Finnaly some interesting facts on acne.

Case study: Propionibacterium acnes strain populations in the human skin microbiome associated with acne

Extract from link discussion:

Since P. acnes is the major skin commensal bacterium found in both acne and healthy skin, this strain-level analysis is important to help understand the role of P. acnes in acne pathogenesis and in skin health. We demonstrate a strong association between strains of RT4 and RT5 with acne and a strong association between strains of RT6 and healthy skin, each with unique genetic elements. Other P. acnes strains, including ribotypes 7, 8, 9 and 10, or interactions among different strains, may also contribute to the development of the disease. In addition, host factors, such as hormone level, sebum production and physical changes in the pilosebaceous unit, may also play a role in acne pathogenesis. Further studies aimed at identifying the specific functions of these strains, host factors in the development of acne, as well as the associations of microbiome characteristics with the sub-types of acne (comedonal, pustular, inflammatory, cystic, etc.) with larger cohort sizes may improve our understanding of the molecular mechanisms of the disease. These studies may also help to develop a targeted therapeutic approach to treat this extremely common and sometimes disfiguring skin disease.
So, basically they found that one strain of the P. Acne bacteria (RT6) only exists in healthy skin individuals, and that acne sufferers P. acne bacteria population had the RT4 and RT5 strains.

Of course, the more sebum production you have (ie. being on steroids ) the bacteria will thrive as they feed of it, but if you have the healthy strain you will unlikely suffer from acne.

Now, how do we get this bacteria on our skin? lol