Which two Gram-positive pathogens are commonly implicated in acute bacterial conjunctivitis in adults?

• A. Staphylococcus aureus and Streptococcus pneumoniae
• B. Pseudomonas aeruginosa and Neisseria gonorrhoeae
• C. Chlamydia trachomatis and Adenovirus
• D. Streptococcus pyogenes and Escherichia coli

Answer: (A)

In adults with acute bacterial conjunctivitis, the most common Gram-positive culprits are Staphylococcus aureus and Streptococcus pneumoniae. Staph aureus is the single most frequent cause, and Streptococcus pneumoniae follows closely as a common second cause. Both of these are Gram-positive cocci and are typical organisms that invade the conjunctival surface, leading to purulent or mucopurulent discharge. Other listed pathogens are either Gram-negative, viral, or intracellular organisms, so they don’t fit the two Gram-positive bacterial players most often responsible in this scenario.