Which finding most strongly suggests a bacterial conjunctivitis when evaluating an ocular infection?

• A. Purulent discharge
• B. Watery discharge
• C. Itchy eyes
• D. Clear, watery discharge

Answer: (A)

The key idea is that the type of discharge helps tell which type of conjunctivitis is most likely. Bacterial infections produce purulent discharge—that thick, opaque pus that often crusts on the lashes and can glue the lids shut. This pus comes from neutrophils and bacteria filling the conjunctival space, which is why purulent discharge is the strongest clue for a bacterial cause. In contrast, viral and many allergic conjunctivitides more often have watery or mucous discharge, with viral cases sometimes accompanying cold-like symptoms and allergies presenting with itching. Clear, watery discharge is the least specific and can occur with irritation or non-bacterial causes. So, the presence of purulent discharge most strongly points toward a bacterial conjunctivitis, guiding the clinician toward appropriate management.