From the Guidelines
The clinical diagnosis of streptococcal pharyngitis is typically confirmed by a rapid streptococcal antigen test or throat culture, which identifies the presence of Group A beta-hemolytic Streptococcus (GABHS) 1.
Key Diagnostic Features
- The diagnosis of streptococcal pharyngitis should be confirmed using a rapid antigen detection test and/or culture of a throat swab 1.
- A positive result on rapid antigen detection testing is diagnostic for group A streptococcal pharyngitis 1.
- A backup culture should be performed in children and adolescents with negative test results 1.
Clinical Presentation
- Patients with group A b-hemolytic streptococcal pharyngitis commonly present with sore throats (generally of sudden onset), pain on swallowing, and fever 1.
- Other findings may include tonsillopharyngeal erythema with or without exudates and tender enlarged anterior cervical lymph nodes (lymphadenitis) 1.
Treatment
- First-line treatment for strep throat involves a 10-day course of penicillin V (250-500 mg, 2-3 times daily) or amoxicillin (500-875 mg, 2-3 times daily), with alternative options including azithromycin (12 mg/kg, once daily for 5 days) or clarithromycin (15 mg/kg, 2 times daily for 10 days) for patients with penicillin allergies 1.
- Symptoms typically resolve within 3-5 days of initiating antibiotic therapy.
Important Considerations
- Accurate diagnosis of streptococcal pharyngitis followed by appropriate antimicrobial therapy is important for the prevention of acute rheumatic fever and suppurative complications 1.
- Inappropriate antimicrobial use for upper respiratory tract infections, including acute pharyngitis, has been a major contributor to the development of antimicrobial resistance among common pathogens 1.
From the FDA Drug Label
Pharyngitis/Tonsillitis In three double-blind controlled studies, conducted in the United States, azithromycin (12 mg/kg once a day for 5 days) was compared to penicillin V (250 mg three times a day for 10 days) in the treatment of pharyngitis due to documented Group A β-hemolytic streptococci (GABHS or S. pyogenes)
The clinical diagnosis for streptococcal pharyngitis is documented Group A β-hemolytic streptococci (GABHS or S. pyogenes).
- The diagnosis is typically made by documented evidence of the presence of GABHS or S. pyogenes.
- The treatment of pharyngitis due to GABHS or S. pyogenes can be done with azithromycin or penicillin V. 2
From the Research
Clinical Diagnosis of Streptococcal Pharyngitis
The clinical diagnosis of streptococcal pharyngitis involves a combination of physical examination, medical history, and diagnostic tests. The following are key points to consider:
- Group A beta-hemolytic streptococcus (GABHS) is the most common bacterial cause of acute pharyngitis 3, 4, 5, 6, 7
- Clinical criteria alone are not reliable enough to diagnose GABHS pharyngitis, and microbiological testing is required for correct diagnosis 3, 6, 7
- The modified Centor score or FeverPAIN score can be used to help physicians decide which patients need no testing, throat culture/rapid antigen detection testing, or empiric antibiotic therapy 4, 5, 7
Diagnostic Tests
The following diagnostic tests are used to confirm the diagnosis of streptococcal pharyngitis:
- Throat culture: considered the diagnostic standard, but results take 1-2 days 3, 6, 7
- Rapid antigen detection testing: provides results in less than 15 minutes, with excellent specificity and sensitivity 6
- Rapid antigen detection tests involve extraction of the group-specific carbohydrate antigen from the GABHS cell wall and identification of the antigen by an immunological reaction 6
Signs and Symptoms
Common signs and symptoms of streptococcal pharyngitis include:
- Sore throat
- Temperature greater than 100.4 degrees F (38 degrees C)
- Tonsillar exudates
- Cervical adenopathy
- Fever 4, 5, 7
- Cough, coryza, and diarrhea are more common with viral pharyngitis 7
Predictors of GABHS Pharyngitis
The strongest independent predictors of GABHS pharyngitis are:
- Patient age of five to 15 years
- Absence of cough
- Tender anterior cervical adenopathy
- Tonsillar exudates
- Fever 4