(go read part one if you haven’t yet)
Its All Because of Agriculture!
This one I confess puts me on shakier ground. The theory goes, livestock are routinely dosed with antibiotics, and hence resistance develops in livestock and crosses over to humans with devastating results. There are some things to like about this theory as a source for resistance mutations, and some things that are questionable. First, though, the core allegation is true- healthy livestock are routinely dosed with antibiotics not to prevent clinical disease but because they gain more weight that way. This is probably a terrible thing- why would we want to be eating the residues of chemicals that induce extra weight gain?6- and it certainly goes along with some other horrible livestock practices (why bother keeping your cow clean if the antibiotics knock out the disease?) and this isn’t the forum to discuss them.
However, not only are some of these antibiotics never used in humans, they sometimes work by methods that are never attempted in human antibiotics. Some bacteria have evolved resistance to drugs never used in livestock.7 Furthermore, some of the worst zoonoses of recent years have developed not because of antibiotic exposure but because of other changes in livestock raising- E. coli adapted to live in the acidic rumens of grain-fed cows are less susceptible to acid-killing in human stomachs, for instance. And of course, the transmission of livestock diseases to humans is as old as animal husbandry- measles, smallpox, anthrax, plague, basically any disease that has ever accidentally an entire civilization probably developed from a livestock or farm-pest host.
The only thing I feel comfortable asserting here is that while mass-dosing livestock is probably bad, it seems unlikely that antibiotic resistance would have been avoided if we hadn’t taken to overmedicating our dinner. And certainly, it won’t go away if we stop.
African Nurses/Ignorant Hicks/Overprotective Parents
Remember when I said western medicine loves its personalistic theories of disease as much as any “primitive society”? There was a comment on that Telegraph article blaming the whole problem on the British National Health Service hiring too many “African Nurses” who don’t wash their hands. Similarly, you hear plenty of stories (even in med school) about how antibiotic resistance is caused by hicks who take antibiotics randomly whenever they feel sick, probably at the wrong dose and for the wrong period of time, maybe they got them in Mexico. In a gentler form, you get the panicky instructions to “take the entire dose, don’t stop when you feel better!” And my third personalistic cause up there relates to the belief, common in the US, Britain and (weirdly) in Russia that “modern” children are too weak, due to having not been allowed to play in the mud and develop resistance to pathogens.
There are elements of potential truth in all of these, except the “African” part (i.e. yes, poor hygeine in hospitals is a problem, but not one that has to do with race or continent of origin) but they are also silly ways of blaming people who are already seen as targets.
The “take all the dose” theory is actually less secure than you think. When dealing with other organisms (say, frogs) and other environmental stressors (say, cold) where resistance is complex and polygenic, exposing the organism to a lower dose of a stressor for several generations selects for offspring more likely to survive at sequentially higher exposures. Hence, if you want frogs on top of your mountain, you’re better off breeding frogs from midway up the mountain than you are breeding frogs from the valleys. The problem is that bacterial resistance isn’t usually polygenic- one mutation, a different ribosome, a different membrane-assembly, an extra efflux pump, and your bug is resistant. Some of these mutations don’t even occur de novo- plasmids are little bits of circular DNA that travel between species as well as between organisms, and plasmids frequently carry resistance genes in their entirety. One copy of a plasmid, in any of the bazillion bacteria in your body right now- on your skin, in your gut- could proliferate to convey resistance to an enormous range of pathogens with very little difficulty. According to a microbiologist I asked (couldn’t find any rigourous studies8) resistance develops as quickly in fully-treated hosts as in half-treated ones. The key necessary and sufficient conditions are a population of bacteria and exposure to an antibiotic, nothing more.
So What Do We Do?
Well, the first thing is relax. Even people who study disease extinctions in mammals talk of islands or island habitats. Ross MacPhee claims (and I wouldn’t question him!) that no continentally-distributed mammal is known to have been wiped out by infectious disease. So, this isn’t the end of humanity. We lived a long time with our pathogens and our 50% pneumonia mortality and we’re still around.
The second thing to do is to go back to those questions about avoiding exposure and improving metabolic and immune health. Public health measures may have been more important than vaccination or antibiotics in reducing deaths from infectious disease in the twentieth century9 and there’s no evidence that basic surveillance, screening, and simple targeted countermeasures will be less effective in a hundred years than they are today. The only major novel epidemics of the twentieth century occurred in holes in the public health safety net- Spanish Flu hit while most of the world’s health departments were shattered by warfare, attrition, and war-inhibited communication. Had Germany and France been sharing medical info, things might have gone differently. HIV was deliberately ignored by politicians who couldn’t get past their own homophobia (and in other countries disdain for IV drug use and prisoners.) (uh, and racism) (and puritanical reluctance to engage meaningfully with STDs, see also Tuskegee) (okay, HIV was a hell of a special case.) Emergent diseases are now so closely watched that you can get regular email updates several times a day. Untreatable diseases like SARS and Ebola regularly crop up and are contained without any medical therapy whatsoever, purely on the strength of a solid, well-informed global public health sector.
The third thing is to avoid stupid panicky ideas. I’m not a doctor (yet) so I can’t give you real medical advice, but I’d be pretty surprised if bathing your children in bleach to prevent MRSA turns out to be a good idea. Likewise, a study that keeps bouncing around suggesting tea tree oil is better at killing MRSA than chlorhexidine is only interesting if you know the difference between colonized and active infection. It kills the random MRSA bugs living on your skin. The study didn’t even look at treating people with folliculitis or abcesses or “spider bite” (I’ve lived and worked in brown recluse territory most of my life and never seen a “spider bite” that wasn’t a staph infection.) Even with antibiotic resistance on the rise, your chances of developing a resistant infection are still a lot less than your chances of getting diabetes, or heart disease.
The fourth thing, and this is the hardest to talk about or hear, is that there might not be anything to do about it. This may just be the shape of things. Its a weird disorder of western thought that problems have solutions, or that people who don’t have solutions shouldn’t discuss problems. Bad stuff happens. Tuberculosis is already making a comeback. Who the heck knows?
6- compare the effects of rumensin with my hypothetical mitochondrial toxin some day
7- for instance the penems in the Greek penem-resistant Klebsiella aren’t used in livestock
8- …but I’d love to see one!
9- this is not a debate I want to wade into, but I tend to think its probably a fair claim