Rapid Strep Test

Rapid Strep Test

Anatomy of a Sore Throat Slideshow

Medical Author: John Mersch, MD, FAAP
Medical Editor: William C. Shiel Jr., MD, FACP, FACR

• Overview of streptococcal throat infection
• What is a rapid strep test?
• Why is identification of streptococcal infection important?
• What is the traditional test for strep throat?
• Why is the rapid test better?
• How is a rapid strep test done?
• What are the limitations of the rapid strep test?

Overview of streptococcal throat infection

The incidence of sore throats (pharyngitis) varies with season, age of the patient, and geographic area. Sore throats can be caused by infection from viruses or bacteria. Fewer than a third of all pharyngitis is bacterial, most commonly from Group A streptococcus infection. Children 5 years to 15 years of age are the common age group affected with infection during winter/early spring season the most common season.

The pediatric population may have different presentations such as:

1. infants (< 1 year of age) low grade fever (< 101 F, 38 C), fussiness, decreased appetite, and often exposure to either daycare or older infected siblings;
   
   
2. children (< 3 years of age) prolonged purulent nasal discharge, low grade fever, and enlarged and tender lymph nodes in the neck area; and
   
   
3. children (> 3 years of age) sudden onset sore throat, moderate fever (> 101 F, 38 C), headache, upset stomach, and enlarged and tender lymph nodes in the neck area.

The majority of sore throats (70% - 85%), then, are causes by viruses. Representative examples are:

• EBV (Ebstein-Barr virus) and CMV (cytomegalic inclusion virus) which may produce a mononucleosis symptom complex,
  
  
• adenovirus (which may be associated with conjunctivitis ("pink eye"),
  
  
• influenza, and
  
  
• miscellaneous others - herpes, rhinovirus (cause of the common "cold"), etc.

Unfortunately, no single characteristic element of either the patient's history or physical exam discriminates between strep and non-strep pharyngitis. Thus, the importance of laboratory evaluation since strep throat should be treated with antibiotics, while relief of symptoms remains the mainstay of treatment for viral sore throats.