Maryn McKenna

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Via Farmworkers, Superbugs Find a Route Away from Drug-Using Farms

September 21, 2014 By Maryn Leave a Comment

Pig farms from the air. Image: Maryn McKenna

Pig farms from the air. Image: Maryn McKenna

One of the persistent questions regarding antibiotic use in meat production, and its effect on the health of humans who live far away from production farms, is: How do the resistant bacteria that result get from one place to another? That is: Most people accept by now that using antibiotics in livestock-raising causes drug resistance to emerge in the systems of those animals, in their guts or on their skin. But whether those newly resistant bacteria leave the farm, and how they make the trip, is both fought over and—despite much investigation—still under-researched.

Some studies have shown that bacteria can move off farms in groundwater, on the feet of flies, and via dust on the wind. What is insufficiently explored—because it is difficult to get large meat-production facilities to cooperate—is whether farm workers themselves are serving as a transport vehicle.

A new study just published (and open-access, so anyone can read it) helps to answer that question. It looks at the possibility that workers on large hog farms are carrying away drug-resistant staph or MRSA, and especially a type of resistant staph — known familiarly as “pig MRSA” and more technically as “livestock-associated MRSA” — that emerged on hog farms a decade ago and is directly linked to farm-drug use.

(If you’ve been visiting Superbug the blog for a while, you might remember pig MRSA; the story of its discovery in a Dutch farmer’s daughter 10 years ago also was told for the first time in Superbug the book. If it’s a new concept to you, you might be interested in this archive here.)

The new study finds that hog farmers are carrying multi-drug resistant livestock-associated MRSA away from the farm and — this is the crucial bit — that their bodies are hanging onto those bacteria, in a way that might allow them to spread, for up to 14 days.

[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: MRSA, North Carolina, ST398

Denmark: Three Deaths from Drug-Resistant "Pig MRSA"

May 12, 2014 By Maryn Leave a Comment

ICStefanescu (CC), Flickr

Image: ICStefanescu (CC), Flickr

A troubling and also kind of odd story came out of Denmark this weekend. In a court proceeding, a microbiologist has disclosed that three residents of the country who had no known connection to farming died of MRSA infections caused by ST398, the livestock-associated strain of drug-resistant staph that first appeared among pig farmers in the Netherlands in 2004 and has since moved through Europe, Canada and the United States.

If the report is correct — and sources have told me it is, but I’ve seen no data to confirm it — it reinforces the concern that bacteria which become resistant because of antibiotic use on farms can move off farms and affect the health of people who have no connection to farming.

Livestock MRSA has always one of the best cases for establishing that, because the drug to which it showed the greatest resistance, tetracycline, wasn’t used against human MRSA in the Netherlands, but was used routinely on farms — so the only place the strain could have picked up its unique resistance pattern was in pigs. (Here’s my long archive of posts on pig MRSA, dating back to my book Superbug where the story was told for the first time.)
[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: agriculture, antibiotics, Denmark, food policy, food safety, MRSA, netherlands, Resistance, ST398

Almost Three Times the Risk of Carrying MRSA from Living Near a Mega-Farm

January 22, 2014 By Maryn Leave a Comment

Pig farms from the air. Image: Maryn McKenna

Pig farms from the air. Image: Maryn McKenna

In the long fight over antibiotic use in agriculture, one of the most contentious points is whether the resistant bacteria that inevitably arise can move off the farm to affect humans. Most of the illnesses that have been associated with farm antibiotic use — resistant foodborne illness, for example — occur so far from farms that opponents of antibiotic control find them easy to dismiss. So whenever a research team can link resistant bacteria found in humans with farms that are close to those humans, it is an important contribution to the debate.

A team from the University of Iowa, Iowa City Veterans Affairs, and Kent State University have done just that. In next month’s Infection Control and Hospital Epidemiology, they survey 1,036 VA patients who lived in rural Iowa and were admitted to the Iowa City facility in 2010 and 2011. Overall, among those patients, 6.8 percent were carrying MRSA, drug-resistant staph, in their nostrils. But the patients’ likelihood of carrying MRSA was 2.76 times higher if they lived within one mile of a farm housing 2,500 or more pigs.
[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: animals, antibiotics, colonization, food policy, hogs, MRSA, Science Blogs, ST398

More on MRSA on Farms and in Farm Workers, and the Arguments for and Against

July 12, 2013 By Maryn Leave a Comment

Photo: ROIrving/ Flickr

In my last post I promised to catch up on some of the other research that has been published on the flow of MRSA (and other resistant organisms) between farm animals and farm workers as a result of farm antibiotic use.

Before I do that, though, I want to nod toward two other great pieces published on this. First, Mark Bittman  examined this issue closely at the New York Times. And Clare Leschin-Hoar also covered the new research at Take Part. (Bonus: Don’t miss her dissection of the news that a National Geographic photographer was arrested in Kansas after taking pictures of a feedlot — from the air.)

