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Group A Streptococcal Infections

OVERVIEW

Group A streptococcal infections are caused by group A streptococcus, a bacterium responsible for a variety of health problems. These infections can range from mild skin infection or sore throat to invasive, 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. Experts estimate that more than 10 million mild infections like these occur every year.

In addition to step throat and superficial skin infections, group A strep bacteria can cause infections in tissues at specific body sites, including lungs, bones, spinal cord, and the abdominal cavity.

STREP THROAT

What is strep throat and what are the symptoms?
Your doctor may call it acute streptococcal pharyngitis. People with strep throat infections have a red and painful sore throat with white patches on their tonsils. A person may also have swollen lymph nodes in the neck, run a fever, and have a headache. Nausea, vomiting, and abdominal pain can occur but are more common in children than in adults.

How does Group A strep spread to others?
Group A strep infections can spread from person to person by direct contact with saliva or nasal discharge. 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 can make it easier for the bacteria to spread. There have also been reports of contaminated food, especially milk and milk products, causing infection. A person becomes sick within 3 days after being exposed to the germ. Once people become infected, they can pass the infection to others for up to 2 to 3 weeks even if they don't have symptoms. After 24 hours of antibiotic treatment, a person will no longer spread the bacteria to others.

How is strep throat diagnosed?

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

What is the treatment for strep throat?

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

Penicillin is considered the medicine of choice for treating strep throat because it has been proven to be effective, safe, and inexpensive. Your doctor may have you take pills for 10 days or give you a shot. Doctors often prefer to give amoxicillin to children with strep throat. If you are allergic to penicillin there are other antibiotics your doctor can give you to clear up the illness. 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 the medicine in order to prevent complications.

What are the complications of strep throat?

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 a jerky movement disorder called Sydenham chorea. 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.

SKIN INFECTIONS

What is impetigo?

Impetigo is an infection of the top layers of the skin and is most common among children ages 2 to 6. It usually starts when the bacteria get into a cut, scratch, or insect bite. Impetigo is usually caused by staphylococcus, a different bacterium, but can be caused by group A streptococcus. Different types of streptococci than those that cause strep throat usually cause skin infections. Therefore, the types of streptococci that cause impetigo are usually different from those that cause strep throat.

What are the symptoms of impetigo?

Symptoms start with red sores or pimple-like lesions (sores) surrounded by reddened skin These lesions can be anywhere on the body, but are found mostly on the face, arms, and legs. Lesions fill with pus, then break open after a few days and form a thick crust. Itching is common. The doctor can diagnose the infection by looking at the skin lesions.

How is impetigo spread?

The infection is spread by direct contact with wounds or sores or nasal discharge from an infected person. Scratching may spread the lesions. From the time of infection until a person shows symptoms is usually a period of 1 to 3 days. Dried streptococci in the air are not infectious to skin with no breaks.

What is the treatment for impetigo?

Your doctor will prescribe antibiotics, as with strep throat. He or she may also prescribe an antibiotic ointment.

What are cellulitis and erysipelas?

Cellulitis is inflammation of the skin and deep underlying tissues. Erysipelas is an inflammatory disease of the upper layers of the skin. Group A streptococcus is the most common cause of both conditions.

What are the symptoms of cellulitis and erysipelas?

Cellulitis is inflammation of the skin and deep underlying tissues. Erysipelas is an inflammatory disease of the upper layers of the skin. Group A streptococcus is the most common cause of both conditions.

With erysipelas, a fiery red rash with raised borders may occur on the face, arms, or legs. Skin will be hot, red, and have sharply defined raised areas. The infection may come back, causing chronic swelling of arms or legs (lymphedema).

How does a person get cellulitis or erysipelas?

Both cellulitis and erysipelas begin with minor trauma, such as a bruise. It can also begin at the site of a burn, surgical incision, or wound, and usually affects an arm or leg. When the rash appears on the trunk, arms, or legs, however, it is usually at the site of a surgical incision or wound. People who have no symptoms, but carry the germ on their skin or in their nasal passages, can transmit the disease.

How are these skin infections diagnosed and what is the treatment?

The doctor may take a sample or culture from skin lesions to identify the bacteria causing infection. He or she may also recover the bacteria from the infected person's blood. Depending on how severe the infection is, treatment involves either oral or intravenous antibiotics.

SCARLET FEVER

What is scarlet fever?

Scarlet fever is another form of group A streptococcal disease that can follow strep throat. It is usually self-limited.

What are the symptoms of scarlet fever?

