Widespread antibiotic resistance found across 71 environments, including oceans, soil and human feces
By Pat Hutchens, The Conversation
Resistance to commonly used antibiotics are in the genes of bacteria everywhere, researchers at the University of Lyon in France have discovered.
A worldwide study of the gene sequences of bacteria, published in the journal Cell Biology today, has found resistance across 71 environments, including oceans, soil and human feces.
The researchers analysed gene samples from public repository websites.
Lead author of the study, Joseph Nesme, said while the finding that antibiotic resistance exists in the environment is not new, the results showed they were present in considerable abundance.
They found that 30 % of total known antibiotic drugs resistance genes could be found in a single soil sample.
“Such results reinforce models that consider the environment as a major reservoir of antibiotic resistance that can be transferred to pathogens,” he said.
Bacteria are known to borrow foreign DNA from their cell environment.
Professor of Infectious Diseases and Microbiology at Australian National University Peter Collingnon said it showed we have to be very careful about where we dispose of antibiotics and resistant bacteria.
“The proper way is making sure we have drugs that have shorter half lives so that they disintegrate and don’t persist in the environment for long periods of time,” he said.
But many of the antibiotic resistant genes found in the microbial communities during this study pre-date the industrial use of medicines.
According to Nesme, this is because most natural antibiotics are derived from soil microorganisms.
“There are still many antibiotic molecules to be found inside this overall environmental diversity,” he said.
Professor Collingnon said this is likely to mean there are new antibiotics that we haven’t found.
“That’s actually how we have found most antibiotics, by looking at natural products and seeing how they inhibited bacteria,” he said.
Allen Cheng, Associate Professor of Infectious Diseases Epidemiology at Monash University, said it’s not really a surprise that there are antibiotic resistant genes in nature because that’s how other organisms defend themselves.
“This [study] really is a survey of all the weapons that are out there. It’s sort of like an inventory of bacterial weaponry and all the defences they might have. It gives us an idea of what bacteria might use to combat antibiotics in the future,” he said.
“I think what this paper doesn’t really tell us is which of these mechanisms is important. Most of them we’ve seen before in some form, but if you use an antibiotic it doesn’t say which of these mechanisms are likely to become the next dominant problem,” Professor Cheng said.
Professor Collingnon said the real problem was that there aren’t really financial rewards, particularly for pharmaceutical companies, to go looking for new antibiotics.
“This is because antibiotics are the one drug that actually cures something. What pharmaceutical companies want is to develop drugs that you, and preferably 20% to 30 % of the population, have to take forever,” he said.
Professor Collingnon said from a research point of view, there were more opportunities to look for new antibiotics using molecular techniques.
“We can also do some of the more basic things we did 30, 40 or 50 years ago. This is where we look at a whole lot of things, either in insects, jungles or soil, and see what products are there that are maybe the antibiotics that we don’t know about yet,“ he said.