Which organism is primarily associated with inflammatory acne?

• A. Propionibacterium acnes
• B. Staphylococcus aureus
• C. Pseudomonas aeruginosa
• D. Haemophilus influenzae

Answer: (A)

Inflammatory acne is driven by Propionibacterium acnes colonizing the hair follicles and interacting with the skin’s sebaceous environment. When sebum production increases, follicles become clogged and create a lipid-rich haven for this bacterium. P. acnes metabolizes sebum and releases inflammatory byproducts, including fatty acids, which provoke an immune response and lead to red, swollen lesions. This specific association with the acne‑prone follicles makes it the primary organism involved.

The other organisms listed aren’t the main culprits in acne. Staphylococcus aureus can cause other skin infections like boils, but it’s not the typical driver of inflammatory acne. Pseudomonas aeruginosa is linked to infections such as hot tub folliculitis and opportunistic wounds, not standard acne. Haemophilus influenzae is a respiratory pathogen and not a common skin resident tied to acne.