I had an excellent conversation this weekend with a gentleman that had some very good questions about a variety of animal agriculture topics, including Confined Animal Feeding Operations (CAFOs). One point he was concerned about was antibiotic resistance. This is not merely a hypothetical topic for me, as my brother had a MRSA infection after battling with idiopathic thrombocytopenia (low blood platelets from an unknown cause). Antibiotic resistance is a topic I’ve touched on here before, because it is not only extremely serious, but has been the subject of sensational journalism that has only clouded the discussion, moving us farther from finding real solutions.
A point of our conversation came to what was my greatest concern for a human health incident involving antibiotic resistant bacteria moving from an animal. It was a surprise to him when I pointed out my greatest fear is a dog with floppy ears (like a Cocker Spaniel) or skin folds (like a bulldog), not cattle in a CAFO. Why, as a veterinarian, would my concerns be directed this way?
Let’s start by looking at the cattle. There is no question that antibiotics use in any situation can lead to bacterial resistance given the right circumstances, but how do we quantify that risk? Bacteria needs to acquire the resistance first, and then that bacteria needs to make the jump from being in a steer to being in a person. Since cattle and humans do not have regular nose-to-skin contact, that means the jump would be most likely to occur after slaughter.
But the slaughter facility is a place where cleanliness is next to Godliness. That may sound counter-intuitive if you’ve never been to one, as it sounds like a messy process, but they are super diligent about food safety there. Which is good, because it makes the transfer of bacteria through food much less likely. So the bacteria would have to get into a worker there.
It could also leave the facility in the meat, which it would then if it were improperly handled by the end user (the restaurant worker or person who bought the meat at the grocery store) it could be transferred. If handled and cooked correctly though, the bacteria wouldn’t survive the cooking process or the cleanup afterwards.
Can this happen? Of course yes. That’s why cattlemen and women work their veterinarians to appropriately treat livestock with antibiotics and other therapies. And it is no longer legal to use medically important antibiotics for growth promotion, a change that was voluntarily made by animal feed manufacturers. Any use of a medically important antibiotic in feed or water now requires authorization by a veterinarian.
Because of all these factors, the statistical likelihood of resistant bacteria from cattle causing a human health issue is very low. To help quantify this risk, a stochastic assessment published in the Journal of Risk Analysis stated, “the predicted risk of suboptimal human treatment of infection with C. coli from swine is only 1 in 82 million; with a 95% chance it could be as high as 1 in 49 million. Risks from C. jejuni in poultry or beef are even less.”
Is 1 in 82 million still a risk? Absolutely, so it is one that I as a veterinarian take seriously in my treatment decisions. That being said, let’s compare it to the situation that I am the most concerned about in my daily practice, which is the dog with a skin or ear infection.
Now why is this dog such a concern? And why did I single out Cocker Spaniels and Bulldogs? It’s not because I don’t like the breeds, because they both rock as pets. It’s because they have features that lend them to have skin infections. In Cocker Spaniels, it’s their floppy ears and in Bulldogs it’s their skin folds. But all breeds, especially those with allergy problems, are at risk of developing skin infections.
Often part of the treatment for skin infections is the antibiotic cephalexin. It is also a common human antibiotic used for a number of conditions. So consider this situation–a person comes in with his dog that has a wicked skin infection. Cephalexin is prescribed for four weeks, but the owner stops giving it after a week and a half because it “looks better”. The system has now been primed for antibiotic resistant bacteria.
Compare this to the cattle in a CAFO. The dog has constant touching contact with people. Unlike the cattle who are most often treated with antibiotics that are seldom used in humans, the dog is being treated with a common first-line human antibiotic. And when the skin infection inevitably returns, it is now more likely to be resistant.
Add to this that the animal-human contact is not with a healthy, 20 to 50 year old worker. Often it is children, or immunocompromised older adults. This means the person’s immune system is less likely to overcome the bacteria on its own. And yes, these issues DO influence my antibiotic treatment decisions in pets, as I will opt for injectable treatment if I’m concerned the owner won’t follow through on giving cephalexin orally. But I cannot do this without the owner’s permission, so if cost is an issue then we’re back at square one.
I’m not going to pretend that I can address all the nuances of antibiotic resistance in animals in one post, or even entirely through my own knowledge. That’s why this topic demands more study and understanding, because it’s not going away. If you are curious about antibiotic resistance or how antibiotics are used in cattle, follow this hyperlink to other blog posts that I’ve written on these topics.
And most importantly, remember the most important person in keeping you or your pet from developing an antibiotic resistant bacteria is you. Take all the antibiotics that are recommended by your doctor (or veterinarian for your pets) and do preventative health measures to keep sickness from starting in the first place. Together, we can keep antibiotic resistance at bay.