Strep throat (also known as pharyngitis or streptococcal pharyngitis) is a bacterial infection caused by Streptococcus pyogenes (also referred to as group A Streptococcus). Strep bacteria are very contagious, and spread by nasal secretions and saliva. Strep throat most often afflicts children younger than 15.
Symptoms of strep throat typically appear several days after exposure to the bacteria. The most common symptom of a strep infection is a sore throat. Individuals may also have trouble swallowing and the tonsils and lymph nodes may feel swollen. Some individuals may experience fever, fatigue or headache. A rash may develop.
Children may also experience a stomachache and vomiting.
Strep throat itself is not particularly dangerous but the infection can worsen, especially if it goes untreated. If strep throat does not improve within two days of beginning treatment, it could indicate the presence of another infection, the spread of strep to other areas outside the throat, or an inflammatory reaction.
Strep bacteria may infect the tonsils and sinuses if left untreated. Also, the middle ear, skin and blood can become infected.
Certain inflammatory conditions may also develop. Scarlet fever may occur in individuals allergic to the strep bacteria. Individuals with Scarlet fever will develop a characteristic rash.
Rheumatic fever may occur several weeks after an individual is infected with strep. Symptoms of this condition include swollen joints and difficulty breathing. It may even affect the heart and nervous system.
Strep bacteria can also cause inflammation of the kidneys. Called poststreptococcal glomerulonephritis, the condition can occur more than seven days after a strep throat infection. One indication of this type of inflammation is brown-colored urine.
Diagnosis & Tests
To diagnose strep throat, a physician will perform a physical exam, as well as several tests.
During the physical, a doctor examines the throat and mouth for signs of infection including redness and swelling. Also, the doctor will check for a fever and feel the lymph nodes, which will be enlarged in the presence of infection.
Many types of bacteria and — more frequently — viruses can cause a sore throat, so to determine what is causing the infection a physician will perform a throat culture, a rapid antigen test or a rapid DNA test.
During a throat culture, the back of throat and tonsils are swabbed and the sample is sent to a lab for analysis. It takes time to obtain the results of a throat culture, however, so in some cases a physician may prefer to use a rapid antigen test. The rapid antigen test shows if foreign substances are present in the throat, and it produces results within minutes. Still, it is not 100 percent accurate and is often used in combination with another test.
A rapid DNA test does not produce results as quickly as an antigen test but with results in less than a day, it is still faster than a throat culture and just as accurate. The test is conducted using a swabbed sample.
Although physicians often suspect that strep bacteria are the cause of a sore throat, researchers at the University of Alabama at Birmingham recently found that another bacteria, Fusobacterium necrophorum, should also be on doctors' short lists. In a study published in the December 2009 issue of the journal Annals of Internal Medicine, the researchers noted that the bacteria might be the culprit of up to 10 percent of sore throat cases in adolescents and early 20-somethings.
Treatments & Medications
It is possible for strep throat to clear up without treatment; however, the risk of complications increases. Moreover, the infection is contagious until treated.
Penicillin and amoxicillin are typically prescribed to treat strep throat. For individuals with a penicillin allergy, newer generations of antibacterials may be used. These include cephalexin, erythromycin and azithromycin. All of these antibiotics kill strep bacteria, alleviate symptoms, and decrease the amount of time an individual is sick. Physicians may also recommend an over-the-counter pain and fever reducer.
Within 24 to 72 hours of beginning treatment, an individual is no longer contagious and he or she will begin to feel better. Still, all medication should be taken for the duration prescribed in order to prevent complications and bacterial resistance.
In addition to medication, individuals should rest from work and school, and avoid chemicals and environments that may further irritate the throat. Also, gargling warm salt water and eating soft and cold foods can soothe the throat.