The new study shows that considerably more types of resistant bacteria than we were previously aware of are present in our intestines when when returning from intercontinentaltravel. The result can be an increase in intractable infections.
“We can ingest resistant bacteria through the food and water in the countries we visit. The resistant bacteria can spread without us becoming ill and noticing them, and the bacteria therefore move quickly across borders,” says Joakim Larsson, Professor in Environmental Pharmacology at the Sahlgrenska Academy, University of Gothenburg, and one of the co-authors of the study.
Resistance genes in the intestines
By sequencing DNA from bacteria in stool samples of 35 Swedish students who had travelled to India and Central Africa, the researchers found that resistance genes had become enriched in their intestines during the trip. In addition, there was an increase in the genes that contribute to moving DNA between bacteria, which may further boost the speed and scope of the spread.
“The fact that so many different genes had increased in number after the trip is worrying, given that none of the people we studied had taken antibiotics. This suggests that it is enough to stay in an environment with a worse resistance situation than in Sweden to aquire resistant bacteria,” says Johan Bengtsson-Palme, doctoral student at the Sahlgrenska Academy and first author of the study.
Good hygiene is essential
An estimated 700,000 thousand people are infected by antibioticresistant bacteria each year. In order to avoid a runaway resistance epidemic, Sweden and the rest of the world must become better at dealing with this problem, and earlier this year antibiotic resistance was top of the agenda at the WHO World Health Assembly.
“Our results suggest that it is not only the overuse of antibiotics that is responsible for the dramatic increase in resistance. Since resistance can spread by healthy people, hygiene is very important in order to limit spread,” says Anders Johansson, Associate Professor of Infectious Diseases at Umeå University and director of the study:
“Infections are often caused by our own intestinal bacteria ending up in the wrong place, for example in the blood or in the urethra. An increased resistance in the normal intestinal flora is therefore a strong risk factor for diseases caused by resistant bacteria.”
According to the researchers, the current study shows that antibiotic resistance is no longer only a problem for healthcare. As good hygiene is likely to reduce the spread of resistant bacteria, efforts should be made to improve the standard of living in a global perspective, and more resources should be devoted to increasing knowledge on how to better prevent the spread of diseases and resistant bacteria.
The study The human gut microbiome as a transporter of antibiotic resistance genes between continents was published in the journal Antimicrobial Agents and Chemotherapy on 10 August.
Johan Bengtsson-Palme, doctoral student at the Sahlgrenska Academy, University of Gothenburg
Anders Johansson, Associate Professor of Infectious Diseases, Umeå University
Joakim Larsson, Professor in Environmental Pharmacology at the Sahlgrenska Academy, University of Gothenburg