> It appears that overprescribing existing antibiotics to people and livestock is a leading cause of rising drug resistance, both of which can be addressed by policy changes.

About 80% of antibiotics sold in the US are used in agriculture[1], where they are given to animals not to treat infections, but to prevent them and to stimulate growth.

Over 60% of infectious disease in humans are spread from animals, and 75% of new diseases in humans are spread from animals[2].

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4638249/

[2] https://www.cdc.gov/onehealth/basics/zoonotic-diseases.html

Much of the emerging evidence is that while the amount used in livestock makes for flashy numbers, it's likely medical overuse in humans is the main driver of the problem.

Recent mini-thread on it by Marc Lipsitch, a Harvard epidemiologist who does a lot of work in the area: https://twitter.com/mlipsitch/status/1206419839872569346

Including use in urban poverty: https://www.nytimes.com/2019/04/07/health/antibiotic-resista...

Where antibiotics are handed out without prescription and people live in squalid conditions.

"70 percent of salmonella infections in Kenya had stopped responding to the most widely available antibiotics, up from 45 percent in the early 2000s."

"Even when the drugs are authentic, many poor Kenyans try to save money by buying just a few tablets instead of the full course — not enough to vanquish an infection but enough to allow bacteria to mutate and gain resistance."

The current population of Kenya is 50m, forecast to increase to 95m by 2050, and 156m by 2100.

Kenya also currently has the scientific output of Serbia, a country 14% the size. Its likely that Kenya will continue to import drugs developed in advanced nations, and internally produce only antibiotic resistance.

https://www.natureindex.com/country-outputs/generate/All/glo...

SO I do a little work in Kenya, and it's really hard there. Because you do have rampant resistance, but you also have lack of drug availability - especially in rural parts of Kenya.

We've got some data suggesting there that stewardship is, relatively speaking, less impactful there than decreases in transmission. Because the environment is heavily contaminated, which is itself conducive to the spread of resistance.

Back in 2017, the FDA banned the use of medicinally important antibiotics in livestock.

https://www.cdc.gov/drugresistance/food.html

This line item for allowed uses from that link:

* Prevent disease in animals that are at risk for becoming sick

Is pretty much a giant loophole.

If those animals are treated, they then need to be pulled out of the food supply until the antibiotic washes out.

It’s not in a farmers best interest to use an antibiotic in those circumstances unless the animal needs it.

>until the antibiotic washes out.

This is part of the problem. If animals are given the antibiotics, then their waste products contain them, and piles of manure or water runoff/storm drains/wastewater ponds form a giant evolutionary experiment for development of drug resistant organisms.

They're not just a problem while they're in animals, they're a problem if they're used at all.

Apparently, most antibiotics don't undergo metabolism in animals, and 40-90% of ingested antibiotics in livestock are excreted in urine and feces[1].

Those antibiotics go on to contaminate groundwater, and as you say, contribute significantly to antibiotic resistance[2].

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4220964/

[2] https://en.wikipedia.org/wiki/Antibiotic_use_in_livestock#An...

That’s often irrelevant. If a cow is going to be slaughtered at 36 months, you can use antibiotics for 95% of their lifetime and still have a 50 days window at the end.

> until the antibiotic washes out.

while I don't want surprise antibiotics in my food, I'm probably more concerned about the antibiotic resistance that antibiotic exposure generates. The flora of those animals _will_ have drug resistance genes that doesn't just "wash out". That resistnce can be passed to other animals or human by direct contact, environment or otherwise.

Does that make any practical difference for animals meant for consumption like beef cattle, hogs, or chickens? You can give them all the antibiotics you want until a few days before slaughter.

It does. The animals will be colonized by bacteria that have "learned" to deal with all those antibiotics you gave. That resistance is easily transmitted.

