Hello welcome to health care magic thanks for your query Cellulitis is deeper infection of skin and underlying tissues..If left untreated it causes life threatening problem.. MRSA means methicillin resistant staphylococcus aureus..Staph aureus has become resistant to methicillin.. Yes MRSA can cause cellulitis.. Cellulitis occurs through minor abrasions or cuts in the skin,,then through that bacteria can get access into our body.. Prompt diagnosis is required and go for culture and antibiotic sensitivity.. If the result shows MRSA then your brother should take clindamycin or vancomycin or linezolid,,depending upon the report of antibiotic sensitivity.. Prevention : in order to prevent cellulitis maintain hygiene,,cleaning of the wound properly if any injury occurs,,regular removal of nails,, Consult surgeon for more suggestions and treatment. Hope you understand my answer Thank you Dr.siddartha