How does Propionibacterium acnes contribute to the development of acne in humans?

• A. By inhibiting the growth of other skin bacteria, leading to fungal infections
• B. By directly destroying skin cells through toxin production
• C. By increasing melanin production, resulting in dark spots on the skin
• D. By producing enzymes and inflammatory compounds that stimulate an immune response in blocked hair follicles

Answer: (D)

Verified step by step guidance

1. Understand that Propionibacterium acnes (now called Cutibacterium acnes) is a bacterium commonly found on human skin, especially in sebaceous (oil-rich) areas.
2. Recognize that acne develops when hair follicles become blocked with sebum and dead skin cells, creating an anaerobic environment favorable for C. acnes growth.
3. Know that C. acnes produces enzymes such as lipases that break down sebum triglycerides into free fatty acids, which can irritate the follicle lining.
4. Learn that C. acnes also releases inflammatory compounds that trigger the body's immune response, leading to inflammation and the characteristic redness and swelling of acne lesions.
5. Conclude that the contribution of C. acnes to acne is primarily through its enzymatic activity and stimulation of inflammation in blocked hair follicles, rather than by killing other bacteria, destroying skin cells directly, or affecting melanin production.