New microbiome research sheds light on how diversity begets diversity in the microbiome

Researchers with McGill University recently published evidence showing that diversity begets greater diversity among microbiomes. Using two thousand microbiome samples and high-throughput amplicon sequencing, the researchers calculated diversity ratios as a proxy for diversity, after which diversity ratios were plotted over time. These main findings prove counter to previous arguments that biodiversity results in a restriction of diversity due to limited space and resources; however, the researchers also found that rates of diversity peak with increased competition for both space and survival in more diverse microbiomes.

This new evidence could yield more insights into how disruptions in the microbiome--such as the increased usage of antibiotics in the food chain and increased usage of pesticides in agriculture--might impact the diversity of the microbiome as a whole. Indeed, previous analyses of microbiota in response to the increased use of antibiotics has found that such antibiotics could decrease the diversity of the gut microbiome, resulting from a decrease in the prevalence of certain bacteria observed. However, the researchers note that while these insights may be valuable in examining biodiversity loss, additional research of the microbiome is still needed.

Special issue on the microbiome highlights targets for diagnosis, prevention, and treatment of infectious diseases

A review article published in The Journal of Infectious Diseases underscores the key roles that an individual’s microbiome can play in the prevention and development of infections as well as its value in diagnosing and treating such infections. The microbiome’s traditional roles of homeostasis include the prevention of bacterial infections by pathogens such as C. difficile as well as viral infections including sexually transmitted infections. The gut microbiome can serve as a reservoir for antimicrobial resistance genes, and genetic information from this reservoir could be a helpful target for the design of new models and application of tools like machine learning. Naturally occurring lung microbiota are known to excrete molecules which can play critical roles in immunity and the function of lung cells. These microbiota could also contribute to the development of prediction models of lung function in cystic fibrosis patients in the absence of infectious diseases. Additional prediction models can be built based on the overabundance of certain naturally-occurring flora in microbiomes including Enterobacteriaceae, which could indicate the future onset of diseases such as necrotizing enterocolitis and sepsis. The growing number of putative roles and information to be gleaned from the microbiome has made the microbiome an attractive target for interventions such as fecal transplantation and live biotherapeutic products. However, these complex products face regulatory challenges related to manufacturing, safety, and uniformity, as well as innovation incentives. LACTIN-V, for example, is an investigatory live microbiome-based treatment that has demonstrated efficacy in Phase II clinical trials to prevent the recurrence of bacterial vaginosis. Researchers are currently examining extremely narrow-spectrum antibiotics such as ridinilazole for C. difficile infections and sideromycins as treatments which can target pathogenic bacteria while sparing naturally occurring microbiota important for preventing future infections.

Finnish study shows that boys, but not girls, grow at slower rates when exposed to antibiotics as neonates

A recent study examining children included in the Southwest Finland Birth Cohort (SFBC) study showed that exposure to antibiotics in male neonates led to significantly lower weight and height gain in the first six years of life, with no difference observed in female neonates. This gender-specific attenuated growth effect was also observed by the researchers when comparing exposure to antibiotics and growth in male versus female neonates in a second, German cohort. Further, this effect was demonstrated in germ-free male, but not female, mice which received fecal microbiota transplants from children who were exposed to antibiotics. When children who were no longer neonates but still under six years of age were exposed to antibiotics, the researchers saw a statistically significant increase in body mass index in both boys and girls. In addition to examining these anthropometric outcomes, the researchers also examined the richness of gut microbiome diversity in a subset of children who were exposed and unexposed to antibiotics as neonates. While the antibiotic-treated children demonstrated a significantly lower level of microbiome richness (i.e., bacterial diversity) at one month of age, they met the same level of richness as untreated children at six months of age and surpassed their untreated counterparts’ microbiome richness at 12 and 24 months of age. However, the treated children’s microbiomes demonstrated a significantly lower abundance of Bifidobacteria, an important digestive bacteria, through the first 24 months of life. The researchers postulated that these findings suggest that alterations to the gut microbiome may cause growth impairment in boys, but not girls, exposed to antibiotics as neonates.