the back of your throat, tonsils and any red areas to collect the sample
  • The sample will be immediately sent to the laboratory for testing

You may experience slight discomfort when the cotton swab touches the throat. The test is, however, not associated with any risks. 

Results usually take two to three days to show up from the day of collection of the sample. 

Normal results:

If the results are normal, the test is reported as negative. It means Streptococcus was not found in the given sample and hence your symptoms are not due to strep throat. Depending on your health, the doctor may prescribe anti-inflammatory and antipyretic (fever-reducing) medications like ibuprofen or paracetamol to offer relief from symptoms.

Abnormal results:

An abnormal result is reported as positive. It means that the sample has shown bacterial growth with strep throat bacteria. Your doctor will prescribe appropriate antibiotics to suppress the growth of streptococci in such case. 

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.


  1. American Academy of Pediatrics [internet]. Illinois (US). When a sore throat is more serious infection
  2. Center for Disease Control and Prevention [internet], Atlanta (GA): US Department of Health and Human Services, Strep Throat: All You Need to Know
  3. Tanz RR. Nelson Textbook of Pediatrics. Acute pharyngitis. 20th ed. Elsevier; 2016: chap 381.
  4. Tanz RR. Nelson Textbook of Pediatrics. Acute pharyngitis. 20th ed. Elsevier; 2016: chap 381.
  5. Ebell MH. Diagnosis of streptococcal pharyngitis. Am Fam Physician. 2014 Jun 15;89(12):976-7. PMID: 25162166
  6. Shulman ST. Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Clin Infect Dis. 2012 Nov 15;55(10):e86-102. PMID: 22965026.
  7. van Driel ML. Different antibiotic treatments for group A streptococcal pharyngitis. Cochrane Database Syst Rev. 2016 Sep 11;9:CD004406. PMID: 27614728
  8. Flores AR, Caserta MT. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. Pharyngitis. 8th ed. Elsevier S. 2015: chap 59.

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