Streptococcal Infections

Streptococcal (strep-tuh-KAH-kul) infections are caused by various strains * of Streptococcus (strep-tuh-KAH-kus) bacteria.


for searching the Internet and other reference sources

Alpha-hemolytic streptococci

Beta-hemolytic streptococci


Group A streptococcal (GAS) infections

Group B streptococcal (GBS) infections


Necrotizing fascitis

Scarlet fever


Strep throat

Toxic shock syndrome

What Are Streptococcal Infections?

Streptococci (strep-tuh-KAH-kye) are common bacteria that live in the human body, including the nose, skin, and genital tract. These bacteria can destroy red blood cells, damage them, or cause no damage at all. The amount of damage they do is used to classify streptococcus strains. The ones that destroy red blood cells are known as beta-hemolytic (he-muh-LIH-tik), and these strains are categorized as groups A through G.

Groups A and B streptococci are most often associated with disease. Group A strep (GAS) infections range from superficial skin infections and strep throat to serious and life-threatening illnesses such as toxic shock syndrome and necrotizing fasciitis (NEH-kro-tie-zing fash-e-EYE-tis). Group B strep (GBS) is the leading cause of life-threatening infections in newborns. In pregnant women, GBS can lead to bladder infections, infections of the womb, and death of the fetus * .

Alpha-hemolytic streptococci are strains that damage red blood cells but do not destroy them. Two important strains are S. viridans (VEER-ih-dans), which is found in the mouth and is involved in tooth decay and endocarditis * , and S. pneumoniae (nu-MO-nye), which can cause pneumonia * , middle ear infection, and meningitis * .

Group A Streptococcus (GAS) Infections

How common are they? According to the National Institute of Allergy and Infectious Diseases (NIAID), more than 10 million cases of mild GAS infections, such as skin and throat infections, are diagnosed each year. Between 9,000 and 10,000 cases of more serious infections, including toxic shock syndrome and necrotizing fasciitis, occur annually. People with immune systems weakened by diseases such as diabetes or cancer, are at a greater risk for developing serious GAS infections.

Are they contagious?

GAS bacteria are contagious and spread through contact with fluid from the mouth or nose of an infected person or contact with infected skin lesions * .

* strains are various subtypes of organisms, such as viruses or bacteria.

* fetus (FEE-tus) is the term for an unborn human after it is an embryo, from 9 weeks after fertilization until childbirth.

* endocorditis (en-do-kar-DYE-tis) is an inflammation of the valves and internal lining of the heart, known as the endocardium (endoh-KAR-dee-um), usually caused by an infection.

* pneumonia (nu-MO-nyah) is inflammation of the lung.

* meningitis (meh-nin-JY-tis) is an inflammation of the meninges, the membranes that surround the brain and the spinal cord. Meningitis is most often caused by infection with a virus or a bacterium.

* lesions (LEE-zhuns) is a general term referring to sores or damaged or irregular areas of tissue.

* tonsils are paired clusters of lymphatic tissue in the throat that help protect the body from bacteria and viruses that enter through a person's nose or mouth.

* lymph (LIMF) nodes are small, bean-shaped masses of tissue that contain immune system cells that fight harmful microorganisms. Lymph nodes may swell during infections.

Some GAS infections

  • Strep throat, or streptococcal pharyngitis (fair-un-JY-tis), is a painful inflammation of the throat. Symptoms include a sore throat with white patches on the tonsils * , swollen lymph nodes * in the neck, fever, and headache.
  • Scarlet fever often occurs along with strep throat or other strep infections. It is caused by strains of group A strep that produce a toxin (or poison) that results in a very red rash and a bright red tongue, along with a high fever.
  • Impetigo (im-pih-TEE-go) is a superficial skin infection common in young children. Symptoms include fluid-filled blisters (one or more) surrounded by red skin. The blisters eventually break and form a honey-colored crust.
  • Cellulitis (sel-yoo-LYE-tis) is an inflammation of the skin and/or its underlying soft tissues. Symptoms include skin that is red, tender, and painful to the touch; fever; and chills.
  • Bacteremia (bak-tuh-REE-me-uh) is the presence of bacteria in the bloodstream, which can spread infection to other organs. Bacteremia that causes symptoms, which is known as sepsis, is associated with fever, rapid heart rate, and low blood pressure that may lead to shock * .
  • Toxin-producing strains of GAS can cause a rare but serious illness called streptococcal toxic shock syndrome. The infection may occur anywhere in the body, and the toxin (poison) is released into the bloodstream, causing low blood pressure and shock.
  • Necrotizing fasciitis (or flesh-eating disease) is a rare, rapidly progressing infection of the deeper layers of skin, muscle and other tissues. Symptoms usually start at the site of an injury, where the skin becomes painful, swollen, discolored (such as red, purple, or bronze), and hot to the touch. The skin gradually becomes darker and blisters can form while the tissues beneath the skin are being damaged. Fever, shock, and multiple organ damage may accompany this serious infection.
  • Rheumatic (roo-MAH-tik) fever, a syndrome involving arthritis * and inflammation of the heart, is actually a complication of untreated strep throat. Rashes and neurological problems also may occur, and people with rheumatic fever may have permanent damage to one or more heart valves.

