Home » S » Strep Throat

Strep Throat

Streptococcal Throat Infection, Streptococcal Sore Throat

What is Strep throat?

Strep throat is a contagious bacterial infection that causes inflammation within the throat. It affects the pharynx (back of the throat) and tonsils (two oval-shaped tissue masses located inside the mouth, at either side of the throat). Sometimes, the adenoid (tissue mass located behind the nose in the upper throat) may also become swollen and infected. Left untreated, strep throat can damage the heart valves (in rheumatic fever) and kidneys (glomerulonephritis).

The bacteria that cause strep throat are from a class of bacteria called group A streptococci (strep), also known as Streptococcus pyogenes or group A beta-hemolytic streptococcus. Most often, a person develops strep throat after exposure to a person already infected with the bacteria. Other times, the bacteria can live harmlessly in the nose or throat for some time without causing infection, and can then be triggered by stress or immune system dysfunction, resulting in infection.

Strep throat occurs most often in children between 5 years and 15 years old, although it may affect people of all ages. Approximately 15 percent of sore throats in children are due to strep throat, according to the American Academy of Family Physicians.

There are many different strains of strep bacteria, which can cause a number of different types of illnesses. Thus, even though people develop antibodies to the particular form of strep with which they were infected, they remain vulnerable to other strains. For this reason, people are often diagnosed with strep throat multiple times.

In addition to strep throat, strep bacteria can cause inflammation and infection in other areas of the body, such as:

Ear, nose and throat problems. These include tonsillitis, sinusitis and otitis media. In some cases, these infections may accompany strep throat. The strep bacteria can also cause bacterial pneumonia.
Skin infections. The strep bacteria can infect the skin, causing impetigo, cellulitis and erysipelas (inflammation in upper layers of the skin). The U.S. Centers for Disease Control and Prevention (CDC) estimates that over 10 million cases of strep-caused skin and throat infections occur every year. In some people, cellulitis infection may develop in the rectum (streptococcal perianal cellulitis) or vagina (streptococcal vaginitis).
Scarlet fever. Infectious disease that may occur following a strep throat infection. It can cause a bright red rash, sore throat and fever.
Severe, invasive infections. These include bacteremia (infection that enters the bloodstream), streptococcal toxic shock syndrome (causes blood pressure to drop and vital organs to fail) and necrotizing fasciitis (flesh-eating disease). These infections can be fatal. An estimated 9,000 invasive infections occur annually in the United States, according to the CDC.

How is it diagnosed?

People who have a sore throat without a runny nose that lasts for more than 48 hours are urged to consult a physician. The physician will perform a physical examination that will likely include a visual inspection of the throat. A tongue depressor may be used to enable clear viewing of the back of the throat. A medical history may be compiled, which can include questions about the frequency of the patient's throat infections. The patient may also be referred to an ear, nose and throat specialist.

Strep throat cannot be diagnosed strictly by symptoms and physical examination. The only way to identify the presence of strep throat is through the following diagnostic tests:

  • Rapid strep test (also called the rapid antigen test). A physician will swab the surface of the tonsils, located at the back of the patient's throat for a tissue sample. This can be analyzed and results are typically available within about 15 minutes. It can detect the strep bacteria in 75 percent to 85 percent of strep throat cases, according to the American Academy of Family Physicians (AAFP).
  • Throat culture. A physician swabs the patient's tonsils(similar to the method used for the rapid strep test) and the tissue sample is then sent to a laboratory for analysis. Results are generally not available for at least a day or two.
Generally, both tests are performed, particularly if the rapid strep test is negative. The rapid strep test allows treatment to begin immediately (if strep throat is detected) and the throat culture is used to confirm this result. Occasionally, the throat culture (a more sensitive test) may detect a strep throat infection that was missed during the rapid strep test. It should be noted that recent antibiotic therapy or gargling with some types of mouthwash prior to these tests may affect results.

A new diagnostic test has been developed that uses DNA technology, called the rapid DNA test. It provides results within a few hours, and may be more sensitive than the rapid antigen test. Patients are urged to consult with the physician about the availability of this test.

Family members who are not currently displaying symptoms of strep throat will sometimes receive a rapid strep test and throat culture to help determine if they are carriers.
It is important to note that strep tests and cultures sometimes miss a number of other types of conditions that also cause severe sore throats. These include severe tonsillitis or tonsillar abscess, diphtheria, and infections of the throat resulting from oral sex. The presence of bacteria growing in the blood (septicemia) can also cause symptoms similar to strep. As a result, further testing may be necessary to rule out these conditions in patients who have sore throats but who test negatively for strep.

In addition, a physician may perform a rapid influenza test to check for the presence of influenza, which has symptoms that often are similar to strep.

