Differential Diagnosis for Viral and Bacterial Pharyngitis

When differentiating between viral and bacterial pharyngitis, it's crucial to consider various factors including symptoms, physical examination findings, and laboratory tests. Here's a structured approach to the differential diagnosis:

• Single Most Likely Diagnosis

  • Viral pharyngitis: This is the most common cause of pharyngitis, often presenting with sore throat, fever, and other viral symptoms like cough and runny nose. The justification for this being the single most likely diagnosis lies in its high prevalence and the fact that most cases of pharyngitis are viral in nature.

• Other Likely Diagnoses

  • Streptococcal pharyngitis (Group A beta-hemolytic streptococcus): This bacterial infection is a common cause of pharyngitis, especially in children, and is characterized by severe sore throat, fever, and absence of cough. It's a likely diagnosis due to its significant impact on public health and the need for specific antibiotic treatment.
  • Infectious mononucleosis: Caused by Epstein-Barr virus, this condition can present with severe pharyngitis, fever, and lymphadenopathy, making it another likely diagnosis in the appropriate clinical context.

• Do Not Miss Diagnoses

  • Lemierre's syndrome: A rare but potentially life-threatening condition that starts with pharyngitis and can progress to septicemia and thrombophlebitis of the internal jugular vein. It's crucial not to miss this diagnosis due to its high morbidity and mortality if not treated promptly.
  • Diphtheria: Although rare in areas with high vaccination coverage, diphtheria is a bacterial infection that can cause severe pharyngitis and is potentially deadly if not recognized and treated early.
  • Peritonsillar abscess: A complication of bacterial pharyngitis that can lead to severe pain, difficulty swallowing, and potentially life-threatening airway obstruction if not promptly diagnosed and managed.

• Rare Diagnoses

  • Gonococcal pharyngitis: Caused by Neisseria gonorrhoeae, this is a rare cause of pharyngitis but should be considered in individuals with high-risk sexual behavior.
  • Tuberculous pharyngitis: Although rare, tuberculosis can affect the pharynx, especially in immunocompromised individuals or those from areas with high TB prevalence.
  • Syphilitic pharyngitis: A rare manifestation of secondary syphilis, which can cause pharyngitis among other symptoms.