31 July 2010

News break: "Pig MRSA" ST398 involved in the death of a child?

The latest postings to the website of the CDC journal Emerging Infectious Diseases include a sad and very troubling letter from physicians in Lyon and Paris, reporting the death from necrotizing pneumonia of a previously healthy 14-year-old girl. That would be sad under any conditions, but here's what makes the death so troubling: It appears to have been caused by MRSA — but not by the community strain, USA300, that has been implicated in a number of deaths from necrotizing pneumonia. (Several such stories are told in SUPERBUG the book.)

Instead, her death appears to have been caused by infection with MRSA ST398 — the livestock-associated strain that was first noted in pigs raised with antibiotics, and the pig-farm workers caring for them, in the Netherlands 6 years ago, and that has since spread across the European Union, Canada and into the United States. (My 3-year archive of ST398 posts is here.)

This may be the first death associated with ST398, though I can't say that for sure as I am away from my big computer and working without my database. I'll update later today and confirm or knock that down.

The physicians say that the girl came in with flu-like symptoms and abdominal pain, was put on IV antibiotics (cefotaxime and amikacin), underwent an exploratory laparotomy that showed nothing, and shortly afterward developed acute respiratory distress and was put on a vent. A chest X-ray was shadowy on both sides. She went rapidly downhill and died 6 days later.

On analysis, the staph strain infecting her was ST398; there was no indication where she had picked it up. The strain had an unusual characteristic: It possessed the ability to make the cell-destroying toxin Panton-Valentine leukocidin, PVL for short, a genetic trick that until now has been a property only of community MRSA strains such as USA300. Though its role is disputed, PVL has been linked to community MRSA's ability to start infections on intact skin, and to the cellular damage that destroys children's lungs in cases of pneumonia caused by USA300. Until now, ST398 has been PVL-negative.

The physicians' letter is short and there's much more to find out about this case. But if the report and analysis are correct, this is bad news. One of the repeated themes in the 50-year evolution of MRSA has been its ability — all staph's ability — to promiscuously swap and share the bits of DNA that confer resistance and enhance virulence. Another, since the emergence of ST398, has been the potential peril of a staph strain adapting and mutating in the millions of farm animals around the world that are routinely given antibiotics — and that for the most part are not checked to see whether they harbor resistant organisms. If this report (and my interpretation) are correct, then those two trends are converging in a way that cannot bode well.

29 July 2010

Advice for science writers, from science writers

Ed Yong, an incisive and prolific science blogger-writer-communications officer, opened up his blog to the science-writing community earlier today, with this invitation:
Every now and then, I get an email from someone who’s keen to get into science writing and wants to know how I started. Whenever I reply, and I always try to, I’m always left with the nagging feeling that my experience is but one of a multitude of routes that people have taken. Science writing (whether you want to call it journalism, blogging, communication and so on) is a diverse field, as are the people working in it. It would be far more illuminating for a newbie to see a variety of stories rather than just one.
...I will be asking science writers around the world to do what they do best – tell a story – about the thing they know best – themselves. This will be a perpetual thread that I hope will act as a lasting resource for the writers of tomorrow to take inspiration from.
That was about 18 hours ago. So far there are 59 comment/stories posted, from some of the brightest and sharpest writers working today, with more to come tomorrow, I am sure. (Also, umm, me. I didn't get in til #51, because I was trying to catch a plane.) Collectively, the comment string is both a peek behind the curtain of how science writers and authors work and think — and think about their work — as well as a trove of advice for anyone else who wants to try this odd and taxing profession.

A selection:

Mark Henderson (#2), science editor of the Times of London: "If you can’t find great stories from everything that’s pouring out of the world’s laboratories, you’re not much of a journalist."

Jonah Lehrer (#4), author of How We Decide and Proust Was a Neuroscientist: "Writing is a craft. There are no born writers. One has to practice and practice and practice."

Maggie Koerth-Baker (#5), BoingBoing.com: "Think of yourself as a business, ask to be paid what you’re worth and stick to your guns, always turn things in on time, learn that editing is not your enemy, and work really, really hard at writing nuanced, factual stories that are still fun to read. Luck helps those who help themselves."

Raima Larter (#16), writer and former chemistry professor: " I don’t think you can go wrong when you make your choices based on what most excites you. Passion can go a long way in carrying you forward in any career."

John Pavlus (#21), writer/filmmaker: "BE curious and ACT curious. Everything else will work itself out from there."

