A streptococcal screen, also called a rapid Streptococcus screening test or rapid strep screen, is a test that determines if you have a type of bacterium called group A Streptococcus (Streptococcus pyogenes) in your throat. This bacterium causes an infection called streptococcal pharyngitis, which is commonly known as strep throat.
Streptococcal infections are common, especially in children between the ages of 5 and 15 years. The infection is spread by contact with infected mucus or saliva.
Your doctor may recommend a rapid strep screening test if you have a sore throat and fever. Other signs of a strep infection include:
- difficulty swallowing
- a lack of appetite
- low energy level
- tender or swollen lymph nodes in the neck
In some cases, people with a strep infection have a pink skin rash that feels like sandpaper.
Because strep throat is less common in adults, your doctor may not order a rapid strep screening unless you have a combination of a severe or recurrent sore throat, a fever, and swollen lymph nodes in your throat.
A rapid screen strep test is simple and can be done in your doctor’s office. You should avoid using mouthwash before the test because it can interfere with results. Otherwise, you don’t need to prepare.
Your doctor will examine your mouth to check for red, swollen areas or other signs of infection. Your doctor will ask you to open your mouth wide and may use a wooden tongue depressor to hold your tongue down.
Then, your doctor will take a cotton swab and brush it against the back of your throat, or oropharynx, to obtain a sample for the test. They may do this twice to get more accurate results. The swabs will be tested with a kit to see if the group A Streptococcus bacterium is present.
The test isn’t painful, but it does cause minor discomfort. If your child is having a rapid strep screen, it’s a good idea to hold their arms or have them seated on your lap. You may need to help restrain your child. Also, the position of the swab may trigger a gag reflex.
The rapid strep screen is fairly reliable, but antibiotics and antiseptic mouthwash can affect the test results. Tell your doctor if you’re taking antibiotics.
The rapid screen strep kit takes about 10 minutes to process. If the test is positive, you have group A Streptococcus in your throat and you probably have an infection. In that case, your doctor will write a prescription for a 5- to 7-day course of antibiotics.
If you are an adult with a negative test and your doctor does not suspect strep throat based on available clinical information, you likely don’t have group A Streptococcus infecting your throat. No antibiotics are needed.
In some cases, if you have symptoms of a strep infection but your test comes back negative, your doctor may order a throat culture. A throat culture swabbing is typically used when the doctor still suspects strep throat in a child or teenager despite a negative rapid strep test result.
A throat culture is similar to a rapid screen test, but the sample is processed more in-depth. It’s also more expensive and takes longer to get results. The results can take up to 48 hours because the swabs are cultured, which means that any bacteria on them are allowed to grow. A throat culture can confirm the presence of group A Streptococcus and other bacteria, and it’s generally considered more accurate than a rapid strep screen.
It’s also important to note that a rapid strep screen test only screens for group A Streptococcus, which is one type of bacterium. This means that if your test is negative, you could still have an infection from another type of bacterium or virus.
The test is easy and quick. It has no major side effects or risks. If you test positive for strep, your doctor will likely prescribe antibiotic therapy and recommend that you drink warm fluids and gargle with salt water.
If you test negative for group A Streptococcus, but still have a sore throat, your doctor may look at other possible causes, including infections from other bacteria or viruses.
If a strep infection is left untreated, it can lead to more serious medical conditions, including:
See your doctor right away if you have any symptoms of strep throat. The doctor can run a streptococcal screen or a throat culture to determine if you have a strep infection. Then they can treat you appropriately based on the type of infection you have.