Antibiotics found in waters flowing into Lake Erie
A variety of veterinary and human antibiotics were found consistently in water sampling in rivers and other tributaries flowing into western Lake Erie, new research has found.
That’s a concern, as it potentially contributes to the already rising global problem of bacteria becoming resistant to antibiotics, said lead researcher Laura Johnson from Heidelberg University in Tiffin, Ohio.
Johnson, the director of Heidelberg’s National Center for Water Quality Research, devotes much of her study to the phosphorus loads and other factors contributing to chronic algae blooms in western Lake Erie.
But she said her team wanted to study the presence of antibiotics in Erie tributaries, and particularly those used with cattle, swine, poultry and other livestock, because the western Lake Erie basin has a considerable amount of livestock and other farming activity.
“We have widespread livestock and increasing intensity of animals in this area,” Johnson said as she presented the findings of her research May 23 in an online forum sponsored by Ohio Sea Grant.
“Antibiotics are water-soluble, so they run off easily,” she said. “They are also excreted in urine and feces, usually without really any changes, and then oftentimes manure is applied to land.
“So there’s a pathway in which antibiotics can enter our environment fairly easily. And we worry about that primarily because of the development of antibiotic-resistant bacteria.”
Bacteria causing foodborne illnesses in humans, such as salmonella, E. coli and campylobacter, are already exhibiting strong resistance to antibiotics,
research shows.
More animals in an area mean more antibiotics in water
Johnson and her team tested for antibiotic presence in western Lake Erie tributaries between 2020 and 2022, starting at three locations: the Sandusky River, Honey Creek, near Tiffin, Ohio, and Rock Creek. The number of testing sites was expanded to another six regional tributaries in 2022, she said.
The researchers used both samples taken all at once and samplings from devices, taking passive water samples over periods of 21 to 28 days. Both sampling types showed some antibiotics frequently detected across rivers and streams — veterinary antibiotics such as lincomycin, monensin, sulfamethazine and thiabendazole; and more typically human-used antibiotics such as clarithromycin, sulfamethoxazole and sulfanilamide.
The veterinary antibiotics’ presence varied over time, but antibiotic levels were often associated with livestock numbers: the more farm animals in a given area, generally the higher the antibiotics levels found in the water.
“This is what we were hoping that we would find, some relationship between compounds and what’s in the watershed,” she said.
The human antibiotic sulfamethoxazole was found consistently across watersheds, which suggests wastewater treatment effluent and septic sources may be contributing as well, she said.
Concern about algae blooms
In addition to making foodborne and other bacterial illnesses tougher to treat, antibiotics resistance might one day make harmful algae blooms in western Lake Erie tougher to control. The algae blooms are caused by cyanobacteria, and 2021 research out of China shows cyanobacteria can develop antibiotic resistance due to antibiotic exposure in the environment.
The bacteria that survive in such conditions are those resistant to the effects of the antibiotics, and they then split and multiply, propagating the antibiotic resistance.
Cyanobacteria produce the liver toxin microcystin, which can cause serious illness in humans and kill exposed pets or livestock. High levels of microcystin detected during a western Lake Erie algae bloom led to the temporary shutdown of the water supply for Toledo and surrounding areas — more than 400,000 people — over a weekend in August 2014.
“Understanding how chronic low-level exposures affect any sort of natural community in an aquatic environment is difficult,” Johnson said.
“I dug into that a little bit, and I haven’t been able to find a lot of very clear evidence that the levels (of antibiotics in western Lake Erie tributaries) that we had would have had a very strong influence. But it is an antibiotic, and the harmful algal blooms are cyanobacteria. So you can imagine if those (antibiotics) levels got high enough, they could certainly play a role in affecting the growth of these harmful algal blooms.”
Growing restrictions on animal antibiotics
Concerned about the rising impact of antibiotic-resistant bacteria on human health treatment, the U.S. Food and Drug Administration in recent years has limited how and when antibiotics are used for livestock.
The FDA in 2017 began requiring that any antibiotics provided to cattle, swine or poultry through feedstock or water come from a veterinarian by specific directive. The use of such antibiotics to improve the growth of animals was also prohibited.
Beginning June 11, the last remaining over-the-counter antibiotic medications for livestock will also require a veterinary prescription, and the businesses that dispense the medications will need a state pharmacy permit and be required to follow all of the rules that entails — likely meaning the farm supply stores that currently provide the antibiotics overthe-counter will be getting out of that business entirely.
The significant changes weren’t exactly embraced by farmers at first, said Lisa Sanford, a veterinarian and co-owner of Sterner Veterinary Livestock Professionals in Westphalia, providing medical services for cattle and sheep throughout Clinton and surrounding counties.
“There was some pushback in the beginning,” she said. “But talking with us more, producers now understand we can help them work through health management issues on things such as nutrition or housing or vaccination protocols for disease prevention.
“People who thought they couldn’t live without (antibiotics for their livestock) are doing very fine without it.”
Regulations also require farmers to record any sick cow given antibiotics that’s used to produce milk or meat, so that it is “not getting into the food chain until the cow has had time to fully metabolize and eliminate that medicine,” said Angel Abuelo, a veterinarian and assistant professor of cattle health at Michigan State University’s College of Veterinary Medicine.
The FDA is also requiring any farm that might use antibiotics to have a demonstrated relationship with a veterinarian. Michigan requires the vet to have visited the farm at least once in the past year, Abuelo said.
“Most farms have already established relationships with a veterinarian, so it’s not really adding anything new for them,” he said.
In addition to protecting the ecology, farmers have another incentive to reduce antibiotic use, keep it out of waterways and help fight rising antibiotic resistance: so they can continue to use effective antibiotics with their animals when necessary, Abuelo said.
“We want to be able to care for the animals under our supervision, and having access to microbials is essential to their welfare and well-being,” he said.