Pharyngitis

Differential for pharyngitis:
- Viral: rhino-, adeno-, corona-, influenza A and B, parainfluenza, echo-, HSV, HIV (ARVS), EBV, CMV
- Bacterial: GAS, Group C streptococcus, N. gonorrhea, C. diphtheriae

Why is it important to differentiate?

- To rule out deep neck space infections from acute pharyngitis
e.g. peritonsillar abscess, parapharyngeal space infeciton, submandibular space infection, epiglottitis
- To diagnose GAS to give antibiotics and prevent sequelae
- TO diagnose EBV/mono gives the patient prognostic info
- To diagnose HIV for obvious reasons both tx, prognosis, prevent further transmission.

GAS diagnosis- Recall the Centor criteria.
- Tonsillar exudates
- Tender anterior cervical adenopathy
- Fever by history
- absence of cough

Most guidelines favor further testing if a patient has 2 of 4 Centor criteria.
Further testing should include rapid strep +/- throat culture.
- Rapid strep: sensitivity 80-90%, specificity 90-100%.
- high specificity of this test allows you to start abx at the visit. Given lower sensitivity, if rapid strep is negative, you still need throat culture.
- Throat culture takse 24-48 hours. It is okay to wait for the culture before initiating abx. Waiting won't cause progression to rheumatic fever. With good technique has sensitivity of 90%, specificity of 95-99%. False positive from carriers of GAS (1-5% ppl).

Pearl: If you suspect a possible non strep bacterial infection, such as gonococcal you must tell the lab, as they may need to plate it on different medium.

Treatment regimens:
- Treatment reduces duration of symptoms, progression to suppurative and nonsuppurative complications, reduces transmission.
- PCN V 500mg po bid x10 days (drug of choice): feels good to give PCN!
- Amoxicillin 875mg bid to 500mg tid x10 days
- Cephalexin 500mg po bid x 10 days
- azithro 500mg x1, 250mg day 2-5.
- Clindamycin 600mg per day in 2-4 div doses x 10 days

(Katharine Cheung MD, 12/13/10)