Strep Throat

Definition

Strep throat is an infection of the mucous membranes lining the pharynx. Sometimes the tonsils are also infected (tonsillitis). The infection is caused by group A beta-hemolytic Streptococcusbacteria, commonly known as strep.

This bacterial infection typically causes a severe sore throat, fever, and difficulty swallowing. Strep throat may also produce a rash, known as scarlet fever, and swollen glands. Untreated, it can lead to rheumatic fever, a serious kidney disorder called glomerulonephritis, and other infections.

Description

Strep throat accounts for 5-10% of all sore throats. Although anyone can get strep throat, it is most common in school-age children. It accounts for about one quarter of sore throats in children ages five to 15. Smokers, and people who are fatigued, immunosuppressed, or who live in damp, crowded conditions are more likely to become infected. Children under age two and adults who do not have contact with children are less likely to become infected.

Strep throat occurs most frequently from November to April. The disease passes directly from person to person by coughing, sneezing, and close contact. Rarely, it may be passed through food, when a food handler infected with strep throat accidentally contaminates food by coughing or sneezing. Statistically, when one member of a household is infected, one out of every four other household members will contract strep throat within two to seven days.

Causes and symptoms

Strep infection may produce a sudden, painful sore throat one to five days after exposure to the Streptococcus bacteria. The pain is indistinguishable from sore throats caused by viral infections.

The infected patient usually feels tired and has a fever, sometimes accompanied by chills, headache, muscle aches, swollen lymph glands, and nausea. Young children may complain of abdominal pain. The tonsils appear swollen and are bright red, and may have white or yellow patches of pus. Sometimes the roof of the mouth is red or has small red spots. Often a person with strep throat has bad breath.

Though most patients display some of these common symptoms, it is possible to have the disease without any of these symptoms. Many young children complain only of a headache and stomachache, rather than the characteristic sore throat.

Occasionally, within a few days of developing the sore throat, patients may develop a fine, rough, sunburn-like rash over the face and upper body, along with a fever of 101-104 °F (38.3-40 °C) and bright red tongue, with a flecked, strawberry-like appearance. When a rash develops, this form of strep throat is called scarlet fever. The rash is caused by toxins released by the streptococcus bacteria. Scarlet fever is no more dangerous than strep throat, and is treated the same way. The rash disappears in about five days. One to three weeks later, patches of skin may desquamate (peel off), as might occur with a sunburn.

Untreated strep throat can cause rheumatic fever. This is a serious illness, although it occurs rarely. The most recent outbreak appeared in the United States in the mid-1980s. Rheumatic fever occurs most often in children between the ages of five and 15, and susceptibility to it may be genetic, since it seems to run in families. Although the strep throat that causes rheumatic fever is contagious, rheumatic fever itself is not.

Rheumatic fever begins one to six weeks after an untreated streptococcal infection. The joints, especially the wrists, elbows, knees, and ankles become red, sore, and swollen. The patient develops a high fever, and possibly a rapid heartbeat when lying down, paleness, shortness of breath, and fluid retention. A red rash over the trunk may come and go for weeks or months. An acute attack of rheumatic fever lasts about three months.

Rheumatic fever can cause permanent damage to the heart and heart valves. It can be prevented by promptly treating streptococcal infections with antibiotics. It does not occur if all the streptococcus bacteria are killed within the first 10-12 days after infection.

During the 1990s, outbreaks of a virulent strain of group A Streptococcus were reported to cause a toxic-shock-like illness and a severe invasive infection called necrotizing fasciitis, which destroys skin and muscle tissue. Although these diseases are caused by group A Streptococci, they rarely begin with strep throat. Usually the streptococcus bacteria enter the body through a skin wound. These infections are rare; however, since the death rate in necrotizing fasciitis is 30-50%, it is wise to promptly treat any streptococcal infection.

Diagnosis

Diagnosis of strep throat begins with a physical examination of the throat. The doctor will also look for signs of other illness, such as a sinus infection or bronchitis, and seek information about whether the patient has been exposed to anyone with strep throat. Patients likely to have strep throat will have a rapid strep test or throat culture, laboratory tests to detect the presence of bacteria.

There are two types of tests to confirm the diagnosis of strep throat. A rapid strep test determines the presence of streptococcal antigen, and results are available in about 20 minutes. The advantage of this test is the speed with which a diagnosis may be made.

The rapid strep test has a false negative rate of about 20%. For this reason, when a rapid strep test is negative, the physician may order a throat culture.

For a rapid strep test or a throat culture, a physician, mid-level practitioner (i.e., nurse practitioner or physician assistant) or nurse will use a sterile swab to reach down into the throat to obtain a sample of material from the sore area. The procedure takes only a few seconds, but may cause some patients to gag.

For a throat culture, a sample of swabbed material is cultured, or grown, in the laboratory on a medium that allows laboratory technologists and technicians to accurately determine whether group A Streptococci is present. Results are available in 24-48 hours. This test is very accurate and also detects the presence of bacteria other than Streptococci. Patients should be reminded by the nurse not to take antibiotics before a throat culture. Even small amounts of antibiotics can suppress the bacteria enough to mask their presence in the throat culture.

In the event that rheumatic fever is suspected, the physician will order a blood test. This test, called an antistreptolysin-O test, determines whether the person has recently been infected with strep bacteria and helps to distinguish between rheumatic fever and rheumatoid arthritis.

