A 51-year-old man comes to the physician for a 1-week history of worsening redness and pain of his left arm. Temperature is 100 F. He works in construction. An image of the arm is shown. Which of the following is the next best step in pharmacologic therapy?
Amoxicillin
Cephalexin
Clindamycin
Gentamicin
Vancomycin
