This study will be conducted as three experiments in accordance with the three aims of the study. Participants will consent to all three of the study experiments separately, as each experiment will have a different consent form. While individual subjects are able to participate in all three sub-studies if they are eligible for all three, there is no requirement for subjects to participate in more than one of the sub-studies. A total of 10 subjects will be enrolled in Experiments 1 and 2, and approximately 14 subjects will be enrolled in Experiment 3. Given that only approximately 75-80% of AD patients are colonized by S. aureus, we expect to screen closer to 18-20 subjects to fulfill the inclusion criteria. Subjects that withdraw from the study will be replaced.