Learn how the skin bacteria Staphylococcus aureus increases the food allergy risk of babies with eczema, according to findings based on data from the LEAP study.
The recent landmark LEAP (Learning Early About Peanut Allergy) study continues to change the way that we think about childhood food allergies. First, the study established that feeding babies peanut-containing foods early and often can reduce their peanut allergy risk by up to 80%.
Now, new findings based on data from the LEAP study strongly suggest that Staphylococcus aureus (staph infection) puts babies with severe eczema at higher risk for a food allergy.
What is Staphylococcus aureus?
- Staphylococcus aureus (commonly called staph infection) is a common type of skin bacteria.
- S. aureus develops on the skin and in the nose.
- Although healthy people can develop a staph infection, it is most common in individuals with eczema, especially severe eczema.
- Babies with severe eczema are already at an increased risk for developing a food allergy.
- However, the new findings from the LEAP study data indicate that S. aureus further increases babies' risk of developing a food allergy if they have severe eczema.
S. Aureus, Eczema, and Food Allergy Risk: The LEAP Study's Data
The LEAP study examined young children at high risk for peanut allergy (children with egg allergy, severe eczema, or both).
- In the study, these children were directed to either consume peanut early and often starting in infancy, or avoid peanut, for 4 years.
- The children were monitored throughout the study period to see if they developed a peanut allergy.
- Then, the same children were monitored for another year in a follow-up study.
During the LEAP study, researchers assessed:
- Whether children had peanut and/or egg allergies
- Children’s levels of IgE antibodies that respond to peanut, egg, and milk
- Whether S. aureus was present on the skin and/or in the nose (using skin and nasal swabs)
- Severity levels of eczema, if it was present
This data was used to arrive at the new conclusions about the relationship between S. aureus and childhood food allergies.
Here’s what the data shows:
1. Eczema Severity, S. Aureus, and Food Allergy Development
Severity of eczema was associated with the presence of S. aureus. In other words, the children in the LEAP study with severe eczema were significantly more likely to have S. aureus.
However, children with any eczema (regardless of severity) who also developed a staph infection were more likely to develop a food allergy.
2. S. Aureus, Peanut Introduction, and Peanut Allergies
Even when children with S. aureus consume peanut early and often, starting in infancy, they remain at increased risk for developing a peanut allergy.
- Only 9 out of 312 children in the LEAP study who consumed peanut early and often still developed a peanut allergy. All but one of these 9 children “were colonized at least once with S. aureus.”
3. S. Aureus and IgE Antibodies
S. aureus increases the number of IgE antibodies to peanut, egg, and milk that children with severe eczema produce.
- When a child has a food allergy, their body mistakenly responds to certain foods that it thinks are harmful invaders. Their immune system produces IgE antibodies to fight allergenic food proteins that enter the body.
- An allergic reaction occurs when IgE antibodies come in contact with a specific allergenic food.
- So, high amounts of peanut-specific, egg-specific, or milk-specific IgE antibodies in a child’s body indicate that a child has an allergy to that food.
- Interestingly, the severity of eczema did not influence the amount of peanut- and egg-specific IgE antibodies produced by a child with S. aureus and any eczema.
- The study reports that “Skin S. aureus colonization at any time point was associated with increased levels of hen's egg white and peanut sIgE independent of eczema severity.”
4. S. Aureus and Egg Allergy Persistence
If young children with severe eczema and S. aureus bacteria had an egg allergy, they were more likely to retain their allergy at 5-6 years of age, compared to those who did not have the skin bacteria.
- Researchers identify this as a key finding because children commonly “outgrow” their egg allergy at a younger age.
5. Relationship Between Eczema, Food Allergies, and S. Aureus
The reasons why eczema increases food allergy risk still remain unknown, but the above findings suggest that S. aureus plays a role.
- Dr. Olympia Tsilochristou, the new study’s lead author, says: "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."
Key Takeaways from the Findings
- Young children with eczema are at higher risk for a food allergy if they have S. aureus.
- Young children with S. aureus remain at increased risk of developing a peanut allergy, even when they consume peanut early and often.
- Young children with S. aureus and severe eczema produce more IgE antibodies to peanut, egg and milk, a sign that they have allergies to these foods.
- Childhood egg allergies are more likely to last through 5-6 years of age if children have severe eczema and S. aureus.
- S. aureus may play a role in increasing the food allergy risk in children with eczema, but we don’t know for sure if this is the case.
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