Case 4 occurred in an 80-year-old female who was admitted due to increasing fatigue and copious diarrhea consistent with community onset CDI. Her risk factors for CDI included advanced age and recent antibiotic use (vancomycin, levofloxacin, and piperacillin–tazobactam). This patient’s initial severity of illness was mild (WBC 9,100/μL, serum creatinine 116% of the premorbid level) and she was treated with oral metronidazole 500 mg three times daily beginning on hospital day 1. After 3 days of metronidazole treatment, her abdominal pain had improved, but the diarrhea persisted and her WBC began trending upward (16,500/μL). On hospital day 4, the patient developed septic shock secondary to CDI. As her CDI had progressed to a severe complicated case, intravenous tigecycline and vancomycin 250 mg four times daily were added. Tigecycline was given as a 100-mg loading dose followed by 50 mg twice daily. The patient was treated successfully with 6 days of triple therapy with tigecycline, vancomycin, and metronidazole. Due to the high risk of CDI recurrence in this patient, a vancomycin taper was completed. The patient was discharged to home and had no CDI recurrence within 28 days of follow-up.
Case 3 occurred in a 38-year-old male who was initially admitted due to acute hypoxic respiratory failure and necrotizing pancreatitis. For this infection, he was treated with piperacillin–tazobactam, which was switched to ampicillin–sulbactam after 10 days by the consulting infectious diseases specialist. On hospital day 25, the patient started developing copious diarrhea (>15 loose stools per day), fever (38.4 °C), and leukocytosis (WBC 13,500/μL) consistent with C. difficile sepsis and severe complicated CDI. The patient’s serum creatinine levels increased 143% relative to baseline. Upon confirmation of CDI on hospital day 26, intravenous metronidazole 500 mg three times daily was initiated. Tigecycline was added on hospital day 27 for dual coverage of enterococcal pancreatitis and C. difficile. Oral vancomycin 250 mg four times daily was also added at this time and metronidazole was discontinued by decision of the treating physician. Fever and leukocytosis subsided and diarrhea improved on 8 days of combination therapy with tigecycline and oral vancomycin. There was no recurrence of CDI on record.