While antibiotic-resistant bacteria are on the rise, the bacteria you might think could be deadly is mostly found where humans and other animals congregate: namely, the Earth’s surface. But researchers from Canada and France have found them in one most remarkable place.
At least 1.27 million people worldwide die each year from antimicrobial resistant bacteria and fungi, According to the Centers for Disease Control and Prevention. Fighting these superbugs is becoming increasingly difficult, although researchers are working on a number of new approaches, including the use of gold, self-assembling “nano-mesh” and shape-shifting antibiotics.
Because antibiotic-resistant microbes pose a major threat to public health, it’s critical to learn as much as possible about them and how they move around our planet. That’s what researchers at Université Laval in Quebec, Canada, and Université Clermont-Auvergne, France, set out to do when they investigated clouds floating around a dormant volcano in the Massif Central region of France. Working from a 1,465-meter (about 4,806-foot) weather station atop the Puy de Dôme, they took 12 cloud samples over a two-year period.
Not only did they find that the cloud contained about 8,000 bacteria per milliliter of water, but there were an average of 20,800 copies of antibiotic resistance genes in the same volume. They also noted that clouds reached by pathways over the ocean had different types of antibiotic-resistant bacteria — which had higher rates of resistance to antibiotics used in livestock — than clouds that passed only over land.
While the atmosphere has long been thought of as a transit point for bacteria, the researchers were surprised to find the same levels of genes in the clouds as they do on Earth’s surface.
“This is the first study to show that clouds contain antibiotic resistance genes of bacterial origin in concentrations comparable to other natural environments,” said Florent Rossi of Université Laval, first author of the study. “These bacteria typically live in vegetation or the surface of soil. They are atomized by wind or human activity, and some of them rise into the atmosphere and participate in cloud formation.”
The high concentration of antibiotic resistance genes in the cloud may be largely due to the use of antibiotics in livestock farming, the study authors said. Tracing the gene’s origin in future studies could help better contain these errors and could be a source of future research for the team.
“Our study shows that clouds are an important pathway for the spread of antibiotic resistance genes over short and long distances,” Rossi said. “Ideally, we’d like to find sources of emissions from human activities to limit the spread of these genes.”
The research has been published in the journal, overall environmental science.