Staphylococcus epidermidis in human skin microbiome associated with acne: A cause of disease or defence?

Propionibacterium acne is a well known bacterium having major role in acne development. However, the role of other skin microbiome in acne development/prevention is still not clear. One of the major problems was associated with poorly understood acne-associated uncultured bacterial populations, influencing acne directly or indirectly. With this in mind, we sought to study the remaining bacterial populations associated with acne and tried to investigate the role of these acne-associated human skin microbiome in disease induction as well as in its prevention. In order to identify the un-explored microbial populations present in acne patients, human skin microbiome isolated from acne lesions were investigated via culturable as well as metagenomics approaches and then the quantitative analysis of two most abundant microbial populations, P. acne and Staphylococcus epidermidis was performed using 16S rRNA gene expression analysis. The populations of P. acne and S. epidermidis were increased in acne patients, as compared to control in a very specific pattern. To understand the overall relevance in terms of biological function, skin explant models were used, in which skin was infected with P. acne, Staphylococcus capitis and S. epidermidis along with possible combinations. Interestingly, we observed that S. epidermidis was involved in acne prevention and an induction of antimicrobial activity was also observed in S. epidermidis after strain improvement during gamma irradiation exposure. It was tempting to speculate that S. epidermidis, a part of the human skin microflora is having a role in acne prevention whereas P. acne and S. capitis are having role in disease progression.