This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Staph.aureus causes vomiting in 6-8 hours. The mechanism of action is: 
Select and explain. 
A. Stimulation of cAMP, B. Vagal stimulation, C. Stimulation of cGMP, D. Acts through ganglioside GM receptor
B: Vagal stimulation
Answer: B: Vagal stimulation 
Explanation: From Harrison:
“Staph. food poisoning result from heat stable preformed enterotoxin. Due to preformed nature, incubation period is short. Toxin stimulates the vagus nerve and vomiting centre of brain. It also appears to stimulate intestinal persistaltic activity”.