Streptococcal (strep) infections are communicable diseases that develop when bacteria of the family Streptococcus invade parts of the body and contaminate blood or tissue.
Most people have some form of strep bacteria in their body at some point. A person who hosts bacteria without showing signs of infection is considered a carrier.
Types of infection
Primary strep infections invade healthy tissue and most often affect the throat. Secondary strep infections invade tissue already weakened by injury or illness. They frequently affect the bones, ears, eyes, joints, or intestines. Both primary and secondary strep infections can travel from affected tissues to lymph glands, enter the bloodstream, and spread throughout the body. Numerous strains of streptococcal bacteria have been identified. Types A, B, C, D, and G are most likely to make people sick.
GROUP A Group A strep (GAS) is the form of streptococcal bacteria most apt to be associated with serious illness. Two of the most severe invasive GAS infections are necrotizing fasciitis or flesh-eating bacteria (destruction of muscle tissue and fat) and toxic shock syndrome (a rapidly progressive disorder that causes shock and damages internal organs). GAS is also the type of strep responsible for strep throat . Strep throat is common and not usually serious. If untreated, however, strep throat can develop into rheumatic fever which can permanently damage the heart and other organs.
GROUP B Group B strep (GBS) most often affects pregnant women, infants, the elderly, and chronically ill adults. Streptococcal infection occurs when bacteria contaminate cuts or open sores or otherwise penetrate the body's natural defenses. The bacteria can be passed from pregnant women to their newborns during childbirth .
GROUP C Group C strep (GCS) is a common source of infection in animals. It rarely causes human illness.
GROUP D Group D strep (GDS) is a common cause of wound infections in hospital patients. GDS is also associated with the following:
- abnormal growth of tissue in the gastrointestinal tract
- urinary tract infection (UTI)
- womb infections in women who have just given birth
GROUP G Normally present on the skin, in the mouth and throat, and in the intestines and genital tract, Group G strep (GGS) is most likely to lead to infection in alcoholics and in people who have cancer , diabetes mellitus , rheumatoid arthritis, and other conditions that suppress immune-system activity.
GGS can cause a variety of infections, including the following:
- bacteria in the bloodstream (bacteremia)
- inflammation of the connective tissue structure surrounding a joint (bursitis)
- endocarditis, a condition that affects the lining of the heart chambers and the heart valves
- inflammation of bone and bone marrow (osteomyelitis)
- inflammation of the lining of the abdomen (peritonitis)
Causes and symptoms
GAS is transmitted by direct contact with saliva, nasal discharge, or open wounds of someone who has the infection. Chronic illness, kidney disease treated by dialysis, and steroid use increase vulnerability to infection. About one of five people with GAS infection develops a sore, inflamed throat and pus on the tonsils (strep throat). The majority of those infected by GAS either have no symptoms or develop enlarged lymph nodes, fever , headache , nausea , vomiting , weakness, and a rapid heartbeat.
Flesh-eating bacteria is characterized by fever, extreme pain , swelling, and redness at a site where skin is broken. Symptoms of toxic shock include abdominal pain, confusion, dizziness , and widespread red skin rash.
A pregnant woman who has GBS infection can develop infections of the bladder, blood, and urinary tract, and deliver a baby who is infected or stillborn. The risk of transmitting GBS infection during birth is highest in a woman whose labor begins before the thirty-seventh week of pregnancy or lasts more than 18 hours or who has the following conditions:
- has a GBS urinary-tract infection
- has already given birth to a baby infected with GBS
- develops a fever during labor
More than 13 percent of babies who develop GBS infection during birth or within the first few months of life develop neurological disorders. An equal number of them die.
Other symptoms associated with strep infections include the following:
- elevated white blood cell counts
- inflammation of the epiglottis (epiglottitis)
- heart murmur
- high blood pressure
- infection of the heart muscle
- kidney inflammation (nephritis)
- swelling of the face and ankles
Between 10,000 and 15,000 invasive GAS infections occur in the United States every year. In 1999, there were 300 cases of toxic shock associated with GAS infection and 600 cases of necrotizing fasciitis. There are millions of cases of strep throat every year, and similar numbers of cases of relatively mild skin infections. Strep throat is most common among school-age children and people who live in group settings (for example, dorms, boarding schools, the military).
Since first emerging in the 1970s, GBS has been the primary cause of life-threatening illness and death in newborns. GBS exists in the reproductive tract of 20 to 25 percent of all pregnant women. Although no more than 2 percent of these women develop invasive infection, if untreated 40 to 73 percent transmit bacteria to their babies during delivery. About 12,000 of the 3.5 million babies born in the United States each year develop GBS disease in infancy. About 75 percent of them develop early-onset infection. Sometimes evident within a few hours of birth and always apparent within the first week of life, this condition causes inflammation of the membranes covering the brain and spinal cord (meningitis), pneumonia , blood infection (sepsis), and other problems.
