Final answer:
Based on the symptoms and circumstances described, the best course of action would be to reassure the patient and send her home with oral rehydration. A stool specimen could also be sent to the lab for a definitive diagnosis. Antibiotics or hospital admission appear unnecessary at this time.
Step-by-step explanation:
Diagnosis and Management of Acute Gastroenteritis
The patient in question is experiencing symptoms such as diarrhea and vomiting, which are suggestive of acute gastroenteritis, potentially caused by foodborne pathogens. The absence of fever and the fact that she lives alone and reheated leftover rice the previous evening, point towards a possible diagnosis of Bacillus cereus food poisoning, which does not typically require antibiotic treatment. Since the patient is not dehydrated and blood pressure and pulse are normal, it is not imperative to admit her for inpatient care or start her on antibiotics like metronidazole.
Moreover, because most bacterial gastrointestinal illnesses are self-limiting and the mainstay treatment is rehydration, the best next step would be to reassure the patient and send home with oral rehydration. However, submitting a stool specimen to the lab could be considered as a precautionary measure for a more definitive diagnosis and to rule out other pathogens. Therefore, the patient should be given instructions on how to maintain adequate hydration and monitor symptoms and advised to seek further medical attention if her condition worsens.