Comprehensive examination of travel-related antimicrobial resistance and the gut microbiome
Authors: Yu Sun, Xi Fu
Journal: The Lancet Microbe (2024)

We read with interest the Article published in The Lancet Microbe by Colin J Worby and colleagues.1Worby CJ Sridhar S Turbett SE et al.Gut microbiome perturbation, antibiotic resistance, and Escherichia coli strain dynamics associated with international travel: a metagenomic analysis.Lancet Microbe. 2023; 4: e790-e799Summary Full Text Full Text PDF PubMed Google Scholar The authors addressed a crucial public health concern: acquisition of Escherichia coli strains and antimicrobial resistant (AMR) organisms by US international travellers. They found that 67·0% of travellers acquired new E coli strains during travel, a substantial portion of whom were carriers of AMR genes. Increases of 15·0% in the overall abundance of antibiotic resistant genes and 56·0% in the abundance of public health threat genes were observed in the gut microbiome after travel. Notably, no association was observed between pretravel microbiome structure and the structure subsequent to acquisition of travel-related AMR organisms. Therefore, the authors claimed that the gut microbiome might not provide suitable colonisation resistance against the AMR organism, which implies that modulating the gut microbiome before travel might not be an effective strategy to improve traveller health. However, we believe that such a conclusion deserves a more thorough examination. In their study, Worby and colleagues1Worby CJ Sridhar S Turbett SE et al.Gut microbiome perturbation, antibiotic resistance, and Escherichia coli strain dynamics associated with international travel: a metagenomic analysis.Lancet Microbe. 2023; 4: e790-e799Summary Full Text Full Text PDF PubMed Google Scholar defined the gut microbiome structure of the travellers using only the Bray–Curtis distance matrix. Although this matrix offers valuable insight, it represents only one dimension of the gut microbiome and has limitations. For instance, this matrix is not a direct measure of gut microbiome health. The Gut Microbiome Health Index (GMHI) introduced by Gupta and colleagues2Gupta VK Kim M Bakshi U et al.A predictive index for health status using species-level gut microbiome profiling.Nat Commun. 2020; 11: 4635Crossref PubMed Scopus (0) Google Scholar offers a more intricate understanding of the gut health status. On the basis of an integrative analysis of 4347 human stool metagenomes from 34 published studies, Gupta and colleagues identified 50 microbial species associated with healthy gut ecosystems and used them to derive the GMHI. The GMHI is a strong prognostic marker of health outcomes, outperforming conventional alpha diversity indexes with an impressive 73·7% accuracy in distinguishing individuals with disease from those who are healthy. Therefore, the GMHI can serve as a reliable predictor of gut health. In addition to the GMHI, the presence and relative abundance of protective and risk-associated gut microbiota taxa can also serve as indices for assessing gut health, given their crucial role in the determination of the overall health of the host. The abundance of these taxa carries functional implications for health, offering a more representative measure of gut health compared to the Bray-Curtis distance. This is because the Bray-Curtis distance quantifies community composition dissimilarity without directly reflecting health status. In light of this, using a list derived from previous studies,2Gupta VK Kim M Bakshi U et al.A predictive index for health status using species-level gut microbiome profiling.Nat Commun. 2020; 11: 4635Crossref PubMed Scopus (0) Google Scholar,3Gacesa R Kurilshikov A Vich Vila A et al.Environmental factors shaping the gut microbiome in a Dutch population.Nature. 2022; 604: 732-739Crossref PubMed Scopus (171) Google Scholar Zhang and colleagues4Zhang M Tang H Chen Y et al.Impact of environmental characteristics on children's gut microbiota–a pilot study in assessing the role of indoor microbiome and metabolites.Environ Res. 2023; 234116114Crossref Scopus (0) Google Scholar calculated the total abundance of protective and risk-associated gut microbiota, revealing interesting associations between environmental exposures and these taxa. Therefore, a more in-depth analysis of these alternative microbiome structure indices is warranted when assessing the pretravel gut microbiome. These indices provide a better indication of the multidimensional gut microbiome structure, which could reveal the intricate connections between the gut microbiome and subsequent acquisition of AMR organisms during travel. We declare no competing interests.