TR Gregory (#29), an evolutionary biologist who has started a companion thread on his own blog: " There is a lot of frustration among scientists and educators with the way new studies are portrayed in the media, but when someone is recognized as an honest and skilled communicator, he or she will be among the ones that scientists hope will discuss their research."

Brendan Maher (#34), features editor, Nature: "Humility and self-assured enthusiasm can coexist."

Eric Michael Johnson (#41), blogger at The Primate Diaries: " Take risks. Make mistakes. Fall flat on your face. The difference between wanting to be a writer and actually being one is in how often you pick yourself back up."

(Stripped of the biographical material, here's my contribution: "Work nights and weekends. Seek mentors. Stay alert to serendipity. When someone wants to tell you a story, listen. Develop expertise. Distrust everyone’s motives, including your own. Always ask another question. Talk to people face to face. Rejoice in complexity, in systems and in persons, and accept that it takes its time revealing its intricacies. Try to tell the truth.")

27 July 2010

Whooping cough: Back, with a vengeance

A few years ago, I went to India on a reporting trip. When I came back, I had a troublesome cough. I figured I'd picked up a bronchitis aggravated by New Delhi's smog-laden air, or by the dung smoke from the fires in the villages where I'd spent most of my time. The cough got worse instead of better. It was especially bad at night: I'd lie down to sleep and that would trigger a paroxysm. Sometimes I'd cough until I couldn't breathe. A few times, I vomited. Eventually my side began to hurt. (Months later, I discovered I'd cracked a rib.)

As a medical reporter, I spent most of my time around doctors and nurses, but I had a rule about never bothering them — first because I was pretty healthy, and second because no one wants to be the guy at the cocktail party who finds out someone's a doc and backs them into the corner of the buffet table. But one day, worn out by the spasms, I mentioned my symptoms to a friend. His eyes got big. He went and got a textbook.

I didn't have bronchitis. I had pertussis — whooping cough.

This made no sense, of course. Between a day job as Scary Disease Girl and a childhood spent moving between continents, I am pretty much the most vaccinated person on the planet.  I'd had my full series of pertussis vaccinations as a child. Surely I was protected?

Actually, no — and unless you've had a booster, neither are you. The immunity created by the 5-dose childhood series wanes over time; by the age of 12, even fully vaccinated people are vulnerable to pertussis again. Since 2006, the Advisory Committee on Immunization Practices has been recommending a single additional pertussis (Tdap) booster for anyone between the ages of 11 and 64. That may seem like overkill — adult cases of pertussis in previously vaccinated people are often milder than the child version; after all, I survived my bout. But as with so many vaccines, the beneficiary here isn't just the adult taking the booster. Even more, it's the more vulnerable person to whom that adult might pass the disease: an elderly person with age-related immune decay; someone with a chronic disease; an infant too young to be vaccinated. In those people, the disease can and does kill — as it did an 18-day-old infant, Nelyn Baker, whom I wrote about in 2004.

Because vaccine immunity fades, pertussis is always with us: in good years, about 1,000 cases across the United States. Lately, though, we're in bad years. Pertussis cases are rising dramatically, in Alabama, Georgia, Arkansas, Texas, South Carolina, Michigan, Oregon and Ohio. The worst by far is California, where so far this year almost 1,500 cases of pertussis have been reported and another 700 are suspected — compared to 258 for the same time period in 2009.

"We are facing what could be the worst year for pertussis that this state has seen in more than 50 years,” Dr. Gilberto Ch├ívez of the California Department of Public Health said last week in a statement put out by the agency's Center for Infectious Disease.

The worst news in this upsetting trend is this: We're doing it to ourselves. As far as anyone can tell, the rise in pertussis is not due to any change in the organism, or to any mysterious error among the manufacturers who make pertussis vaccines. It's due to vaccine refusal, to parents turning away from vaccines because they think the vaccines are more harmful than the diseases they prevent — or, more selfishly, because they think the wall of immunity created by other vaccinated children will protect their unimmunized ones.

That's an incorrect assumption, by the way. Work published last year by several scientists at Kaiser Permanente of Colorado found that unvaccinated children were 23 times more likely to contract pertussis than vaccinated ones. (Glanz, McClure, Magid et al., Pediatrics 2009, doi:10.1542/peds.2008-2150.) And yet, as numerous stories (LA Times, MedPage Today) have pointed out, California's epidemic has blossomed in a state that gives some of the most generous "personal belief exemptions" from vaccination — and the epidemic's worst hot spots neatly correlate with the most concentrated areas of vaccine refusal.

