The Importance of Donor Selection in Fecal Microbiota Transplantation (FMT)
What Is Fecal Transplantation?
It is the procedure of transplanting into the patient’s large intestine a material obtained by processing stool collected from healthy donors with high microbial flora biodiversity in the digestive system. Its abbreviated name in the international literature is FMT (Faecal Microbiota Transplantation).
What Is Microbial Flora?
We coexist with microorganisms — single-celled, thousands of species, trillions in number, constantly self-renewing, consisting mostly of bacteria, viruses, and yeasts — that live in peace with us in certain parts of our body. All of these together are called microbial flora. What we are discussing here is the digestive system flora. We serve as hosts to our Digestive System Flora and provide their nourishment. Our Digestive System Flora, in turn, contributes to our antimicrobial defense in all the regions they inhabit, helps maintain moisture and acidity in those regions, enables the digestion of certain foods through enzymatic activities, plays an important role in the synthesis of certain structures (vitamins, etc.), secretes certain neurotransmitters involved in neural signaling, and contributes to countless other vital functions. In short, healthy life without our flora is not possible. We refer to all these microorganisms that settle and reside throughout our digestive system as the digestive system flora. Each of them has a specific location within the digestive system where they settle and live. Under normal conditions, they do not colonize or survive outside their designated area. Situations such as flora settling outside its designated area, disruption of its composition (dysbiosis, etc.), excessive proliferation in certain regions (SIBO disease, etc.), or an increase in the numbers of certain groups (in obesity cases) are all pathological and each of these is a cause of disease.
How Is Microbial Flora Acquired?
From birth, we begin to acquire microbial flora from the environment we come into contact with. The nature of the microbial flora acquired during specific developmental periods varies (newborn, adolescent, puberty, pregnancy, old age, etc.). The microbial flora of a healthy individual reaches optimal biodiversity in their twenties. The process that begins with the flora acquired from the mother at birth is further shaped especially by the people most frequently contacted, the foods consumed, and other environmental exposures.
What Happens If Our Microbial Flora Weakens?
If the biodiversity of our microbial flora decreases — that is, if it weakens — it becomes insufficient to contribute to the functions of the region it inhabits, and as a result, absorption and digestive disorders may develop, along with food allergies, infections, dementia, and in later stages, diseases associated with autoimmune processes.
How Can We Strengthen Our Microbial Flora?
We can introduce new members to our flora, strengthen our existing flora, and protect our current flora by: spending close and prolonged contact with people who have healthier and more biodiverse flora from birth, eating healthily, receiving breast milk for as long as possible, maintaining a natural, adequate, and balanced diet, avoiding processed foods as much as possible, and refraining from unnecessary medication use (especially antibiotics), among other practices.
What Can Be Done If Our Microbial Flora Is Weak and We Cannot Strengthen It?
If we are unable to strengthen our flora by natural means and the existing flora damage or weakness is causing certain diseases (allergies, nutritional disorders, autoimmune diseases, etc.), the only thing to be done is FLORA TRANSPLANTATION or FECAL TRANSPLANTATION (FMT).
What Are the Donor Selection Criteria in FMT Treatment?
Donor candidates must meet the exclusion criteria given in Table 1 below and must have a sufficient score as specified in Table 2.
