Fecal Microbiota Transplantation (FMT) involves transferring stool from a donor into a recipient’s gastrointestinal tract. This procedure aims to restore a healthy balance of microbes in the patient’s gut, primarily to treat recurrent Clostridioides difficile infection. Donor screening is stringent because the donated material is an unlicensed biological product, requiring maximum patient safety. The evaluation rules out the risk of transmitting infectious agents or unhealthy microbial profiles.
Infectious Disease Screening Requirements
Immediate disqualifiers are communicable pathogens transferable through fecal material or blood products. All potential donors undergo laboratory testing, including blood serology and direct stool analysis, to identify transmissible infectious agents. Blood screening is mandatory for viral infections such as:
- Human Immunodeficiency Virus (HIV)
- Hepatitis B (HBV)
- Hepatitis C (HCV)
- Syphilis
- Human T-lymphotropic Virus (HTLV)
Stool samples are analyzed to detect common bacterial, viral, and parasitic threats, even in asymptomatic individuals. This includes testing for Clostridioides difficile, as a carrier could inadvertently cause the infection FMT is meant to treat. Pathogens like Salmonella, Shigella, Campylobacter, Giardia, and Cryptosporidium must also be absent.
Screening also focuses on multi-drug resistant organisms (MDROs), which pose a significant risk to often immunocompromised recipients. Exclusions include colonization by Methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococci (VRE), and Extended-spectrum β-lactamase (ESBL)-producing bacteria. This screening prevents the direct transfer of any organism that could cause illness.
Gastrointestinal Health History Exclusions
Donors are disqualified if their gastrointestinal history suggests an unstable gut microbiome, even if they appear healthy. Since FMT aims to provide a diverse and stable microbial community, conditions that disrupt the gut environment are immediate exclusions. A history of Inflammatory Bowel Disease (IBD), including Crohn’s Disease and Ulcerative Colitis, is an absolute disqualifier due to the profound underlying dysbiosis.
Individuals with Irritable Bowel Syndrome (IBS), chronic unexplained diarrhea, or chronic constipation are also excluded. These functional disorders suggest the donor’s microbial profile may not be robust enough to successfully colonize a recipient. A history of gastrointestinal cancers, colonic polyps, or Celiac disease also results in exclusion, due to potential underlying chronic inflammatory factors.
Recent gastrointestinal procedures, such as a colonoscopy or major abdominal surgery, cause a temporary exclusion period. This waiting time ensures the gut flora has fully recovered from preparatory bowel cleansing or surgical stress. These exclusions ensure the efficacy of the transplant by selecting donors with a high-functioning microbial ecosystem.
Lifestyle and Medication-Related Disqualifiers
Lifestyle factors and recent medical interventions can disqualify a donor by increasing the risk of unknown infection or altering the microbiome’s health. The use of antibiotics is a significant temporary exclusion, usually requiring a waiting period of three to six months since the last dose. Antibiotics disrupt the gut flora, making the donor’s microbiome unstable and less effective for transplantation.
Temporary deferral is triggered by recent travel to high-risk endemic areas, especially those with high rates of traveler’s diarrhea or parasitic infections. This waiting period (typically three to six months) is necessary because the individual may have been exposed to pathogens that could be in an incubation phase. High-risk behaviors related to bloodborne pathogens, such as illicit drug use or high-risk sexual activity, result in exclusion due to the risk of a window period infection undetectable by serology.
Receiving a new tattoo or body piercing within the last six months is another temporary disqualifier, due to the risk of transmitting bloodborne viruses. Chronic use of certain medications, even non-antibiotics like high-dose proton pump inhibitors (PPIs), can significantly alter the gut environment and may lead to permanent disqualification. Many exclusions allow for a defined washout or observation period before re-screening.
Systemic and Metabolic Health Criteria
Disqualification extends to systemic, non-gastrointestinal diseases linked to an unhealthy gut microbiome (dysbiosis). The goal is to avoid transferring a microbial profile that could predispose the recipient to chronic illness. Individuals who are severely obese (Body Mass Index over 30 kg/m²) are excluded because obesity is associated with a distinct, less diverse microbial signature.
Metabolic disorders like Type 1 and Type 2 Diabetes are also disqualifiers, as the gut microbiome plays a role in metabolic regulation and insulin sensitivity. Donors must be metabolically healthy to provide an optimal profile, given the potential for transferring metabolic traits.
A history of certain autoimmune disorders, such as Rheumatoid Arthritis, Systemic Lupus Erythematosus, or Multiple Sclerosis, results in exclusion. These conditions are associated with changes in the gut microbiome, posing a theoretical risk of influencing the recipient’s immune regulation. Excluding these systemic conditions ensures the donor’s microbiome is robust and benign, mitigating long-term risks.