Antibiotics Are Messing With Us

… in ways we don’t even realize. Debora McKenzie reviews Martin J. Blaser’s Missing Microbes, which explores the manifold effects these drugs have had on our bodies:

Missing Microbes is partly about [the rise of antibiotic-resistant bacteria]. But it is mainly a story you may not know, about the damage antibiotics do when they actually work. There have already been reports that antibiotics may cause obesity by disrupting gut bacteria that play a role in nutrition. Farmers use antibiotics to fatten livestock; we’re not so different, it seems. This book explains that such microbial disruption is widespread, often irreversible, and surprisingly damaging.

Antibiotics may also have made us taller. And by disrupting immune reactions, they may be involved in modern plagues such as diabetes, allergies, some cancers, maybe even autism. … We evolved with loads of microbes, especially in our gut; our bacteria outnumber our own cells 10 to 1. These complex communities are the delicately balanced results of long evolutionary struggles. We disrupt them at our peril.

Yet every time we take a typical antibiotic, we carelessly wipe out masses of innocent bacterial bystanders. Experiments in mice and epidemiology in humans implicate these losses in autoimmune disorders such as asthma, type 1 diabetes and Crohn’s disease. Meanwhile, babies delivered by Caesarian section are not colonised by the right bacteria, from their mother’s birth canal. And gut microbes affect nerves and immunity in ways that have led researchers to investigate potential links to autism.

But, after watching Blaser’s interview with Jon Stewart, Derek Lowe finds Blaser’s advocacy of narrow-spectrum antibiotics – which target specific families of bacteria – misguided:

The market for a narrow-spectrum agent would necessarily be smaller, by design, but the cost of finding it would … be greater, so the final drug would have to cost a great deal per dose – more than health insurance would want to pay, given the availability of broad-spectrum agents at far lower prices. It could not be prescribed without positively identifying the infectious agent – which adds to the cost of treatment, too. Without faster and more accurate ways to do this (which Blaser rightly notes as something we don’t have), the barriers to developing such a drug are even higher.

And the development of resistance would surely take such a drug out of usefulness even faster, since the resistance plasmids would only have to spread between very closely related bacteria, who are swapping genes at great speed. I understand why Blaser (and others) would like to have more targeted agents, so as not to plow up the beneficial microbiome every time a patient is treated, but we’d need a lot of them, and we’d need new ones all the time. This in a world where we can’t even seem to discover the standard type of antibiotic.