Bacteria on children’s skin was similar to their mothers’ and affected by factors that included method of delivery and breastfeeding in a study of 154 children aged 10 years and younger.
Understanding the wrote Ting Zhu of Fudan University, Shanghai, China, and colleagues.
In a study published in the Journal of Investigative Dermatology, the researchers compared the skin microbiota of the 158 children aged 1-10 years and 50 mothers using 16S rRNA gene amplicon sequencing after collecting study samples from three skin areas: face, calf, and ventral forearm. The samples were pooled into 36 groups based on age, gender, and skin site.
“We observed significant differences in alpha diversity and the most prevalent taxa and identified factors that contributed to variation at each site,” the authors reported.
Overall, the “alpha diversity” – a measure of microbial diversity used in microbiome studies – of the skin microbiome increased with age, with the highest alpha diversity seen in the 10-year-olds (n = 28), notably on the face, but differences in alpha diversity between skin sites were seen only in the 1-year-olds (n = 26). Overall, the most commonly identified bacterial phyla at all skin sites in children were Proteobacteria (42%), Firmicutes (25%), Actinobacteria (13%), and Bacteroidetes (11%). In the three sites, the genera with high relative abundance (over 3%) included Streptococcus (13%), Enhydrobacter (6%), and Propionibacterium (5%). Of these, Streptococcus and Granulicatella showed negative linear correlations with age.
The researchers found significant differences between the bacterial communities of 10-year-olds delivered by Cesarean section and those delivered vaginally, particularly in the facial samples; however the difference wasn’t observed among face samples taken from 1-year-olds, according to the authors. They found significant variation in bacteria in calf samples based on whether the children were fed breast milk, formula, or a combination.
When the researchers examined the correlations between mother/child pairs, they found that the relative abundance of most bacteria in the children were more similar to their mothers than to unrelated adults, and they found the strongest correlations for the genera Deinococcus, Microbacterium, Chryseobacterium, Klebsiella, and Enhydrobacter. The relationships between the bacterial communities of mothers and children may be influenced by the shared living environment, topical products, and daily diet, they noted.
The study findings were limited by not controlling for certain variables, including daily diet, choice of topical products, bathing habits, and daily variation in environmental factors, the researchers wrote. However, the results show “that the skin microbiome is strongly affected by the surrounding microenvironment and that the alpha diversity of the skin microbiome increases during childhood,” they concluded.
The study was fully funded by Johnson & Johnson International, and several coauthors are employees of that company. Lead author Ms. Zhu had no financial conflicts to disclose.
SOURCE: Zhu T et al. J Invest Dermatol. 2019 August 13. doi: 10.1016/j.jid.2019.05.018.