I understand the problem with antibiotic resistance, but telling a farmer that an animal treated by antibiotics can't enter the food supply until after treatment ends doesn't really solve the problem when it comes to animals raised as food -- the farmer can treat the animal with antibiotics for nearly all of its life, only stopping the treatment just before slaughter.

Totally agreed. I'm naive to much around Ag/Husbandry. If that's what farmers do, that is a concern. From a microbiology point of view, the concept that "washing out" the drug before slaughter improves anything is flawed. It will be a reservoir of smoldering antibiotic resistance as long as that practice persists.

That's good to know, thanks for the link. However, up until recently, you could buy 55-gallon drums of antibiotics without a license on sites like Alibaba.

It seems like overprescribing to a cow is such low hanging fruit.

I understand that if my 5-day-old child marginally needs antibiotics, that the doctor may prescribe to appear active.

But couldn’t sensible legislation end over-prescription to livestock overnight? Is this really an issue of beating the cow lobby?

The "cow lobby" is large multinational corporations... so yes it's an issue beating their lobbyists. Also, a side effect of antibiotics is weight gain in livestock - so even legislation that ostensibly outlaws use for the direct purpose of directly adding to profits, language in regulation is generally kept for medical purposes of "reducing disease" among herds. Disease that is at a high rate because of high density feedlot practices...

> a side effect of antibiotics is weight gain in livestock

Original article in Nature: https://www.nature.com/articles/nature11400

There have been quantitative calculations for antibiotics taught for years in ag departments, and known among industry practitioners. Farming is a highly quantitative industry, and any agent of growth promotion is tracked carefully along with feed energy & cost inputs. Today you may have to go back to older documents to see talk about it in a more open manner though.

Here's a more industrial type of analysis paper (2003)

https://www.cambridge.org/core/journals/journal-of-agricultu...

I think a weight loss factor could be added to legal antibiotics to remove the benefits of their overuse.. Caffeinated cows on a rampage might correct the industry.

Overprescribing antibiotics to animals helps keep meat cheap. Politicians have a hard time with the headwinds caused by ads like “Evil big-government libs are raising the price of your steak!!” So it doesn’t happen. You’d probably be surprised how cheap some feed antibiotics are — Tylan powder being a good example.

In short, yes, it is beating lobbyists and opportunistic political opponents. Even if this issue is important to you, political capital is not limitless, so it has to be weighed against a whole host of other issues.

There is a tragedy of the commons problem as well: from massive over-use of the same antibiotics in farm animals. Antibiotic susceptibility is a asset of the commons. And there are farmers who are incentivized to ruin it for everyone else.

I would interpret this as roughly equivalent to the biomedical industry telling Congress they need to put the meat industry in its place. Stopping use of antibiotics in animal husbandry will raise the price of meats, decreasing the market for them. It seems that Congress is, by neglect, accepting some human deaths in exchange for cheap meat and a few animal husbandry jobs.

I work in this area, and a couple notes:

- The free market is actually doing a really good job driving down antibiotic use in livestock.

- There's not a huge amount of evidence that livestock use of antibiotics has as big an impact on human resistance patterns we see. Overuse in human populations is a big enough problem on its own. Medicine has, in some ways, been really eager to abdicate its own role in developing resistance by pointing at veterinary use.

- There are a number of policy changes already in effect, but all they can do is kick the can down the road a little. Bacteria will develop resistance to antibiotics - it's what they do. Some more easily, some less easily. This is a treadmill you can never get off - all stewardship does is control the speed. Even with good stewardship programs, we'll still need new classes of antibiotics.

> It appears that overprescribing existing antibiotics to people and livestock is a leading cause of rising drug resistance, both of which can be addressed by policy changes.

I worry that any changes in that area will be too little too late.

I've seen this in sports and games. Sometimes everybody know they should make a move to catch up with the current leader but if they do they probably spend too many resources and lose from the others close to them. So they wait for somebody else to self sacrifice and the leader eventually wins. The leader here are the superbugs and I'm afraid that no normal market rules can make us win this race.