Propionibacterium acnes is a relatively slow growing, (typically) obligate anaerobe gram positive bacterium that is linked to the skin condition acne. The genome of the bacterium has been sequenced and a study of the bacterium genome has shown several genes that can generate enzymes for degrading skin and proteins that may be immunogenic (activate the immune system).

This bacteria is largely commensual and thus present on most people's skin; and lives on fatty acids in the sebaceous glands on sebum secreted by pores. It may also be found throughout the gastrointestinal tract in humans and many other animals. It is named after its ability to generate propionic acid.

Role in disease

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When a pore is blocked this anerobic bacteria overgrows and secretes chemicals that break down the wall of the pore, spilling bacteria such as Staphylococcus aureus into the skin, forming an acne lesion (folliculitis).

It has also been found in corneal ulcers, and on very few occasions damaging heart valves leading to endocarditis, and infections of joints (septic arthritis) have been reported.

Antibiotic sensitivity

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P. acnes can be killed by benzoyl peroxide, tetracycline group and other antibiotics, many antibacterial preparations and phototherapy. Unfortunately, tetracycline-resistant P. acnes is now quite common.

References

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• New Scientist news
• Propionibacteria (Kenyon College)

Actinobacteria

Propionibacterium acnes | 痤瘡丙酸桿菌