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26-07-2011 | Immunology | Article

Low gut bacteria diversity in infancy increases allergy risk in children


Free abstract

MedWire News: Infants with low intestinal bacterial diversity have an increased risk for developing allergic rhinitis, allergic sensitization, or an elevated peripheral white blood cell count by the age of 6 years, suggest study findings.

The researchers found that there was no association between the diversity of gut bacteria and development of asthma or atopic dermatitis, however.

These results suggest "that an imbalance in the intestinal microbiome is influencing the development of allergic disease," say Hans Bisgaard (University of Copenhagen, Denmark) and colleagues.

Bisgaard and team assessed links between the diversity of intestinal microflora between the age of 1 and 12 months and subsequent development of a variety of atopic conditions by the age of 6 years in 411 children with high atopic risk who were participating in the Copenhagen Prospective Study on Asthma in Childhood.

Bacterial diversity was measured using a technique called 16S ribosomal RNA polymerase chain reaction and denaturing gradient gel electrophoresis (DGGE), as well as by conventional culturing.

The mean number of DGGE bands, indicating different bacterial species, found at 1 month and 12 months were 6.0 and 8.5, respectively. Using conventional culture, the mean number of species found in samples taken at the corresponding ages were 1.8 and 2.2.

The researchers found that early intestinal bacterial diversity, measured at 1 and 12 months of age, was significantly inversely associated with risk for allergic sensitization, allergic rhinitis, and having a high peripheral white blood cell count.

Infants with staphylococcaceae cultures at 1 month, but not 12 months, were significantly more likely to develop allergic sensitization at the age of 6 years. However, no other associations between bacterial species and atopic endpoints were recorded.

No links between low intestinal bacterial diversity and the development of asthma or atopic dermatitis were observed.

"This might align with the different genetics of sensitization, asthma, and eczema, as recently demonstrated by genomic analyses," write Bisgaard and co-authors in the Journal of Allergy and Clinical Immunology.

They summarize: "Although the causal direction of these associations between the bacterial diversity of the intestinal flora and the development of atopic disease cannot be determined, the findings support the general hypothesis that imbalance of the human microbiome in infancy modifies the development of lifestyle-associated disorders, such as atopic disease."

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Helen Albert

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