Fecal therapy for Aibolitis
Fecal transplantation and koalas
Maxim Rousseau, Polit.roo
Fecal Microbiota Transplantation (FMT) has gained popularity in just the last few years. It turned out to be the most effective way to transfer intestinal bacteria from one patient to another and proved its effectiveness in the fight against certain diseases. Now scientists, who are preoccupied with the problems of preserving rare animals, also resort to transplanting symbiont bacteria. Several reports on this topic were made recently at the annual conference of the American Society of Microbiology in Atlanta. A review of them is published on the website of the journal Nature (Sara Reardon, Faecal transplants could help preserve vulnerable species).
The history of fecal transplantation began with studies on the effect of bacteria living in the intestine on the body. For example, in one study, the bacterial flora of the intestines of twins was compared, one of which was fat and the other was thin. It turned out that in the intestine of the thin twin there are more types of bacteria than in the thick one. Moreover, when microflora samples from these intestines were transplanted to laboratory mice, those mice that got the intestinal bacteria of the fat man began to get fat, and those that received bacteria from the intestines of the thin brother remained thin. When fat and thin mice were placed in the same cage, fat mice, gradually becoming infected with thin bacteria, lost weight again.
The results of this and similar experiments led to the creation of a new method of therapy – fecal transplantation. This method is used to treat not only obesity, but Crohn's disease, ulcerative colitis, obesity and even diabetes. "Transplantation" is performed through the mouth or through the intestines.
During one of these trials, the use of fecal transplantation for the treatment of intestinal disease caused by Clostridium difficile was investigated. This bacterium lives in the intestine often, and becomes pathogenic after many other bacteria die from the use of antibiotics. Clostridium difficile itself is resistant to most antibiotics. The disease occurs in hospitals or after discharge in people who have been treated with antibiotics, and proceeds in the form of severe recurrent diarrhea. In the USA, it causes the death of up to 14 thousand people in a year.
The first report on the use of FMT to combat this disease was made in the fall of 2012 at the annual conference of the American Society for the Study of Infectious Diseases (Infectious Diseases Society of America). At Henry Ford Hospital in Detroit, clinical trials took place between May 2010 and December 2011. During this time, 49 patients were treated, 43 of them fully recovered in a short time. The material for transplantation was injected into the colon through a tube in the form of a homogenized solution of 30-50 grams of feces in warm water. The study revealed no side effects or complications after fecal transplantation.
Then another series of clinical trials was conducted, which showed that fecal transplantation led to the cure of 94% of patients, whereas only 31% recovered when treated with the powerful antibiotic vancomycin, and 23% in the control group receiving placebo. Doctors prematurely stopped the trial, as they considered it unethical to deprive patients from the control groups of therapy, the effectiveness of which was already proven. A report on these trials was published on January 31, 2013 in The New England Journal of Medicine. In the summer of 2013, the new treatment method was officially approved in the USA.
The researchers tried to avoid fecal transplantation by growing cultures of the right bacteria and injecting only them into the patient's body. But such treatment did not bring success. Apparently, success depends not so much on the number of species in the bacterial community, but on the complex ratio of their numbers, which is difficult to reproduce, but easy to obtain during transplantation.
In Russia, the first experiments on the use of fecal transplantation began in March 2014 at the Center for New Medical Technologies of the Novosibirsk Institute of Chemical Biology and Fundamental Medicine SB RAS. Novosibirsk doctors also used fecal transplantation to combat Clostridium difficile. According to the director of the Institute, academician Valentin Vlasov, after transplantation, the symptoms of the disease disappear in one day. Samples for transplantation were taken from relatives of the patient and injected into his gastrointestinal tract using an endoscope.
At the current conference in Atlanta, a group of scientists told about the relationship of the koala diet with the bacterial population of its digestive system. The aim of the researchers was to find out whether changes in the composition of bacteria in the intestines of an animal are related to changes in its diet and whether fecal transplantation (the main method of transplanting intestinal bacteria) will help increase the probability of survival of these rare animals.
