Travel to the tropics: Impact on gut microbiota

Visitors to low- and middle-income countries (LMICs) encounter numerous new intestinal microbes, including diarrhoeal pathogens and multidrug-resistant (MDR) bacteria, such as extended-spectrum β-lactamase-producing Enterobacterales (ESBL-PE). Consequently, many develop travellers' diarrhoea (TD) and/or become colonised by ESBL-PE. We explored the impact of LMIC travel, TD, and ESBL-PE/diarrheal pathogen colonisation on gut microbiota.

The present study included 92 participants from the clinical vaccine trial OEV123, who spent 12 days in Benin, West Africa, and provided exploratory pre- and post-travel stool microbiota samples. The samples were subjected to quantitative polymerase chain reaction (qPCR) to detect diarrhoeal pathogens and 16S rRNA gene amplicon sequencing for microbiota profiling.

Travel significantly altered gut microbiota, showing reduced richness, decreased α-diversity, and a 40-fold increase in Escherichia/Shigella. qPCR detected diarrhoeagenic Escherichia coli (DEC) in post-travel stools of 89 % of the 92 participants. No specific microbiota signatures were linked to TD or ESBL-PE acquisition. Participants acquiring multiple DEC pathotypes had higher pre-travel levels of Ruminococcaceae and Coprococcus spp., while their post-travel microbiota was enriched with oxygen-tolerant and oral and upper gastrointestinal tract-associated taxa.

Travel to an LMIC significantly impacted intestinal microbiota. Individuals with high pre-travel proportions of Ruminococcaceae and Coprococcus spp. acquired a greater DEC pathotype diversity. However, no specific pre-travel microbiota profile was identified as protective against or predisposing to TD or acquisition of MDR bacteria.