Pertussis is an awful disease. A child in the throes of a paroxysm sounds like nothing else on earth. Children turn blue, give themselves black eyes, die. We kept it down to manageable levels with the help of a vaccine. That we would willingly bring it back it is beyond belief.

(For a physician's take on pertussis, see this post by my fellow former Scibling Pal MD. The CDC's information page on pertussis is here and the National Network on Immunization Information explains the vaccination schedule here. H/t to the infectious-disease mailing list ProMED for starting me thinking.)

21 July 2010

Hospitals want patients to eat antibiotic-free meat

Huge news, and hat tip to excellent food-policy writer Monica Eng at the Chicago Tribune: In a piece published Tuesday, she details that 300 hospitals in the Chicago area and nationwide have begun preferentially buying and serving meat that is raised without the use of antibiotics.
Using the ingredients is primarily a response to patient demand, said (Carolyn Lammersfeld, national director of nutrition at Cancer Treatment Centers of America) but the centers are also "watching the controversy over the nontherapeutic use of antibiotics and their potential to cause resistant strains of bacteria."
The issue is of particular concern for cancer patients, who have compromised immune systems, she noted. "Many also might already being taking antibiotics, so they don't want additional ones in food if they can avoid it," Lammersfeld said.
The drug-free meat is more expensive, but the cost balances out within the budget:
(Diane Imrie, director of nutrition services at Fletcher Allen Health Care in Vermont) estimated that her food costs rose about $67,000 last year when she switched to antibiotic-free chicken from conventional. "But that's also about the same cost as treating a single MRSA infection," she said.
It's interesting to see this story land just as a new paper in Foodborne Pathogens and Disease is making the rounds. The paper (Jiayi Zhang, Samantha K. Wall, Li Xu, Paul D. Ebner. "Contamination Rates and Antimicrobial Resistance in Bacteria Isolated from “Grass-Fed” Labeled Beef Products," doi:10.1089/fpd.2010.0562) compares the bacterial burden in grass-fed and conventionally raised beef and finds no significant  differences: equivalent amounts of both drug-sensitive and drug-resistant bacteria in both types of beef. 

It concludes, "There are no clear food safety advantages to grass-fed beef products over conventional beef products" — an assertion that's likely to be seized on by those who see no need to change current antibiotic use in agriculture. (For an example of that POV, here's the testimony from last week's House of Representatives hearing by Richard Carnevale, DVM of the Animal Health Institute.)

I suspect though that the paper's analysis doesn't look far enough. Here's one example: the authors found that Enterococcus species in both conventional and grass-fed meat were resistant to chloramphenicol, erythromycin, flavomycin, penicillin, and tetracyline — drugs that are used in agriculture (and that could have been given to the grass-fed animals, which were not guaranteed to have been raised drug-free). But  Enterococcus spp. isolates from conventional beef were more frequently resistant to daptomycin and linezolid — which are new-to-market drugs of last resort in human medicine that are not given to animals.

That finding, right there — the migration of resistance to a human-only drug into an organism carried by an animal — signals one of the insoluble problems of overuse of antibiotics. Once created, resistance factors move horizontally among bacteria, from the farm to humans, and apparently in this case, from humans to the farm as well. We have almost no control over their movement, and on the agricultural side, almost no surveillance to detect it, either. That argues for reducing the overuse of antibiotics in human medicine and on the farm. 

If this health care coalition's refusal to purchase meat raised using antibiotics helps to enlarge the market for drug-free meat, then it may reduce ag antibiotic use, and therefore the selective pressure that encourages resistant organisms to emerge. That can only be a good thing.

(The paper in Foodborne Pathogens has also been covered by my former colleagues at CIDRAP; here's their link.)

20 July 2010

Hi, I'm back.

Hello again, constant readers. If you've been following the ongoing implosion at my briefly-new-and-now-former home at Scienceblogs, you'll know why we're back here blowing the dust off things. If not, never mind: There's way too much news to talk about, anyway.

To maintain some continuity, I've changed the URL for this site to Superbugtheblog.com, though the former address, drugresistantstaph.blogspot.com, will also now redirect here. RSS feed buttons are in the sidebar.

I'll be cleaning things up in the next day or so and updating the archives. But in the meantime, I'm back and I hope you are too.

