A 79-year-old woman presents to the Emergency Department from a nursing home with severe diarrhea and dehydration. The symptoms started yesterday and are associated with fever and abdominal pain. She has had approximately 15 nonbloody, watery bowel movements since then and has been getting weaker. Upon further questioning of the nursing home staff, she had pneumonia 1 week ago and is finishing treatment. Her other medical problems include hypothyroidism, hypertension, and coronary artery disease. Her temperature is 39.8°C, blood pressure is 96/64 mmHg, heart rate is 92 beats per minute, and respiratory rate is 18 breaths per minute. Initial screening laboratory values show a leukocyte count of 22,300/mm3 , a hemoglobin of 13.8 g/dL, and a platelet count of 480,000/mm3 . Further diagnostic workup is pending.
What is the most appropriate next step in management?
A. Decrease the patient’s dose of levothyroxineOral vancomycin and IV metronidazole. This patient has a severe infection due to Clostridium difficile, which colonizes the intestinal tract and releases toxin A/B that damages the colonic mucosa. It is a very common nosocomial pathogen, and infection frequently occurs after antibiotics due to alteration of the gut flora. The severity can range from mild (loose stools without dehydration) to severe (profuse watery diarrhea, severe colitis, and toxic megacolon). Diagnosis can be made by testing the stool for C. difficile toxins, or with endoscopy showing pseudomembranous colitis. If C. difficile is suspected, the causative antibiotic should be stopped immediately and appropriate contact measures implemented (e.g., washing hands with soap and water upon entering and exiting the patient’s room). In addition, antibiotics should be started, which are based on the severity of disease. Severe C. difficile infection (indicated by >12 bowel movements per day, high fever, serum leukocyte count >15,000/mm3 , acute kidney injury, sepsis, age >65 or 70, etc.) should be treated with oral vancomycin since the drug has poor oral bioavailability, making it through the gut to act locally in the infected colon. Other options include oral vancomycin with IV metronidazole, or per rectal vancomycin with IV metronidazole (especially if the patient has an ileus). (C) Oral metronidazole alone is appropriate for mild infections; however, this patient is severely ill. (D) Oral vancomycin is preferred to IV vancomycin given its direct contact to infected colon.
(A) Iatrogenic hyperthyroidism can cause diarrhea, but would have other signs (marked tachycardia, mental status changes, etc.) without such a marked leukocytosis, as is seen in this patient. (B) Surgical colectomy is an option for severe infections based on abdominal CT results (e.g., bowel perforation, toxic megacolon), but it is not the next step in management for this patient.