SAG and Alzheimer disease: The aims of this study were: (i) to compare the prevalence and types of SAg-encoding genes between S. aureus isolated from AD patients and from healthy controls, (ii) to make the same comparison within the AD group between different sample sites (nares, lesional skin, non-lesional skin), and (iii) to evaluate the frequency of SAg genes among S. aureus isolated from lesional AD skin.