{"id":2581152,"date":"2021-06-11T13:42:19","date_gmt":"2021-06-11T17:42:19","guid":{"rendered":"https:\/\/www.futurity.org\/?p=2581152"},"modified":"2021-06-14T12:09:53","modified_gmt":"2021-06-14T16:09:53","slug":"superbugs-international-travelers-antimicrobial-resistance-2581152","status":"publish","type":"post","link":"https:\/\/www.futurity.org\/superbugs-international-travelers-antimicrobial-resistance-2581152\/","title":{"rendered":"International travelers carry ‘superbug’ stowaways"},"content":{"rendered":"
Carried like stowaways in the guts of international travelers, new and potentially deadly strains of antimicrobial resistant superbugs may be coming to a community near you, according to a new study.<\/p>\n
“Even before the COVID-19 pandemic, we knew that international travel was contributing to the rapid global increase and spread of antimicrobial resistance,” says Alaric D’Souza, an MD\/PhD student at Washington University in St. Louis. “But what’s new here is that we’ve found numerous completely novel genes associated with antimicrobial resistance that suggest a worrisome problem on the horizon.”<\/p>\n
The research confirms that international travelers often return home with an unexpected bounty of new bacterial strains jostling for position among the thousands that normally reside within the gut microbiome<\/a>.<\/p>\n Poverty, poor sanitation, and changing agricultural practices have turned many low-income, developing regions into hot spots for diseases spread by bacteria, including infections that are increasingly resistant to a range of antibiotic drug treatments.<\/p>\n High-population densities make it easy for these bacteria to be shared among community residents and travelers through exposure to contaminated drinking water and food, or poorly sanitized restrooms, restaurants, hotel rooms, and public transportation. Back at home, travelers run the risk of transferring these novel bacteria to family, friends, and other community residents.<\/p>\n The research, conducted with Maastricht University in the Netherlands, involved analyzing bacterial communities in the gut microbiomes of 190 Dutch adults before and after travel to one of four international regions where the prevalence of resistance genes is high: Southeastern Asia, South Asia, North Africa, and Eastern Africa.<\/p>\n Researchers randomly selected and analyzed fecal samples from a larger, multicenter investigation of about 2,000 Dutch travelers, the majority of whom were tourists, known as the Carriage Of Multi-resistant Bacteria After Travel (COMBAT) study.<\/p>\n “We found significant travel-related increases in the acquisition of resistance genes, abundance, and diversity encoded by bacteria that are endemic to the region visited,” says D’Souza, lead author of the paper in the journal Genome Medicine<\/a><\/em>.<\/p>\n “These findings provide strong support for international travel<\/a> as a vector for the global spread of clinically important antimicrobial resistance genes and highlight the need for broader surveillance of antimicrobial resistant bacteria in the gut microbiomes of returning travelers.”<\/p>\n Co-senior authors John Penders, a medical microbiologist at Maastricht University, and Gautam Dantas, professor of pathology and immunology at Washington University designed the study. Manish Boolchandani, a member of the Dantas Lab during the research and a 2020 graduate of the university’s doctoral program in computational and systems biology, is also a first author of the paper.<\/p>\n The World Health Organization, the US Centers for Disease Control and Prevention, and other agencies have described the rapid spread of antimicrobial resistance as one of the most serious public health threats now facing the world\u2014a looming medical catastrophe that could outweigh the chaos created by the COVID-19 pandemic.<\/p>\n “While previous studies have scanned travelers’ stool samples for well-known antimicrobial resistant bacteria<\/a>, we used a combination of whole metagenome shotgun sequencing and functional metagenomics to identify both known and novel genes that code for antimicrobial resistance,” Dantas says.<\/p>\n More traditional genomic techniques look for distinctive genetic signatures of individual pathogens. But such tests can only find known pathogens, while metagenomic sequencing can identify all organisms present in a given sample: good bacteria, dangerous bacteria, and even those that are completely new.<\/p>\n In all, the researchers detected 121 antimicrobial resistance genes across the gut microbiomes of the 190 Dutch travelers. More than 40% of these resistance genes (51 of them) were only discovered using the more sensitive metagenomics technique, suggesting that the more conventional approaches are missing potentially dangerous genes.<\/p>\n Equally concerning, the study’s results confirmed that 56 unique antimicrobial resistance genes had become part of the travelers’ gut microbiomes during their trips abroad, including several mobile, high-risk resistance genes, such as extended-spectrum \u03b2-lactamases (ESBL) and the plasmid-borne colistin resistance gene,\u00a0mcr-1.<\/p>\n Resistance to beta-lactam<\/a> antibiotics is emerging worldwide and confers broad resistance to treatment by penicillins and other important antibiotics.<\/p>\n The\u00a0mcr-1\u00a0genes protect bacteria from another antimicrobial drug called colistin, which is the last-resort treatment for infections by multidrug-resistant gram-negative bacteria. If colistin resistance spreads to bacteria that are resistant to other antibiotics, those bacteria could cause truly untreatable infections, the CDC has warned.<\/p>\n Because metagenomic analysis allows researchers to study all the bacteria and genes in a collection of gut microbiome samples as one large mixed community of organisms, it also provides opportunity to explore complex ecological interactions between these organisms.<\/p>\n While bacteria may slowly evolve resistance from repeated exposures to antibiotics over time, diverse bacterial communities also share antimicrobial resistance genes through a more rapid process known as horizontal transfer, usually via the exchange of mobile genetic elements that allow snippets of DNA to jump from one bacterium to another.<\/p>\n “Since genes that code for resistance to different classes of antibiotics are often located on the same mobile elements, a single horizontal exchange has the potential to convert bacteria previously susceptible to antibiotics into a multi-drug resistant organism,” Dantas says.<\/p>\n Researchers also used metagenomic techniques to piece together important contextual information about resistance gene location and function.<\/p>\nBroader surveillance needed<\/h3>\n
High-risk resistance superbugs on the move<\/h3>\n
International travelers bring superbugs home<\/h3>\n