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.

Cow’s milk allergy (CMA) is an increasingly common problem among children and adults that requires the use of appropriate diagnostics to eliminate allergic reactions and prevent unnec-essary dietary regimes. The current diagnostics methods are imperfect hence new, more effective methods are still being sought. Component-resolved diagnostics (CRD) is one of them. CRD assesses sensitivity to individual allergen molecules using purified native or recombinant allergens. The present paper reviews the role of CRD in diagnosing CMA, as well as the benefits and limitations of its use, especially in predicting allergy development or acquiring immunotolerance. It examines the possibility of replacing the current gold diagnostic standard with component tests directed against specific milk proteins. In addition, CRD could be helpful in the evaluation of prognosis. However, CRD allows for improvement in clinical management, particularly of polysensitized subjects, there is still no cogent evidence that it offers more efficient CMA diagnostics than existing tests.

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