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. The definitive diagnosis of strep throat can be made with simple laboratory testing.
A doctor will conduct a physical exam, look for signs and symptoms of strep throat, and probably order one or more of the following tests:
Predictive factors that make strep throat more likely include:
A doctor may recommend a rapid strep screening test if you have a sore throat and fever. Other signs of a strep infection include:
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:
When the diagnosis of strep throat is confirmed by laboratory testing or when it is highly suspected clinically, antibiotics are generally prescribed. If administered early, antibiotics can help decrease the duration of symptoms (by about 1 day), and they can also make individuals less contagious within 24 hours of initiating treatment. More importantly, antibiotics are effective in preventing the uncommon potential complications of strep throat. Without antibiotic treatment, strep throat will generally improve on its own within 2 to 5 days, as it is a self-limited disease that will run its course without complications in the majority of cases.
The full course of antibiotics should be taken, even if the individual is feeling better after a few days. Premature discontinuation of antibiotics can result in relapse of illness, generation of antibiotic resistant organisms, or in the development of complications from inadequately treated strep throat. The antibiotics that are generally recommended include the following:
This effective, inexpensive antibiotic can be administered orally for 10 days, or a one-time injection can be administered in those individuals who may not be compliant or able to tolerate oral medications. Penicillin derivatives, such as amoxicillin, are also effective.
This class of antibiotics has been found to be very effective in the treatment of strep throat, and is a reasonable alternative to penicillin.
This class of antibiotics (erythromycin, azithromycin (Azithromycin 3 Day Dose Pack, Azithromycin 5 Day Dose Pack, Zithromax, Zithromax TRI-PAK, Zithromax Z-Pak, Zmax) and clarithromycin (Biaxin, Biaxin XL, Biaxin XL-Pak) and are recommended in individuals who have a penicillin allergy.
Have your child stay home from school or daycare until the fever is gone and he has been on an antibiotic for at least 24 hours. Same for you and the workplace. Other tips:
Yet untreated strep can cause serious diseases, such as: