A 1-week-old infant has bilateral mucopurulent eye discharge. What explains the etiology of the discharge?

• A. The mother probably has an STD
• B. The infant likely has a plugged tear duct
• C. This is bacterial conjunctivitis
• D. This is viral conjunctivitis

Answer: (A)

Neonatal conjunctivitis acquired during birth from an infected mother is the likely cause here. A 1-week-old with bilateral mucopurulent eye discharge fits with bacterial conjunctivitis that is transmitted through the birth canal, most commonly from organisms such as Neisseria gonorrhoeae or Chlamydia trachomatis. If the mother has an STD, the infant is exposed during delivery and can develop conjunctival infection in the first days to weeks of life; this vertical transmission explains why both eyes are involved and why the discharge is mucopurulent. The other scenarios are less consistent: a plugged tear duct tends to cause tearing with mild discharge and is usually not a sudden bilateral mucopurulent presentation in a newborn; viral conjunctivitis often presents with more watery discharge and a different clinical course; while bacterial conjunctivitis is possible, linking the infection to a maternal STD best explains the neonatal etiology.