Supplementary Material for: Cheek Microbial Communities Vary in Young Children with Atopic Dermatitis in China

<b><i>Background:</i></b> Atopic dermatitis (AD) is a chronic, recurrent skin condition with recently increased incidence in younger children. AD development has been correlated with the skin microbiome, and <i>Staphylococcus aureus</i> enrichment causes significant increases in skin lesions. <b><i>Objective:</i></b> Our objectives were to compare the microbial diversity of the cheek skin of children with or without AD aged 0–1 years in China, and to determine whether 4 types of skin-isolated bacteria could inhibit <i>S. aureus</i> in vitro. <b><i>Methods:</i></b> The skin microbial samples of cheek skin of children were sequenced by 16S rRNA V1-V2 region. Four skin isolated bacterial fermentation supernatants were tested for effects on <i>S. aureus</i> growth, membrane formation, and induction of cytokine secretion from HaCaT cells. <b><i>Results:</i></b> Bacterial diversity decreased significantly in skin with severe AD compared to healthy skin (<i>p</i> &lt; 0.01). Seven phyla had content &gt;1%, 4 of which differed in AD (<i>p</i> &lt; 0.05). 38 genera had content &gt;1%, 15 differed (<i>p</i> &lt; 0.05). Differences in 8 species were observed (<i>p</i> &lt; 0.05). In vitro antibacterial and cellular experiments showed that <i>S. aureus</i> growth, biofilm formation, and induction of interleukin (IL)-1α and IL-6 secretion from HaCaT cells were significantly inhibited by <i>Klebsiella oxytoca</i>, <i>Kocuria rhizophila</i>, and <i>Staphylococcus epidermidis</i> culture supernatants (<i>p</i> &lt; 0.05). <b><i>Conclusion:</i></b> Skin microbiome changes in children varied with age and with AD. There were complex interactions between skin isolated bacteria and <i>S. aureus</i> which could inhibit <i>S. aureus</i> growth and biofilm formation in vitro, suggesting that these microorganisms could be used in AD treatment.