Patients in the surgical intensive care unit with severe C. diff. are eligible and if consented will be randomized in a 1:1 ratio to a control group or the treatment group. Each group will undergo a colonoscopy on day one of the study. A 14 French Cook colonic decompression catheter will be placed at that time. This catheter is a 175cm long soft flexible catheter designed to be placed in the colon. Its usual use is to remove air from a colon that is dilated. The catheter is placed into the colon by first placing a guidewire through the colonoscope. The colonoscope is then removed leaving the guidewire in place. The catheter is then thread into the colon over the guidewire. An xray is obtained to confirm the location of the catheter and then the guidewire is removed. The guidewire is a very thin, soft, flexible wire. The patient will not have any undue discomfort secondary to the catheter. The control group will have 250cc of sterile saline solution instilled through the catheter into the colon every 6 hours. The study group will have 250cc of vancomycin solution instilled every 6 hours. The solution will be 2 grams vancomycin dissolved in a 1 liter normal saline irrigation bottle. The catheter will be clamped in both groups after instillation until the next treatment. Of note, both groups will receive the current standard treatment of 500mg IV metronidazole every 8 hours and 250mg oral vancomycin every 6 hours throughout the study. Every day the patients will have a blood draw to check the white blood cell count as is the current practice. The patients will also have a vancomycin trough level checked via blood test. This will occur just prior to the first dosing on treatment day number 3. This will be a blinded lab value as to not unblind the investigators. At resolution Patients will undergo a repeat colonoscopy when there is a decrease of diarrhea (less than 3 stools daily) and a normalized white blood cell count or on day 7 if symptoms persist. The expected length of treatment is approximately 7 days. If there is no improvement at fourteen days, the trial will be stopped for futility. The trial will also be halted if the attending physician determines that the patient needs surgery or if the clinical status of the patient has deteriorated to a point where keeping the patient enrolled will potentially cause harm. Follow-up after completing the trial will consist of phone interviews to screen for recurrence of infection. A weekly phone call will be made for the first three weeks and then two monthly calls will take place after that for a total of three months follow-up. The primary investigator will make these phone calls.