The intestinal microflora in allergic Estonian and Swedish 2-year-old children

Background The prevalence of allergic diseases seems to have increased part icularly over the past 35-40 years. Furthermore, allergic disease is less c ommon among children in the formerly socialist countries of central and Eas tern Europe as compared with Western Europe, It has been suggested that a r educed microbial stimulation during infancy and early childhood would resul t in a slower postnatal maturation of the immune system and development of an optimal balance between TH1- and TH2-like immunity. Aims To test the hypothesis that allergic disease among children may be ass ociated with differences in their intestinal microflora in two countries wi th a low (Estonia) and a high (Sweden) prevalence of allergy. it; Methods From a prospective study of the development of allergy in relation to environmental factors, 29 Estonian and 33 Swedish 2-year-old children we re selected. They were either nonallergic (n = 36) or had a confirmed diagn osis of allergy (n = 27) as verified by typical history and at least one po sitive skin prick test to egg or cow's milk. Weighed samples of faeces were serially diluted (10(-2)-10(-9)) and frown under amaerobic conditions. The counts of the various genera and species were calculated for each child. I n addition, the relative amounts of the particular microbes were expressed as a proportion of the total count. Results The allergic children in Estonia and Sweden were less often coloniz ed with lactobacilli (P < 0.01), as compared with the nonallergic children in the two countries. in contrast, the allergic children harboured higher c ounts of aerobic micro-organisms (P < 0.05), particularly coliforms (P < 0. 01) and Staphylococcus auereus (P < 0.05). The proportions of aerobic bacte ria of the intestinal flora were also higher in the allergic children (P < 0.05), while the opposite was true for anaerobes (P < 0.05). Similarly, in the allergic children the proportions of coliforms were higher (P < 0.05) a nd bacteroides lower (P < 0.05) than in the nonallergic children. Conclusions Differences in the indigenous intestinal flora might affect the development and priming of the immune system in early childhood, similar t o what has been shown in rodents. The role of intestinal microflora in rela tion to the development of infant immunity and the possible consequences fo r allergic diseases later in life requires further study, particularly as i t would be readily available for intervention as a means for primary preven tion of allergy by the administration of probiotic bacteria.