Strep Throat
Strep Throat
Disease History, Characteristics, and Transmission
Introduction
A sore throat is one of the most common symptoms sending people to the doctor. It often precedes a cold, flu, or other respiratory infection. Most sore throats are caused by viral infection. Strep throat, or Streptococcal pharyngitis, is a bacterial throat infection with “strep” being a shortened for Streptococcus pyogenes, the causative agent. Most people carry S. pyogenes in their throat and on their skin and normally it causes no problems.
Strep throat is considered a mild infection, although it can be very painful. Left untreated, it can sometimes lead to serious complications, such as rheumatic fever. Strep throat responds promptly to antibiotic treatment, which will also stop the infection spreading to others. The majority of sore throats will not respond to anti-biotics, because they are caused by viruses. That is why strep throat should be properly diagnosed wherever possible, to prevent the unnecessary use of antibiotics.
Disease History, Characteristics, and Transmission
The S. pyogenes bacterium belongs to a large group of bacteria called the streptococci, which occur in characteristic long chains. They are subdivided according to the antigen proteins they bear on their surfaces. S. pyogenes is, therefore, sometimes called Group A streptoccoccus (GAS), since it carries the A antigen. A certain amount of GAS is found on the skin of most people without causing illness; this is known as colonization. However, besides strep throat, GAS can also cause impetigo (a skin infection) and scarlet fever. Some strains of GAS are also responsible for necrotizing fasciitis, which involves the soft tissue under the skin, and toxic shock syndrome, both of which are potentially fatal.
WORDS TO KNOW
ANTIBIOTIC RESISTANCE: The ability of bacteria to resist the actions of antibiotic drugs.
COLONIZATION: Colonization is the process of occupation and increase in number of microorganisms at a specific site.
FOMITE: A fomite is an object or a surface to which an infectious microorganism such as bacteria or viruses can adhere and be transmitted. Transmission is often by touch.
IN CONTEXT: SOCIAL AND PERSONAL RESPONSIBILITY
According to the Division of Bacterial and Mycotic Diseases at Centers for Disease Control and Prevention (CDC), “the spread of all types of GAS infection can be reduced by good hand-washing, especially after coughing and sneezing and before preparing foods or eating. Persons with sore throats should be seen by a doctor who can perform tests to find out whether the illness is strep throat. If the test result shows strep throat, the person should stay home from work, school, or day care until 24 hours after taking an antibiotic. All wounds should be kept clean and watched for possible signs of infection such as redness, swelling, drainage, and pain at the wound site. A person with signs of an infected wound, especially if fever occurs, should seek medical care. It is not necessary for all persons exposed to someone with an invasive group A strep infection (i.e., necrotizing fasciitis or strep toxic shock syndrome) to receive antibiotic therapy to prevent infection. However, in certain circumstances, antibiotic therapy may be appropriate. That decision should be made after consulting with your doctor.”
SOURCE: Centers for Disease Control and Prevention (CDC), Coordinating Center for Infectious Diseases, Division of Bacterial and Mycotic Diseases.
The symptoms of strep throat include throat pain and difficulty in swallowing, headache, fever, and swollen glands. The tonsils might be red and swollen with white patches and streaks of pus. Strep throat is distinguished from other conditions, such as tonsillitis or viral throat infection, by testing a throat swab for the presence of GAS.
Possible complications of strep throat include rheumatic fever and kidney inflammation. These may set in weeks after the first symptoms of the throat infection. Rheumatic fever may be indicated by joint pain or rash, while the urine may become dark if the kidneys are infected. Rheumatic fever is potentially serious, as it can lead to permanent damage of the heart valves with impairment of heart function. Other possible complications include tonsillitis, scarlet fever, sinus infection, and ear infection.
GAS is highly contagious and strep throat is spread through coughs, sneezes, and contact with objects, such as kitchen utensils and bathroom items, that have been used by an infected person (fomites). The infection often spreads rapidly through family members, schools and child care centers—anywhere, in fact, that people come into close contact.
Scope and Distribution
Strep throat is most common among children aged from 5 to 15, although it can affect people of any age. It is most often seen in late fall, winter, and spring. In the United States, the risk of complications from strep throat is low.
Treatment and Prevention
Strep throat is usually treated by an antibiotic, such as penicillin, amoxicillin, clarithromycin, or cephalosporin. The treatment reduces the severity and duration of symptoms, and stops the infection from passing to others. Symptoms will start to clear within a day or two of starting antibiotics. It is important to finish the whole course of prescribed antibiotics. Stopping medication early will increase the risk of complications and encourage the growth of resistant organisms.
Rest, plenty of water, and soothing foods will also help relieve the pain of strep throat, as will gargling with salt water. Acetaminophen and ibuprofen may be prescribed for pain and fever, although aspirin is not recommended for young children with strep throat because it can contribute to the development of Reye's syndrome, a potentially life-threatening illness.
As with many infections, the best way to prevent strep throat is by good personal hygiene, including covering the mouth and nose when coughing or sneezing and washing the hands frequently and thoroughly. For a child with recurrent strep throat, tonsillectomy (removal of the tonsils) may be helpful. A study carried out by the Mayo Clinic in 2006 showed that children with recurrent strep throat with intact tonsils are three times more likely to develop subsequent episodes compared to those who have their tonsils removed.
Impacts and Issues
Accurate diagnosis of the cause of a sore throat is important. Viral infections should not be treated with antibiotics. Not only will the infection not respond, but the inappropriate prescription of antibiotics has been linked to anti-biotic resistance, which is a growing public health problem. Strep throat can be diagnosed with rapid tests for GAS antigen or DNA. Courses of antibiotics prescribed for strep throat should always be completed, because stopping early also encourages antibiotic resistance.
See AlsoAntibiotic Resistance; Bacterial Disease; Impetigo; Necrotizing Fasciitis; Scarlet Fever; Toxic Shock.
BIBLIOGRAPHY
Web Sites
Centers for Disease Control and Prevention. “Group A Streptococcal (GAS) Disease.” October 11, 2005. <http://www.cdc.gov/ncidod/dbmd/diseaseinfo/groupastreptococcal_g.htm> (accessed May 1, 2007).
MayoClinic.com. “Strep throat.” November 3, 2006. <http://www.mayoclinic.com/health/strep-throat/DS00260> (accessed May 1, 2007).