Antibiotic-resistant bacteria found in clouds: study
For a team of Canadian and French researchers, dark clouds on the horizon are potentially ominous not because they signal an approaching storm – but because they were found in a recent study to carry drug-resistant bacteria over long distances.
When dark clouds gather, your innate scientific nature will remind you that the rain is about to fall.
However, scientists have made a new discovery related to the greying of clouds, and in a new study they say that such clouds could be carrying drug-resistant bacteria.
The study was carried out by Canadian scientists and published in the journal Science of the Total Environment.
The researchers say this new evidence shows that with the bacteria present in the cloud, the atmosphere has become a pathway for the spread of antibiotic resistance genes on a large scale.
"This is the first study to show that clouds harbour antibiotic resistance genes of bacterial origin in concentrations comparable to other natural environments," says Florent Rossi, one of the authors of the study and a professor at the Faculty of Science and Engineering at Université Laval.
The scientists took about 12 cloud samples from a dormant volcano in France called the Puy de Dôme summit. This was done at an atmospheric research station more than 1,400 metres above the ground. This was done over a period of two years using a technique called high flow rate "vacuum".
The results of the analysis showed that the cloud samples had an average of about 8,000 bacteria per millilitre of cloud water.
"These bacteria normally live on the surface of vegetation or soil. They are aerosolised by the wind or by human activities, and some of them rise into the atmosphere and participate in the formation of clouds," says Rossi.
Some of the human activities that scientists believe contribute to the transport of antibiotic resistance genes into the atmosphere include the use of antibiotics in agricultural practices and also as a form of medicine.
"Oceanic clouds and continental clouds each have their own signature of antibiotic resistance genes. For example, continental clouds contain more antibiotic resistance genes used in animal production," explains Rossi.
The researchers explain that not all clouds have the same amount of bacteria: some can have anywhere from 300 to more than 30,000 bacteria in every millilitre of cloud water. Of these bacteria, five to 50 per cent could be either alive or potentially active. About 29 subtypes of antibiotic resistance genes were found in the air.
"Our study shows that clouds are an important pathway for antibiotic resistance genes to spread over short and long distances. Ideally, we would like to locate emission sources from human activities to limit the spread of these genes."
Scientists have previously described antibiotic resistance as a "silent pandemic".
Scientists publishing their findings in The Lancet estimated that antimicrobial resistance can cause about 1.27 million deaths each year.
"If all drug-resistant infections were replaced by no infections, 4-95 million deaths could have been prevented in 2019, whereas if all drug-resistant infections were replaced by drug-susceptible infections, 1-27 million deaths could have been prevented," the Lancet study said.
At the time, six leading pathogens were identified, all of which have been highlighted by the World Health Organization.
According to the new study, the health effects of the spread of these antibiotic-resistant genes should be investigated in future research.
