The presence of pus is a sign of what kind of infection?

• A. Bacterial infection
• B. Viral infection
• C. Fungal infection
• D. No infection

Answer: (A)

Pus signals the body’s inflammatory response to bacteria. It’s a thick, often yellowish fluid made up of dead white blood cells, bacteria, and tissue debris, which typically appears when bacteria invade tissue and the immune system floods the area with neutrophils to fight the infection. This makes bacterial infections the best match for why pus occurs.

Viral infections usually don’t produce pus as a defining feature; they may cause redness, swelling, or vesicles but not the purulent discharge typical of bacteria. Fungal infections can cause itching, scaling, and crusting, but pus isn’t the hallmark finding. No infection wouldn’t present with pus either.