Differential Diagnosis for Gram Positive Cocci in Pairs

• Single Most Likely Diagnosis
  • Streptococcus pneumoniae: This bacterium is commonly found in pairs (diplococci) and is a major cause of pneumonia, meningitis, and other infections. Its gram-positive and diplococci morphology makes it a prime candidate for this description.
• Other Likely Diagnoses
  • Streptococcus pyogenes (Group A Streptococcus): Although typically found in chains rather than pairs, certain conditions or preparations might make them appear in pairs. They are a common cause of pharyngitis and skin infections.
  • Enterococcus species: These can appear as pairs and are known for their role in urinary tract infections and as part of the normal gut flora, though they can cause severe infections, especially in immunocompromised patients.
• Do Not Miss Diagnoses
  • Streptococcus agalactiae (Group B Streptococcus): While more commonly associated with chains, this pathogen can be seen in pairs and is a critical cause of neonatal sepsis and meningitis, making its identification crucial.
  • Staphylococcus species misidentified as Streptococci: Though Staphylococci are typically found in clusters, certain viewing conditions might mislead the observer into thinking they are in pairs. The distinction is crucial due to differences in antibiotic resistance and disease manifestations.
• Rare Diagnoses
  • Gemella species: These are gram-positive cocci that can appear in pairs and are part of the normal oral flora but can cause endocarditis and other infections, especially in immunocompromised hosts.
  • Abiotrophia species: Formerly known as nutritionally variant streptococci, these bacteria require special growth conditions and can appear in pairs. They are rare causes of endocarditis and other infections.