Maryn McKenna

Journalist and Author

Farm Antibiotics: 'Pig Staph' in a Daycare Worker

By Leave a Comment

It’s been just about seven years since an alert epidemiologist in the Dutch town of Nijmegen identified an aberrant strain of MRSA, drug-resistant staph, in a toddler who was going in for surgery to fix a hole in her heart. The strain was odd because it didn’t behave normally on the standard identifying tests, and because it had an unusual resistance factor — to tetracycline, a drug that it should not have been resistant to, because the Netherlands had such low rates of MRSA that tetracycline wasn’t being used against the bacterium there.

Pursuing the source of the strain, researchers at Radboud University found it in the toddler’s parents and sister, and in the family’s friends. Not knowing where else to look, they asked what the parents and their friends did for a living; discovered they were all pig farmers; and went to their farms, and checked the pigs, and found it being carried by them, too. Suddenly, that strange resistance pattern made sense: The Netherlands uses more antibiotics in pig agriculture than any other country in the European Union, and the drug that it uses the most is tetracycline. Clearly, the aberrant strain — known as MRSA ST398 for its performance on a particular identifying test — at some point had wandered into pigs, become resistant to the drugs being given to the pigs, and then crossed back to humans, carrying that new resistance factor as it went.

[Read more…]

World Health Day: Time to tackle resistance

By Leave a Comment

Tomorrow, Thursday, is World Health Day, an annual observance that the World Health Organization uses to focus attention on some critical global-health issue. This year, they’ve chosen antimicrobial resistance as the issue that most needs highlighting. