microbiome

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.

About 58.5% of a baby's microbiota come from various parts of its mother's body, according to a study of the transmission of microbes between mother and child in the first month of life. The research, published in Cell Host & Microbe, is based on samples collected from 120 mother-baby pairs, with material from their nose/throat, saliva, skin, milk, vagina and faeces. It compares babies born by caesarean section and vaginally, and confirms that the reduced transfer of faecal microbes in caesarean births can be partially compensated by other transmission routes, such as breastfeeding.

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.   

The establishment of the baby's microbiota occurs around the time of birth, when it receives bacteria directly from the mother. A study in the journal Cell suggests that genes can also be transmitted between them by horizontal transfer, without the need for the passage of these micro-organisms.

Two studies published in the journal Nature Communications have found specific characteristics in the microbiota of people with depression, including populations of different ethnicities and habits.

A study has found a link between caesarean delivery and changes in the microbiome, as well as a reduced response to pneumococcal and meningococcal vaccines in children. The results are published in the journal Nature Communications.