*Article* **A Combined Analysis of Gut and Skin Microbiota in Infants with Food Allergy and Atopic Dermatitis: A Pilot Study**

**Ewa Ło´s-Rycharska 1,\*, Marcin Goł˛ebiewski 2,3,\*, Marcin Sikora <sup>3</sup> , Tomasz Grzybowski <sup>4</sup> , Marta Gorzkiewicz <sup>4</sup> , Maria Popielarz <sup>1</sup> , Julia Gawryjołek <sup>1</sup> and Aneta Krogulska <sup>1</sup>**


**Abstract:** The gut microbiota in patients with food allergy, and the skin microbiota in atopic dermatitis patients differ from those of healthy people. We hypothesize that relationships may exist between gut and skin microbiota in patients with allergies. The aim of this study was to determine the possible relationship between gut and skin microbiota in patients with allergies, hence simultaneous analysis of the two compartments of microbiota was performed in infants with and without allergic symptoms. Fifty-nine infants with food allergy and/or atopic dermatitis and 28 healthy children were enrolled in the study. The skin and gut microbiota were evaluated using 16S rRNA gene amplicon sequencing. No significant differences in the α-diversity of dermal or fecal microbiota were observed between allergic and non-allergic infants; however, a significant relationship was found between bacterial community structure and allergy phenotypes, especially in the fecal samples. Certain clinical conditions were associated with characteristic bacterial taxa in the skin and gut microbiota. Positive correlations were found between skin and fecal samples in the abundance of *Gemella* among allergic infants, and *Lactobacillus* and *Bacteroides* among healthy infants. Although infants with allergies and healthy infants demonstrate microbiota with similar α-diversity, some differences in β-diversity and bacterial species abundance can be seen, which may depend on the phenotype of the allergy. For some organisms, their abundance in skin and feces samples may be correlated, and these correlations might serve as indicators of the host's allergic state.

**Keywords:** atopic dermatitis; dysbiosis; food allergy; gut; infants; microbiota; skin; 16S rRNA sequencing
