UCSD-Colgate Skin microbiome project. human skin metagenome

The human skin microbiome has been suggested to play an essential role in maintaining health by contributing to innate defense of the skin. These observations have inspired speculation that the use of common skin washing techniques may be detrimental to the epidermal antibacterial defense system by altering the microbiome. In this study, several common skin cleansers were used to wash human forearms and the short-term affect on abundance of the antimicrobial peptide LL-37 and the abundance and diversity of bacterial DNA was measured. Despite small but significant decreases in the amount of LL-37 on the skin surface shortly after washing, no significant change in the bacterial community was detected. Furthermore, Group A Streptococcus did not survive better on the skin after washing. In contrast, the addition of antimicrobial compounds benzalkonium chloride or triclocarban to soap prior to washing decreased the growth of Group A Streptococcus applied after rinse. These results support prior studies that hand washing techniques in the health care setting are beneficial and should be continued. Additional research is necessary to better understand the effects of chronic washing and the potential impact of skin care products on the development of dysbiosis in some individuals.