Late-onset GBS develops between the ages of seven days and three months. It often causes meningitis. About half of all cases of this rare condition can be traced to mothers who are GBS carriers. The cause of the others is unknown. GBS has also been linked to a history of breast cancer. Approximately 5 percent of babies who develop GBS die. However, those who survive often have debilitating problems after the disease. Infections caused by the other types of strep are rare.
When to call the doctor
If the child has a fever and sore throat , a wound that seems to be infected, a rash, is acting very sick, or has any other symptoms of strep infection, the doctor should be consulted.
Strep bacteria can be obtained by swabbing the back of the throat, the vagina, the rectum, or the infected area with a piece of sterile cotton. A blood sample can also be taken. Microscopic examination of the smear can identify which type of bacteria has been collected. A rapid strep test may be done to test for step throat infection. This kind of test gives results within the hour. A sample may also be sent to a lab for traditional culturing, which takes from one to two days, because this form of testing is more accurate than the rapid strep test.
Penicillin and other antibiotics are used to treat GAS and other types of strep infection. It usually takes less than 24 hours for antibiotics to eliminate an infected person's ability to transmit the infection, but antibiotics always need to be taken for the full course prescribed by the doctor to prevent reinfection or other complications.
Guidelines developed by the American Academy of Obstetrics and Gynecology (AAOG), the American Academy of Pediatrics (AAP), and the Centers for Disease Control and Prevention (CDC) recommend administering intravenous antibiotics during labor to a woman at high risk of passing GBS infection on to her child and offering the medication to any pregnant woman who wants it.
Initiating antibiotic therapy at least four hours before birth allows medication to become concentrated enough to protect the baby during passage through the birth canal. Babies infected with GBS during or shortly after birth need to be treated right away, but they may still die. Those who survive often require lengthy hospital stays and develop vision or hearing loss and other permanent disabilities.
Conventional medicine is very successful in treating strep infections. However, several alternative therapies, including homeopathy and botanical medicine, may help relieve symptoms or support the person with a strep infection. For example, several herbs, including garlic ( Allium sativum ), echinacea ( Echinacea spp.), and goldenseal ( Hydrastis canadensis ), are believed to strengthen the immune system, thus helping the body fight a current infection, as well as helping prevent future infections.
GAS is responsible for more than 2,000 deaths a year. About one in five people infected with flesh-eating bacteria die. So do three out of every five people who develop streptococcal toxic shock syndrome. Strep throat, however, is almost never fatal, although left untreated it can result in diseases such as rheumatic fever that can affect the heart.
Early-onset GBS kills 15 percent of the infants it affects. Late-onset disease claims the lives of 10 percent of babies who develop it. GBS infections are fatal in about 20 percent of the men and non-pregnant women who develop them. About 10 to 15 percent of non-GAS strep infections are fatal. Antibiotic therapy, begun when symptoms first appear, may increase a patient's chance of survival.
Washing the hands frequently, especially before eating and after using the bathroom, and keeping wounds clean can help prevent strep infection. Exposure to infected people should be avoided, and a family physician should be notified if the child develops an extremely sore throat or pain, redness, swelling, or drainage at the site of a wound or break in the skin.
Until vaccines to prevent strep infection become available, 12 monthly doses of oral or injected antibiotics may prevent some types of recurrent infection if necessary. Pregnant women should be screened for GBS during the last few weeks of pregnancy. About one fourth of pregnant women are thought to carry GBS in their vaginal or rectal tracts. If GBS is found to be present, antibiotics can be administered intravenously during labor. This greatly reduces the chance of GBS being transmitted from mother to baby when the baby is in the birth canal. The chances are believed to be reduced from one in 200 that the baby will develop GBS infection to one in 4000.
Strep infections can develop into life-threatening or debilitating problems if not treated promptly. Ensuring the child takes the full course of antibiotics prescribed by the doctor even if the symptoms have gone away can prevent life-threatening complications such as rheumatic fever. Pregnant women should be screened for GBS during the last weeks of pregnancy to help ensure that GBS does not infect their newborns.
Bacteremia —Bacterial infection of the blood.
Bursitis —Inflammation of a bursa, a fluid-filled cavity or sac. In the body, bursae are located at places where friction might otherwise develop.
Osteomyelitis —An infection of the bone and bone marrow, usually caused by bacteria.
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Tomasz, Alexander, ed. Streptococcus Pneumoniae: Molecular Biology & Mechanisms of Disease. Larchmont: Mary Ann Liebert, Inc., 2000.
"Early Results Show Promise for Strep Vaccine." Vaccine Weekly (September 2004): 76.
Tish Davidson, A.M. Maureen Haggerty