Staphylococcus aureus (S. aureus) is present in the skin of patients with AD who frequently suffer from S. aureus superinfections, and it has therefore been suggested that sensitization occurs via the skin.17 By contrast, E. coli and other bacteria (eg, Haemophilus influenza) which have been reported as sources for IgE‐reactive antigens3, 4, 15 can be found mainly in the gut and in the respiratory tract, suggesting that other routes and mechanisms of allergic sensitization may be important. This evidence concerns the gene IGHE and Alzheimer disease.