Which organism is the most common cause of conjunctivitis in children?

• A. Moraxella catarrhalis
• B. Streptococcus pneumoniae
• C. Haemophilus influenzae
• D. Staphylococcus aureus

Answer: (C)

In children, bacterial conjunctivitis is most often caused by Haemophilus influenzae. Non-typeable strains of this organism commonly colonize the nasopharynx and can spread to the conjunctiva through hand-to-eye contact, especially in settings with close contact and young ages. These bacteria are known for producing a mucopurulent discharge and eyelid matting, which fits the typical clinical picture of acute conjunctivitis in kids. While other bacteria such as Moraxella catarrhalis, Streptococcus pneumoniae, and Staphylococcus aureus can cause conjunctivitis, Haemophilus influenzae remains the most frequent culprit in pediatric cases, making it the best answer. The child’s age and frequent concurrent upper respiratory infections also align with Haemophilus being a common pediatric pathogen responsible for conjunctivitis.