Maryn McKenna

Journalist and Author

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How Agriculture's Growth Promoters Might Work: A Mouse Study Sheds Some Light

August 19, 2014 By Maryn Leave a Comment

Rama (CC), FLickr

Rama (CC), Flickr

The farm practice that underlies most agricultural use of antibiotics is known as “growth promotion”: It calls for giving very small doses of antibiotics routinely to meat animals because those doses cause them to gain fat and muscle more quickly than they would otherwise. Growth promotion dates back to the early days of the antibiotic era, and has always been somewhat mysterious. Though there were attempts to pick apart its mechanisms in the 1950s and 1960s (I’ve been reading some fascinating old accounts), for the most part, people simply accepted that it worked. It’s only in the past decade or so, as interest has increased in the microbes that reside everywhere in our and animals’ bodies (a vast community generally known as the microbiome), that researchers have begun trying to dissect what is going on.

The scientific team that has probably pursued this most intensely is the NYU Langone Medical Center lab led by Martin J. Blaser. Blaser published a popular account of their research into antibiotics’ effect on obesity, asthma, diabetes, and other disorders in Missing Microbes: How the Overuse of Antibiotics Is Fueling Our Modern Plagues, published in April. (Disclosure: I reviewed the book for Nature.) Two years ago, the team showed that giving small doses of antibiotics to very young mice affected genes controlling metabolism of nutrients, and caused the mice to gain weight. Now they have followed up that research with detailed work exploring how much the timing and length of antibiotics affects weight gain. Though the work is still in mice, it leads to provocative conclusions about how growth promoters work in livestock, and what early-life antibiotics might do to humans as well.

[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: antibiotics, growth promoters, microbiome, Resistance

Fecal Transplants: The FDA Steps In

May 19, 2013 By Maryn Leave a Comment

Hi constant readers: I am traveling again, and while I’m in a far time zone, news has broken that you might be interested in. So while I don’t have a full understanding myself yet of what’s going on, I’m going to throw up what I’ve got, because I know how many people are interested in this.

Briefly: The US Food and Drug Administration has decided to bring the semi-outlawed — but very safe and very effective — procedure called “fecal transplant” under its auspices, ruling that to perform it, physicians must have applied for an “investigational new drug application,” or IND. This requires a lot of advance paperwork, 30 days of consideration, and does not return not a guaranteed yes. For the transplants, which have been performed informally but carefully by a growing number of physicians as a treatment (and often cure) for devastating C. difficile infection, it may improve safety, but it can’t help but impose obstacles and delay. (My past posts on fecal transplants here and here.)

[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: C.diff, FDA, microbiome, SciAm, Science Blogs

Fecal Transplants: A Clinical Trial Confirms How Well They Work

January 17, 2013 By Maryn Leave a Comment

A little more than a year ago, I wrote a piece in Scientific American about fecal transplants — replacing the stool in someone’s colon with stool donated by someone else — as a treatment for the pernicious, recurrent diarrhea caused by Clostridium difficile infection.

I have been a journalist for two decades, and some of my stories have won prizes, triggered hearings and legislation, and caused people to change their minds about significant social issues — but I don’t think anything I have written has ever proved as sticky with an audience as that 1,500-word column. In the 60 or so weeks since it was published, I have heard from more than 100 people — yes, that’s more than 1 per week — who are afflicted with C. diff, believe that a transplant could help them, but cannot find a doctor who agrees that the procedure has merit.

A paper published Wednesday evening in the New England Journal of Medicine may give those patients assistance, and change those doctors’ minds. It represents the first report from a completed randomized trial of fecal transplants, and it finds that the treatment worked much better than the powerful antibiotics that are usually given for C. diff infection — so much better, in fact, that the trial was ended early, because the monitoring board supervising the trial’s execution could not ethically justify withholding the transplants from more patients.

[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: microbiome, Science Blogs

Fecal Transplants: They Work, the Regulations Don't

December 9, 2011 By Maryn Leave a Comment

Lara Thompson was 26 when her life fell apart.

She was living in Rhode Island and working in HIV prevention research when she unexpectedly developed nausea and diarrhea. It was early 2008, a few weeks after New Year’s, and she thought she might have picked up a stomach virus at a holiday gathering, or stressed her system with overindulgence. She expected the symptoms would pass after a few days. They didn’t.

“In three weeks, I dropped 15-20 pounds,” she says now. “I couldn’t keep anything in; I would have to run to the bathroom at a moment’s notice. I was so lethargic I had to stay home from work.”

When she consulted her doctor, she found out what was bothering her was more complex than a virus. Somehow, her intestinal lining had become infected with Clostridium difficile, or C. diff, a tough and persistent bacterium that has been rising in incidence and gaining antibiotic resistance, becoming increasingly difficult to treat.

[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: C.diff, FDA, microbiome, SciAm, Science Blogs

Antibiotics: Killing Off Beneficial Bacteria … for Good?

August 26, 2011 By Maryn Leave a Comment

It’s an accepted concept by now that taking antibiotics in order to quell an infection disrupts the personal microbiome, the population of microorganisms that we all carry around in our guts, and which vastly outnumbers the cells that make up our bodies. That recognition supports our understanding of Clostridium difficile disease — killing the beneficial bacteria allows C. diff room to surge and produce an overload of toxins — as well as the intense interest in establishing a research program that could demonstrate experimentally whether the vast industry producing probiotic products is doing what it purports to do.

But implicit in that concept is the expectation that, after a while — after a course of antibiotics ends — the gut flora repopulate and their natural balance returns.

What if that expectation were wrong?

[Read more…]

Filed Under: Science, Science Blogs, Superbug Tagged With: antibiotics, C.diff, diabetes, microbiome, obesity, Science Blogs

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