← Scroll to view →
| Criteria for the Last Three Months | Criteria for the Last Six Months | Time-Independent Criteria |
|---|---|---|
|
– Hospitalized individuals – Those receiving intravenous treatment – Those who received live vaccines – Those who used antibiotics – Those who used antifungals – Those who underwent parasite treatment – Those who used antivirals – Those who received dental treatment – Those who underwent surgical procedures – Those with a history of animal bites – Those with open wounds – Those who had diarrhea – Suspected sexual exposure – Those with active infections – Those who gave birth – Travel to high-risk regions |
– Chemotherapy – Radiotherapy – Hormone therapy – Immunosuppressive treatment – Intensive care treatment – Oral STOP exceeding 7 days – Major surgical procedure – Blood transfusion – Those who had HAV infection – Contact with agricultural pesticides |
– Being an HIV carrier (AIDS) – Being a Hepatitis B carrier – Being a Hepatitis C carrier – Those with chronic infectious diseases – BMI below 20 kg/m² (underweight) – BMI above 30 kg/m² (overweight) – Diabetic patients using insulin – Those with autoimmune disease – Ulcerative colitis patients – Crohn’s disease patients – Celiac disease patients – Those with lactose intolerance – Those diagnosed with digestive system cancer – Those who underwent digestive system surgery (except appendectomy) – Those who received less than 6 months of breast milk – Those diagnosed with Leaky Gut Syndrome (LGS) – Drug addicts – Alcoholics – Healthcare workers – Sex workers – Homosexuals – Those over 50 years of age – Schizophrenics – Autistic individuals – Toxic industrial workers – Pregnant women – Oral feeding cessation exceeding three weeks |
*Source: Kanlioz M, Ekici U, Ferhatoğlu MF. Total Gastrointestinal Flora Transplantation in the Treatment of Leaky Gut Syndrome and Flora Loss. Cureus. 2022 Nov 3;14(11):e31071. doi: 10.7759/cureus.
← Scroll to view →
| CRITERION | SCORE | Donor Score | |||
|---|---|---|---|---|---|
| Age (years) | 0–20 yrs → 5 | 21–30 yrs → 4 | 31–40 yrs → 3 | 41–50 yrs → 2 | 50+ yrs → 1 | |
| Breast Milk (months) | 1–6 mo↓ → 6 | 6 mo↑ → 9 | 9 mo↑ → 12 | 12 mo↑ → 15 | 24 mo↑ → 18 | |
| Place of Residence | Rural → 10 | Urban → 3 | Metropolis → 0 | ||
| Chemotherapy | None → 10 | Received → 0 | |||
| Radiotherapy | None → 10 | Received → 0 | |||
| Hormone Therapy | None → 10 | Received → 0 | |||
| Antibiotics 3+ Weeks | None → 10 | Received → 0 | |||
| Immunosuppressive Therapy | None → 10 | Received → 0 | |||
| Oral Feeding Cessation | None → 10 | ≤7 days → 5 | 7+ days → 0 | ||
| Intensive Care Treatment | None → 10 | ≤7 days → 5 | 7+ days → 0 | ||
| History of Diabetes | None → 10 | Prediabetes → 3 | Diabetes → 0 | ||
| Allergic Disease | None → 5 | Present → 0 | |||
| Autoimmune Disease | None → 5 | Present → 0 | |||
| Family History of Autoimmune Disease | None → 2 | Present → 0 | |||
| Industrial Food Consumption | None → 5 | Very rare → 2 | Present → 0 | ||
| History of Dysentery | None → 5 | ≤3 → 2 | ≥4 → 0 | ||
| History of Gastroenteritis | None → 5 | ≤5 → 2 | ≥6 → 0 | ||
| GI Surgery | None → 10 | Present → 0 | |||
| Chronic Medication Use | None → 5 | Present → 0 | |||
| Nutritional Disorder | None → 10 | Present → 0 | |||
| Alcohol Use | None → 10 | Rarely → 2 | Very frequent → 0 | ||
| TOTAL SCORE: | |||||
|
DONOR QUALITY BY SCORE ★ 125 points and above: Ideal Donor ★ 100–124 points: Very Good Donor ★ 90–99 points: Good Donor ★ 80–89 points: Acceptable Donor ★ 70–79 points: Poor Quality Donor ★ 69 points and below: Very Poor Quality Donor |
Total Donor Score: | ||||
*Source: Kanlioz M, Ekici U, Ferhatoğlu MF. Total Gastrointestinal Flora Transplantation in the Treatment of Leaky Gut Syndrome and Flora Loss. Cureus. 2022 Nov 3;14(11):e31071. doi: 10.7759/cureus.
