Check the donor stool!

Six new cases of complications after fecal transplantation have been registered

Polina Loseva, N+1

Six patients became ill after intestinal bacteria transplantation. Two of them were cured at home, two more – in the hospital. Two died, but it is still unclear whether their deaths should be linked to the consequences of transplantation. The cause of the disease is called pathogenic strains of E. coli. Now the donor stool samples will be tested on them too. This is reported by a press release on the website of the Open Biome donor chair bank.

Fecal transplantation is considered a promising means to combat a whole range of diseases, from obesity to autism. Despite the fact that the use is officially approved only in the case of certain intestinal infections, the method is actively used in many clinical studies. However, this procedure, like any other, is associated with some risks. When a person receives foreign intestinal bacteria, his body is usually weakened. And if there is a pathogenic strain among the donor microbes, it gets a chance to multiply and take over the patient's body.

Doctors reported two such cases in the summer of 2019: after the transplant, patients became infected with E. coli resistant to a variety of antibiotics. One of them could not be saved. This happened because the donor stool sample that the deceased patient received was not tested for antibiotic resistance. The order of the FDA, which required such a check, appeared after this sample was selected and frozen.

Now doctors have reported new side effects from intestinal microbiota transplantation. Two immunocompromised patients received microbiota from different donors to fight clostridial intestinal infection. Soon one of them developed diarrhea, the second was in the hospital for other reasons, but both had an enteropathogenic strain of E. coli in their stools. It is known that some people can wear it asymptomatically, while others develop an intestinal disorder that goes away after a few days. Both patients were soon discharged from the hospital, but the samples of the transplanted bacteria were destroyed.

Four other patients also suffered from clostridial infection and received microbiota from the same donor. Subsequently, they were found to have strains of E. coli that secrete a shiga-like toxin (similar to the one secreted by the shigella bacterium, the causative agent of dysentery). When this strain multiplies in the intestine, the patient may experience pain, fever, nausea and diarrhea. Two of the infected patients were treated at home, two more were in the hospital, and all recovered.

Later, it was reported that two more patients who received a bacterial transplant from the same donor died. However, it is still unknown whether their death is related to transplantation. One of them suffered from a chronic heart disease, and a pathogenic strain of E. coli could not be detected in the stool of the other.

All stool samples that these patients received were stored in the OpenBiome biobank. As a representative of the biobank told the STAT portal, the bank has already sent about 55 thousand samples for clinical trials. This is the first case of complaints about side effects, which shows that the probability of their development is extremely low. However, the FDA has issued a warning about the possible risks of fecal transplants, and OpenBiome has strengthened the procedure for testing donor stool for pathogens. The previous technique did not allow to identify the strain producing shiga toxin, and the samples were not tested at all for the enteropathogenic strain.

From the editor
Do not think that side effects and, possibly, the death of patients is associated with careless testing. The fact is that the human intestinal microbiome consists of many types of bacteria with their own characteristics. It is impossible to check all of them for security. In addition, it is difficult to predict in advance how a particular strain will behave in a weakened body, and which infection will be fatal against the background of concomitant diseases of the patient. Therefore, it turns out that every accident serves as an excuse to make the procedure for selecting donor samples stricter.

Animal experiments show that fecal transplants have many more potential applications. In separate trials, they made mice stronger, prolonged their lives and made neurons in their brains divide, and also reduced anxiety in rats after spinal cord injury. Meanwhile, another variant of microbiota transfer is already being used in humans – from the vagina.

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