Microbiota souvenirs can pass customs and spread antimicrobial resistance

A study by researchers at the University of Washington School of Medicine in St. Louis suggests that international travelers are bringing back superbugs with new and potentially deadly antibiotic resistance to the gut microbiota. I am. Scientists have worked with researchers at Maastricht University on the intestinal microbial flora of 190 Dutch adults before and after trips to Southeast Asia, South Asia, North Africa, and East Africa, where resistance genes are prevalent. Bacterial community was analyzed. The results confirmed that international travelers usually return home with an unexpected payload of thousands of new bacterial strains normally present in the gut microbiota.

“from before COVID-19 (New Coronavirus Infection) At the pandemic, we knew that international travel contributed to the rapid global increase and the spread of antimicrobial resistance, “said the team, a PhD / doctoral student at the University of Washington. Alaric D’Souza, co-lead author of the study, said. Genome medicine“But what’s new here is the discovery of a number of completely new genes associated with antimicrobial resistance, suggesting that there is a concern on the horizon.” D’Souza and colleagues. Explains the discovery in a treatise with the following title:Destinations shape the acquisition of antibiotic resistance genes, population growth, and diversity changes for Dutch travelers“

Antimicrobial resistance (AMR) is a major global public health threat, and resistant strains are currently disabling antibiotics and limiting treatment options, the authors write. International agencies, such as the US Center for Disease Control and Prevention, describe the rapid spread of antibiotic-resistant strains as one of the most serious public health threats facing the world today. “The global spread of AMR threatens decades of success in treating bacterial infections with antibiotics,” the authors say.

Although AMR is rising worldwide, the team continued that there are significant geographical differences in the prevalence and type of resistant strains and their AMR genes. This is an impending medical catastrophe that can outweigh the turmoil caused by the COVID-19 pandemic. Low- and middle-income countries generally have a greater burden of endemic AMR than high-income countries. Poverty, poor hygiene, changing agricultural practices, and the abuse of antibiotics on people and livestock have made many developing regions hotspots for bacterial spreads.

“Travel abroad may facilitate the transfer of resistant strains and AMR genes from endemic areas to other parts of the world,” scientists said. Overcrowding in endemic areas exposes contaminated drinking water and food, or poorly disinfected toilets, restaurants, hotel rooms, and public transport to these AMR bacteria to community residents and travelers. Investigators pointed out that it is becoming easier to spread. And when people return home from a trip, they run the risk of transferring these new bacteria to family, friends, and other local residents. However, scientists said, “Travelers returning home are rarely tested for resistant strains or the AMR gene unless they show clinical symptoms. Therefore, the risk of acquiring the AMR gene by traveling abroad is still high. Not confirmed. “

Traditional genomic techniques look for characteristic genetic features of individual pathogens, but sometimes only known pathogens can be found. In contrast, metagenomic sequencing makes it possible to identify all organisms present in a particular sample, the role of the human microbiome as an AMR reservoir, and how this role is affected by international travel. Provides new insights about. “All DNA extracted using shotgun metagenomic sequencing can be sequenced and the AMR genes within these shotgun metagenomics can be directly sequenced by mapping reads to a select AMR gene database. Can be identified “

In a new study, the team used techniques such as shotgun sequencing of the entire metagenomics and functional metagenomics to determine the amount and diversity of the AMR gene in the fecal microflora of 190 Dutch before and after their trip to the Netherlands. , Function, resistant bacterial structure, and context were investigated. Various international places. Fecal samples analyzed as part of the study were randomly selected from a large multicenter survey of approximately 2,000 Dutch travelers, most of whom were travelers and post-travel multiresistant strains. Known as COMBAT research.

The study was co-designed by Dr. John Penders, a medical microbiologist at Maastricht University, and Dr. Gautam Dantas, a professor of pathology and immunology at the University of Washington. Dr. Manish Boolchandani, a member of the Dantas Institute during his research and who completed his PhD in Computational Systems Biology at the University in 2020, is also the lead author of this treatise.

Their analysis detected 121 antimicrobial resistance genes throughout the intestinal microflora of 190 Dutch travelers. Over 40% of these resistance genes (51 of which) were found only using more sensitive metagenomics techniques. This suggests that potentially dangerous genes are missed by more traditional approaches. “In previous studies, we have scanned well-known antibiotic-resistant strains in traveler’s stool samples, but we have combined shotgun sequencing of the entire metagenome with functional metagenomics to combine antibiotic resistance. We have identified known and novel genes that code for, “says Dantas.

D’Souza added: These findings strongly support international travel as a vector of the worldwide spread of clinically important antimicrobial resistance genes, and broader surveillance of antimicrobial resistant bacteria in the intestinal microflora of returning travelers. It highlights the need for. Interestingly, the team further commented: “… Travel-induced formation of intestinal resistance membranes correlates with geographical destinations, so individuals returning to the Netherlands from the same destination country may have similar resistance membrane characteristics. It got higher. “

Of particular concern, the results of this study confirmed that 56 unique antimicrobial resistance genes were incorporated into the intestinal microflora of travelers while traveling abroad. It contains several highly mobile and high-risk resistance genes, such as the extended spectrum β-lactamase (ESBL). A plasmid-mediated colistin resistance gene, mcr-1. Resistance to beta-lactam antibiotics has emerged worldwide, providing widespread resistance to treatment with penicillin and other important antibiotics.

The mcr-1 gene protects the bacteria from another antibacterial drug called colistin. Colistin is the last resort for infections with multidrug-resistant Gram-negative bacteria. The CDC warns that if colistin resistance spreads to bacteria that are resistant to other antibiotics, those bacteria can cause truly untreatable infections.

Metagenomic analysis allows researchers to study all bacteria and genes in a collection of gut microbiota samples as one large mixed organism population, thus exploring complex ecological interactions between these organisms. Opportunities to do so are also provided.

Bacteria can gradually evolve resistance from repeated exposure to antibiotics, but diverse bacterial communities are usually mobile genetic elements that allow fragments of DNA to jump from one bacterium. Through exchange, through a faster process known as horizontal gene transfer, the antibacterial resistance gene is shared by another. “Genes that encode resistance to different classes of antibiotics are often located on the same moving element, so a single horizontal exchange can replace previously antibiotic-sensitive bacteria with multidrug-resistant organisms. May be converted to, “says Dantas.

Researchers also used metagenomic technology to stitch together important contextual information about the location and function of resistance genes. “There is a significant association between resistance genes and mobile genetic elements, and it is the main way resistance genes spread among bacteria,” said D’Souza. “In our study, resistance genes are carried by pathogens. It was not possible to show that this is possible, but it is clear that this is possible. In addition, international travelers may introduce resistance genes into their communities upon return, which is a possibility. Future research that works directly is a priority. “

The authors, “Our results show that international travel causes significant disruption to intestinal resistance, including the acquisition of the AMR gene for last resort antibiotics and the AMR gene with the mobility gene component. It reveals destination-specific changes to traveler resistance, such as co-localization of … The current AMR-infested burden on low- and middle-income countries is the acquisition of the traveler’s AMR gene. May be reduced. “

Dantas added: “Identifying new antibiotic-resistant strains and genes may play an important role in slowing the global spread of resistant strains and guiding potential treatments for related diseases. Research lays the foundation for these efforts by providing new insights into the underlying genetic mechanisms that rapidly acquire and share antimicrobial resistance genes throughout people’s intestinal microflora during international travel. “