Eczema + Staphylococcus Aureus = increased risk of food allergy?
Staphylococcus aureus infections could be related to a greater risk of food allergies in young children with severe eczema, according to an international study that opens the way to the development of new approaches to prevent food allergies.
Staphylococcus aureus is a bacterium that is naturally present in the nose and skin of healthy people but is more abundant in children with eczema, especially when it is severe. This skin disorder is also a risk factor for developing food allergies. Thus, it could be easily imagined that the link between Staphylococcus aureus and food allergies in people with eczema is related to the severity of this disorder.
This hypothesis was tested by a team of researchers using data collected during the LEAP* study which monitored 640 children who were identified as high risk for peanut allergy (based on an existing egg allergy or severe eczema, or both) from early childhood to the age of 5. The results, published in 2015, had shown that preventing peanut allergy could be achieved, paradoxically, by introducing peanut to infants who are at high-risk for developing this allergy.
S. aureus, known culprit?
In this new part of the LEAP study, the analysis of the nose and skin microbiota of the children participating in the study showed that the more significant the Staphylococcus aureus colonization was, the more severe the eczema was and the more it worsened over time. The combination of these two disorders (Staphylococcus aureus infection + eczema), regardless of severity, is often associated with an increased production of molecules** as part of the allergic reaction to peanuts, chicken egg white and milk. While it generally wanes with age, egg allergy persists in about 40% of children under study; and peanut allergy appears even in children who were preventively exposed from a very young age. The presence of Staphylococcus aureus in the nose or skin could thus lead to an allergic reaction to some diseases.
Towards a new potential therapeutic avenue
According to the researchers, S. aureus could prevent the development of a natural tolerance to eggs and peanuts, which would thus trigger the allergy. They thus suggested that eradicating S. aureus in children with eczema could prevent food allergies; and argue that further work should be carried out to elucidate the role of this bacterium in the development of these two disorders.
*Learning Early About Peanut Allergy
**IgE : immunoglobulin E is a molecule secreted by the body during an allergic reaction
Olympia Tsilochristou, du Toit G, Sayer PH et al. Association of Staphylococcus aureus colonization with food allergy occurs independently of eczema severity. J Allergy Clin Immunol, 2019; doi.org/10.1016/j.jaci.2019.04.025