Low microbial diversity early in life preceded atopic eczema
Published Online December 8, 2011
The knowledge map of microbiology is being rewritten. The advent of powerful molecular methods has made it possible to assess the total gut microbiota unprejudiced. There is no need to decide what bacteria to analyze in advance any longer. The question is whether previous findings underlying the hygiene hypothesis still hold true. Maybe the increase of allergic disease in affluent countries is caused by a low diversity of the gut microbiota rather than a change in specific bacterial taxa?
In The Journal of Allergy and Clinical Immunology (JACI), Abrahamsson and colleagues present a study from Sweden, in which they have analyzed the microbial diversity and composition with barcoded 16S rRNA gene 454-pyrosequencing in stool samples at one week, one month and 12 months of age in 20 infants developing IgE-associated eczema and 20 infants without any allergic manifestations until two years of age.
Infants who developed atopic eczema had a lower diversity of the total microbiota and also the bacterial phyla Bacteriodetes and Protebacteria and the genus Bacteroides than infants without any allergic manifestations. Proteobacteria, comprising gram negative bacteria, were also more abundant at 12 months of age in infants without allergic manifestations.
The results support the hypothesis that low microbial diversity early in life is associated with increased risk for allergic disease, although the difference in diversity seems to be more important for certain bacteria. Before preventive measures can be taken, however, it remains to reveal which factors that influence the establishment of the gut microbiota in early childhood.
The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.