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Antimicrobial Resistance and Changes to the Gut Microbiome after International Travel

Massachusetts General Hospital investigated how international travel contributes to the contraction and carriage of antimicrobial resistance (AMR).

During the virtual IDWeek conference, investigators from Massachusetts General Hospital presented their study of the antibiotic resistant Enterobacterales as it changes the gut microbiomes of US international travelers.

The investigators performed metagenomic sequencing on DNA extracted from the stool of 273 US travelers before and after they travelled internationally. They used Kraken2 to assess the microbial gut composition before using the Resistance Gene Identifier (RGI) and ResFinder to map the antibiotic resistance gene (ARG) content.

Investigators specifically examined the change in gut profile and resistome associated with (1) all international travel, (2) travel to certain geographic regions, and (3) traveler’s diarrhea.

The results showed a clear perturbation in the gut biome after traveling internationally. This change was greater in participants who were already receiving treatment for diarrhea during their travel. Regardless of health outcome, there was an observed loss in microbial diversity after travel (p=0.011), but this was loss was most significant and consistent in travelers to Southeast Asia (SEA; loss of gut diversity 81%).

Travel to South Asia was also associated with a significantly higher relative abundance of E. coli compared to other destinations (p=0.04). However, 78% of all travelers had a greater presence of E. coli after their trip, including the 85% of travelers who also acquired AMR bacteria. Relative abundance of Pasteurellales was higher in the pre-travel stool samples of participants who acquired AMR bacteria post-travel (FDR=0.08).

Finally, the investigators found a significant increase in ARG content in the post-travel samples, with differences in the magnitude of acquisition correlated with travel destination. South America was associated with the greatest increase in overall ARG content, while SEA had the greatest increase in resistome diversity. Overall, 72% of all international travelers had a greater resistance burden post-travel.

The investigators concluded that these gut microbial perturbations after international travel may be important factors in the global spreading of AMR.