1. A pastry chef cut his finger while slicing a cake. After a week, the site of the injury is warm, red, and swollen, and begins draining pus. While preparing some cream pies, he contaminates the custard with drainage from the lesion. The pies were eaten several days later by patrons of the restaurant. Within 4 hours they developed diarrhea and vomiting with no fever. Which of the following organisms would be most likely to cause these symptoms?