Sounds a bit like OCD to me.You are never going to be in danger of contracting anything to nasty out in public and if you stay inside all the time then you aren't living.Try and just wipe and disinfect the areas in your house that require that like the kitchen sink,bench and wet areas and don't worry to much about the rest of the house.
MRSA is methicillin resistant staphylococcus serous ...a serious (sometimes fatal) staph infectiom that is resistant to some antibiotics. if you would like more info just google MRSA
Oops..made a typo.. It's staphylococcus aerous