Usually Benign Bact. Bacteria, e.g. Staphylococcus aureus, grow center out, are frequently present skin & respiratory tract, especially nose. Mrsa merely means resistant multiple abs. Control of bacteria, as all, a function of immune system. Sa most commonly a commensal bacteria, but reality not good for marketing fear. Dietary choices, activities, emotions, any internal control affecting staph & immune sys can change.
Staph aureus. This is a bacteria which is round and surrounded by a cell wall. It buds off the cell wall and makes new cell wall for itself, which is one of the avenues allowing attack by antibiotics.