Antibiotic resistance owing to overuse of antibiotics is a growing problem worldwide. A new study has revealed that not just antibiotic overuse, but even traveling can make people vulnerable to antibiotic resistance if they eat contaminated food and water containing resistant bacteria.
The research team found that Swedish exchange students who studied in India and in central Africa returned from their sojourns with an increased diversity of antibiotic resistance genes in their gut microbiomes even though none of the students took antibiotics either before or during the travel period. These resistance genes were not particularly abundant in the students prior to their travel period, but the increases are nonetheless quite significant.
The researchers said, "The increase seen in resistance genes could have resulted from ingesting food containing resistant bacteria, or from contaminated water." Anders Johansson from Umea University in Sweden said, "We asked students going abroad on exchange programs to provide a sample of their feces before and after traveling."
The use of metagenomics sequencing, a modern method, enabled the team to sample the entire microbiome of each student, and to sequence every resistance gene therein, rather than focusing on resistance genes in those few bacterial species that grow well on culture plates. The investigators found a 2.6-fold increase in genes encoding resistance to sulfonamide, a 7.7-fold increase in trimethoprim resistance genes, and a 2.6-fold increase in resistance to beta-lactams, all of this without any exposure to antibiotics among the 35 exchange students.
The research was published in Antimicrobial Agents and Chemotherapy.