Gut microbiota of children with atopic dermatitis: Controlled study in the metropolitan region of São Paulo, Brazil.

Background: It is possible that imbalances in the composition of the gut microbiota or the relationship of the microbiota with the host may be implicated in the origin of allergy. Therefore, we studied the intestinal microbiota of children with atopic dermatitis (AD). Methods: Cross-sectional study with 81 children aged 5-11; 23 with AD and 58 controls. Surveys were conducted to obtain demographic, socioeconomic and neonatal data. Diagnosis of AD was made based on the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Eubacteria, Bacteroidetes, Firmicutes, B. fragilis, E. coli, Lactobacillus spp., S. aureus, E. faecalis, Salmonella spp., M. smithii, Bifidobacterium spp., C. difficile and C. perfringens were quantified using real-time PCR. Results: The analysis showed an association between presence of C. difficile (OR: 5.88; 95 % CI: 1.24; 27.98), greater abundance of bifidobacteria (OR: 11.09; 95 % CI: 2.14; 57.39) and a lower abundance of lactobacilli (OR: 0.07; 95 % CI: 0.01; 0.51) in the gut microbiota of children with AD. Counts of Eubacteria (0,05 x 10(3) and 8.49 x 10(3)), B. fragilis (0.72 x 10(9) and 4.5 x 10(9)), Lactobacillus spp. (0.02 x 10(8) and 0.38 x 10(8)), E. coli (0.13 x 10(9) and 1.52 x 10(9)) and M. smithii (0.02 x 10(8) and 0.31 x 10(8)) were lower in children with AD (P < 0.05). Conclusions: This study confirmed that children living in the metropolitan area of sao Paulo (Brazil) with AD have a different microbiota pattern with higher prevalence of C. difficile, lower abundance of Lactobacillus and greater abundance of bifidobacteria, regardless of socioeconomic status. (C) 2019 SEICAP. Published by Elsevier Espana, S.L.U. All rights reserved.