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Strep throat is caused by Group A Streptococcus bacteria. It is the most common bacterial infection of the throat.
Pharyngitis - streptococcal; Streptococcal pharyngitis
Causes, incidence, and risk factors
Strep throat is most common in children between the ages of 5 and 15, although it can happen in younger children and adults. Children younger than 3 can get strep infections, but these usually don't affect the throat.
Strep throat is most common in the late fall, winter, and early spring. The infection is spread by person-to-person contact with nasal secretions or saliva, often among family or household members.
There are many strains of strep. Some strains can lead to a scarlet fever rash. This rash is thought to be an allergic reaction to toxins made by the strep germ. On rare occasions, strep throat can lead to rheumatic fever if it is not treated. Strep throat may also cause a rare kidney complication.
Strep throat may be very mild, with only a few symptoms, or it may be severe. Often, persons with strep throat get sick 2 to 5 days after they are exposed to the bacteria that causes the illness.
Symptoms usually begin suddenly, and can include:
Some strains of strep throat can lead to a scarlet fever-like rash. This rash is thought to be an allergic reaction to toxins made by the strep bacteria.
Signs and tests
A rapid test can be done in most health care provider offices, but misses a few of the cases. A throat swab can be tested (cultured) to see if strep grows from it. However, it will take one to two days for results to come back.
If the rapid test is negative, it may be followed by a culture, to find all the cases that might have been missed. This is more likely to be needed in children.
Be aware that most sore throats are caused by viruses, not strep. Sore throats should only be treated with antibiotics if the strep test is positive. Strep cannot be accurately diagnosed by symptoms or a physical exam alone.
Even though strep throat usually gets better on its own, antibiotics are taken to prevent rare but more serious complications, such as rheumatic fever.
- Penicillin or amoxicillin has been traditionally recommended and is still very effective. There has been resistance reported to azithromycin and related antibiotics.
- Antibiotics should be taken for the full 10 days, even though symptoms are usually gone after few days.
Most sore throats are soon over. In the meantime, the following remedies may help:
- Drink warm liquids. Honey or lemon tea is a time-tested remedy.
- Gargle several times a day with warm salt water (1/2 tsp of salt in 1 cup water).
- Drink cold liquids or suck on popsicles to soothe the sore throat.
- Suck on hard candies or throat lozenges. This is often as effective as more expensive remedies, but should not be used in young children because of the choking risk.
- Use a cool-mist vaporizer or humidifier to moisten and soothe a dry and painful throat.
- Try over-the-counter pain medications, such as acetaminophen. Do NOT give aspirin to children.
The probable outcome is good. Nearly all symptoms resolve in one week. Treatment prevents serious complications associated with streptococcal infections.
On rare occasions, strep throat can lead to rheumatic fever if it is not treated. Strep throat may also cause a rare kidney complication called post-streptococcal glomerulonephritis.
Calling your health care provider
Call if you develop the symptoms of strep throat, whether or not you think you were exposed to someone with strep throat. Also, call if you are being treated for strep throat and are not feeling better within 24 - 48 hours.
Most people with strep are contagious until they have been on antibiotics 24 - 48 hours. Thus, they should stay home from school, daycare, or work until they have been on antibiotics for at least a day.
Get a new toothbrush after you are no longer contagious, but before finishing the antibiotics. Otherwise the bacteria can live in the toothbrush and re-infect you when the antibiotics are done. Also, keep your family's toothbrushes and utensils separate, unless they have been washed.
If repeated cases of strep still occur in a family, you might check to see if someone is a strep carrier. Carriers have strep in their throats, but the bacteria do not make them sick. Sometimes, treating them can prevent others from getting strep throat.
Gerber MA, Baltimore RS, Eaton CB, et al. Prevention of rheumatic fever and diagnosis and treatment of acute Streptococcal pharyngitis: a scientific statement from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee of the Council on Cardiovascular Disease in the Young, the Interdisciplinary Council on Functional Genomics and Translational Biology, and the Interdisciplinary Council on Quality of Care and Outcomes Research: endorsed by the American Academy of Pediatrics. Circulation. 2009 Mar 24;119(11):1541-51.
Alcaide ML, Bisno AL. Pharyngitis and epiglottitis. Infect Dis Clin North Am. 2007;21:449-469.
Del Mar C, Glasziou PP, Spinks A. Antibiotics for sore throat. Cochrane Database Syst Rev. 2006 Oct 18;(4):CD000023.
Altamimi S, Khalil A, Khalaiwi KA, Milner R, Pusic MV, Al Othman MA. Short versus standard duration antibiotic therapy for acute streptococcal pharyngitis in children. Cochrane Database of Systematic Reviews 2009, Issue 1. Art. No.: CD004872.
This article uses information by permission from Alan Greene, M.D., © Greene Ink, Inc.
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Review Date: 1/10/2010
Review By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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