A 15-year-old boy is brought by his mother to the Emergency Department due to nausea, multiple episodes of vomiting previously ingested food, and three loose bowel movements. His mother notes that the boy reheated the leftover rice stored in the refrigerator the night before. Physical examination reveals a tired child who is afebrile with dry mucous membranes. He has pink palpebral conjunctivae, clear breath sounds, a soft abdomen with mild tenderness at the epigastric area, and full pulses. Which of the following is the most likely causative agent?a. Bacillus cereus
b. Campylobacter jejuni
c. Clostridium botulinum
d. Vibrio cholerae

The correct answer is a. Bacillus cereus

Explanation:

Bacillus cereus is the bacteria that causes food poisoning in the form of acute intoxication. It release toxins in the food and spread through previously cooked food, fried rice, vegetables, etc.

It is able to cause two gastrointestinal illnesses like diarrhoeal syndrome and an emetic (vomiting) syndrome. The signs and symptoms the enterotoxin appear within 24 hours after ingestion of the toxin.  

So as here the boy is getting nausea, multiple episodes of vomiting and three loose bowel movements after eating leftover rice stored in the refrigerator the night before therefore in this situation the most likely causative agent is a. Bacillus cereus.