Pharyngitis is defined as an infection or irritation of the pharynx and/or tonsils. The etiology is usually infectious, with most cases being of viral origin. These cases are benign and self-limiting for the most part. Bacterial causes of pharyngitis are also self-limiting, but are concerning because of suppurative and nonsuppurative complications. Other causes include allergy, trauma, toxins, and neoplasia.
In the end, the decision to treat or not treat pharygitis rests with the probability of having a group A beta-hemolytic streptococcal infection, specifically. Most other causes are self-limiting, and more importantly, do not require antibiotic therapy.
The Centor criteria have been used in the past as a way to diagnose and treat GAS pharyngitis. These include the following:
- Fever
- Anterior cervical lymphadenopathy
- Tonsillar exudate
- Absence of cough
Assess for group A beta-hemolytic streptococcal (GAS) infection if clinically suspected. A suggested algorithm as is follows.
- In general, patients should not be treated without a positive culture or positive rapid antigen detection test result because of increasing antibiotic resistance. Guidelines from the Infectious Diseases Society of America (IDSA) and American Heart Association state that microbiologic confirmation (via a rapid antigen test or culture) is required for the diagnosis of GAS.
- Perform rapid antigen detection test if GAS is clinically suspected based on history and physical examination. If positive, begin antibiotic therapy. Testing does not usually need to be performed on patients with acute pharyngitis whose clinical and epidemiologic features do not suggest GAS as the etiology (Centor score 0-1).
- Patients who are positive for all 4 Centor criteria can often be treated with antibiotics without antigen testing or cultures.
- Household contacts of patients with GAS infection or scarlet fever should be treated for a full 10 days without testing only if they have symptoms consistent with GAS.
- If clinically doubtful or the above criteria are not met, it is best to await rapid antigen or culture results to initiate antibiotic therapy.
You should recognize Strep pyogenes.