Staph can usually be treated with antibiotics, but over the decades, some strains of staph -- like MRSA -- have become resistant to antibiotics that once destroyed it. MRSA was first discovered in 1961. It's now resistant to methicillin, amoxicillin, penicillin, oxacillin, and many other common antibiotics.
While some antibiotics still work, MRSA is constantly adapting. Researchers developing new antibiotics are having a tough time keeping up.