Which gram-negative bacteria is known to cause angular blepharoconjunctivitis and is associated with shared eye makeup?

• A. Proteus mirabilis
• B. Klebsiella pneumoniae
• C. Moraxella
• D. Bordetella pertussis

Answer: (C)

Angular blepharoconjunctivitis is classically caused by Moraxella lacunata, a Gram-negative diplobacillus that has a long association with this eyelid and conjunctival infection. The presentation often includes crusting and redness at the outer canthi, and epidemiologically it’s linked to transmission through shared eye makeup. In the lab, you’d expect to see Gram-negative diplobacilli on a conjunctival smear, which fits Moraxella anatomy and helps confirm the diagnosis. The other organisms listed don’t typically cause this specific eye condition: Proteus mirabilis and Klebsiella pneumoniae are more commonly associated with urinary or respiratory infections, and Bordetella pertussis causes whooping cough. So the organism most consistent with angular blepharoconjunctivitis and the makeup-sharing clue is Moraxella.