IGHE and Alzheimer disease: IgE sensitization to bacterial antigens, particularly from S. aureus, has been shown to be clinically relevant in respiratory allergy and AD.3, 5, 14 Sensitization to Gram‐negative bacteria (eg, H. influenzae) may also have protective activity,2, 4, 46 but the clinical relevance of IgE sensitization to E. coli has not been investigated so far.