Antimicrobial Resistance in Antarctic Soils

The 21st century has been known as an age of both good, and bad change. The development of modern technology and advanced medicine has allowed for longer, more luxurious lives for many people. However, the threat of climate change, due to the combination of the exhaustion of the planets’ natural resources and the emission of greenhouse gases from man-made sources, has weighed heavily on our society. Scientists fear that with warming temperatures and rising sea levels, ice from the poles will melt and reveal ancient bacteria that have long since been locked away for hundreds of years. To add to that threat, antimicrobial resistance (AMR) is now one of the most pressing health crises plaguing our world. Being the cause of over 30,000 deaths annually with little to no treatment options, there is a push amongst scientists to better understand the origin, evolution and spread of AMR. This push is causing researchers to study the environment in remote regions of the planet, to assess how encompassing this concern really is. It is known that AMR can be found in both water and soil from natural and man-made sources, creating a perfect model for the severity of the spread of AMR. Researchers at The University of Chile sought to explore the impact and prevalence of AMR factors in the Antarctic Peninsula soil. By surveying the inhabited and non-inhabited islands of the peninsula, they can investigate the extent of human contribution to the AMR crises, as well as, explore the vast microbial diversity that thrives in the harsh climate. These studies are particularly relevant in areas highly impacted by global warming, with soil exposure and ice melting exposing humans to newly emerging or reemerging diseases. First, the researchers took over 200 soil samples, isolated the bacteria within, and tested their resistance to 15 commonly used clinical antibiotics. 7 of the antibiotics had significant resistance, with a 3-6-fold increase in non-inhabited areas. This suggests that human contribution is not the main driver of AMR in this region. The only exception was the antibiotic ciprofloxacin, which had a 10-fold increase of resistance in inhabited areas. The researchers also found that 50 isolates were resistant to 4+ antibiotics, mainly collected from non-inhabited areas. Even more astounding was the fact that 31 isolates were found to be resistant to 7+ antibiotics, also from non-inhabited areas. Although this data shows many multiresistant bacteria are thriving in these remote soils, it is important to note that human intervention does not seem to be the main driver for the presence of these resistant bacteria. This resistance may be due to a natural and likely ancestral process of evolution, one meant to aid in the bacteria’s ability to grow in changing environments. To further uncover the genetic factors playing a role in the multiresistant bacteria, the researchers selected 2 Pseudomonas strains that were found to be resistant to 9+ antibiotics. One of these strains contains a mobile element that can be easily transferred between neighboring bacteria and could be a key player in the spread of AMR. Through genetic analysis of these strains, they found a high number of matches corresponding to genes encoding pumps and transporters, that likely aid in resistance. Understanding what genes are playing a part in the resistance, helps scientists look for new ways around this problem.

In the end, the researchers classified the diversity of organisms in the Antarctic Peninsula that carried AMR. They found that around 13% of the samples were resistant to 7 or more antibiotics, and have determined potential genes that play a role in this multiresistant trait. The researchers demonstrated that the resistance found in these soils likely stems from natural evolution, and humans do not play a large role in the spread of AMR in this study. Additionally, this work can be used as a guide to compare the possible human contribution of AMR in these habitats. The research of AMR in the Antarctic Peninsula provides relevant information on the impacts of ice melting and soil exposure due to global warming and how this affects the abundance and spread of resistance genes.