A 54-year-old female with diabetes mellitus complains of increased facial pain, fevers, and chills. She developed an infection around her neck a few weeks ago. She thought it would go away; however, despite taking over the counter medications, the infection has now started to drain. She has been diabetic for 20 years and takes an oral hypoglycemic. Her diabetes is under good control. She denies any trauma, travel, and does not smoke. On physical exam, there is an area of infection at the base of her right neck that is draining a serosanguinous discharge. The surrounding area is red and indurated. There is no crepitus. A histological staining of the drainage shows gram-positive branching bacteria. There are black spots on the histology slide. What is the best treatment?