[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: agriculture, animals, antibiotics, food, food policy, food safety, hogs, MRSA, Science Blogs, ST398

"Pig MRSA" Carried by Workers from North Carolina Intensive Hog Farms

July 5, 2013 By Maryn Leave a Comment

Pig farms from the air. Maryn McKenna, Creative Commons License

I saved this post until today to allow everyone to get their holiday hot dogs guilt-free. Now that’s over: An important study has just been published which makes a close connection between the emergence of antibiotic-resistant bacteria, and the use of antibiotics on large-scale conventional hog farms. Bonus: It involves the resistant bacterium MRSA ST398 (known in shorthand as “pig MRSA”), which is widespread in Europe but up to this point has been found mainly in only one state in the US, Iowa. With this paper, the count rises to two(see Update): The study subjects in this paper are hog-farm workers in eastern North Carolina.

A quick explanation of why this is important: “Pig MRSA” is a particular strain of drug-resistant staph that is slightly different from the hospital and community (sports, gym) varieties. It was first spotted in the Netherlands in 2004, in the toddler daughter of pig farmers and in the family’s pigs. Since then, it has spread widely across Europe, not just in agriculture, but in healthcare and in everyday life, and has also been found widely in retail meat.

The question of whether livestock production’s use of antibiotics causes antibiotic-resistant bacteria to move into the wider world is much argued-over, and pig MRSA, or ST398 to be polite, is crucial to that dispute. That’s because, unlike most resistant bacteria, it has a genetic signature that makes an inarguable link back to farm drug use. More on that below. (If you want more, here’s an archive of my posts on ST398; the story of its emergence in 2004 and what happened afterward is told in my 2010 book SUPERBUG.)

Now, the study. Quick summary, with more unpacking to follow: Researchers checked livestock-farm workers in North Carolina to see whether they were carrying staph, and also drug-resistant staph. The workers formed two groups: one group worked at conventional hog operations, which routinely use antibiotics, and the other group at antibiotic-free farms. Both groups carried staph and also drug-resistant staph, which would be expected; about 30 percent of the population carries sensitive staph and about 4 percent carries the drug-resistant form. But, the key difference: Workers from the conventional, antibiotic-using farms were many times more likely to carry staph with the specific signature of farm-drug use.

That illuminates a potential occupational risk to the workers — and it also suggests that the workers could be a channel for that farm-influenced bacterium to move off the farm.

[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: agriculture, animals, antibiotics, food, food policy, food safety, hogs, MRSA, North Carolina, Science Blogs, ST398

To Prevent MRSA In Hospitals, Don't Prevent Only MRSA

May 30, 2013 By Maryn Leave a Comment

Practically since the multi-drug resistant bacterium MRSA became a public health issue in the 1960s, health care has been arguing over how best to prevent its spread — particularly in hospitals, where the bug first became a problem and where the most vulnerable patients are concentrated. The camps break down, more or less, into procedures which look for MRSA specifically, and procedures which reduce the risk of spreading any pathogen in the hospital environment. The MRSA-specific strategies, popular in Europe and in some health-care systems in the US, involve checking patients to see who is carrying the bacterium, and then taking extra care with those who are positive, usually by isolating them within the hospital and making sure health care workers wear protective gear when they encounter them. The more general ones involve mandating actions, usually but not always things  that health care workers do — such as washing their hands more regularly and bathing patients with disinfectant — which will reduce the risk of not only MRSA transmission but of any other pathogen as well.

The back and forth between these views has been intense and prolonged; most of the infectious-disease meetings I’ve attended over the past 6 years have staged some sort of debate between representatives of the two sides. In the United States, the “active detection and isolation” strategy (often just called “search and destroy”) has been ascendant; among other things, it has been written into law in at least nine states, and adopted by the VA healthcare system. It has been demonstrated to work (though that demonstration was later challenged), but it is costly in staff time and also in equipment, since detection is usually done by molecular methods; and isolation has been shown to be rough on patients as well.

In the latest round — though given the contentiousness of this debate, probably not the last — a strong study just published in the New England Journal of Medicine, describing a careful trial of both systems, establishes that the non-specific strategy works better to reduce not just MRSA, but hospital-associated infections of all kinds.

