The human skin is home to countless microorganisms that we can't see. These microbes help define who we are. Our invisible passengers contribute to our health in numerous ways including educating our immune system, protecting us from pathogens, and mediating skin disorders. They are also known as the skin microbiome. In a new study, researchers investigated how the skin microbiome is transmitted between players in a contact sport, using roller derby as their model system.
The skin is the largest organ and an important barrier that regulates microbial entry into the human body. Despite the importance of the skin ecosystem to human health, we know very little about the forces that shape microbial structure and composition in the skin environment. The ways in which the skin microbiome is affected by external factors is a subject of renewed interest and so researchers hypothesized that contact sports could represent an ideal setting in which to study how human to human interactions influences microbial ecosystems. The researchers took their questions into the world of roller derby to explore how touching in a contact sport affects microbial transfer among athletes. DNA analysis revealed that bacterial communities predict team membership, with teammates sharing distinct microbial communities, and that when opposing teams competed in an hour-long bout their microbial communities became significantly more similar.
Differences among teams' unique skin microbiomes -- determined by pre- and post-game swabs taken from exposed upper arms -- were driven in part "by the presence of unique indicator taxa that are commonly associated with human skin, gut, mouth and respiratory tract." Brevibacterium, for example, was found to be the strongest indicator for the DC Roller Girls of Washington, D.C. Researchers found that microbial communities on the host team in Eugene, Oregon, more closely resembled surface samples taken from the local roller rink itself.
The mixing of bacterial communities during a bout, the researchers found, was likely the result of skin-to-skin contact. "Human to human contact is the most parsimonious interpretation for the significant changes in skin microbiome we observed," the researchers concluded. Scientists have long known that bacteria can spread among people due to contact. This study is the first to illustrate the promise of using contact sports to understand how human interactions can influence our microbiome.
Population growth is likely to increase the rate of person-to-person contact in expanding urban areas. Studying these skin ecosystems could have implications for health care, disease transmission and general understanding of urban environmental microbiology.