Increased global travel may be contributing to the spread of antibiotic resistant genes, according to a Swedish study.
Supposedly healthy travellers may pick up bacteria with resistant genes and move them "very long distances," the researchers say.
The findings come from a study of a group of 35 exchange students who travelled from Sweden to India and central Africa.
None of the students took antibiotics – and yet analysis found increases in resistance of up to seven times among their gut bacteria.
The research used a technique called metagenomic sequencing to sequence every resistance gene found in the student microbiomes.
Performed before and after their expeditions, this showed a 7.7 times increase in genes resistant to trimethoprim and 2.6 times increases in resistance to sulfonamide and to beta-lactams.
The findings have been published in Antimicrobial Agents and Chemotherapy.
The research also found an increase in genes for an enzyme which dismembers penicillin, extended spectrum beta-lactamase. This was in one student at the outset – but was found in 12 when they returned.
Researcher Dr Anders Johansson, of Umeå University, Sweden, said: "We hypothesised that the gut microbiome of humans serves as a vehicle for moving many different resistance genes very large distances, even in the absence of antibiotic treatment."
He added: "Currently, I head an infection control department, and from this position it is very evident that resistance is no longer generated primarily in the hospital."
Antimicrobial Agents and Chemotherapy 10 August 2015 [abstract]

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