S. aureus increases risk of food allergy in children with severe eczema

LONDON: Infection with Staphylococcus aureus (SA) bacterium can lead to food sensitization, food allergy, and can impair tolerance to foods in children with severe eczema, according to a recent study. SA is a bacterium that can be found in the nose and the skin of healthy individuals but is more common in sufferers of eczema, especially severe eczema.

The team of researchers from King's College London found that young children with severe eczema who are infected with SA produce more IgE against peanut, egg, and milk indicating they have a food allergy to each of these. These children were also more likely to have their egg allergy persist at the age of 5 or 6 years in comparison to children that did not have SA present.

Results of the study, published in the Journal of Allergy and Clinical Immunology, could be an important consideration in future interventions aimed at inducing and maintaining tolerance to food allergens in eczematous infants.

Olympia Tsilochristou and colleagues conducted the study to investigate the association of S aureus colonization with specific IgE (sIgE) production to common food allergens and allergies in early childhood independent of eczema severity. They also determined the association of S aureus colonization with eczema severity and persistence.

Food allergy is an abnormal response of the immune system against a harmless substance (such as eggs or peanuts) which it considers as an intruder. This is accompanied by the release of a molecule or else antibody known as Immunoglobin E (IgE). When IgE encounters the intruder on the skin or within the body it releases chemicals, such as histamine that cause the allergic reaction. Allergic reactions to food can cause a variety of symptoms including skin features such as hives, itching, flushing or eczema flares or shortness of breath and wheezing, or gastrointestinal complaints such as vomiting, abdominal pain, or heartburn.

Young children with moderate to severe eczema should be tested for food allergies if they have had one of the reactions noted above to food that occurred shortly after eating it. Testing is also recommended if their eczema has not improved with standard medical care.

"We do not know yet the exact mechanisms that lead from eczema to food allergy, however, our results suggest that the bacteria Staphylococcus aureus could be an important factor contributing to this outcome," said Tsilochristou.

These results build on the earlier ones from the Learning Early About Peanut Allergy (LEAP) study which demonstrated that infants who were at a high risk of developing peanut allergy but consumed a peanut? containing snack throughout the study were prevented from later developing a peanut allergy.

In this current study, scientists found that children with SA on their skin and/or nose were more likely to develop peanut allergy despite them being fed with peanut from early ages as part of the LEAP study protocol.

"This could be an important consideration in future interventions aimed at inducing and maintaining tolerance to food allergens in eczematous infants," concluded the authors.

For detailed study log on to https://doi.org/10.1016/j.jaci.2019.04.025