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Summary of the symposium

My Little Microbes

A great deal of information is available on the development of microbiota in children. But where to start reading? This was the question that faced Pamela Browne of Vrije Universiteit, Amsterdam, when she began her doctoral studies. Her search led to the publication of a medical handbook, which gives a clear overview of the latest scientific insights into the development of the microbiota in infants and young children in sickness and health. Four co-authors spoke about their contribution to the book during a scientific symposium to mark its publication.

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Development of the Microbiota after Birth

Thanks to new molecular DNA techniques, we have learnt a lot about our microbiota and the role it plays in sickness and in health. However, many factors can influence the initial colonization of a baby’s gut and the further development of the intestinal microbiota. These include the duration of the pregnancy, delivery method, breast or formula feeding, environmental factors and medication (including antibiotics). If all goes well, we live in symbiosis with our microbiota, have a healthy metabolism and a well-developed immune system. But many things can go wrong during the child’s early years, leading to a delayed or abnormal development of the microbiota (dysbiosis) and possibly adverse effects on health in later life. Links have been found between the presence of a disturbed microbiota and diseases such as atopic eczema, asthma, allergies, diabetes, coeliac disease, gastroenteritis and inflammatory bowel disease. 



Perinatal Influences on Microbiota Development

The crucial time for microbiota development is from the perinatal period (just before and after birth) up to and including the first few years of a child’s life. Medical interventions such as exposure to antibiotics via the mother, a caesarean, admission to hospital and postnatal treatment with antibiotics have a huge effect on the intestinal microbiota, according to Anita Kozyrskyj, professor of Paediatrics at the University of Alberta in Canada. “Such interventions lead to a drop in the number of bifidobacteria and Bacteriodes species, together with a rise in the number of staphylococci, enterococci and clostridium species.” These findings are now confirmed by systematic reviews, Prof. Kozyrskyj added. In Canada, most births take place in hospital. As a result, nearly forty percent of the children are exposed to antibiotics in the womb. “The Bacteriodes level is still significantly low three months after birth if the babies were born by caesarean or exposed to antibiotics in utero. A striking increase in the number of clostridia and enterococci, due to antibiotic resistance, is also frequently observed. Babies born by emergency caesarean show a particularly marked abnormality in microbiota pattern.” 





Gut Microbes help Immune System Mature

Prof. Jenmalm discussed the immune system of children and the development of allergies in further detail. “The intestinal microbiota play an important role here. The immune system has to mature during the first year of life, and this is precisely the period when the intestinal microbiota is undergoing great changes,” she said. “The immune system needs certain stimuli if it is to mature properly. The intestinal microbiota represents a large, varied and continuous stimulus of this kind.” Prof. Jenmalm carried out a small exploratory study on children who became allergic and later also asthmatic, and found a low diversity of Bacteriodetes during the first few months of their life. “This low diversity during the first year of life probably slows the maturation of the system that provides the initial barrier to infection in the immune system,” she explained. This initial period is a suitable time for treatment to improve the development of the immune system, but in her opinion more research is needed before probiotics can be recommended to prevent the development of allergies.

Summary of symposium My Little Microbes_1381

Interested in reading more about the role of the microbiota in childhood? You can order the book: Microbiota in health and disease: from pregnancy to childhood here 



Vaginal Seeding for a Better Start

The speakers at the symposium displayed great interest in the use of vaginal seeding to correct the effect of caesarean delivery on the microbiota. This treatment involves smearing newborn babies with bacteria derived from the mother’s vaginal microbiota. It has so far been found to be most effective in restoring the skin and oral microbiota, and less so for the gut. “Vaginal microbiota on its own is probably not enough,” said Prof. Jenmalm. “We may need the mother’s intestinal microbiota too.” In coming years she will be carrying out further research on the effect of this treatment on the development of allergies. Hania Szajewska, professor of Paediatrics at the Medical University of Warsaw in Poland, is also fascinated by the idea of vaginal seeding. “The demand for this treatment is on the rise. This is probably the most natural way of boosting the intestinal microbiota after a caesarean, thus reducing the risk of medical complaints later on in life.”



