Many diseases related to bacteria, such as inflammatory bowel disease or colorectal cancer, are associated with an overgrowth of gut bacteria considered 'bad'. However, a study published in the journal Cell suggests that changes in microbial load, rather than the disease itself, could be the driving factor behind the presence of these harmful species associated with pathologies.
Mice with Alzheimer's disease are more resistant to the development of colorectal tumors, a study shows. An inverse relationship between Alzheimer's and cancer has already been shown in epidemiological studies in humans. An imbalance in certain intestinal bacteria contributes to this negative correlation in mice, adds the article published in PNAS.
An international team with Spanish participation has developed a database with the metagenome of bacteria, fungi, and yeasts present in more than 2,500 foods, mostly dairy products, followed by beverages and fermented meats. The authors identified more than 10,800 microorganisms, half of which were previously unknown species. The study, published in Cell, shows that food-associated microorganisms are present in 3% of the adult gut microbiome and 56% of that of newborns.
Research has identified 31 biomarkers in the gut microbiota of children that are associated with autism spectrum disorder (ASD) and could have diagnostic value. The gut microbiota includes bacteria, viruses, fungi and archaea. The team replicated the results, published in Nature Microbiology, in three cohorts and analysed faecal samples from more than 1,600 children and children in total, with and without ASD, in China.
After the first year of life, the father's contribution to his baby's microbiota is comparable to the mother's contribution, whether born vaginally or by caesarean section, says a study published in Cell Host & Microbe. In addition, faecal microbiome transplants from the mother to her baby can restore the microbiome in the case of caesarean birth, says the study, which included 74 babies and involved Spanish participants.
Vitamin D enhances the response to cancer immunotherapy in mice via the gut microbiome, according to a study published in Science. The role of vitamin D in cancer immune modulation had already been studied in previous studies. Now, the authors suggest that this nutrient acts on intestinal epithelial cells, altering the composition of the microbiome and favoring a species of bacteria called Bacteroides fragilis, which regulates immunity against cancer.
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.
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.