S aureus in Children With Eczema May Play a Role in Development of Food Allergies

Young children with severe eczema who are infected with Staphylococcus aureus may be at a higher risk of developing a food allergy, investigators at King’s College London found in a new study.

Published in the Journal of Allergy and Clinical Immunology, the study sought to investigate the association of S aureus colonization with specific Immunoglobulin E (sIgE) production with common food allergens and allergies in early childhood independent of eczema severity.

“It is well established that patients with eczema are frequently affected by colonization of their skin (and their nose) with Staphylococcus aureus,” Olympia Tsilochristou, MD, a physician at King’s College London and the first author on the study, told Contagion®. “The authors, therefore, set [out] to investigate [whether] patients with eczema are more prone to develop food sensitization/allergy if they are colonized with this bacterium.”

Investigators collected nasal and skin swabs from young children with severe eczema enrolled in the Learning Early About Peanut Allergy (LEAP) and LEAP-On (12-month extension of the LEAP study: Persistence of Oral Tolerance to Peanut) studies at baseline and at 12, 30, and 60 months of age, and cultured them for S aureus. Sensitization was identified via measuring sIgE levels, peanut allergies were identified primarily via oral food challenge, and persistent egg allergies were identified primarily via skin prick tests.

A total of 48.8% of the 640 participants had some form of S aureus colonization (32.2% skin and 32.3% nasal) on at least 1 LEAP study visit, though most of the children had positive test results only once. Participants between 4 and 11 months of age recorded the greatest rates of colonization (18% for skin and 15% for nose). S aureus colonization and concurrent eczema severity (measured via the SCORAD index) were significantly associated across all study time points.

Participants who has S aureus isolated from their skin also had higher levels of IgE antibodies to hen’s egg and peanuts than those who never had S aureus during approximately a 4-year follow-up. Children with S aureus present on their skin or in their noses were 1.57 (95% CI, 1.02-2.42; P = .042) times more likely to have their egg allergies persist at age 5 or 6 years compared with children who were not colonized with the bacterium.

“This is significant as most children with [an] egg allergy usually outgrow this at an earlier age,” Tsilochristou said. “[The] authors also reported that the children that had S aureus were more likely to develop [a] peanut allergy despite them being fed with peanut from early ages as part of the LEAP study protocol. This was particularly interesting as it suggests that S aureus infection may have potentiated an accelerated form of peanut allergy development and/or inhibited tolerance mechanisms through peanut consumption.”

Of note, Tsilochristou pointed out, was that the results were independent of eczema severity.

The study results indicate that clinicians should consider S aureus as an additional risk factor in the development of food allergies, and also as a potential environmental factor when considering future interventions in inducing or maintaining tolerance to food allergens.

According to Tsilochristou, future studies may focus on advanced techniques and interventional methods of eradicating S aureus in early infancy.