[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: CDC, MRSA, Science Blogs

News From The Road: No Drugs, Few Strategies, But A Little Good News On Antibiotic Resistance

April 28, 2013 By Maryn Leave a Comment

So, hi, constant readers. Sorry, didn’t mean to disappear for quite that long. I’ve been on the road, first teaching for a week at the University of Wisconsin as their Science Writer in Residence, and then in New York to attend the annual meeting of the American Society of Journalists and Authors, where I received the June Roth Memorial Book Award for Superbug. (Plus, in between those two, I recorded an episode of the Virtually Speaking Science podcast with Tom Levenson, which you can find here, about the looming post-antibiotic disaster; and an episode of Skeptically Speaking with Marie Claire Shanahan, which you can find here, about the emerging story of H7N9 flu; and got tangentially involved in the Boston bomber manhunt.)

While I was offline, a far amount of news happened. In the next few days, I’ll do my best to catch up. Here’s a start, all on infections and antibiotic resistance.

[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: antibiotics, HAI, IDSA, Iowa, MRSA, Resistance, Science Blogs

Gene Sequencing Pinpoints Antibiotic Resistance Moving From Livestock to Humans

March 28, 2013 By Maryn Leave a Comment

The antibiotic era was barely 20 years old when people started raising concerns about using the new “miracle drugs” in agriculture. Penicillin first entered use in 1943, streptomycin in 1944, tetracycline in 1948 — and by 1965, the United Kingdom’s Agricultural Research Council was hearing testimony that organisms common in food animals, especially Salmonella, were becoming resistant to the antibiotics being used on the animals while they were alive. By 1969, the UK government had compiled an official report outlining the danger, and by 1973, a task force of the US Food and Drug Administration had concurred, and concluded the only safe action was to withdraw approval to use antibiotics in animals. (At which, as we now know, they would never be successful.)

The policy difficulty regarding this long-recognized problem has never been the emergence of resistant bacteria on farms; no one seriously disputes that resistance emerges whenever antibiotics exert selective pressure on bacteria, killing the vulnerable and opening an ecological niche into which the surviving not-vulnerable can expand. The  sticking point has been the difficulty of proving that those resistant bacteria depart from farms, cross to humans, and cause resistant illness in them. Stuart Levy demonstrated it in 1976, on an experimental farm plot he set up just to make the proof. Most of the rest of the research, though — and after decades, there are hundreds of pieces of research — has been observational and retrospective: Looking at the drugs administered to populations of animals (about which we have very little data), measuring the antibiotic-resistant illness that arises in the human population, and making increasingly sophisticated backward matches between the resistance factors that show up in humans and the drugs that are deployed primarily on farms.

Demonstrating the bacterial traffic prospectively and experimentally, as Levy did, is challenging not just logistically but also ethically. It is difficult to imagine a study design that could trace specific animals, their meat, and their eaters in a large group of free-living humans; and unless you have volunteers, as Levy did, the study would push ethical boundaries as well. But having that lack of definition in the middle of the animal-to-human bacterial flow permits uncertainty — which proponents of continued ag antibiotic use exploit.

A new study of Danish farmers and their livestock may have ended that uncertainty. It is still retrospective, but its observations — using whole-genome sequencing — are so fine-grained that their tracing of the bacterial traffic seems to me to be difficult to challenge.

[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: agriculture, animals, antibiotics, food, food policy, MRSA, Resistance, Science Blogs, ST398

Livestock MRSA Found For First Time In UK Milk

December 26, 2012 By Maryn Leave a Comment

This paper almost slipped by me. It was published quietly a few weeks ago, and it’s a little eyebrow-raising. From EuroSurveillance, the open-access peer-reviewed bulletin of the European Centre for Disease Prevention and Control (Europe’s CDC): The ST398 strain of MRSA, better known as “livestock-associated MRSA” or just “pig MRSA,” has been found for the first time in milk in England. (And therefore probably in cows, or at least on farms.)

Apparently there has been an ongoing study looking for any evidence of MRSA in UK cows, possibly because of this news from last year (of which more in a minute). Between last January and July, the program tested 1,500 samples of milk from farms’ bulk tanks — that’s the cooler in which milk from a number of cows is collected until it can be picked up by a truck for processing — and found seven of the samples were contaminated by MRSA. All seven isolates were MRSA ST398, the livestock-associated strain. Three came from one farm, so five farms had MRSA in their tanks.  According to the paper, this is the first discovery of ST398 in the UK other than one finding in horses in 2009.

[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: agriculture, animals, food, food policy, milk, MRSA, Science Blogs, ST398, UK

News Round-Up: Sausage, Soil, Skeeters, Camping, China, Chimps And Other Hazards

August 31, 2012 By Maryn Leave a Comment

This has been my week: Oh, wow: I should write about that. No, wait — that. Damn, new news; I’ll blog this paper instead. Except, hold on — this one is great too…

So to solve my indecision before the week ends, here you go: Most of this week’s most interesting news, in round-up form.

[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: agriculture, antibiotics, China, counterfeit, drugs, food, food policy, food safety, foodborne, meat, MRSA, Reuters, russia, Science Blogs, South Korea, TB

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