Antidepressants Kill Bacteria

Fuoxetine is a selective serotonin reuptake inhibitor. Its most famous trade name is the antidepressant Prozac®, one of the most widely prescribed drugs in the world. At the 111th meeting of the American Society for Microbiology, researchers reported finding extremely miniscule amounts of fluoxetine in Lake Erie.The researchers reassured reporters that what they found was well below concentrations that could affect humans. When the researchers exposed Escherichia coli (typically referred to as E. coli) and another gut bacteria Enterococcus to this concentration of the antidepressant, it killed the bacteria.

So it turns out that Prozac® is not only an antidepressant, its an antibiotic—and an antibiotic against E. coli, a bacteria associated in the media and popular imagination with food contamination, illness, and even death.

Of significance, this is going on in an open body of water—Lake Erie—far from any likely source of contamination. And while we might celebrate the death of E. coli, the researchers wonder out loud what the implications are for the rest of the microbial biome in the lake and the further effect on the lake’s ecology. For example, it is known that the drug damages the reproductive systems of mollusks (that is, clams and such) and the brains of some fish.

But not us, not humans.

As I mentioned, the fluoxetine was discovered far from where one might expect it. The way this drug and other drugs make it into open bodies of water is through the outflow of wastewater treatment plants. If someone takes the drug, trace amounts are in her or his urine. When she or he flushes the toilet, the drug wends its way to a treatment plant. At the treatment plant, well established engineering practices required by water quality regulations make it safe for the water to be released into an open body of water, whether a lake or a river.

Unfortunately, the engineering does not remove the drug nor do water quality regulations require its removal. The same is true for other pharmaceuticals as well as a wide variety of other biologically active chemicals such as pesticides and herbicides. You might think that pesticides and herbicides won’t come out in urine because no one ingests them—but you’d be wrong because residues of the toxins persist on food, which is eaten, which is metabolized, which is excreted in urine. And rinsing the food first only sends the chemicals directly down the drain and on to the wastewater treatment plant and then to some body of water.

So long as we use these chemicals, they will be in our urine, in our wastewater, in open bodies of water, and from there, through ecological and hydrologic cycles, into what we eat and drink.

Although that’s something to consider, I want to move on by returning to what happens as a consequence of an antidepressant being in a body of water. The researchers are clearly concerned that the ecological web of Lake Erie is being damaged. But not us, not humans. The concentration is too low.

In a recent study, researchers reported in the journal Gastroenterology that disrupting the balance of gut microbes in previously healthy mice using an antibiotic causes behavioral changes in the mice—specifically, it causes depression and anxiety. The change was both behavioral and neurological. The level of a substance called brain derived neurotrophic factor (BDNF) increased. Such an increase is associated with depression and anxiety. When the researchers stopped the antibiotics, the depression, anxiety, and elevated BDNF ceased.

The implication is this…

Kill off gut bacteria, cause depression and anxiety. If someone reports depression and anxiety, what will their doctor likely prescribe for them? An antidepressant. That could be killing gut bacteria, causing an imbalance, and thus aggravating the original condition. Ironic, isn’t it?

As I’m sure you’re aware, the disruption of our gut ecology has the potential to damage our health in a wide variety of ways, far beyond causing depression and anxiety.

How do we protect ourselves?

A number of things come to mind. Better wastewater engineering. Better control over the disposal of pharmaceuticals and toxins. Reduced use of pharmaceuticals and toxins. Better nutritional support for our gut ecology.

Those pharmaceuticals and toxins are part of our way of life, intended to make life better. More specifically, they are developed and sold to make a specific aspect of our life better. The consequences are left to others because the driving social force is the sale, not the development, not the better life. The consequences are left to others because “better life” means “better life for humans with a specific condition in the context of a political economy in which things get produced because someone can make money off of it.” The driving social force should instead be “better for life, period.” Lake Erie, my gut and yours, every ecosystem, the whole thing.