Wanderlust, antibiotic resistant genes, and gut bugs

Travelers beware: there’s a travel bug floating around, and it might actually make you think twice about your next adventure. In one recent study, researchers observed acquired antibiotic resistant genes in those traveling abroad after just two days.

Researchers previously revealed that certain antibiotic resistant genes might be passed from bacteria in a human gut while abroad. Over 100 travelers gave stool samples. Prior to leaving, a travelers gut was made up of less than 10 percent antibiotic-resistant genes. Upon returning, the travelers' antibiotic-resistant gene abundance increased to as high as 55 percent.

The team took daily stool and skin samples from seven different travelers from the Netherlands before, during, and after traveling to India, South Korea, China, Canada, and the Philippines to determine how quickly these antibiotic resistant genes are acquired.

After arriving at their destination, the travelers acquired the antibiotic resistant genes as quickly as 48 hours.

Researchers have concluded that international travel leads to high acquisition of antibiotic-resistance genes, but were surprised at how quickly they were acquired. In addition, researchers observed the genes for a prolonged period after travelers returned home.

Antibiotic resistant genes in tourists

The type of drug resistance acquired relied heavily on the destination. Within two days of reaching India, two travelers acquired qnrB, a resistant gene to quinolones, one of the world’s most often prescribed antibiotics for hospital-acquired pneumonia and other infections. The travelers’ microbiome retained the new genes for at least a month after they had returned home. In India, prevalent resistance to quinolones, which are manufactured and over-prescribed within the country, is well documented.

Two travelers visited South Korea and India and acquired CTX-M genes, which destroy penicillin, cephalosporins, and other related antibiotics. The number of people in South-East Asia carrying these genes has risen significantly in the last decade from two to 70 percent.

Don’t drink the water

The most likely source of new resistance genes found in travelers? Researchers believe the food and water that contain native bacteria are the most likely culprits. Researchers don’t believe that the travelers acquired the genes during their flights because of the nature of the study.

Antibiotic-resistant gene acquisition may also stem from poor sanitary conditions, which provide more opportunities for contamination than in the USA or Europe. The researchers’ results resonate with many previous studies that show travel increases risk of infection.

Healthy participants did not experience any serious consequences; however, researchers are more concerned about the consequences on immunocompromised people or those currently taking antibiotics. These patients might be more at risk of adverse outcomes.

New ongoing studies include observing whether these new resistance genes acquired by a traveler can be passed to family and friends.

Many questions arise from this research. Can it be replicated in a larger study? Other than antibiotic resistant genes, what other bugs do we catch when traveling? These results hint that travel may make your microbiome more diverse. Just the more reason to go on that next adventure, not spend the weekend at home!

References

von Wintersdorff, C.J.H., Penders, J., Stobberingh, E.E., et al. High Rates of Antimicrobial Drug Resistance Gene Acquisition after International Travel, the Netherlands. Emerging Infectious Diseases. 20(4):649-57. 2014. doi:  10.3201/eid2004.131718

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