Today, the World Health Organization (WHO) published a list of 12 antibiotic-resistant bacteria that pose the greatest threat to human health. On it? A bunch of bacteria that have become resistant to modern antibiotics used to treat people who get sick from them including several bacteria resistant to one of our last resort drugs, carbapenem. The bacteria listed overlap with the previously published CDC list where eight of the 18 antibiotic resistant bacterial threats have been detected in the U.S. food supply (see chart below).
This is the latest reminder that we are in danger of running out of antibiotics that to treat serious and deadly infections. We are setting medicine back to the turn of the 20th century when simple infections could maim or even kill. To change the course, we must curtail overuse and misuse of antibiotics not only in human medicine but in the livestock industry, where more than 70 percent of medically important antibiotics in the US are sold.
In Maryland, there is legislation pending that would do just that. The Keep Antibiotics Effective Act of 2017 is a critical bill that would address the overuse of antibiotic in the livestock industry by ensuring they are used only when animals are sick and not as a primary tool for preventative health.
Taking action like this at the state level is critical because current federal policy still allows for routine low dose, long term use of antibiotics in the absence of disease, a practice that fuels antibiotic resistance.
The bill in Maryland would also collect certain data on antibiotic use. We need better, more refined data on antibiotic use to track what happens after the Keep Antibiotics Effective Act becomes law, to confirm its having the big public health benefit that is hoped for it. That’s exactly the kind of data that will result from the law.
It’s more important now than ever to act: We know more than ever about antibiotic resistance threats on the farm. There are still surprises, however, and a few lines of evidence suggest that we have been underestimating the antibiotic resistance in our food supply.
For the longest time, scientists looking for resistance amidst a “haystack” of bacteria have examined one straw or needle—one bacterium—at a time. Find and test a few needles, or so went the thinking—and you’d have enough by which to judge the entire haystack. But what if you could look for resistance in the whole haystack at once? It turns out that is exactly what scientists have begun doing with cutting-edge DNA sequencing technology. In one fell swoop, they can look for drug resistance among the bacteria contained in a sample of food, river water or pig manure. Looking at the whole haystack has uncovered collections of previously undetected resistance genes in these farm environments.
In one of the latest reported studies scientists were given unprecedented access to look for resistance to last resort drugs (colistin and carbapenems) in all sorts of environments in China—on commercial farms and in slaughterhouses, on flies, dogs and farmers, and in supermarkets. Using the haystack approach, they found much higher levels of resistance everywhere they looked. That suggests that resistance is much more prevalent everywhere, including on or associated with farms. Previously we just hadn’t been very good at looking.
Farm-associated superbugs, in fact, also may be more diverse than previously thought. Most attention has been focused on resistance among only the two bacteria most commonly thought of in terms of bacterial food poisoning: Salmonella and Campylobacter. We, along with colleagues at the Food Animals Concern Trust, reviewed the scientific literature and we found clear evidence suggesting that eight of the CDC’s 18 antibiotic resistant bacterial threats have been detected in the U.S. food supply (see chart below). Also, five of the nine listed below have resistance profiles that clearly overlap with WHO’s recently announced list of global resistance threats. In the US, many of these bacterial threats are either not captured by the current food system surveillance or rely on older testing (i.e. only looking at the needles, not the haystack).
Table: Resistant Threats and Food Animals
Detected in U.S. food Animals
Detected in retail meat (US or globally)
On CDC threats list
Carbapenem-resistant Enterobacteriaceae (CRE)
Extended spectrum Beta-lactamase producing Enterobacteriaceae (ESBLs)
Vancomycin-resistant Enterococcus (VRE)
Multidrug-resistant Pseudomonas aeruginosa
Drug-resistant non-typhoidal Salmonella
Methicillin-resistant Staphylococcus aureus
Vancomycin-resistant Staphylococcus aureus
Bacteria don’t recognize borders between farms and communities and that antibiotic use in one location can have resistance consequences in another. The science backing this is only growing stronger. Major health organizations and agencies including the WHO and CDC have been sounding the alarm on the global need to curtail antibiotic use, including in livestock production to address antibiotic resistance that threatens public health. With this new list, WHO is reminding us again that action is needed now.
In light of the slow progress at the federal level, it’s up to the states to keep our miracle drugs working when sick people need them. Maryland’s Keep Antibiotics Effective Act of 2017 would take a powerful step forward to protect public health.