AYESHA RASCOE, HOST:
Antibiotic-resistant infections are on the rise across the world. So-called superbugs caused more than a million deaths in 2019, and that number could reach 10 million people a year by 2050. A new study points to one surprising potential culprit for the spread of antibiotic resistance - air pollution. NPR's Gabriel Spitzer has been looking into the research, and he joins us now. Welcome.
GABRIEL SPITZER, BYLINE: Hey, Ayesha.
RASCOE: So first, let's talk about antibiotic resistance and how it spreads. Can you give us a refresher on exactly what it is?
SPITZER: Sure. So when someone takes an antibiotic, the meds kill off most of the bacteria - the vulnerable bacteria - but, sometimes, a few hardier microbes survive the antibiotic attack. And those resistant bacteria are then free to thrive and spread and cause infections that resist our best drugs. So that could look like MRSA - those really stubborn staph infections that we hear about - or souped-up versions of TB or gonorrhea. And the thing is, antibiotics aren't only used for, you know, strep throat or an ear infection or whatever. They're also used on a gigantic scale in farming and aquaculture.
RASCOE: So what is it that's ending up in the air?
SPITZER: Well, it's not that antibiotics are leaking into the air and exposing people. It's the germs. So all those activities like agriculture and sewage treatment, even the handling of hospital waste - they leave behind a lot of resistant bacteria and deposit it in the soil in the waterways. And then there's also all this free-floating genetic material from the bacteria that's mixed in with those deposits, including some that carry the genes for resistance to antimicrobials, and those can actually spread resistance all on their own. So ultimately, that material doesn't just stay in the soil or the water. The wind can kick up particles and aerosols, and the microbes catch a ride. And once they're in the air, they can be inhaled by people.
RASCOE: So these bacteria are basically hitchhiking on the particles of air pollution, and then that's spreading infections?
SPITZER: Well, yeah, it's still a little unclear whether the airborne bacteria and genes are actually making people sick with antibiotic-resistant infections. But this new study basically looked at the correlation between the two and found that all over the world, higher levels of particulate air pollution seem to correspond with higher levels of antimicrobial-resistant infections. And the research team, who are mostly based at a university in China, tried to control for a bunch of other factors that might affect the resistance - things like socioeconomic status and how much people spend on health care - and the link was still there.
But that's not to say, Ayesha, that the levels are the same everywhere. The study finds that much of Africa and South Asia seem to bear the highest burden from both the pollution and the drug-resistant infections. Now, those tend to be lower-income countries, as well as the places where the data is the least complete.
RASCOE: So how much of a problem is this? Like, how much of this big, global health problem is because of air pollution, specifically?
SPITZER: The study doesn't prove that pollution is causing the infections, but they found that the portion of resistance that's associated with particulate pollution - it adds up to a big chunk of the increase in antibiotic resistance over the past couple of decades - like, 12%. And that translates to about 480,000 premature deaths over that period.
RASCOE: Wow. I mean, and that's on top of all the other well-known really nasty health effects from particulate air pollution, you know, like lung disease.
SPITZER: Yeah, that's right. And the authors point out that this could mean that reducing air pollution is another lever to control antibiotic resistance. So if you bring down the pollution, you might get this extra benefit of reducing the spread of superbugs.
RASCOE: That's Gabriel Spitzer of NPR's Science Desk. Thank you so much, Gabriel.
SPITZER: You're welcome.
RASCOE: And you can learn more about this topic and see an illustration of the flying bacteria on our Goats and Soda blog at npr.org, right?
SPITZER: That's exactly right. Transcript provided by NPR, Copyright NPR.
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