Group A Streptococcal Infections (Strep)

What is strep?

Group A streptococcal (strep) infections are caused by group A streptococcus, a bacterium responsible for a variety of health problems. These infections can range from a mild skin infection or sore throat to severe, life-threatening conditions such as toxic shock syndrome and necrotizing fasciitis. Most people are familiar with strep throat, which along with minor skin infection, is the most common form of the disease. Health experts estimate that more than 10 million mild infections (throat and skin) like these occur every year.

In addition to step throat and superficial skin infections, group A strep bacteria can cause infections in tissues (group of cells joined together to perform the same function) at specific body sites, including lungs, bones, spinal cord, and abdomen.

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What are the symptoms of strep throat?

If you have strep throat infection, you will have a red and painful sore throat and may have white patches on your tonsils. You also may have swollen lymph nodes in your neck, run a fever, and have a headache. Nausea, vomiting, and abdominal pain can occur but are more common in children than in adults. Your health care provider may call it acute streptococcal pharyngitis.

How do people get strep throat?

You can get strep throat and other group A strep infections by direct contact with saliva or nasal discharge from an infected person. Most people do not get group A strep infections from casual contact with others, but a crowded environment like a dormitory, school, or an institutional setting such as a nursing home can make it easier for the bacteria to spread. There have also been reports of contaminated food, especially milk and milk products, causing infection. You can get sick within 3 days after being exposed to the germ. Once infected, you can pass the infection to others for up to 2 to 3 weeks even if you don't have symptoms. After 24 hours of antibiotic treatment, you will no longer spread the germs to others.

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How is strep throat diagnosed?

Your health care provider will take a throat swab. This will be used for a culture (a type of laboratory test) or a rapid strep test, which only takes 10 to 20 minutes. If the result of the rapid test is negative, you may get a follow-up culture to confirm the results, which takes 24 to 48 hours. If the culture test is also negative, your health care provider may suspect you do not have strep, but rather another type of infection. The results of these throat cultures will affect what your health care provider decides to be the best treatment. Most sore throats are caused by viral infections, however, and antibiotics are useless against them.

How is strep throat treated?

If you have a strep infection, your health care provider will prescribe an antibiotic. This will help reduce symptoms, and after 24 hours of taking the medicine, you will no longer be able to spread the infection to others. Treatment will also reduce the chance of complications.

Health experts think penicillin is the best medicine for treating strep throat because it has been proven to be effective, safe, and inexpensive. Your health care provider may have you take pills for 10 days or give you a shot. If you are allergic to penicillin there are other antibiotics your health care provider can give you to clear up the illness. Children with strep throat are usually treated with amoxicillin.

During treatment, you may start to feel better within 4 days. This can happen even without treatment. Still, it is very important to finish all your medicine to prevent complications.

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What can happen if a strep infection goes untreated?

Untreated group A strep infection can result in rheumatic fever and post-streptococcal glomerulonephritis (PSGN). Rheumatic fever develops about 18 days after a bout of strep throat and causes joint pain and heart disease. It can be followed months later by Sydenham's chorea, a disorder where the muscles of the torso and arms and legs are marked with dancing and jerky movements. PSGN is an inflammation of the kidneys that may follow an untreated strep throat but more often comes after a strep skin infection. Both disorders are rarely seen in the United States because of prompt and effective treatment of most cases of strep throat.


Source: National Institutes of Health, National Institute of Allergy & Infectious Diseases  11/2005

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