Pathogenic staphylococcus was obtained from the purulent wound of the patient. Its antibiotic sensitivity was determined to be as follows: penicillin growth inhibition zone – 8 mm; oxacillin – 9 mm, ampicillin – 10 mm, gentamicin – 22 mm, lincomycin – 11 mm. What antibiotic should be chosen for treatment in this case?