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.
Case 6 occurred in an 84-year-old female admitted from a nursing home with altered mental status, leukocytosis (WBC 19,300/μL), and acute kidney failure (serum creatinine increased 497% relative to baseline). The patient was admitted to the ICU with severe complicated CDI with septic shock. Intravenous metronidazole 500 mg three times daily and oral vancomycin 125 mg four times daily were started on hospital day 1. The patient’s diarrhea and leukocytosis persisted (WBC 41,200/μL) and intravenous tigecycline was added on hospital day 7 as a 100-mg loading dose followed by 50 mg twice daily. She was treated with combination tigecycline, vancomycin, and metronidazole for 3 days. The patient’s diarrhea resolved and her WBC decreased yet remained elevated (WBC 33,600/μL). Tigecycline was discontinued per the family’s decision to switch her to oral antibiotics for discharge to hospice. This patient was classified as clinical failure due to non-resolving leukocytosis and sustained response was unevaluable due to the lack of clinical cure. No side effects associated with tigecycline use were noted in the electronic medical record.