Rapid Strep Test

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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 either viruses or bacteria. Less than one-third of all pharyngitis is bacterial, the most common bacteria being Group A streptococcus (GAS). Children 5 years to 15 years of age are the most common age group infected by group A strep. Infection is most common during the winter/early spring season. This is likely due in part to the seasonal variation of strep bacteria concentration in the community as well as the higher likelihood of close proximity of individuals due to either weather conditions and/or school attendance during winter months.

The pediatric population may have different presentations of GAS infection:

  1. Infants (< 1 year of age) low grade fever (< 101 F, 38 C), fussiness, decreased appetite, often following 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
  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. Other upper respiratory symptoms such as runny nose and cough are not usually associated with strep throat.

The majority of sore throats (70% to 85%) are caused by viruses. Representative examples are:

  • EBV (Epstein-Barr virus) and CMV (cytomegalic inclusion virus) infections may produce a mononucleosis symptom complex (sore throat, fever, disproportionate fatigue, tender and swollen neck lymph nodes, and commonly enlargement of the spleen and liver);
  • 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 examination discriminates between GAS 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.

Medically Reviewed by a Doctor on 4/11/2014