Koalas (Phascolarctos cinereus) are famous for feeding on eucalyptus leaves, and not every type of eucalyptus (and there are several hundred of them) is suitable for them to eat. Individual local koala populations also have their own preferences. As the area of forests in Australia is shrinking, for the sake of saving koalas, they are relocated from areas of logging to other forests, but even with the apparent abundance of food, sometimes relocated koalas die of hunger, although koalas who live permanently in this forest quietly eat the leaves of local eucalyptus trees.
Koala ecologist Ben Moore from the University of Western Sydney and his colleagues suggested that the problem may be caused by incompatibility between the available species of eucalyptus and the species composition of koala intestinal bacteria. To study the diet and intestinal microflora of koalas, scientists collected fecal samples from 200 koalas from twenty different populations from all over Australia. After studying the remains of plants, they found that some koalas fed exclusively on the leaves of Eucalyptus prutovidnogo (Eucalyptus viminalis). Other koalas ate the leaves only of the oblique eucalyptus (Eucalyptus obliqua). A very small proportion of animals were able to eat the leaves of both species. At the same time, differences were observed even in koalas from the same population. They could live ten meters apart from each other, but have different food preferences.
When Moore and his colleagues analyzed the microbial composition of faeces, they found that koalas that prefer eucalyptus rod-shaped have a different composition of intestinal bacteria compared to what they eat eucalyptus oblique. To check whether the difference in diet was the cause or consequence of different microbiomes, the researchers transplanted the feces of six koalas that ate eucalyptus oblique to six other individuals who ate eucalyptus rod. Within 18 days after the procedure, the microbiomes of the recipient koalas became almost identical to the microbiomes of the donor animals. Some of the animals that underwent intestinal bacteria transplantation began to eat the leaves of eucalyptus oblique. Ben Moore believes that fecal transplants between koalas can help increase the number of types of food available to individual animals and increase their chances of survival.
At the same conference, a report was presented by Eria Rebollar from the National Autonomous University of Mexico, who studies communities of symbiotic bacteria in amphibians. Bacteria living on their skin play a special role in the life of amphibians. In some cases, they can protect their hosts from chytridiomycosis, a dangerous disease caused by fungal pathogens Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamndrivorans (Bsal) (for more information about this disease, see the essay "Decline and Disappearance of amphibians"). In her laboratory, Eria Rebollar isolates and studies bacterial strains with antifungal properties. At the conference, she said that transplanting such strains from frog to frog helps protect recipients from chytridiomycosis.
In other studies, fecal transplantation was performed even between different animal species. A team led by Denise Dearing from the University of Utah studied the microbiome of desert hamsters (Neotoma lepida), a North American rodent species. It turned out that in the intestines of desert hamsters there are bacteria that allow them to eat plants containing oxalates, which in many other animals cause deposits of kidney stones. When these bacteria were transplanted into the intestines of ordinary laboratory rats using fecal transplantation, they also acquired the ability to digest oxalates.
Scientists from the California Zoo in San Diego compared the bacterial intestinal population of two species of rhinoceros: the southern white rhinoceros (Ceratotherium simum simum) and the Indian rhinoceros (Rhinoceros unicornis). An important difference between these rhinos is that the Indian rhinoceros reproduces well in captivity, while the southern white rhinoceros does so very rarely, which hinders conservation efforts of this species.
Phytoestrogens, substances of plant origin that affect the activity of female genital organs, were found in the feces of white rhinoceroses. They enter the rhinoceros body from plants (mainly soybeans and alfalfa). Indian rhinos in the zoo ate the same food, but their feces did not contain phytoestrogens. From this, the researchers concluded that intestinal bacteria of different species are able to decompose these substances to varying degrees.
When the white rhinos in the zoo were transferred to plant food without phytoestrogens, the effect followed quickly enough. Two females who could not bear offspring for a long time became pregnant within two years and gave birth to healthy cubs. The zoo's molecular biologist Candace Williams said that now all rhinos living there have been transferred to feed without phytoestrogens and recommend that colleagues from other zoos do this.
Candace Williams herself is now trying to determine which bacteria cope with phytoestrogens in vivo. To do this, she compares microbiome samples taken from rhinos in zoos and in the wild.
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