First and foremost, the donor candidate must be healthy and must not have taken antibiotics, probiotics, or alcohol within the last three weeks prior to transplantation. Standard physical and systemic examinations are performed on donor candidates. Donor candidates who meet these criteria are then evaluated for health status and communicable diseases through a series of blood, urine, and stool tests. Individuals who pass all of these stages may be accepted as donor candidates.
Can Anyone Be an FMT Donor?
Anyone who meets the criteria stated above can be an FMT donor.
What Is Donor Biodiversity?
It is a term indicating how diverse the components that make up the donor candidate’s microbial flora are. This can be illustrated most simply as follows: the greater the variety of technical personnel and engineering specialties in a factory, the higher the quality and sophistication of the products manufactured. The human digestive system can be thought of in exactly the same way as a factory. The greater the diversity of our flora, the healthier our digestive system functions will be. High donor biodiversity is a prerequisite sought in a donor candidate. If the donor candidate’s biodiversity is insufficient, there is no need to proceed to the next stages — that person cannot be a donor.
How Can FMT Treatment Increase the Patient’s Biodiversity?
By transferring microbial flora components that did not previously exist in the patient’s large intestine, it becomes possible to perform certain functions that could not be carried out in the past, to revive lost functions, and thereby to treat diseases caused by missing flora elements. The acquisition of a flora element that was previously absent in us increases our biodiversity. The acquisition of flora components that were never present in us, or that existed in the past and were lost over time, can be achieved through FMT.
Why Do We Want to Increase Biodiversity in FMT Treatment?
To achieve higher quality and more functional large intestine (colon) function.
Is Genetic Relatedness Between Donor and Patient Required?
No.
Do the Donor and Patient Need to Be the Same Gender?
No.
Why Do We Ask Patients to Find Their Own Donor?
Knowing the donor candidate’s past life history is important for evaluating the Table 1 criteria more reliably. It is important for us to more accurately assess the dietary habits, alcohol, drug, and tobacco dependencies, and past illnesses of a person whose background we know.
Another consideration is that the most effective way to eliminate the patient’s questions about the donor is for the patient to find the donor candidate themselves.
How Many Types of FMT Are There Based on the Material Used?
– Fresh FMT (Real-Time FMT): Stool collected from the donor is processed in the shortest possible time and transferred to the patient’s large intestine. The time involved here is approximately 30–60 minutes. Performing the transplant in the shortest possible time is the most important factor in increasing the success of FMT treatment.
– Frozen FMT: FMT samples collected from healthy donor candidates are stored at -400C. They are retrieved and used when needed.
– Capsule FMT: FMT material is placed inside a capsule form. Patients swallow these capsules orally with water to allow them to reach the intestines. The capsules are produced in a form that opens in the intestine.
Which FMT Is the Most Effective Based on the Material Used?
The most effective method is Fresh (Real-Time) FMT. This is because what we are transferring here are living microorganisms. They must reach the large intestine while maintaining their viability and with the least possible damage. The most effective method for this is Fresh FMT.
Frozen FMT has lower efficacy compared to Fresh FMT.
Capsule FMT has the least efficacy among these methods.
What Is the Most Important Donor-Related Factor in FMT Efficacy?
Beyond the donor’s health criteria, the most important factor is the donor’s biodiversity and the application of the FMT method using the greatest possible number of donors.
Which Method of Transferring FMT Material to the Colon Is More Effective?
FMT material is transferred to the colon by the following methods:
– Rectal Enema Method
– Colonoscopy Method
– Endoscopy Method
– Endoscopy and Colonoscopy Method
– Oral Capsule Method
Among these methods, the simultaneous use of both endoscopy and colonoscopy to transfer FMT material to multiple sites provides the most successful outcomes from FMT treatment.
Assoc. Prof. Dr. Murat KANLIÖZ
General Surgery Specialist