Which organism is detected as Gram-negative intracellular diplococci in conjunctival smears?

• A. Moraxella catarrhalis
• B. Neisseria gonorrhoeae
• C. Chlamydia trachomatis
• D. Streptococcus pneumoniae

Answer: (B)

Seeing Gram-negative intracellular diplococci in a conjunctival smear points to Neisseria gonorrhoeae as the cause of gonococcal conjunctivitis. This organism is a Gram-negative diplococcus that is often found inside neutrophils in purulent eye discharge, so the presence of intracellular Gram-negative diplococci is a highly characteristic clue for gonorrheal infection. Other organisms either don’t show this intracellular diplococci pattern on routine Gram stain or are Gram-positive, as in Streptococcus pneumoniae, which helps explain why they’re less likely in this scenario. Chlamydia trachomatis, while it can cause conjunctivitis, is not seen as Gram-negative diplococci on standard Gram stain and requires special testing or NAAT for detection; Moraxella catarrhalis is a Gram-negative diplococcus but typically does not present with abundant intracellular organisms in neutrophils the way gonococcus does.

Clinically, this finding signals a urgent treatment approach because gonococcal conjunctivitis can progress rapidly and threaten corneal involvement, so systemic antibiotics are indicated and you would evaluate for concurrent sexually transmitted infections. Culture on selective media like Thayer-Martin can confirm the diagnosis, and management often considers coinfection with Chlamydia, guiding broader empiric therapy.