Last week, we had more news about the relationship between the way we raise our animals for food, and antibiotic-resistant infections.
The news was that scientists think antibiotics at sub-lethal doses create mutations in bacteria.
What does this have to do with resistance to antibiotics? First of all, people have to understand that over time, antibiotics are getting less effective. We've all heard these "scare stories" on the news about "superbugs" that are resistant to multiple antibiotics. If you look at the statistics, you'll find that this is a growing problem for hospitals--every year there are more of these infections by bacteria that are tougher and tougher to treat with our conventional medications. Humanity is locked in an "arms race" between bacteria and the drug companies--we make innovative antibiotics, and the microbes figure out ways to get around them.
Scientists worry that the microbes are getting "smarter" over time because of the ubiquitous use of antibiotics in general society. The question of what's causing that is controversial. Some people say it's because doctors are overprescribing antibiotics for infections that don't need them, and some people say it's because we are putting too many antibiotics in animal feed.
Why do we need to put antibiotics in animal feed? In the case of chickens, it's to overcome the weak chicken immune system. Chickens are raised in huge farms, where thousands of birds share a confined space. If infection sets up in that environment, it can decimate the entire flock within a few days. So to overcome this, they put antibiotics in the feed of the animals.
The chicken farm owners and trade groups have papers to show that this is harmless, and that the problem of antimicrobial resistance is mostly the fault of overprescribing doctors.
As a person who eats chicken, I can see both sides of this issue. Chicken is plentiful because of large-scale farming, which is made possible by antibiotics in feed. This becomes a political issue: take away people's cheap plentiful chicken and be prepared to hear from them at the polls.
The point that antibiotic overprescribing leads to antibiotic resistance has, I think, been embraced by the medical community and by American patients as well. People I see understand that you don't need to give antibiotics for a viral illness, whereas they might have demanded antibiotics for illness only a few years ago.
On the other side, I think we need to come up with innovative ways to farm poultry without resorting to antibiotics in feed. As papers like the one I mentioned above show us, it's certainly possible that antibiotics in animal feed are contributing to rapid resistance to antibiotics.
The way this works is probably that the mutations created by antibiotics allow bacteria to evolve drug resistance faster than they would otherwise evolve. Most of these mutations will be harmful and lead to cell death, but a very few will, by random chance, give the bacteria drug resistance. These resistance mutations will then propagate through natural selection until the entire strain has these genes. It's ironic that the very medicines designed to treat infections can create resistant bacteria, but that appears to be how it works.
CDC has a nice information page about antibiotic resistance.
So the next time you bite into that chicken sandwich or order the chicken parm at your favorite restaurant, think about how that bird made it to your plate. Perhaps if we all demanded safer food production, we could make our hospitals safer. After all, the bacteria always win--we just want to forestall that as long as possible!
For more information, check out the audio podcast I made about this, hosted at my medical news and information website, InteractMD.com
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