An otherwise healthy 15-year-old boy sustains a deep puncture wound in his left heel while playing in a junkyard. Four days later, his father brings him to the emergency department because the boy has become lethargic and has developed shaking chills. He refuses to bear weight on his left foot. The patient's temperature is 39.7° C (103.4° F). Physical examination shows a warm swollen, and extremely tender area around the puncture wound. A specimen through uninfected tissue is obtained via percutaneous needle biopsy. A Gram stain of this sample is most likely to show which of the following?