Features of the microbiota of the skin, small and large intestine in children with atopic dermatitis: relationships, diagnostic, approaches to correction

Atopic dermatitis (AD) is a widespread chronic, genetically determined, multifactorial dermatosis in children, the main factors of which are considered to be dysfunction of the skin barrier, changes in immune responses, as well as disruption of the skin microbiome and, probably, the microbiome of the small and large intestine. The mechanisms of the relationship between the microbiome of the skin and intestines in children with AD require further study. The role of small intestinal bacterial overgrowth (SIBO) in the course of atopic dermatitis in children and its effect on the effectiveness of therapy continues to be studied.

The aim of the study was to evaluate the incidence of SIBO in children with atopic dermatitis and the effectiveness of treatment of mild to moderate atopic dermatitis in children, as well as the state of the skin and intestinal microbiome, when a prebiotic and probiotic component is included in external therapy.

Research materials and methods: 82 children were examined, including 33 people with mild to moderate AD (main group), aged 8.0 [5.0 : 15.0] years, of whom 16 (48.5%) girls and 17 (51.5%) boys, as well as 49 practically healthy children in at the age of 9.0 [5.8 : 16.2] years, 27 (55.1%) girls and 22 (44.9%) boys. The determination of the hydrogen-induced (H₂-SIBO) and methanogenic variants of the course (CH₄-SIBO) in all patients with AD and children of the comparison group was performed using noninvasive methods: the hydrogen breathing test «Lactofan» («AMA», Russia) and the hydrogen-methane test «GastroCheckGastrolyzer» («Bedfont Scientific Ltd», Great Britain). A dynamic clinical, laboratory and functional examination of 19 children with atopic dermatitis in the subsiding stage of exacerbation, who used only a biotic complex (lactobacilli + fructooligosaccharides) as external therapy, was also conducted. The SCORAD index was evaluated, the microbiome was studied from the affected areas of the skin and in feces by PCR 16S sequencing, and the spectrum of short-chain fatty acids (acetic, propionic, butyric, and isoacids) by gas-liquid chromatography in feces. The statistical analysis was performed using the StatTech v program. 4.1.2 («Stattech», Russia), online platforms for Omics data analysis («Metware Cloud», China).

Results and conclusions: In almost all patients with AD (93.9%), SIBO was diagnosed using a hydrogen-methane breath test. In practically healthy children, SIBO of various types was detected in 28 (57.1%), the hydrogen-induced variant in 18 (36.7%) and the methanogenic variant of SIBO in 10 (20.4%) of the examined patients. In patients with AD, both the frequency of various types of SIBO and the frequency of the hydrogen-induced variant of SIBO were statistically significantly higher than in the comparison group (p<0.05). The methanogenic variant of SIBO was diagnosed in 21.2% of children with AD and in 20.4% of children in the comparison group, respectively (p>0.05).

In children with atopic dermatitis, there is a significant decrease in moisture and an increase in the pH of the skin, a deviation in the composition of the microbiome of the skin and intestines towards an increase in pathogenic and opportunistic microorganisms, and a decrease in the Shannon and Pielou biodiversity indices. AD therapy in children using external care products with a biotic complex allowed to achieve positive changes in functional parameters (humidity, pH) and the skin microbiome, and a distinctly positive clinical effect was obtained.

However, there was no significant improvement in the state of the intestinal microbiome, an increase in the Shannon and Pyelou indices in the intestinal microbiota, probably due to the lack of oral probiotics.

Aleksandr M. Shabalov has completed his PhD at the age of 30 years from Saint Petersburg State Pediatric Medical University, Ministry of Health of the Russian Federation, Saint Petersburg, Russia. He is the MD, Assistant Professor of the Department of Children's Diseases, Kirov Military Medical Academy, Saint Petersburg, Russia. He has over 120 publications that have been cited over 420 times, and his publication h-index is 9. He is a pediatrician and gastroenterologist interested in functional disorders of gastrointestinal tract, SIBO, GERD, pediatric allergy, obesity, MAFLD with 19 years of experience.