A food poisoning outbreak occurs 2 to 4 hours after consumption of contaminated custard-filled pastries. Staphylococcus aureus is implicated. The enterotoxin responsible acts as a superantigen and stimulates the vagus nerve. Which receptor on the enteric nervous system does staphylococcal enterotoxin primarily stimulate to cause the rapid vomiting?

• A Muscarinic M1 receptors on gastric parietal cells
• B Dopamine D2 receptors in the chemoreceptor trigger zone
• C 5-HT3 (serotonin) receptors on vagal afferent nerves in the gastrointestinal tract ✓
• D Histamine H1 receptors on gastric smooth muscle

Explanation

Staphylococcal enterotoxin stimulates 5-HT3 (serotonin) receptors on vagal afferent nerves in the gastrointestinal mucosa, triggering the vomiting reflex via the nucleus tractus solitarius. This explains the rapid onset of vomiting (2-6 hours). Although the enterotoxin is also a superantigen that causes systemic cytokine release, the emetic effect is mediated locally through serotonin receptors on vagal afferents, not through a direct central mechanism.

Reference: Murray, Rosenthal, and Pfaller Medical Microbiology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.