Treatment

Strep throat is treated with antibiotics. Penicillin is the preferred medication. The typical dose for adults is Penicilin V, 250 mg by mouth, four times a day or 500 mg twice a day. Alternatively, 250 mg of erythromycin may be given four times a day. Oral antibiotics must be taken for 10 days. Patients must be advised to take the entire amount of antibiotic prescribed. They must be warned not to discontinue taking the medication when they feel better. Stopping the antibiotic early or failing to complete the prescribed course of medication can lead to a return of the strep infection. Occasionally, a single injection of benzathine penicillin G 1.2 million units IM (intramuscularly) is given instead of 10 days of oral treatment.

About 10% of the time, penicillin is not effective against the strep bacteria. In such instances, other antibiotics such as amoxicillin (Amoxil, Pentamox, Sumox, Trimox), clindamycin (Cleocin), or a cephalosporin (Keflex, Durocef, Ceclor) may be prescribed. Erythromycin (Eryzole, Pediazole, Ilosone), another inexpensive antibiotic, is given to patients who are allergic to penicillin. Scarlet fever is treated with the same antibiotics as strep throat.

Without treatment, the symptoms of strep throat begin subsiding in four or five days. However, because of the possibility of contracting rheumatic fever, glomerulonephritis, or other infections, it is vital to treat strep throat promptly with antibiotics. If rheumatic fever does occur, it also is treated with antibiotics. Anti-inflammatory drugs are used to treat joint swelling and diuretics are used to reduce water retention. Once the rheumatic fever becomes inactive, children may continue on low doses of antibiotics to prevent a reoccurrence. Necrotizing fasciitis is treated with intravenous antibiotics.

Home care for strep throat

Patients may be taught home care measures to relieve the discomfort of their strep symptoms. They may be counseled by the nurse, mid-level practitioner, or physician to:

• Take acetaminophen or ibuprofen for pain. Aspirin should not be given to children because of its association with Reye's syndrome.
• Gargle with warm double strength tea or warm salt water, made by adding one teaspoon of salt to eight ounces of water, to relieve sore throat pain.
• Drink plenty of fluids, but avoid acidic juices like orange juice because they irritate the throat.

• Eat soft, nutritious foods like noodle soup. Avoid spicy foods.
• Avoid smoke and smoking.
• Rest until the fever is gone, then resume strenuous activities gradually.
• Use a room humidifier, as it may make sore throat sufferers more comfortable.
• Be aware that antiseptic lozenges and sprays may aggravate the sore throat rather than improve it.

Alternative treatment focuses on easing the symptoms of strep throat through herbs and botanical medicines. Honey, eucalyptus, and menthol-infused drops and syrups may all soothe the soreness of strep throat. These treatments should never be used in place of antibiotic therapy. They should be used in addition to antibiotics, since they address symptoms rather than the underlying infection.

Prognosis

Patients with strep throat begin feeling better about 24 hours after starting antibiotics. Symptoms rarely last longer than five days.

Patients remain contagious until they have taken antibiotics for 24 hours. Children should not return to school or childcare until they are no longer contagious. Food handlers should not work for the first 24 hours after antibiotic treatment, because strep infections are occasionally passed through contaminated food. People who are not treated with antibiotics can continue to spread strep bacteria for several months.

About 10% of strep throat cases do not respond to penicillin. Patients with even a mild sore throat after a 10 days of antibiotic treatment should be advised to return to the doctor. One explanation for a persisting sore throat may be that the patient is simply a carrier of strep, and the sore throat is the result of another infectious (bacterial or viral) agent.

Timely administration of antibiotics within the first week of a strep infection acts to prevent rheumatic fever and other complications. If rheumatic fever does occur, the outcomes vary considerably. Some cases may be cured; others cause permanent damage to the heart and heart valves. In rare cases, rheumatic fever can be fatal.

Necrotizing fasciitis has mortality (death rate) of 30-50%. Patients who survive often suffer a great deal of tissue and muscle loss. Fortunately, this complication of a Streptococcus infection is very rare.

Health care team roles

Physicians, nurses, mid-level practitioners, and laboratory technologists are involved in the diagnosis and treatment of strep throat. In contacts with patients they can reinforce the value of adherence to prescribed treatment and can instruct patients in selfcare and home care measures to relieve symptoms.

Patient education

Nurses, mid-level practitioners, and laboratory personnel have opportunities to teach patients how to minimize the risks of transmission by reinforcing the importance of personal hygiene, safe food handling, and avoiding exposures. They must also emphasize the importance of prompt and complete treatment of strep infection to prevent consequences and recurrence.

Prevention

There is no way to prevent getting a strep throat. Patients may be counseled about how to reduce the risk of transmission. Risk may be minimized by:

• washing hands well and frequently, especially after nose blowing or sneezing and before food handling
• disposing of used tissues properly
• avoiding close contact with someone who has a strep throat
• not sharing food and eating utensils with anyone
• not smoking

KEY TERMS

Desquamate— To peel off or exfoliate the skin.

Glomerulonephritis— A serious kidney disorder that sometimes results from an untreated strep infection.

Lactobacillus acidophilus— A bacteria found in yogurt that changes the balance of the bacteria in the intestine in a beneficial way.

Resources

BOOKS

Professional Guide to Diseases, 5th edition. Springhouse, PA: Springhouse Corp., 1995.

The Washington Manual of Medical Therapeutics, 30th edition. Philadelphia, PA: Lippincott Williams & Wilkins., 2001, pp. 304.

OTHER

National Institute of Allergy and Infectious Diseases. "Group A Streptococcal Infections." NIAID Fact Sheet. (February 1998). ?http://www.niaid.nih.govfactsheets/strep.htm?.