A 46-year-old woman underwent fine-needle aspiration of her left breast. Within a week, she developed erythema and swelling at the biopsy site. Despite treatment with oral antibiotics and 5 surgical debridements, her wounds continued to expand, and she developed fever and leukocytosis (peak white blood cell count [WBC], 74 000/μL with 12% bands) as well as hypotension, hyponatremia, and acute renal failure. (To convert white blood cells to number of cells ×109/L, multiply by 0.001.) She also developed new erythema at a catheter insertion site in her right arm. This wound was debrided, yielding negative cultures.