Research News

25 Mar 2021

Role Of Gut Microbiota In Travel-Related Acquisition Of Extended Spectrum β-lactamase-Producing Enterobacteriaceae

What a week for the Tun Lab! 
After their publication in Gastroenterology and the award they received at the 2021 Inventions Geneva Evaluation Days for the “Innovative Sewage Testing Tool for SARS-CoV-2” project, Hein Min Tun and PhD student Ye Peng publish in the Journal of Travel Medicine (Oxford Academic) about the role of gut microbiota in the acquisition of antimicrobial resistant bacteria during international travels. 
International travel could facilitate the spread of antimicrobial-resistant bacteria including extended spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E). Previous studies, which attempted to understand the role of gut microbiota in the acquisition of antimicrobial resistant bacteria during international travels, are limited to western travellers.

We established a prospective cohort of 90 Hong Kong travellers to investigate gut microbiota determinants and associated risk factors for the acquisition of ESBL-E. Baseline characteristics and travel-associated risk factors were gathered through questionnaires. Faecal samples were collected in 3-4 days before and after travel. Antimicrobial susceptibility of ESBL-E isolates was tested, and gut microbiota were profiled by 16S rDNA amplicon sequencing. Non-parametric tests were used to detect potential associations, and logistic regression models were used to quantify the associations. Random forest models were constructed to identify microbial predictors for ESBL-E acquisition.

In total, 49 (54.4%) participants were tested negative for ESBL-E colonization before travel and were followed up after travel. A total of 60 ESBL-E isolates were cultured from 20 (40.8%) participants. Having low Actinobacteria richness and low abundance of short-chain fatty acid-producing bacteria in the gut microbiota before travel increased the risk of acquiring ESBL-E and the risk can be further exacerbated by eating raw seafood during travel. Besides, post-travel ESBL-E positive participants had increased abundances of several opportunistic pathogens such as Staphylococcus, Enterococcus, Escherichia/Shigella and Klebsiella. The random forest model integrating pre-travel microbiota and the identified travel-related risk factor could predict ESBL-E acquisition with an area under the curve of 75.4% (95% confidence interval: 57.9–93.0%).

In this study, we identified both travel-related risk factors and microbiota predictors for the risk of ESBL-E acquisition. Our results provide foundational knowledge for future developments of microbiota-based interventions to prevent ESBL-E acquisition during international travels.

24 Mar 2021

Ethnicity Associations With Food Sensitization Are Mediated By Gut Microbiota Development In The First Year Of Life

New publication from the Tun Lab! 
Dr Hein Min Tun, Ye Peng (PhD student) and team published in Gastroenterology about the relationship between food sensitization and the development of gut microbiota during the first year of life, with fellow colleagues from University of Alberta and University of Toronto, Canada, within the CHILD Cohort Study, a robust Canadian research platform to understand development of disease so it can be predicted, prevented or better treated.
Background and aims: Increasing evidence supports the role of early-life gut microbiota in developing atopic diseases, but ecological changes to gut microbiota during infancy in relation to food sensitization remain unclear. We aimed to characterize and associate these changes with the development of food sensitization in children.
Methods: In this observational study, using 16S rRNA amplicon sequencing, we characterized the composition of 2844 fecal microbiota in 1422 Canadian full-term infants. Atopic sensitization outcomes were measured by skin prick tests at age 1 year and 3 years. The association between gut microbiota trajectories, based on longitudinal shifts in community clusters, and atopic sensitization outcomes at age 1 and 3 years was determined. Ethnicity and early life exposures influencing microbiota trajectories were initially examined, and post hoc analyses were conducted.
Results: Four identified developmental trajectories of gut microbiota were shaped by birth mode and varying by ethnicity. The trajectory with persistently-low Bacteroides abundance and high Enterobacteriaceae/Bacteroidaceae ratio throughout infancy increased the risk of sensitization to food allergens, particularly peanut at age 3 years by 3-fold (adjusted OR, 2.82; 95% CI, 1.13-7.01); a much higher likelihood for peanut sensitization was found if infants with this trajectory were born to Asian mothers (adjusted OR, 7.87; 95% CI, 2.75-22.55). It was characterized by a deficiency in sphingolipid metabolism and persistent C. difficile colonization. Importantly, this trajectory of depleted Bacteroides abundance mediated the association between Asian ethnicity and food sensitization.
Conclusions: This study documented an association between persistently-low gut Bacteroides abundance throughout infancy and sensitization to peanut in childhood. It is the first to show a mediation role for infant gut microbiota in ethnicity-associated development of food sensitization.