Streptococcal Pharyngitis: Diagnosis and Treatment


What is it?

Bacteria are responsible for cases of streptococcal pharyngitis of group A beta-hemolytic being the most common bacterial etiology. A rapid positive antigen test can be considered a definitive test for treatment; a negative result should be followed by a confirmatory culture when streptococcal pharyngitis is strongly suspected.

The objectives of treatment include the prevention of suppurative and non-suppurative complications, the reduction of clinical signs and symptoms, the reduction of bacterial transmission and the minimization of adverse effects to antimicrobials. The selection of antibiotics should be done carefully due to allergies that occur in some patients. Patient education can help reduce recurrence.

Pharyngitis caused by group A beta-hemolytic streptococci, commonly called “streptococcal pharyngitis”, has an incubation period of two to five days and is more common in children from five to 12 years of age. The disease can occur in groups and is diagnosed more frequently in the winter.

Group A beta-hemolytic streptococci are usually transmitted by direct person-to-person contact, probably through droplets of saliva or nasal secretions and overcrowding. Outbreaks resulting from human contamination of food during preparation have also been reported.

Most cases of beta-hemolytic streptococcal pharyngitis are an acute illness in which there is a predominant sore throat, a temperature above 38.5 ° C, fever, chills, myalgias, headaches and nausea. Physical findings may include petechiae on the palate, pharynx and tonsils, erythema, exudates, and cervical adenopathy. However, many patients do not conform to the textbook image. Children, for example, may present with abdominal pain or vomiting.

Diagnostic tests

The throat culture remains the gold standard for the diagnosis of streptococcal pharyngitis.


Although penicillin is effective, it has drawbacks. About 10% of patients are allergic to penicillin, and compliance with a four-times-a-day dosing schedule could be difficult. The use of the intramuscular route can overcome the problems of dosage compliance, but the injection is very painful.

Amoxicillin is less expensive and has a narrower spectrum in antimicrobial activity, being administered once a day. Suspensions of this drug taste better than suspensions of penicillin. However, side effects can occur such as gastrointestinal problems and skin rashes.

Erythromycin is recommended as a first alternative in patients allergic to penicillin, absorbing better when administered with food and is as effective as penicillin, although studies have shown that 15 to 20% of patients can not tolerate their effects.

The broad spectrum of Azithromycin allows administration once a day, and a shorter course of treatment. It is also associated with a low incidence of gastrointestinal side effects, and a four-day course of this antibiotic has been shown to be as effective as a 10-day treatment.