Fecal microbiota transplant (FMT) is a promising cure for relapsing Clostridium difficile infection, a usual cause of antibiotic-related diarrhea in which serious cases can result in death. However, a case published in the Infectious Diseases Society of America, recommends that clinicians must avert choosing stool donors who are obese and overweight. Additionally, the report raises questions with regard to the role of gut bacteria in human health and metabolism. These thoughts were raised when a woman who was cured of a recurrent Clostridium difficile infection using stool sourced from an obese donor unexpectedly became obese a year and a half after her surgery.

During the woman’s FMT in 2011, her usual weight was around 130 pounds and her BMI (body mass index) was twenty-six. At 32 years old, her weight had always been stable and normal. Due to her relapsing C. difficile infection, she went on an FMT. Her transplant utilized a stool of a healthy overweight teenage girl through the process of colonoscopy in order to return the healthy balance of bacteria in her gut, treating her Clostridium difficile infection.

Obese Donors could result in Obesity in Recipients after a Fecal Microbiota Transplant

Sixteen months after the transplant, the woman gained over 30 pounds and her BMI went from 26 to 33, reaching the medical criteria for obesity. Despite her exercise program and a clinically prescribed liquid protein food diet, her weight continued to persist.None of her efforts seemed to help her lose the weight. Three years later, she has a weight of 177 pounds with a BMI of 34.5. It is possible that there were other life factors that contributed to her weight gain like aging, genetic factors, stress associated to her illness and the resolution of her C. difficile infection. Yet, as mentioned above, she was not obese prior to undergo the transplant.

Researchers are curious about the effects of the donor’s stool and the negative impact recipients metabolism. This connection between weight gain and gastrointestinal tract is further supported by recently published animal researches, whereas the transplant of gut bacteria from an overweight to a normal weight mice could point to a marked fat increase. Due to this human and animal data connection, clinicians recommend choosing stool donors to who are not obese for FMT.

This case only emphasizes many unanswered questions with regard to donor selection and the significance of studying the long-term effects of FMT. Ultimately, it is hoped that these studies will lead to the determination of defined combination of beneficial bacteria which can be grown, manufactured and handled to enhance human health. For now, consider taking a form of probiotics to help grow naturally-occurring good bacteria in your gut.


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