anti-antibiotics

My inspirations for posts often come from what I manage to read in between deadlines and my social life, and as often as not, that means the New York Times. I don't read all the op-ed columnists... I'm in agreement with CPP about Ms. Maureen Dowd, though clearly CPP is more dedicated to reminding us that she takes up valuable column inches with her insubstantial, ill-informed populism. Which might be excusable if she were funnier, but... I read Kristof every couple of weeks, which is generally enough to keep up with his various crusades. While he's usually right, and is an articulate voice for his cause du jour, his anecdote-to-preachiness format can become stale. But lately Kristof is beating a dead horse (well, pig) that I cannot tire of: the overuse of antibiotics in livestock feed and what that means for global public health.

Here are his March 12th and March 15th columns on the topic. As a microbiologist, I tend to focus on the implications for infectious disease (the prevalence of antibiotic resistance genes in all microbes, including human pathogens), but the organ damage that comes from repeated bacterial infection that we're unable to shorten with antibiotics... another scary consequence.

I also have to give Kristof credit for the PLoS One study he cites, which comes from the lab of science blogger and awesome female microbiologist Tara Smith!

Americans' antibiotic use continues to be out of control. According to the American College of Physicians, 50% of antibiotic prescriptions each year are given to patients with viral infections, not bacterial infections. Antibiotics can help you prevent/clear up bacterial infections you have secondary to a viral infection, for instance, an ear infection that builds while one is congested with a common cold, but it cannot, will not directly clear the viral infection. Even when antibiotics are prescribed for actual bacterial infections, it irks me to no end that otherwise intelligent people do not follow the dosing instructions that come with their antibiotics. Some of my closest relatives stop their antibiotic treatments a few days early in order to have some pills to take the next time they feel an infection (possibly a viral one...) coming on. Grrrrrrr! This is wrong for so many reasons... so many reasons that I have to stop myself and maybe post about this topic another time.

But if you do have leftover antibiotics, don't flush your medicines into the water supply either... this is something I hadn't considered before finding links for this post, but flushing antibiotics also introduces those chemicals to the huge number of microbes in our wastewater and further selects for antibiotic-resistant bacteria.

As much as I could go on about all the ways that treating human infections has led to increased antibiotic resistance, including outside of developed nations with strong health infrastructures, it's something of a moot point. And that's because most of the antibiotics we use in this country are not given to humans -- they are given to healthy livestock animals. Scientific American says 70%, the UN says 50%... I think it's safe to say it's a majority of the antibiotics administered in this country every year. These drugs are not going to sick animals -- not animals suffering with bacterial infections that can and should be treated. We give antibiotics to healthy livestock because of the way we raise most of our meat in this country -- at such dense conditions, with such high bacterial loads in their environment that outbreaks of bacterial infections are inevitable.

Giving animals antibiotics also speeds their development, so our meat gets larger faster. I'm not entirely sure why this is, but I imagine that not having to spend as much energy on ones immune system would facilitate growth.

Some reading this post may know that we don't use the same antibiotics for humans and livestock. However, we effectively do. Stick a methyl group on a human antibiotic -- one that doesn't impact its antibacterial action, and it's now a livestock-ready antibiotic with the same mechanism of action... and resistances developed to livestock antibiotics show cross resistance to related human antibiotics.

I'm pretty terrified about the increased prevalence of these superbugs in communities outside of hospitals... it means the bacteria aren't at a competitive disadvantage relative to the more antibiotic-susceptible bacteria that are thought to be the majority of the bacteria in our environment. It means that humans, who carry the Staphylococcus aureus bacterium on our skins, have started carrying methicillin-resistant S. aureus as part of their normal flora. This in turn means that injuries as small as a paper cut will let those MRSA into your body...

One thing I do to reduce my antibiotic load on the environment is eating antibiotic-free meats, like the delicious local, free-range pork in a paprika sauce I ate tonight at a restaurant. I started being strict about this four or five years ago, and I definitely eat less meat than I did before. I also buy the more expensive no-hormone, no-antibiotic milk and yogurts (I can't give up my wide cheese selection though...). These small things make me feel like a more responsible microbiologist; the animal welfare improvements and the economic support of smaller farmers are secondary benefits to me. I know I'm lucky to have access to local farms that can provide these meats, and that I have the middle class income to afford them. But I think changing our agricultural policies, and what we chose to subsidize, could bring down the cost of farming that's better for public health.