By Ananya Sen
A straight walk from India to the Arctic is approximately 4,000 miles. The trip includes the hot and humid climate of India, the temperate and dry climate of central Europe, and finally the rugged and frozen tundra of Svalbard in the Arctic Circle. Imagine embarking on this adventure as a gene. Seem unlikely? Yet, a recent study from a team of researchers led by David Graham at Newcastle University describes a gene from a superbug that has made the journey.
Superbugs are bacteria that have developed resistance to most antibiotics; they remain unaffected by the antibiotics that have been designed to kill them. Bacteria that produce carbapenemases are commonly referred to as “superbugs” since carbapenems are drugs that are used as a last resort after all other options have been exhausted. Bacteria evolve to resist the overused antibiotics and can spread the mechanism of resistance to other bacteria, generating several different types of superbugs. Unfortunately, the more we overuse or misuse antibiotics, the more opportunities pathogens have to become superbugs. Increased geographical mobility of these bacteria will only make things worse.
How did these researchers find antibiotic resistance genes in the Arctic? The work stemmed from investigations of the methane release due to microbial activity in thawing permafrost. The researchers sampled 40 different soil types along the coastline bordering the Arctic Ocean. When they sequenced the soil samples, the researchers discovered 131 antibiotic resistant genes, one of which was the gene for the carbapenemase, blaNDM-1.
This gene was first detected in 2007 in a hospital patient in India. The same gene was also found in surface waters in urban India in 2010. The other antibiotic resistance genes included those that conferred resistance to aminoglycosides and b-lactams. Some of those genes were not “local” to the Arctic, meaning that they had been carried there from more distant lands.
The highest concentration of these “foreign” genes was found near fresh water sources teeming with wildlife. This observation prompted the scientists to hypothesize that humans, birds, or a combination of the two served as vehicles for bacterial gene mobility. Graham’s group had previously found that the blaNDM-1 genes were abundant in India particularly in areas with poor sanitation. The bacteria could have easily contaminated local food and water supplies allowing their dispersal. Unsurprisingly, these genes are now being detected in many countries around the globe.
Combating antibiotic resistance involves three approaches: preventing the evolution of superbugs by reducing antibiotic use, developing alternative methods to fight infections, and improved sanitation and water quality worldwide. For example, Svalbard is located north of Norway, which has one of the lowest incidences of antibiotic resistance because of its rigorous sanitation practices. Even so, it is not immune to the spread of antibiotic resistance that can arise from other country.
Ananya Sen is currently a graduate student in Microbiology at the University of Illinois at Urbana-Champaign. When she’s not studying oxidative stress, she is busy pursuing her passion for scientific writing. Currently she contributes articles to ASM, ScienceSeeker, and her own blog where she discusses the history of various scientific processes.
