MRSA is a type of staphylococcal bacteria that has developed resistance to a number of widely used antibiotics. Staphylococcal (staph) bacteria are relatively common.About 1 in 3 people carry staph bacteria harmlessly on their skin, usually inside their nose and on the surface of their armpits, groin and buttocks.RSA is a type of staphylococcal bacteria that has developed resistance to a number of widely used antibiotics. Staphylococcal (staph) bacteria are relatively common.