A 17-year-old male is brought to the emergency department after a motorcycle accident resulting in a deep, contaminated crush injury to his thigh. Twelve hours later, the area is markedly swollen with significant crepitus, and the patient complains of severe pain that seems disproportionate to the wound’s appearance. An exudate smear shows gram-positive bacilli but very few leukocytes. This presentation is highly suggestive of which diagnosis?