How is Strep throat treated?

Antibiotics are usually required to treat strep throat. While these are often not given until tests confirm the diagnosis of strep through, rapid stress tests allow the diagnosis to be made within minutes. Even without antibiotics, strep infection will clear on its own. However, antibiotics are necessary to kill the bacteria, limit the spread of infection and prevent medical complications. People who do not take antibiotics are contagious for a longer period of time and are at greater risk of developing serious complications related to the strep.

Antibiotics may be provided in pill, liquid or injectable form. Patients with strep throat should begin to feel better within a day or two of beginning antibiotic treatment. It is important to take the complete course of antibiotics prescribed, which usually lasts for 10 days to 14 days. Failure to take the entire course of treatment may increase the risk of serious medical complications (e.g., rheumatic fever, glomerulonephritis) or lead to development of antibiotic-resistant bacteria.

People with strep throat may continue to be contagious for at least 24 hours after beginning antibiotic treatment. They should not return to work or school until they have taken antibiotics for at least one day, the fever is gone and they feel better. Antibiotic treatment limits the spread of infection but does not prevent strep throat from recurring in a particular patient. Patients who are not treated with antibiotics may be contagious for weeks after an infection.

If a patient who has tested positive for strep throat does not respond to antibiotic treatment, it may be because that patient is a carrier (carries the bacteria in the body but never develops an infection). In addition, the existing condition may not be strep throat at all, but a viral infection. A way to confirm this is to test the patient for strep throat when signs of infection are no longer present. A healthy, asymptomatic patient who tests positive for strep throat is considered a carrier. It is not usually necessary to treat carriers, who are much less contagious than people who have symptoms of strep throat.

Patients can manage symptoms by getting plenty of rest and nourishment. Adequate fluid intake (e.g., water, juice, broth) can help prevent dehydration. In addition, certain over-the-counter pain medications (e.g., acetaminophen, ibuprofen) can help reduce the fever and pain associated with strep throat. Parents should never give aspirin to children or adolescents since it may increase the risk of Reye syndrome, a potentially fatal condition.

Additional self-treatment methods for strep throat include:
  • Gargle with warm salt water
  • Drink cool or warm liquids
  • Eat soft foods (e.g., soup, popsicles)
  • Use a humidifier
Patients are urged to avoid consuming acidic products (e.g., orange juice, lemonade), since they may sting the throat. Environments that include cigarette smoke or fumes from paint or cleaning products should also be avoided, since these may irritate an already sore throat. In addition, patients are urged to ask their physician about whether or not throat lozenges may help. Parents of children with strep throat are urged to remember that lozenges can pose a choking hazard for young children. Some lozenges may aggravate the symptoms of strep throat.

Although rare, a tonsillectomy is sometimes recommended for patients with repeated episodes of strep throat (e.g., more than five episodes in one year). Some studies suggest that strep throat infections occur much less often after a tonsillectomy. Patients are urged to consult their physician to weigh the benefits and risks of this type of surgery.
Patients should call their physician if they notice any of the following after completing their treatment:
  • Cola-colored urine
  • Fever
  • Pain or swelling in the joints
  • Rash
  • Shortness of breath



What might complicate it?

Complications result from strep infection that is not treated promptly. Scarlet fever includes a rash with the strep infection. Abscess formation around the tonsil can occur. Rheumatic fever or rheumatic heart disease is a most serious complication, and can affect the heart valves and muscle; congestive heart failure can develop. Another complication is inflammation of the kidneys (acute glomerulonephritis). In severe cases, kidney failure may occur. Strep can also involve the brain (strep meningitis).

Predicted outcome

The prognosis for treated strep throat is good. The infection responds to treatment within ten days, and no lasting effects are expected. The predicted outcome for untreated disease is variable, but significant long-term medical problems can develop, including rheumatic heart and kidney disease.


Other bacterial and viral infections can have similar symptoms and physical signs, including pus on the tonsils (this is why a throat culture is needed to accurately identify strep). Infectious mononucleosis can also resemble strep throat, but will last longer than strep. Inflammatory kidney disease may also be caused by sepsis or other bacterial infection.

Appropriate specialists

Internist or pediatrician, cardiologist or nephrologist for complications of strep, otolaryngologist and infectious disease specialist.

Seek Medical Attention

  • You or a family member has symptoms of a strep throat.
  • The following occur during treatment:
    • Temperature is normal for 1 or 2 days, then fever develops.
    • New symptoms appear, such as nausea, vomiting, earache, cough, swollen glands, skin rash, severe headache, nasal drainage or shortness of breath.
    • Joints become red or painful.
    • Dark urine, rash, chest pain or fatigue develops (may occur up to 3 to 4 weeks later).

Last updated 5 July 2015