In addition to the symptoms of strep throat, a red rash appears on the sides of the chest and the abdomen. It may spread to cover most of the body. This rash appears as tiny, red pinpoints and has a rough texture like sandpaper. When pressed on, the rash loses color or turns white. There may also be dark red lines in the folds of skin. People with scarlet fever may get a bright strawberry-red tongue, and their faces are flushed while the area around the mouth remains pale. The skin often peels after recovery usually on tips of fingers and toes. In severe cases, a patient may have a high fever, nausea and vomiting.

How does a person get scarlet fever?

A person can get scarlet fever the same way they get strep throat - through direct person-to- person contact with throat mucus, nasal discharge, and saliva of an infected person.

What is the treatment for scarlet fever?

Like strep throat, a doctor treats scarlet fever with antibiotics.

SEVERE STREP INFECTIONS

What are the more severe streptococcal infections?

Some types of group A streptococcus bacteria cause severe infections. These include:

  • Bacteremia (blood stream infections)
  • Toxic shock syndrome
  • Necrotizing fasciitis (sometimes called flesh-eating disease)

According to the U.S. Centers for Disease Control and Prevention (CDC), 8,800 cases of severe group A streptococcal disease were reported in 2000, a rate of 3.1 per 100,000 people.

All severe group A strep infections may lead to shock, organ failure, and death. Health care workers must recognize and treat such infections quickly.

Doctors diagnose these infections by looking at blood counts and doing urine tests as well as cultures of blood or fluid from a wound site. Antibiotics include penicillin, erythromycin, and clindamycin. If tissue damage is severe, a doctor may need to remove the tissue surgically or amputate the limb.

Who is at greatest risk for severe infection?

  • Children with chickenpox
  • People with suppressed immune systems
  • Burn victims
  • Elderly people with cellulitis, diabetes, blood vessel disease, or cancer
  • People taking steroid treatments or chemotherapy
  • Intravenous drug users
  • Severe group A strep disease may also occur in healthy persons with no known risk factors.

RESEARCH

Through research, scientists have learned that there are more than 120 different strains of group A streptococci, each producing its own unique proteins. Some of these proteins are responsible for specific group A streptococcal diseases. With support from the National Institute of Allergy and Infectious Diseases (NIAID), scientists have determined the genetic sequence, or DNA code, for three different strains of the group A streptococcus organism.

By studying an organism's genes, scientists learn which proteins are responsible for virulence, crucial information that will lead to new and improved drugs and vaccines. NIAID funds are supporting research for developing a group A streptococcus vaccine. An effective vaccine will prevent not only strep throat and impetigo, but more serious invasive disease and post-infectious complications like rheumatic fever.

Two different vaccine approaches are being evaluated in clinical trials in the NIAID Vaccine and Treatment Evaluation Units. More information is available at the following NIAID Web site: www.niaid.nih.gov/dmid/vaccines/backgrnd.htm.

MORE INFORMATION

National Institute of Allergy and Infectious Diseases
Office of Communications and Public Liaison
31 Center Drive, MSC 2520
Bethesda, MD 20892-2520
http://www.niaid.nih.gov

Medlineplus
U.S. National Library of Medicine
8600 Rockville Pike
Bethesda, MD 20894
301-496-6308
http://medlineplus.gov

Centers for Disease Control and Prevention
Public Inquiries/MASO - Mail Stop F07
1600 Clifton Road
Atlanta, GA 30333
http://www.cdc.gov

Information on PSGN:

National Institute of Diabetes, Digestive, and Kidney Diseases
National Kidney and Urologic Diseases Information Clearinghouse
3 Information Way
Bethesda, MD 20892-3580
1-800-891-5390
http://www.niddk.nih.gov

Information on Sydenham chorea:

National Institute of Neurological Disorders and Stroke
Office of Communications and Public Liaison
P.O. Box 5801
Bethesda, MD 20824
1-800-352-9424
http://www.ninds.nih.gov

NIAID is a component of the National Institutes of Health (NIH). NIAID supports basic and applied research to prevent, diagnose, and treat infectious and immune-mediated illnesses, including HIV/AIDS and other sexually transmitted diseases, illness from potential agents of bioterrorism, tuberculosis, malaria, autoimmune disorders, asthma and allergies.

Press releases, fact sheets and other NIAID-related materials are available on the NIAID Web site at http://www.niaid.nih.gov.

Prepared by:
Office of Communications and Public Liaison
National Institute of Allergy and Infectious Diseases
National Institutes of Health
Bethesda, MD 20892

U.S. Department of Health and Human Services
August 2002