A throat culture is a laboratory test mainly used to detect Streptococcus pyogenes (group A streptococcus), the bacterium responsible for strep throat. It can also be used in certain cases to identify other bacteria, such as Neisseria gonorrhoeae, or specific fungi, although fungal detection is not part of the standard test.
Before having a throat culture, it’s important to follow some instructions, such as stopping antibiotic treatment only if advised by a doctor. Fasting isn’t required, but it’s best to avoid eating or drinking for one hour before the test to prevent interference with the results.
A doctor, usually a primary care provider or pediatrician, may order a throat culture after evaluating symptoms and signs of infection to determine the most appropriate treatment for the cause of the sore throat.
What it is used for
A throat culture is primarily used to detect group A streptococcus, the main cause of strep throat. In some cases, it can also identify other microorganisms, such as Neisseria gonorrhoeae or certain fungi, when clinically suspected.
This test helps doctors choose the most appropriate treatment based on the infection’s cause. It’s generally recommended for people with sore throats when strep throat is suspected.
When a throat culture is recommended
A throat culture is most commonly ordered for children between 5 and 15 years old who develop sudden symptoms such as sore throat, fever, headache, abdominal pain, red spots on the tonsils or palate, and swollen lymph nodes in the neck.
The test helps confirm the cause of pharyngitis and guide treatment, which may include antibiotics to reduce bacterial growth and relieve symptoms.
Types of throat cultures
The table below shows the main differences between a standard throat culture and one that includes an antibiotic sensitivity test (also known as an antibiogram).
Overall, while both tests help identify the cause of a throat infection, adding an antibiotic sensitivity test provides valuable information about which antibiotics are most effective, allowing for more targeted and successful treatment.
Rapid strep test
A rapid strep test is a quick diagnostic method used to detect antigens from Streptococcus pyogenes (group A streptococcus) using a throat swab. Results are typically available within 10 to 20 minutes, allowing healthcare providers to confirm or rule out strep throat during the same visit and begin treatment promptly if needed.
Unlike a throat culture, which requires the bacteria to grow in a laboratory over 24 to 48 hours, the rapid strep test does not identify other bacteria or provide information about antibiotic sensitivity. When the rapid test result is negative but symptoms strongly suggest strep throat, a throat culture may be performed to confirm the diagnosis and ensure accuracy.
How to prepare for the test
Before a throat culture, some simple precautions should be followed:
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Avoid eating or drinking for at least one hour before the sample is collected.
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Avoid using mouthwash or brushing teeth during the hour before the test.
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Stop antibiotic treatment only under medical supervision (it’s usually recommended to wait 24–48 hours after stopping antibiotics before collecting the sample).
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Prolonged fasting (6–8 hours) is not necessary; the main advice is simply to avoid food or drinks immediately before the test to prevent interference.
How the test is performed
A throat culture is performed in a laboratory after being ordered by a doctor. The sample is usually collected before starting antibiotics or after pausing treatment under medical guidance.
To collect the sample, the healthcare professional uses a tongue depressor, a cotton swab, and a transport medium to send the specimen to the lab.
The person opens their mouth and sticks out their tongue while the technician uses the tongue depressor to view the throat. The swab is then rubbed firmly against the back of the throat (oropharynx) and placed in a tube containing a transport solution, which is sent to the laboratory for analysis.
The procedure may cause mild, brief discomfort but takes only a few seconds. Afterward, the person can eat and drink normally.
Understanding results
The lab report identifies the microorganism isolated and, if applicable, its antibiotic sensitivity, allowing the doctor to determine the most effective treatment.
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Positive result: Indicates the presence of a pathogenic microorganism explaining the symptoms.
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Negative result: Indicates normal throat flora or absence of significant microorganisms; in this case, treatment focuses on relieving symptoms rather than prescribing antibiotics.
It’s important to remember that throat culture results should always be interpreted alongside a doctor’s clinical evaluation. A positive result doesn’t necessarily indicate a severe infection, and a negative result doesn’t completely rule out infection if symptoms persist. The final treatment decision should always consider both lab findings and the patient’s clinical symptoms.