Strep throat is a common bacterial infection, especially in school-aged children, caused by the bacterium Group A Streptococcus (GAS). The primary symptom is often a sudden and painful sore throat, which prompts many people to seek medical attention. While it is possible for the infection to present with only a sore throat, this is less typical than a presentation involving several other characteristic signs. Differentiating strep from a more common viral sore throat is important because only the bacterial infection requires antibiotic treatment.
Symptom Variability in Strep Throat
While a sore throat can be the sole complaint, the classic presentation of a strep infection usually involves a rapid onset of throat pain along with other specific symptoms. Many individuals experience a fever, often 101°F or higher, and painful swallowing. A physical examination may reveal red and swollen tonsils, sometimes displaying white patches or streaks of pus (exudate). Other common indicators include tiny red spots, called petechiae, visible on the palate, and swollen, tender lymph nodes in the neck. Unlike a common cold, strep throat rarely presents with typical upper respiratory symptoms such as a cough, runny nose, or hoarseness.
Other Common Causes of a Sore Throat
The vast majority of sore throats are caused by viruses, not bacteria, meaning antibiotics are ineffective for most cases of pharyngitis. Viral infections, such as the common cold, flu, or mononucleosis, frequently cause throat discomfort accompanied by cough, congestion, and a runny nose. These accompanying symptoms typically point toward a viral cause, which resolves on its own with supportive care.
Sore throats can also result from non-infectious sources that do not require medication. Allergies often trigger post-nasal drip, where excess mucus irritates the back of the throat, resulting in a scratchy sensation. Environmental factors like dry air, pollution, or chronic conditions such as acid reflux can also lead to throat irritation and pain.
The Importance of Testing for Confirmation
Because symptoms alone are not sufficient to definitively diagnose strep throat, medical testing is required to confirm the presence of Group A Streptococcus. The diagnostic process typically begins with a Rapid Strep Test (RST), which involves swabbing the back of the throat and tonsils for a sample. The RST is valued for its speed, providing results within minutes, and its high specificity, meaning a positive result is very reliable.
However, the RST has a lower sensitivity, potentially missing between 5% and 20% of true strep infections (false negatives). For children and adolescents with a negative RST but a high clinical suspicion of strep, a backup throat culture is often performed. The throat culture, considered the gold standard, involves sending the swab to a laboratory to incubate for 24 to 48 hours, allowing any bacteria present to grow for a definitive diagnosis.
Treatment and Complication Prevention
Once a strep infection is confirmed by testing, a full course of antibiotics is prescribed, most commonly penicillin or amoxicillin. Starting treatment within the first 48 hours of symptom onset helps reduce the duration and severity of the illness. Patients must complete the entire 10-day course of medication, even if symptoms improve quickly.
The primary reason for antibiotic treatment is not symptom relief but the prevention of rare but serious complications. The most significant complication is Acute Rheumatic Fever (ARF), an inflammatory condition that can permanently damage the heart valves, joints, brain, and skin. Treatment also prevents Post-streptococcal Glomerulonephritis, which involves inflammation of the kidneys.