Hi, I appreciate your concern about your son. Most commonly MRSA (Methicillin Resistant Staphylococcus aureus) infections are skin infections. MRSA is a kind of bacteria which resistant to certain antibiotics like Methicillin, Amoxicillin, Oxacillin etc. You can prevent this from happening again by some simple measures like avoiding the sharing of personal fomites (like comforters, towels, blades etc), making him wash his hands frequently with an antibacterial hand sanitizer and particularly take care of any minor injuries like cuts or other small wounds by keeping them sterile and covered, last but not the least maintaining a proper personal hygiene as you are already doing. Take Care!