07 July 2010

Antibiotic use in animals: The feds move, a little

This is an addition for archival purposes of a post that originally appeared at Scienceblogs.

(You leave the country for a few days -- I spoke at a conference in Brussels, which was was lovely, thanks for asking -- and all kinds of news breaks out. So, sorry to be late on this, but it's an important issue.)

Last week, the Food and Drug Adminstration took the first (baby, mincing, tentative) steps to address the problem of antibiotics being used in animal agriculture, not to treat disease, but to make animals grow up to market weight faster. This practice -- variously called subtherapeutic dosing, growth promotion, and "for production purposes" in the FDA's exceedingly careful language -- has been fully banned in the European Union for 4 years, and some aspects of the practice have been banned longer.

The simple reason for the ban: There's decades of good science and real-world experience showing that it contributes to the development of drug-resistant organisms in farm animals and the farm environment, organisms that leave farms in the animals and in their manure, and also contaminate the environment beyond farm borders via leakage into groundwater and dust blowing off manure lagoons.That movement off the farm is critical because many of the drugs used in agriculture are the same, or close analogs, of drugs used in human medicine; so resistance that develops on the farm endangers human health as well. (MRSA ST398, livestock-associated MRSA, is the latest example of this. Find a long archive of posts on ST398 here.)

Just to be clear, growth-promoters don't treat disease; they're given to healthy animals solely for the purpose of getting them up to sale weight and to market faster. The ways in which antibiotics are given to livestock to treat or prevent disease have their own issues, but those are not part of the FDA effort. (Historical note: The growth-promoting effect of trace amounts of antibiotics was first recognized in 1947, when scientists at Lederle were looking for something to do with the leftover fermentation mash from the manufacture of chlortetracycline, fed it to chickens, and discovered they thrived on it. Stuart Levy's The Antibiotic Paradox tells this story in detail.)

In human medicine, when we give antibiotics to people who are not sick with a bacterial illness, we call it inappropriate use -- and aim massive education campaigns at the practice in an attempt to dial it down. In contract, the animal side has had a free pass for a long time, to the extent that it remains unclear how many antibiotics are used in farming in the US (best estimate: about 70% of all antibiotic use in the US per year), and there is no organized surveillance that would look at what organisms are emerging in animals from that use.

The FDA has been trying to put curbs on growth promoters since the 1970s, always without success; the lobbying against it, by agriculture and also by pharmaceutical interests, is reliably intense. There's been a parallel effort in Congress to limit the use in animals of drugs that have close analogs in human medicine, via the Preservation of Antibiotics for Medical Treatment Act, or PAMTA, authored by Rep. Louise Slaughter (D-NY), Congress's only microbiologist. PAMTA has been introduced in several Congresses but this year finally gained some traction. Last year, the Obama administration signaled, in testimony by then-new assistant FDA commissioner Joshua Sharfstein, that it might be friendly to the idea of dialing back on growth-promoter antibiotic use, and it looked as though the long logjam might finally be broken.

Well, OK: Not broken, exactly. Just shifted a little, and maybe showing a tiny bit of light.

On Tuesday, the FDA released a "draft guidance" that proposes animal ag do two things: stop using growth-promoting subtherapeutic dosing, and administer antibiotics to animals under the supervision of a veterinarian. That's the good news.

The bad news: It's only a guidance, not a regulation. In other words, it has no force in law. It's more like a request -- though in a press conference last week, Sharfstein suggested it might also be a shot across agriculture's collective bow:
We have the regulatory mechanisms and the industry knows that. But we are also interested in what things can be done just voluntarily that they would do them. And I think it'll be interesting to see how the industry responds to this and how - what direction their comments take. ...We're not handcuffed to the steering wheel of a particular strategy at this point. We really want to understand what people think. And but we're also - I'm not ruling out anything that we could do to accomplish these important public health goals. (Transcript)

Reactions to the FDA announcement were predictable -- effectively "No science, more research needed": Here's the National Cattlemen's Beef Association, the National Pork Producers Council, and a standing statement by the Animal Health Institute. (Supporting the FDA move: the Pew Charitable Trusts, the New York Times.)

The draft guidance stays open for public comment for 60 days, until Aug. 30. The required Federal Register posting is here, with the mailing address. Electronic comments can be left at Regulations.gov; the docket number for the guidance is FDA-2010-D-0094; 33 comments have been posted already.