Observing Microbiome Changes After Single-Dose Antibiotics for Traveler's Diarrhea

Segment Description: Mark Riddle, MD, DrPH, associate dean of clinical research, University of Nevada, Reno, associate chief of staff for research, VA Sierra Nevada Health System, speaks to Contagion at ACG 2019 about the results of a study looking into microbiome changes associated with single-dose antibiotics for the treatment of traveler's diarrhea.

Interview transcript (modified slightly for readability):

Riddle: We looked at subjects' stool functional microbiome before they got their treatment [single-dose antibiotics]. We looked at it seven days after. And then we looked at it at 21 days.

We didn't see a lot of change in the functional microbiome of those that were treated. There were some acute changes, but then they reverted around day 21. We also looked for measures of antibiotic resistance. We looked at a resistome, a compilation of all resistance genes that you can find in the stool, as well as some targeted genes that were specific to ESBL-producing Enterobacteriaceae. We didn't see any real increase of those as well.

Our main conclusions were that the study was small, but that we don't see major disturbances and major resistance acquisition with single-dose antibiotics. We didn't have a comparison group of a three day multi-dose regimen, and we didn't have a placebo group. Interpretations of our results have to be with caution.

But the amount of ESBL that we detected in this trial was much less than that's which has been seen in these observational studies. If you go to Africa, on average, 35% of travelers returning will have ESBL-producing E coli acquisition, we saw around 9%. Because we didn't see a lot of resistance acquisition, we couldn't really detect differences in the microbiome that would explain that.