A report released today by the United Nations says that we’ve neglected a major component of the superbug problem: the environment. It serves as a reservoir for bacterial genes that create antimicrobial resistance, and it receives farm run-off and pharmaceutical effluent that let new resistance emerge.
“The same drivers that cause environment degradation are worsening the antimicrobial resistance problem,” Inger Andersen, executive director of the UN Environment Programme, known as UNEP, said in a statement. “The impacts of antimicrobial resistance could destroy our health and food systems.”
The 120-page policy document, “Bracing for Superbugs,” recognizes the environment as a place where antibiotic resistance both arises and wreaks havoc, causing as many as 1.27 million deaths per year. It’s a problem that public health planners have already recognized for hospitals and urgent care centers, as well as farms that produce livestock, fish, and crops. The report gives researchers a framework for understanding pathogens that don’t stay confined within those economic sectors, such as resistant bacteria that appear downstream of hospital sewage plants and agricultural fungicides that transform common hospital infections into untreatable ones. It says that governments should write regulations to curb antibiotic pollution, lean on food producers to reduce antibiotic use, improve sanitation systems to remove resistant bacteria from sewage, and create monitoring programs to verify whether environmental protections are working.
Practically speaking, it elevates UNEP as a leader in the global struggle to control resistant bacteria, connecting it to other UN agencies—the World Health Organization, World Organization for Animal Health, and Food and Agriculture Organization—in a “One Health” approach linking human, animal, and environmental concerns. That’s significant, because nations are already developing plans for controlling antibiotic resistance via a UN process that began in 2016. Now countries are being urged to consider environmental protection as they try to reduce resistant infections in people.
It’s a long-overdue move that reframes the superbug problem, transforming it from an issue created by misbehaving users to a shared responsibility for an imperiled planetary microbiome.
“The environment is the one thing that connects the different sites of selection for antimicrobial resistance in a meaningful way,” says Claas Kirchhelle, a historian of science and medicine and an assistant professor at University College Dublin. “And long term, it’s where stewardship of antimicrobials should be heading, not just over the next two to three years, but 20 to 30.”
It seems remarkable that the role of the environment has been neglected until now, given that the first antibiotics were refined from the products of organisms found in nature. Yet two years ago, when Kirchhelle and researchers from six other countries looked through 75 years of international policy statements on drug resistance, they found only two—out of 248—in which the environment merited sustained concern. “It was legitimate to think of this solely from a human health perspective—after all, people die from AMR in the millions,” he says, referring to antimicrobial resistance. “But we’ve been talking about how to regulate AMR for half a century, yet we still have rising antimicrobial usage and rising antibiotic resistance. So it is time to really think broader.”
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Complicated diagrams in the UNEP report show that both resistant bacteria and raw antibiotics and fungicides enter the environment from many points: hospital sewage, manufacturing effluent, crop spraying, livestock feed. Once in the environment, antibiotics and fungicides can affect organisms that are already present. In addition, as resistant bacteria enter the environment from those other sources, their genes can break loose and get taken up by other organisms, or be altered by exposure to soil microbes wielding defensive compounds of their own. Any of those changed or strengthened pathogens then can be transported along many pathways—the migratory flights of birds, the travel patterns of wildlife, or the routes of surface waters or high-altitude winds—to end up back in the human world.
“It’s important to recognize the very different roles the environment plays” in fostering resistance, says Joakim Larsson, a professor of environmental pharmacology at the University of Gothenburg in Sweden who coauthored a comprehensive review of the problem last year and advised the UNEP project in its early stages. “The environment is a route for transmission of resistant bacteria, that's clear. But what’s underappreciated is that the environment is a source of resistance. If we look at the resistance genes that we have in bacterial pathogens, they came from somewhere—and that was, in some way, through interaction with environmental bacteria.”
Understanding that the environment was always the source of genes that bacteria used to defend themselves—which we renamed “drug resistance” when we adopted their chemical weapons as our own—suggests that this resistance can’t be eradicated. But it can perhaps be reframed. If we can recognize that even necessary antibiotic prescriptions will nuke our gut flora, we ought to be willing to protect the biodiversity of the global bacterial environment as well.
Preserving that balance has not received enough attention. Case in point: Despite several years of concern and protests, the US Environmental Protection Agency has authorized spraying Florida citrus groves with more than 650,000 pounds of streptomycin—about 46 times what the US gives to medical patients each year—in a last-ditch effort to control citrus-greening disease. “The EPA has not properly studied what this will do to antibiotic resistance in the environment, but any public health expert can guess it’s not going to be a good result,” says Matt Wellington, public health campaigns director for the nonpartisan nonprofit US PIRG, which is part of a coalition suing to stop the spraying. “The pathways by which drug-resistant bacteria get to people are through the environment: the soil, the water, the air.”
If this starts to sound like a tragedy of the commons—the destruction of a shared thing that everyone uses and no one takes responsibility for—well, that would not be wrong. The solutions to such a tragedy are regulation and restraint, and in terms of antimicrobial use, those may be having an effect. A new analysis of global antibiotic use in livestock (which, in volume, far outstrips medical human use) reveals that it has declined in Europe and China, due to new regulations, since an international assessment made in 2015. But globally, agricultural antibiotic use is still increasing; the team projects it will rise to 107,472 metric tons by 2030. And only 43 countries in the world disclose their farm-drug sales.
“You can’t be serious about creating accountability without transparent country-level reporting,” Thomas Van Boeckel, the lead author of the new analysis and an assistant professor of health geography at the University of Gothenburg, told WIRED by email. It’s one example of the data that will have to be produced—and the responsibilities that will have to be faced—for our shared microbial commons to be preserved.