Toni Gabaldón

The risk of developing resistant bacteria is higher in some people, such as those who have to take long-term antibiotics after organ transplantation. To try to reduce them, a phase 1 clinical trial has performed a fecal transplant on 10 people who had previously received a kidney transplant and had resistant bacteria. The fecal transplants accelerated decolonization, shortened the time it took to test negative for multidrug-resistant organisms, and, according to the authors, may also "reduce the recurrence of infections." The results are published in the journal Science Translational Medicine.

An opinion piece signed by researchers from the Universities of Aberdeen and Nottingham (UK) has outlined some of the inaccuracies, exaggerations and misconceptions they say are taking place around research on the human microbiome. Some of these are curiosities, like the false belief that we have ten bacteria for every human cell. Others are more relevant, such as the fact that many specific associations between the microbiome and disease have not been confirmed in follow-up studies. According to the authors, it is important to raise awareness about myths and misconceptions to avoid unproductive research projects and preserve public confidence in microbiome science. The article is published in the journal Nature Microbiology.

Faecal microbiota transplantation can be administered by oral capsules, colonoscopy or rectal enema, among other routes. Two meta-analyses evaluate its benefits and side effects for treating two types of disease. The first focuses on recurrent infections with Clostridioides difficile, a bacterium that can cause very severe diarrhoea; it includes six studies in Europe and North America involving 320 adults and concludes that in immunocompetent people, faecal transplantation is more effective than antibiotics. The second focuses on irritable bowel diseases, such as ulcerative colitis and Crohn's disease; it includes 12 studies with 550 participants and has less clear results.

Two studies have found changes in the microbiome of patients affected by chronic fatigue syndrome. In particular, they have found a decrease in both butyrate and certain bacteria that produce butyrate. Butyrate is a factor related to the protection of the intestinal barrier and appears to play a role in the regulation of the immune system. Both papers are published in the journal Cell Host and Microbe.

An international team including researchers from Spain has analysed the level of exchange of microbial strains between different generations (vertical transmission) and between people who share a household or are close contacts (horizontal transmission). The analysis, published in the journal Nature, is based on about 9,700 microbiome samples from the faeces and saliva of people with different lifestyles from countries. According to the research, the transmission of bacteria is more frequent for the mouth microbiome than for the gut microbiome among people living together.   

A metagenomic comparison of the infant gut microbiome of industrialised and non-industrialised populations reveals robust differences that researchers say are lifestyle-dependent. The research involved samples from infants of Hadza, a group of modern hunter-gatherers living in Tanzania, and is published in the journal Science.