Background: Over the last few decades, several studies from different parts of the world have indicated an increasing prevalence of allergic diseases. This has been related to environmental factors, like changes of microbial pressure. Our previous studies have demonstrated differences in the intestinal microbiota between allergic and non-allergic children.
Aim: To test the hypothesis that the intestinal microbiota and IgE response are related, both in allergic and non-allergic 5-year-old Estonian children.
Methods: The study group comprised 19 allergic and 19 non-allergic 5-year-old children, selected from a larger group who had been followed from birth. The diagnosis of allergy was based on clinical examination of the children and on data obtained from the questionnaires. The faecal microbiota were quantified by seeding serial dilutions on nine different media for incubation in different environment. The composition of the gut microbiota was expressed both as absolute counts of the various species and their relative share among the total counts of identified microbiota.
Results: Bifidobacteria were less commonly detected in children with allergic diseases than in healthy children and clostridia comprised a higher proportion among their gut microbes. Children with specific IgE antibodies to defined allergens had higher counts of clostridia and the counts of clostridia correlated with the level of serum IgE, but only so in allergic children. In non-allergic children, the serum IgE levels showed a positive correlation with the counts of bacteroides.
Conclusion: The development of allergic diseases seems to be associated with the composition of the gut microbial ecosystem. High counts of potential pathogens, such as clostridia, are associated with clinical manifestations of allergy and IgE antibody formation.