Fecal Transplantation for C difficile: A How-To Guide

David A. Johnson, MD


February 15, 2013

In This Article

Donor and Patient Preparations

Donor Preparation

The donor is told that a formed soft stool is needed on the morning of the procedure. I typically give the donor either a bottle of magnesium citrate or a double dose of a milk of magnesia to take the night before. I ask the donor to deliver the stool within 6-8 hours in a sterile or clean cup. The stool must be relatively fresh.

Some patients have been treated successfully with frozen stool, and this might be something we will see more often in the future.

A substitute for donor stool has been developed and was reported in the January issue of Microbiome.[7] A synthetic stool sample was created from 33 isolates of bacteria from the stool of a healthy volunteer. Two patients with CDI were successfully treated with this product. We may see more use of artificial fecal transplant in the future.

Stool Sample Preparation

We ask the donor for about 50 g of stool (more or less what would fill a specimen cup). Enough stool is needed to prepare an infusate by mixing the stool with a nonbacteriostatic (preservative-free) saline.

Some clinicians shake the mixture manually. We have used the blender technique. If you are going to use a blender, make sure that you understand that the stool is a level-2 biohazard, and preparation should take place under a hood in your lab. We blend the stool and nonbacteriostatic saline and then strain it through gauze so that the result is an infusate that is not full of particulate matter. Dr. Larry Brandt uses the term "malted-milk consistency" to describe it. I like the mixture to be slightly thinner because particulate matter tends to clog up the biopsy channel of the colonoscope.

The necessary volume of infusate is 300-500 mL. Using too little (< 200 mL) can contribute to a CDI relapse. We typically aspirate it into 60-mL syringes and then instill it at the time of colonoscopy.

Patient Preparation

Before an FMT, the patient must be vigorously prepared, even "overprepped," so that no residual stool is present. I use a 3-dose prep for patients, beginning 2 days before the procedure (ie, a morning dose and an evening dose the day before, and a morning dose the day of the procedure). I instruct patients that it is extremely important to be compliant with these instructions to make sure that the prep is very complete. If patients have a history of constipation, I ask them to do a 2-day liquid diet (with clear liquids only the day before the procedure), and then follow the 3-dose prep described above.

In patients who are being actively treated for CDI, we typically have the patient stop antibiotics for about 3 days to avoid any antibiotic exposure to the microflora.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as: