Strep Throat

Streptococcal Throat Infection, Streptococcal Sore Throat

What is Strep throat?

Strep throat is a contagious bacterial infection caused by group A streptococci, producing a sore throat and fever. The bacteria spread through the air by a sneeze or cough, or by physical contact. The infection spreads easily in homes, schools or other areas where people are in close, continued contact with each other. The incubation period is generally three to five days.

Strep throat is easily treated with antibiotics. But if strep infection is left untreated, serious complications of the heart or kidneys can result. Infants, the elderly and people with compromised immunity are at risk for more serious complications of strep throat.

How is it diagnosed?

History is of sore throat and pain on swallowing. It may be accompanied by headache, fever, loss of appetite, fatigue, hoarseness, and a dry cough. There might be contact with another person known to have strep. Mild infections may not show symptoms, however.

Symptoms of complicated strep disease include persistent sore throat, joint pain (arthritis), skin rash, abdominal pain, and occasionally involuntary movements. The sudden appearance of blood in the urine indicates kidney involvement, as can swelling around the ankles or eyes, and shortness of breath or fatigue.

Physical exam reveals an inflamed pharynx, tonsils and palate. A fever is usually present. Pus may or may not be seen on the tonsils and throat. Tender and enlarged lymph nodes in the neck can be noted.

Streptococcal infection can also involve the joints, especially the knees, ankles, wrists, or elbows, manifesting with swollen, painful joints (acute arthritis). The arthritis often moves from one joint to another. A red, raised rash may appear on the skin for short periods of time. If the infection has affected the heart, a characteristic heart murmur may be detected.

Involvement of the kidneys may be accompanied by high blood pressure or fluid retention (edema) the presence of blood or high levels of protein in the urine.

Tests: Strep throat is diagnosed by culturing the bacteria from a throat swab. If systemic infection is observed, bacteria may be isolated from blood or the infection may be diagnosed indirectly by the presence of streptococcus-specific antibodies in serum. When kidney disease is suspected, a urinalysis will show blood or protein in the urine, and bacteria may be cultured from either the blood or urine. A kidney biopsy is done rarely, to diagnose involvement of the kidneys.

How is Strep throat treated?

Strep throat is treated with antibiotics. Non-prescription medications may be used for relief of pain and reduction of inflammation. If systemic disease develops, individuals are given antibiotics to treat any residual strep throat infection, and anti-inflammatory drugs are used to control joint pain and swelling. For more serious inflammation, corticosteroids may be needed.

If rheumatic fever develops, bed rest of between two and twelve weeks is needed. Antibiotics may be continued for years to prevent reinfection; preventive antibiotic therapy may be needed prior to dental or surgical procedures, throughout the individual's life.

Kidney disease is treated symptomatically. High blood pressure is treated with anti-hypertensive drugs. Water retention is reduced by diuretics and a low-salt diet. For severe complications, kidney dialysis may be needed.


Information Brand Generic Label Rating Amoxil Amoxicillin On-Label Augmentin Amoxicillin/Clavulanate On-Label
Motrin Motrin Ibuprofen Off-Label

Ilosone (Erythromycin), Keflex (Cephalexin)

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 27 May 2012

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