Review Question - QID 216281

A 45-year-old man presents to the emergency department with shortness of breath. He had been shoveling snow in his driveway when he began experiencing chest tightness, dizziness, and difficulty breathing. His medical problems include asthma for which he uses inhaled budesonide and formoterol. He is also completing a course of ciprofloxacin for a urinary tract infection. His temperature is 98.6°F (37.0°C), blood pressure is 130/90 mmHg, pulse is 96/min, and respirations are 26/min. His symptoms improve after the administration of oxygen, albuterol, and systemic glucocorticoids. After discharge, another asthma medication is added to his regimen by his primary provider. Two days later, he returns to clinic with vomiting, headache, and insomnia. He has a witnessed seizure in the clinic waiting area. His fingerstick glucose is 102 mg/dL and his serum alanine aminotransferase and aspartate aminotransferase are 20 U/L and 30 U/L respectively. Which of the following is the mechanism of the most likely causative agent?