Review Question - QID 210832

A 31-year-old G1P1 woman presents to the physician with fever, chills, and pain of her right breast in the past week. She recently gave birth to her first child and has been breastfeeding for the past 7 weeks. On physical exam, the patient has redness and swelling of her right breast that is warm to the touch and tender to light palpation. An image of her breast is shown in Figure A. On closer inspection, the physician notes a small fissure in the nipple with surrounding purulence. Which of the following pathogens is the most likely cause of her condition?