Diversity of the Human Skin Microbiome in Early Life
In the first days after birth, an infant's skin barrier undergoes significant function changes. With these changes to the skin barrier come evolutions in an infant's skin microbiome; the skin barrier changes create environments favorable to some microbes and not favorable to others. Rapid surface colonization defines this period in an infant's development.
The authors of this study sought to learn more about the infant skin microbiome and how it evolves. The infant skin microbiome was compared to the adult skin microbiome to see if it is distinct in structure and function. How the infant skin microbiome evolves as the infant ages and how it varies across body sites were also studied.
The participants in this study were 31 healthy infants ranging in age from 3 weeks to 1 year. Infants were divided into 3 groups according to age:
- 1-3 months
- 4-6 months
- 7-12 months
- Samples from the infant skin microbiome were collected from 3 skin sites:
- Lower volar forearm
- Samples were also taken from 5 mothers to serve as the adult skin microbiome controls
- Mothers bathed themselves and their babies using JOHNSON'S® Head-to-Toe™ Baby Wash the night before they came to the testing lab
- Various methods were used to sequence and analyze the infant skin microbiome samples including:
- Bacterial tag-encoded FLX-titanium amplicon pyrosequencing approach (bTEFAP)
- Diversity and richness analyses
- Principal-component analysis
Data from the 3 skin sites were combined and the number of operational taxonomic units (OTUs) of bacteria did not change significantly with age. However, within each age group, differences were found across the skin sites for the number of OTUs.
- There were no differences across skin sites in 1- to-3-month-olds, but there were fewer OTUs on the arm compared with the buttock and forehead in 4- to-6-month-olds and compared with the buttock in 7- to-12-month-olds
- The relative abundance of the community of genera significantly increased with age
- The most abundant classes of bacteria present in all infant skin samples:
- In the 2 youngest age groups, Streptococci and Staphylococci accounted for up to 40% of the skin microbiome. The rest of the skin microbiome was made up of 23 other genera
- The low-predominance genera increased with age, while Streptococci and Staphylococci decreased significantly
- Across the 3 sites, the population evenness of colonies present in the infant skin microbiome increased significantly with age
The infant skin microbiome differs from that of an adult in which microbes are present and in what quantities. In addition, while the adult skin microbiome is mostly stable, the infant skin microbiome continues to evolve in the early years of life. This may have implications on an infant's future health, as this period of evolution offers a chance to nurture the skin microbiome. A healthy skin microbiome resists colonization of harmful microbes and may impact the development of overall skin immunity, and potentially, the systemic immune system.
1. Capone KA, Dowd SE, Stamatas GN, Nikolovski J. Diversity of the human skin microbiome early in life. J Invest Dermatol. 2011;131(10):2026-2032.