Making the diagnosis

With skin infections, a doctor may take a sample from the affected area to culture * . For other types of suspected infections, blood samples are drawn and swabs of fluid from the patient's nose and throat are cultured for bacteria. A rapid strep test on a sample taken with a throat swab can also be done in a doctor's office.


Superficial skin infections often are treated with topical (on the skin) antibiotic ointments. Other GAS infections are treated with oral (by mouth) or intravenous * (IV) antibiotics. Serious GAS infections require hospitalization, where patients receive IV fluids and antibiotics. In some cases, such as with necrotizing fasciitis, surgical removal of damaged tissue is necessary. Treatment of rheumatic fever depends on the severity of the disease but includes using antibiotics to treat strep infections, anti-inflammatory medicines such as high-dose aspirin, and medications to treat heart complications.

What to expect

Symptoms of strep throat usually improve within 1 to 2 days after starting antibiotics. Skin infections often clear up within a week, but more serious infections can take weeks or even months to heal. Complications from serious bacterial infections include sepsis, shock, organ damage and failure, and death.

* shock is a serious condition in which blood pressure is very low and not enough blood flows to the body's organs and tissues, Untreated, shock may result in death.

* arthritis (ar-THRY-tis) refers to any of several disorders characterized by inflammation of the joints.

* culture (KUL-chur) is a test in which a sample of fluid or tissue from the body is placed in a dish containing material that supports the growth of certain organisms. Typically, within days the organisms will grow and can be identified.

* intravenous (in-tra-VEE-nus), or IV, means within or through a vein. For example, medications, fluid, or other substances can be given through a needle or soft tube inserted through the skin's surface directly into a vein.


Maintaining good health and hygiene can help reduce the risk of bacterial infection. Not sharing food or eating utensils, washing hands frequently, and cleaning and bandaging cuts and scrapes can help prevent the spread of bacteria.

A doctor examines a patient's sore throat. Most sore throats are caused by infections, however, they can also be caused by allergies and environmental irritants such as smoke. Custom Medical Stock Photo, Inc.
A doctor examines a patient's sore throat. Most sore throats are caused by infections, however, they can also be caused by allergies and environmental irritants such as smoke.
Custom Medical Stock Photo, Inc.

Group B Streptococcus (GBS) Infections

How common are they?

According to the Centers for Disease Control and Prevention, GBS is the most frequent cause of life-threatening infections in newborns. Early screening of pregnant women for GBS and treatment have reduced infection rates by approximately 70 percent. Currently, 17,000 cases of GBS infection occur annually in the United States.

Are they contagious?

GBS infections are contagious and can pass from mother to child before or during birth. At least 25 percent of women are carriers of GBS at some point in their life but do not become ill from it. The bacteria can be found in the bowel, vagina * , bladder, and throat.

* vagina (vah-JY-nah) is the canal, or passageway. in a woman that leads from the uterus to the outside of the body.

* urinary (YOOR-ih-nair-e) tract infection, or UTI, is an infection that occurs in any part of the urinary tract. The urinary tract is made up of the urethra, bladder, ureters, and kidneys.

Some GBS infections

  • Newborns can develop sepsis, pneumonia, and meningitis due to infection with GBS. Symptoms of GBS infection in newborns include fever, irritability, extreme sleepiness, breathing difficulties, and poor feeding.
  • GBS bacteria in pregnant women can cause urinary tract infections * as well as chorioamnionitis (kor-e-o-am-nee-on-EYE-tis, infection of the womb and membranes surrounding the fetus) and stillbirth (a fetus that is dead at birth). Symptoms of urinary tract infection include fever, pain, and a burning sensation during urination. Women with chorioamnionitis often do not show symptoms of infection until after childbirth. Symptoms include fever, belly pain, and rapid pulse.
  • The most common GBS infections in other people are urinary tract infections, sepsis, tissue infections, and pneumonia. GBS infections, including pneumonia and sepsis, are more likely to be found in people with weakened immune systems or chronic diseases, such as diabetes.

Making the diagnosis

GBS infections are diagnosed by performing cultures of blood, urine, or cerebrospinal fluid * to identify the bacteria.


GBS infections are treated with antibiotics, often intravenously, and they usually require a hospital stay, particularly for newborns. Pregnant women with urinary tract infections usually are treated with antibiotics as well.

What to expect

Recovery can take several weeks. Complications in infants, particularly those with meningitis, include hearing and vision loss and brain damage. Approximately 5 percent of cases of GBS disease in newborns are fatal.


