Gut Microbiota Dynamics in Travelers Returning from India Colonized with Extended-Spectrum Cephalosporin-Resistant Enterobacteriaceae: a Longitudinal Study

Intestinal colonization by extended-spectrum cephalosporin-resistant Enterobacteriaceae (ESC-R-Ent) in healthy volunteers has been attributed to travel to high prevalence countries. However, the effects of traveling and ESC-R-Ent colonization on the human gut microbiota are unknown. We aimed to characterize the microbiota of volunteers traveling to India and correlate it with potential colonization status shifts.Forty volunteers living in Switzerland underwent screening before and after a trip to India, and also 3, 6 and 12 months after traveling. ESC-R-Ent screening and microbiota analysis based on 16s rRNA high throughput sequencing was performed at all time points Colonization before traveling was 10%, rising to 76% after traveling. Colonization decreased over time, as rates of 33%, 26% and 18% were reported at 3, 6 and 12 months, respectively. The Shannon Diversity Index was lower in colonized individuals (P=5.6e-5) and after travel (P=0.023). The overall microbial community was affected in colonized compared to non-colonized individuals (Jaccard index, P=0.002, variance adjusted weighted UniFrac P=0.025). Hierarchical clustering grouped individuals into three different clusters. Individuals remained in the same cluster overtime and this was not influenced by travel (P=0.53) or colonization status (P=0.31).