A 10 year old girl was bitten on the leg by a neighborhood dog and received several stitches 5 days ago. This morning she complained of increasing pain, and her mother noticed that the area around the stitches as red and warm to the touch. Her mother brought her to the pediatrician’s office where she is diagnosed with a wound infection and prescribed a 14-day course of an antibiotic she has taken in the past. Hours after beginning her course of antibiotics, the girl develops wheezing and hives. What is the most likely cause of her new symptoms? What cellular and molecular mechanisms are responsible for these symptoms?