Pharyngitis. This post will cover the points you need to know for your board exams as well as for teaching residents on the daily rounds. Please don't use the information here to treat your patients.
Most commonly viral in adults and most commonly by Rhinovirus followed by Coronavirus, adenovirus, herpes simplex, parainfluenza, influenza, EBV, CMV, acute HIV, and coxsackievirus.
Bacterial causes are less common in adults but pay attention to group A beta-hemolytic streptococci (GABHS) due to fear of rheumatic fever. Other bacteria include Neisseria gonorrhea, corynebacterium diphtheria, Chlamydophila pneumonia and mycoplasma pneumonia.
Infectious mononucleosis caused by EBV is usually characterized by fever, sore throat and posterior lymphadenopathy (as opposed to predominately anterior in bacterial), lymphocytosis, and increased ALT/AST/LDH levels. Tonsils are enlarged and easily mistaken for GABHS. Giving amoxicillin will lead to pruritic rash.
Cough, laryngitis, and stuffy nose are not characteristic of streptococcal pharyngeal infection; their presence suggests another cause (usually viral or allergic).
Rapid heterophil antibody test (Monospot test) for EBV (might be negative the first week) and rapid strep test for GABHS are commonly done. Although throat culture is more sensitive and gold standard, but other tests are more practical.
PCN is the first-line treatment GABHS pharyngitis:
1. Penicillin V or Amoxicillin:
- Children: 250 mg (or 12.5 mg/kg) orally every 6 hours for a total of 10 days.
- Adults: 500 mg orally every 6 hours for a total of 10 days.
2. First-Generation Cephalosporins (for Penicillin-Allergic Patients):
- Cephalexin (Keflex): 250 mg orally every 6 hours for a total of 10 days.
3. Clindamycin (for Penicillin-Allergic Patients):
- Children: 20 mg/kg/day divided into 3 doses for a total of 10 days.
- Adults: 300 mg orally every 6 hours for a total of 10 days.
4. Macrolide Antibiotics (for Penicillin-Allergic Patients):
- Azithromycin (Zithromax): 500 mg on the first day, followed by 250 mg daily for the next 4 days (total of 5 days).
The information in this post is not for patients and shouldn't be used in treating patients. Please refer to your doctor for medical advice.