Which two pathogens are associated with Phlyctenular Keratoconjunctivitis? (Choose 2)

Which two pathogens are associated with Phlyctenular Keratoconjunctivitis? (Choose 2)

• A. Tuberculosis and Streptococcus
• B. Tuberculosis and Staphylococcus
• C. Streptococcus and Pseudomonas
• D. Pseudomonas and Staphylococcus

Answer: (B)

Phlyctenular keratoconjunctivitis is driven by a delayed-type hypersensitivity reaction to bacterial antigens at the ocular surface. The two pathogens most consistently linked to this reaction are Mycobacterium tuberculosis and Staphylococcus aureus. Tuberculous proteins can trigger ocular sensitization in individuals with TB exposure, while staphylococcal blepharitis provides Staph aureus antigens that provoke the same immune response at the limbus, leading to a small nodular phlyctenule and surrounding inflammation. The other pathogens listed are not the classic triggers for PKC, since this condition is not typically driven by those organisms’ antigens.