aureus isolates from 71 AD patients identified 349 SAg-encoding genes, of which 22 (6.3%) were found in isolates from the nares (0.4 ± 0.6 genes per isolate), 99 (28.4%) from the non-lesional skin (3.7 ± 3.9 genes per isolate), and 228 (65.3%) from the lesional skin (4.2 ± 4.5 genes per isolate). This evidence concerns the gene SAG and Alzheimer disease.