Most newborn cases can be prevented by testing women in the thirty-fifth to thirty-seventh week of pregnancy for the bacteria. A culture of fluid from the vagina and rectum * can determine whether a woman has GBS. If she does, giving IV antibiotics during labor reduces the risk of passing GBS to the baby. Vaccines * to prevent GBS infections during pregnancy are being developed.

Alpha-Hemolytic Streptococcus Infections

How common are they?

Infections with alpha-hemolytic strep bacteria are common; many strains live naturally in humans.

Shaking Hands with

Ignaz Philipp Semmelweis (1818—1865) was a Hungarian physician who suspected that doctors could spread disease by not washing their hands thoroughly after working with cadavers before delivering babies. At the time, up to 30 percent of women who gave birth in hospitals died of puerperal (pyoo-ER-puh-rul) fever, a group A strep bacterial infection that occurred after childbirth. Semmelweis noticed that women who delivered their babies with midwives were less likely to become ill. He had his student doctors wash their hands with an antiseptic, which is a solution that prevents the growth of bacteria. Because the idea that germs could cause disease had not yet been introduced, Semmelweis' ideas about hand washing were not well received until many years later.

* cerebrospinal (seh-ree-bro-SPY-nuhl) fluid is the fluid that surrounds the brain and spinal cord.

* rectum is the final portion of the large intestine, connecting the colon to the anus.

* vaccines (vak-SEENS) are preparations of killed or weakened germs, or a part of a germ or product it produces, given to prevent or lessen the severity of the disease that can result if a person is exposed to the germ itself. Use of vaccines for this purpose is called immunization.

* sinuses (SY-nuh-ses) are hollow, air-filled cavities in the facial bones.

Some alpha-hemolytic strep infections


  • Bacterial pneumonia is an inflammation of the lungs that often occurs after or along with an upper respiratory infection. Symptoms may develop quickly and can include fever, chills, cough, rapid breathing, chest pain, belly pain, and vomiting. Before antibiotics were developed, bacterial pneumonia was the most common cause of death in adults.
  • Otitis (o-TIE-tis) media is an inflammation of the middle ear. The infection usually is associated with ear pain and sometimes with fever.
  • Sinusitis (sy-nyoo-SY-tis) is an inflammation of the sinuses * , usually due to infection. Symptoms include a stuffy nose, colored discharge (green, yellow, or tinged with blood) from the nose, tenderness around the eyes, and headache or a feeling of pressure in the head.
  • Meningitis is an inflammation of the membranes covering the brain and the spinal cord. Symptoms include fever, weakness, vomiting, irritability, and stiff neck.

After Hungarian physician Ignaz Semmelweis (1818-1865) had the physicians at a Vienna, Austria, hospital wash their hands regularly with an antiseptic, the hospital's mortality rate fell dramatically. Library of Congress
After Hungarian physician Ignaz Semmelweis (1818-1865) had the physicians at a Vienna, Austria, hospital wash their hands regularly with an antiseptic, the hospital's mortality rate fell dramatically.
Library of Congress


  • Endocarditis is an infection of the inner surface of the heart or heart valves that can be caused by S. viridans and other bacteria. Bacteria can enter the bloodstream (during a dental procedure, for example) and attach to already damaged heart tissue or an abnormal heart valve, causing more damage. Symptoms include extreme tiredness, weakness, fever, chills, night sweats, and weight loss. The infection can progress, resulting in problems with heart function in some cases.

Making the diagnosis

Depending on the type of infection, a diagnosis is made by testing blood, sputum * , or cerebrospinal fluid samples for signs of the bacteria.


Oral or IV antibiotics are used, depending on the severity of the infection. A hospital stay may be needed, particularly in cases of pneumonia or meningitis. Long courses of antibiotics, lasting several weeks or more, may be required to treat endocarditis.


Vaccines against S. pneumoniae are now given routinely to infants and the elderly, as well as to children and adults with weakened immune systems or certain medical conditions. People with abnormal or damaged heart valves are given courses of antibiotics when they have some types of surgical procedures, including dental work, to help prevent endocarditis from developing from the shedding of bacteria into the bloodstream that occurs with these procedures.

* sputum (SPYOO-tum) is a substance that contains mucus and other matter coughed out from the lungs, bronchi, and trachea.



U.S. Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, Atlanta, GA 30333. The CDC posts information about streptococcal infections at its website.
Telephone 800-311-3435

U.S. National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894. The National Library of Medicine has a website packed with information on diseases (including streptococcal infections), consumer resources, dictionaries and encyclopedias of medical terms, and directories of doctors and helpful organizations.
Telephone 888-346-3656

Website . KidsHealth is a website created by the medical experts of the Nemours Foundation and is devoted to issues of children's health. It contains articles on a variety of health topics, including streptococcal infections.

See also
Congenital Infections
Endocarditis, Infectious
Otitis (Ear Infections)
Skin and Soft Tissue Infections
Sore Throat
Urinary Tract Infections

User Contributions:

Comment about this article, ask questions, or add new information about this topic: