Differential Diagnosis for Gram-Positive Cocci in Pairs in Oral Smear Gram Stain

• Single Most Likely Diagnosis
  • Streptococcus viridans: This is the most common cause of gram-positive cocci in pairs found in oral smears. They are part of the normal oral flora and can be associated with various conditions, including dental caries and endocarditis.
• Other Likely Diagnoses
  • Streptococcus pneumoniae: Although more commonly associated with respiratory infections, S. pneumoniae can be found in the oral cavity, especially in cases of aspiration or oral colonization.
  • Streptococcus pyogenes (Group A Streptococcus): While typically associated with pharyngitis, S. pyogenes can be present in the oral cavity and may be identified in oral smears, particularly in the context of an acute infection.
• Do Not Miss Diagnoses
  • Enterococcus species: These bacteria can be part of the oral flora but are more commonly associated with urinary tract infections and endocarditis. Their presence in an oral smear could indicate a more serious underlying condition.
  • Staphylococcus aureus: Although S. aureus is typically gram-positive cocci in clusters, some strains can appear in pairs. It's crucial to consider S. aureus due to its potential for causing severe infections, including endocarditis and sepsis.
• Rare Diagnoses
  • Abiotrophia species: These are fastidious gram-positive cocci that can appear in pairs and are known to cause endocarditis, particularly in patients with pre-existing heart conditions.
  • Gemella species: These bacteria are part of the normal oral flora but can cause infections, including endocarditis, in rare cases. Their identification in an oral smear would be unusual but warrants consideration in the appropriate clinical context.