The Microbiota and Auto-immune Diseases

In her presentation, Prof. Szajewska discussed the role of intestinal microbiota in the development of allergies and auto-immune diseases – in particular food allergies, type 1 diabetes and coeliac disease - in children. The incidence of these diseases is increasing in Europe. “There is a clear link between dysbiosis in young children and the development of allergies and auto-immune diseases. The observed decrease in Bacteriodes and increase in Clostridium may give rise to allergies. But this is always a correlation; no causal relationship can be established,” Prof. Szajewska stressed. A number of recent studies also indicate that the intestinal microbiota may play a role in the development of coeliac disease. “But just as in the case of the other diseases, it is not yet known whether the changes in the microbiota occur before the start of the disease. To sum up, this is a new, exciting field of research, but we’re not there yet, by a long way. This may also be said of the modulation of the microbiota by probiotics, prebiotics and synbiotics in order to raise tolerance and reduce the incidence of all kinds of allergies and inflammatory reactions.”



Probiotics and Allergies

Prof. Szajewska is often asked whether pre-, pro- and synbiotics really work and are suitable for use on patients. But scientific allergy associations such as WAO and EAACI do not yet give recommendations in this field, since they do not believe that probiotics currently have a role to play in the prevention or treatment of allergies. However, there is one exception: eczema. “Probiotics do most probably have a positive effect in preventing eczema, but the evidence for this is weak. Probiotics are effective as a group, but as soon as you start to study individual bacterial species you find that there is an improvement, but it is not statistically significant. L. rahmnosus (GG ) seems quite promising, but more research is needed. We still don’t really know which is the best probiotic to use, when you should start giving it and when you should stop.” The best advice she can offer at present is: “There is no magic bullet, but you should avoid caesareans if possible, breast feed for six months and try to use antibiotics as little as possible.” 



“There is a clear link between dysbiosis in young children and the development of allergies and auto-immune diseases.” – Prof. Hania Szajewska



Probiotics in Pediatric Gastro-enterology

Koen Huysentruyt, paediatric gastroenterologist at the University Hospital in Brussels, has a more practical approach. His presentation dealt with possible ways of stimulating the development of the intestinal microbiota in infants and young children. According to him, the probiotics most commonly used for this purpose are bifidobacteria (B. longum, B. breve, B. infantis), lactobacilli (L. casei, L rahmnosus (GG), L reuteri, L. plantarum) and the yeast Saccharomyces boulardii. It should be realized that not all probiotics have the same properties, Koen Huysentruyt stressed. A study of the gastro-intestinal survival of S. boulardii showed a marked drop in the number of cells of most products. The researchers also tested various probiotic food supplements and dairy products, and found that half of the products contained different species than those mentioned on the label. In fact, a third of the food supplements did not contain any living species at all. “That is not acceptable,” said Koen Huysentruyt. In response to this finding, the Probiotics and Prebiotics working group of the European Society of Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) issued a position paper stressing the need for stringent quality control of probiotic products sold as health aids. “We need to ensure that these products contain the active ingredients mentioned on the label, that there is no question of contamination and that they contain sufficient live bacterial cells up to the stated use-by date.”  


The ESPGHAN working group has also recommended which probiotics can best be used to treat acute gastroenteritis or acute diarrhoea. “While the evidence is still relatively weak, a distinct effect may be observed when L. rahmnosus GG and S. boulardii are given to supplement the standard treatment. The average duration of the diarrhoea is reduced by a day,” said Koen Huysentruyt. Administration of these two probiotics was also found to help children with antibiotic-associated diarrhoea (AAD). In babies with severe cramps (colic) L. rahmnosus GG did nothing to alleviate pain, but reduced crying by one hour on average per day. “So all participants in the study were happy after all,” Koen Huysentruyt commented. When asked whether he would prescribe probiotics for his patients, he replied that he did so sometimes – but more to reassure the parents than because of any objective benefit. “You need to make it very clear what you’re promising the parents. The extra hour’s sleep may not all be during the night but may be spread out throughout the day, ten minutes here, ten minutes there.” 






Summary of symposium My Little Microbes

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