Beta Throat Infection
What Is Strep Throat? Symptoms and Diagnosis
Group A streptococcal pharyngitis, commonly known as “strep throat,” is an infection of the throat and tonsils caused by the bacterium Streptococcus pyogenes. Viruses are the most common cause of sore throats; streptococcal infections are more common in school-aged children in particular. The cause of a sore throat cannot always be distinguished by examination alone.
How does strep throat spread?
The bacterium is usually transmitted through an infected person's respiratory secretions during close contact. Schools, nurseries and crowded settings can increase close contact. Hand hygiene and covering the mouth when coughing help reduce the risk of transmission.
What are the symptoms?
Group A streptococcal infection may cause the following symptoms:
- Sudden onset of a sore throat and difficulty swallowing
- Fever
- Redness or white exudate on the tonsils
- Tender lymph nodes at the front of the neck
- Headache, abdominal pain, nausea or vomiting in some children
Cough, a runny nose, hoarseness, mouth ulcers and red eyes are more suggestive of viral infections. However, symptoms alone cannot establish a definitive diagnosis.
How is strep throat diagnosed?
The doctor assesses the symptoms and examination findings to decide whether testing is needed. The following tests are used when group A streptococcal infection is suspected:
- Rapid antigen test: This is performed using a throat swab and provides results quickly. A positive result supports the diagnosis. As the test's sensitivity can vary, a negative result may be confirmed by culture in some patients.
- Throat culture: This checks for bacterial growth from a throat swab. The CDC considers culture the reference method for diagnosis.
- Respiratory PCR test: This can detect the genetic material of pathogens included in the panel used. The pathogens covered by the PCR panel and the types of samples accepted vary depending on the test used.
Our laboratory offers throat culture, rapid testing and respiratory PCR testing options. The appropriate test is determined based on the patient's age, symptoms, examination findings and clinical assessment.
For children aged three years and older, the CDC recommends confirmation with a throat culture if the rapid test is negative. In adults, a culture is generally not routinely required after a negative rapid test; the doctor may decide based on the clinical situation and risks.
Does every sore throat require antibiotics?
No. Most sore throats are caused by viruses, and antibiotics are not effective against viral infections. When group A streptococcal infection is confirmed by testing, the doctor may recommend antibiotic treatment. The choice of medication and duration of treatment must be determined by the doctor; antibiotics should not be started without medical advice or stopped early.
When should you see a doctor?
Seek medical assessment without delay if you have significant difficulty breathing or swallowing, an inability to swallow saliva, rapidly worsening symptoms, neck swelling or severe weakness. Contact your doctor again if there is no improvement within 48 hours of starting treatment.