Is Cow Manure Another Reason Why Our Antibiotics aren’t Working?

Groundbreaking research by U.S. scientists has found antibiotic resistant genes in cow manure. Could this be contributing to our rising resistance to antibiotics?

For a long time now, scientists have been aware of a number of antibiotic resistant genes. While usually benign, these genes could become a problem if they were ever to be adopted by bacteria that cause hospital infections, leading to superbugs that normal antibiotics can’t treat and, as a result, possibly life-threatening consequences.

Now Yale University researchers have identified 80 unique antibiotic resistant genes after testing dairy cow manure, and about three quarters of those genes weren’t previously known to science. This matters because dairy cow manure is often used as fertilizer in food growing, and so there is a real chance that those genes could reach bacteria, which create food-borne illnesses.

The study, which is published this month in mBio or the online open-access journal of the American Society for Microbiology, saw researchers use a sequencing technique to identify the genes. The researchers found that three quarters of the genes were only distantly related to genes that had already been identified, while they were also able to identify an entirely new gene family. The latter gene group would potentially create a resistance to a family of antibiotics known as chloramphenicol. This is an antibiotic that is often given to cattle in order to treat respiratory infections. When the researchers then exposed a laboratory strain of E.coli to the genes, they found that the E.coli then became resistant to the antibiotic.

Concerns have previously been raised about the use of antibiotics in agriculture and the impact and how they may increase drug resistance. Due in part to the incredibly poor welfare standards in which poultry are kept, it tends to be poultry that are fed an abundance of antibiotics to fight off disease, and food watchdogs have for a long time now said that this kind of practice will have consequences for human health. Indeed, there is some evidence to support that antibiotics in our food have already contributed to antibiotic resistance, along with an overuse of antibiotics to treat human health problems. This new research points out that farming practices surrounding livestock may also be cause for concern.

The fact that the genes hadn’t before been identified is actually a good thing, though. It means that, at least for now, they’re unlikely to be a threat to our health as they aren’t yet infiltrating the food chain in a meaningful way. However, the researchers believe that there is a chance that cow manure may harbor “an unprecedented reservoir” of antibiotic resistant genes. Obviously, this could pose a significant worry if we want to ensure that our existing antibiotics continue working until we come up with new solutions to the problem of pathogenic bacteria.

The researchers, therefore, will be carrying out a series of studies to try to pinpoint whether these genes are infiltrating our foodchain and at what point.

“The diversity of genes we found is remarkable in itself considering the small set of five manure samples,” researcher Jo Handelsman is quoted as saying. “This is just the first in a sequence of studies — starting in the barn, moving to the soil and food on the table and then ending up in the clinic — to find out whether these genes have the potential to move in that direction. We’re hoping this study will open up a larger field of surveillance, to start looking at new types of resistance before they show up in the clinic.”

There are a number of ways science is looking at tackling the problem of antibiotic resistance. They include limiting antibiotic use and creating entirely new kinds of antibiotics. In the meantime, however, limiting the use of antibiotics in agriculture will be vital and, while the farming industry has appeared to largely ignore calls for greater action, this is a problem that evidently isn’t going away.

Photo credit: Thinkstock.


Carrie-Anne Brown

thanks for sharing

Janice Thompson
Janice Thompson3 years ago

Too much antibiotics in the poop?

Debbie Crowe
Debbie Crowe3 years ago

It figures. We added cow manure to the soil in our garden. Now, I'll be afraid to eat anything!

Jennifer H.
Jennifer H3 years ago

This is no surprise. What goes in must come out. This is obvious and all farmers no it. The problem is the big farmers/ranchers don't care.

BJ J3 years ago

It took scientists how long & how much $$ to figure out what any small-time farmer would know? What's the next research project - to find out if cows (& most animals) have 4 legs & a tail??

Gerald L.
Gerald L3 years ago

A manure pile never caused this much damage; The New Age Dangers of Chemical Pharming!

Deadly Texas fertilizer plant explosion blamed on regulatory failures.

By the Center For Public Integrity, on April 23, 2014

Failures at “all levels of government” contributed to last year’s fertilizer plant explosion in West, Texas, which killed 14 people and injured 226, the U.S. Chemical Safety Board reported Tuesday.

Investigators determined that a large amount of ammonium nitrate was ignited by a fire and leveled the facility. They found, among other things, that there is no state fire code and that “counties under a certain population are prohibited from having them.” They identified 1,351 facilities around the country that store ammonium nitrate.

More stories about Chemistry, Disaster and Accident, Oxidizing agents, Nitrates, Fertilizers, Nitrogen metabolism, Ammonium nitrate, Ammonium nitrate disasters, U.S. Chemical Safety Board;

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Val M.
Val M3 years ago


Julie W.
Julie W3 years ago

I use cow manure in my garden. But as cows are grass-fed in Australia, hopefully we use less antibiotics, though I do know we use them. It's impossible to get manure from organic farmers.

Alexandra G.
Alexandra G4 years ago


Gerald L.
Gerald L4 years ago

***** to Holly W; Let's hope this drives home the message to Congress to impose stronger regulations on antibiotic use for animals. Maybe these big farming operations will have to treat the cows better (giving them more space; feeding them grass their bodies are designed for, rather than grain) and manure can remain a valuable part of the nutrients for raising vegetables.

Feeding them grass is a historical practice; Sun = Grass = Grazing Ruminants = Lots of value added by-products many here don't want us to have part of our diet. I am not sure what their progenitors survived on? Before all our modern transportation systems were developed in the last century allowing atrocious food miles, even air freight for winter asparagus from Chile.

And Holly the value of green manure compared to all the nitrate pollution from using chemical fertilizers and all the Carbon needed to produce it, including potash mining, urea etc.

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