Ear piercing altered the skin microbiome

Canadian scientists analyzed the skin microbiome in people in the area of ear piercing and found that this procedure significantly affects the diversity of microbial communities of the skin. As reported in Proceedings of the Royal Society B, bacteria characteristic of moist environments, including Staphylococcus epidermidis, became prevalent on the skin after the piercing.

Divergence of communities of coexisting bacterial species can be caused by changing environmental conditions, but stochastic (random) processes - the order and timing of migration, random extermination of populations - can also play a significant role in it. The processes of reassembly of human microbial communities after pathological changes have received increasing attention in the community of microbiologists and clinicians, as they can be used in the treatment of certain diseases. In particular, clinicians and scientists are interested in the skin microbiome.

The most common genera of bacteria that inhabit human skin are known to be Cutibacterium, which is found mainly in areas with high sebum activity, and Staphylococcus, which dominates moist areas. The skin's bacterial communities protect the skin from pathogenic bacteria, and shifts in its microbiome are associated with the development of atopic dermatitis, psoriasis, acne, and chronic wounds. These shifts can be caused by a variety of factors (use of cosmetics and topical creams, sun exposure, mineral bathing and relocation), but no one has yet studied how they are affected by piercings.

Rowan Barrett and colleagues from McGill University have for the first time investigated how ear piercing changes the local skin microbiome. To do this, the authors studied microbiome samples from the ear piercing site of 28 people 12 hours, one day, three days, one week and two weeks after piercing. By analyzing amplicon sequences, they found that earlobe piercing was associated with a significant increase in the diversity of variants of this sequence, that is, the diversity of microorganisms increased at the puncture site. Two weeks later, the scientists recorded a significant increase in beta diversity. They hypothesized that the puncture site would increase the number of bacteria suitable for the wetter environment created by exudation after skin damage.

Two weeks after the piercing, the researchers found the microbiome of the piercing to be dominated by Actinobacteria (Actinomycetota) and Firmicutes (Bacillota), followed by Proteobacteria (Pseudomonadota) with relatively few Bacteroidetes (Bacteroidetes). Actinobacteria were mainly represented by the families Propionibacteriaceae and Corynebacteriaceae, particularly the genera Cutibacterium and Corynebacterium. Firmicutes mainly included the genera Staphylococcus and Streptococcus. The major taxa of the piercing microbiome were Cutibacterium acnes and Staphylococcus epidermidis. The relative abundance of C. acnes significantly decreased and S. epidermidis significantly increased during the observation period.

These data will help to further explore in more detail how these changes may affect human health. For example, an imbalance between C. acnes and S. epidermidis is known to promote skin inflammation through cytokine production, while S. epidermidis is more likely to cause infection on central venous catheters and joint prostheses.