World travellers often import multi-resistant gut bacteria

People who travel to distant destinations often take multi-resistant intestinal bacteria back home as a souvenir. These are bacteria that are not (any longer) sensitive to the usual antibiotics. This is shown by recent research by microbiologists from Maastricht University. The study also found that travelers returning from Southeast Asia are the most likely to import multidrug resistant bacteria, including bacterial species that have built up resistance to virtually any type of antibiotic. The results were published today in the scientific journal Genome Medicine.

Multi-resistant bacteria

A team of scientists from Maastricht University and Washington University in the United States examined the digestive system of 190 Dutch travelers for the presence of antibiotic-resistant (AMR) genes. The researchers did this by analyzing poo samples from travelers before and after their visit to areas in Africa and Asia. A healthy microbiome contains bacteria and other microorganisms that live in the human digestive tract. AMR genes have evolved naturally in such gut bacteria over thousands of years through exposure to antibiotics naturally produced by environmental bacteria. Modern misuse and overuse of antibiotics in healthcare and livestock is accelerating this process. Multi-resistant bacteria therefore no longer respond to treatment with antibiotics to which they have become resistant. The researchers found not only an increase in the amount and diversity of AMR genes in stool samples from return travelers, but also high-risk AMR genes that even offer resistance to so-called 'last resort antibiotics'. These are antibiotics that are used when all other types of antibiotics have stopped working.

Risk area

Six of the ten identified high-risk AMR genes were present in the gut after travel, but not before. It means that they can only have been obtained while traveling. For example, the MCR-1 gene was only found in poo samples from returned travelers. This gene confers resistance to colistin, a last resort for infections such as pneumonia and meningitis. The researchers found the MCR-1 gene mainly in the gut microbiome of people who had traveled to Southeast Asia. “Multi-resistant bacteria are one of the biggest public health problems worldwide in the near future,” said study leader John Penders, affiliated with the Department of Medical Microbiology at Maastricht University. “Estimates indicate that by 2050, more people may die from infections caused by multidrug resistant microorganisms than currently from cardiovascular disease or cancer. In the Netherlands, the risk of infection with multi-resistant bacteria is relatively small. However, it is important to take resistance into account if someone happens to develop an infection, such as a bladder infection, shortly after returning from a long journey. Certainly when it concerned a trip to a risk area.”

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