Staph infections are usually treated with cephalosporins, sulfa drugs, nafcillin or vancomycin, according to Mayo Clinic. A test to determine the type of staph bacteria is sometimes used to determine the type of bacteria and which antibiotic is most effective for the particular infection.
Serious staph infections are usually treated with vancomycin due to the fact that staph strains have become resistant to most traditional antibiotics, notes Mayo Clinic. This type of antibiotic must be given intravenously. However, some antibiotics used to treat staph infections can be administered orally. Only about 10 percent of staph infections respond to penicillin, as of 2015.