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In my previous post, I described the concept of what antibiotics are, and how people are generally wrong when they worry about it as a toxicity issue. The problem is far more difficult to parse - the promotion of antibiotic resistance. But even that gets oversimplified; we can expand on that later.
Why are antibiotics used in farming?
(Found another excellent blog post on this issue).
The statistic often quoted is the 80% of all commercially produced antibiotics are used in farming. The exact number varies depending on the sourcing, but the basic conclusion is the same - an enormous amount of antibiotics are used on farm animals (antibiotics used on plants are seldom a concern for humans). However, one problem with this statistic is that it lumps all antibiotics together, as if they are all equivalent. Some are indeed more equal than others, but in general, antibiotics used in agriculture are related to, but not the same ones used in common medical prescription.
The animals we like to cultivate and eat (pigs, cattle, chicken) are genetically quite related to humans, and thus, share many of the common disease vulnerabilities to the same microbes. Consequently, we end up using the same therapies when our livestock get ill - an antibiotic used to treat an infection in a human is just as likely to work on a pig infected with a related bacterium. The worry here is that since we are indeed so closely related, genetic information can jump between bacteria that infect livestock to those that infect humans - carrying with them any resistance mechanisms that are selected by use of the antibiotics. Thus, the same antibiotic may lose effectiveness when prescribed to a human patient.
The practice of subtherapeutic dosing with antibiotics can exacerbate the problem. Basically, when animals are treated with small doses of antibiotics, they fatten up faster. This is thought to be due to a change in the microbiome makeup, the cohort of microbes that live among different animals -- including humans. This effect is so significant that our mass produced meat industry has grown dependent on it. Implementing outright bans on this practice can have massive economic repercussions.
This problem is a thorny one indeed - controlling commercial antibiotic use is far from trivial, and the microbes all around us are constantly producing potential antibiotics (and defensive systems) anyway. But note that cultivated plants are not a problem - I propose that a better solution is the promotion of the move away from vertebrate meat sources. After all, bacteria that infect mealworms are less likely to be related to those that trouble humans, and classes of antibiotics used to raise those can be used with impunity. One possible solution to this brewing crisis: entomophagy.