is an antibiotic that belongs into the Penicillin group of drugs. It is used to fight a number of different infections caused by bacteria. In the US it is widely used to treat penicillin-resistant Staphylococcus aureus ("Staph"). However, with the introduction and widespread use of oxacillin, antibiotic resistant strains called "oxacillin-resistant Staphylococcus aureus (ORSA)" have become increasingly prevalent worldwide. Please also refer to MRSA.