Day 1 - On the morning of Day 1, the gauze will be removed from participants' forearms, and 10 µL PBS containing 104 CFU of avirulent Streptococcus pyogenes (strain NZ131 M49) will be applied to the center of each of the squares previously drawn on participants' forearms. The bacteria will be spread within each square to evenly coat the surface of the skin within the square. The bacteria will then be allowed to air dry. Once dry, skin swabs will be rubbed over two of the squares on each forearm to collect a sample of the bacteria on the forearm at that location. After swabbing, these areas will be immediately disinfected with 70% alcohol. The forearms will then be wrapped again in gauze. One hour later, the gauze will be removed, and two more squares on each forearm will be swabbed for bacteria. These squares will then be disinfected with 70% alcohol, and gauze reapplied to the forearms. One hour later (two hours post-washing), the gauze will be removed, and the remaining two squares on each forearm will be swabbed for bacteria. Both forearms will then be washed with 70% ethanol and rinsed with water to remove any remaining bacteria. This will conclude the study-related procedures for Day 1. Participants are then free to shower, sunbathe, exercise and apply any creams or lotions to their forearms until the following week.