Fecal Microbiota Transplantation (FMT) is a medical procedure that involves transferring stool from a healthy donor into the gastrointestinal tract of a recipient. This process is designed to restore a balanced community of microbes in the gut. The primary medical application for this treatment is addressing recurrent Clostridioides difficile infection (C. diff). The procedure works by introducing thousands of beneficial microorganisms from the donor’s sample to outcompete the harmful C. diff bacteria and reestablish a healthy microbial environment in the colon.
Sourcing and Processing the Transplant Material
The process begins with the rigorous selection of a qualified donor. Potential donors undergo extensive screening, comparable to the standards used for blood or organ donation. This includes a detailed medical history review to rule out chronic illnesses, autoimmune disorders, and risk factors for infectious diseases. Laboratory testing is then performed on both blood and stool samples to exclude transmissible pathogens. Blood tests check for viruses like Hepatitis A, B, and C, and HIV. Stool testing analyzes for parasites, pathogenic bacteria, including multidrug-resistant organisms, and the presence of C. diff.
Once a sample is collected from an approved donor, it moves to the processing stage. The donated stool is mixed with a sterile liquid, such as saline, to create a suspension. This mixture is thoroughly homogenized and filtered to remove any large particulate matter. The resulting liquid suspension is either used immediately as a “fresh” sample or prepared for freezing and long-term storage in a “frozen” format.
Patient Preparation and Administration Routes
Preparation involves specific steps the recipient must take. Patients are typically instructed to stop taking antibiotics two days before the scheduled transplant to clear the gut and make it more receptive to the new microbiota. For procedures targeting the lower gastrointestinal tract, the patient must undergo a bowel cleansing regimen, similar to that for a colonoscopy, using laxatives or enemas.
The method of delivering the microbiota varies, with the goal of transporting the therapeutic material to the colon where the C. diff infection resides.
Colonoscopy
Colonoscopy is a common and highly effective route. A physician delivers the suspension directly into the large intestine using the scope’s working channel. This method is invasive and requires sedation, but it ensures precise placement, offering success rates often exceeding 90% for recurrent C. diff.
Upper Gastrointestinal Delivery
One method involves using a nasogastric or nasojejunal tube, inserted through the nose and guided into the stomach or small intestine. The stool suspension is then infused through the tube. This is less invasive than a colonoscopy but carries a slight risk of aspiration.
Oral Capsules
Oral capsules contain processed, freeze-dried fecal material. This non-invasive route eliminates the need for an endoscopy or sedation. Patients swallow a large number of capsules, which are specially coated to resist stomach acid and ensure the delivery of the microbes to the intestines.
Retention Enema
A final, less common route is a retention enema, where the suspension is delivered directly into the rectum. This is the least invasive option but typically only reaches the lower part of the colon.
The procedure itself is relatively quick, often taking less than an hour, and is followed by a short period of monitoring.
Immediate Follow-up and Success Measurement
Following the transplant, patients are typically observed briefly, especially if sedation was used. Post-procedure care includes recommendations to avoid non-essential antibiotics or other medications that could disrupt the newly introduced microbial community. Patients may also be instructed to remain in specific positions to aid in the retention and distribution of the transplanted material.
Success is defined by the resolution of C. diff-associated diarrhea without recurrence. Clinical resolution is generally determined by the absence of diarrhea for an eight-week period following the transplant. Many patients report symptom improvement within a few days to a week. Follow-up appointments monitor the patient’s clinical status and confirm the infection has not returned.