Friday, March 13, 2020

Antibiotic Use in Livestock - Does it Cause Antibiotic Resistance in People?

Adriane Good

As I was scrolling through Facebook last week, I saw a very interesting article in the Canadian Cattlemen’s magazine. It was titled ‘Study finds Enterococcus bacteria resistance in people not related to antibiotic use in cattle’. This is a finding of huge importance to the livestock industry, so of course I had to read more.

Dr. Tim McAllister, a researcher at the Agriculture and Agri-Food Canada Research and Development Center in Lethbridge, is one of almost two dozen multi-disciplinary scientists in Canada involved in a series of research projects looking at whether antibiotic use in livestock is increasing antibiotic resistance in humans, and if so, what we can do about it. While this is a Canadian research initiative, antibiotic resistance is a global issue, so this research applies here too.

To back up a little bit, antibiotics are used in livestock production in a variety of methods. Livestock producers use antibiotics to treat illness in their animals. Nobody wants to see a sick calf, so ranchers treat those sick calves with antibiotics to bring them back to health, just like we do with people. The use of prophylactic antibiotics is lesser known. In some cases, livestock will be given a dose of antibiotics to prevent disease. This occurs when there is a high risk of animals getting sick. For example, a feedlot might give antibiotics to a group of new calves coming in if they’re looking especially stressed and a little sick. Stressed animals get sick much easier than animals that aren’t stressed, and mixing calves with other calves is a great way to spread disease. Sometimes with stressed cattle, the first sign of illness you see is death, so treating them before you see signs keeps them alive. One of the most commonly used antibiotics in livestock production are ionophores. These are used to treat coccidiosis and modulate the rumen environment in cattle. Altering the rumen environment not only increases feed efficiency, but also decreases the amount of methane cattle produce.

Antibiotics are classified into 4 categories – low importance to human health, medium importance, high importance, and very high importance. In all of livestock production, antibiotics that are of very high human importance are used less than 5% of the time, while they are used 30% of the time in human medicine. Antibiotics that are of low and medium importance to human health make up almost 80% of the antibiotic use in livestock but make up less than 10% of antibiotics used in human medicine. This shows that livestock production is using the lower importance antibiotics that human medicine doesn’t rely on.

Antibiotic use by category of importance. From

Dr. McAllister’s study focused on beef cattle and looked specifically at enterococcus bacteria species found in cattle and humans. They sequenced the genome of these bacteria and found that the species of bacteria that pose a threat to human health are not the same species found in cattle. They also discovered that the genes responsible for antibiotic resistance in the enterococcus bacteria in humans are associated with antibiotics that are not used in beef production. This suggests that antibiotic resistance in humans is caused by antibiotic use in humans, and antibiotic resistance in cattle is the result of antibiotic use in cattle.

Of course, we still can’t be too cautious. Antibiotics are a very important tool for human health, just as they are for livestock health. While this research is encouraging, it’s important that we use antibiotics responsibly in both human health and livestock health. For livestock producers, make sure you’re reading and following the label when giving antibiotics. Having a good veterinary client patient relationship will also help as your vet can help you make sure you have diagnosed problems properly and are treating them with the right product. It’s also a great idea to minimize stress on your animals, keep up to date on vaccinations, ensure adequate nutrition, and use biosecurity practices to minimize the chances of animals getting sick.  

For the original article in Canadian Cattleman's, check out:

For more information on antibiotic use in beef cattle and antibiotic resistance, go to:

No comments:

Post a Comment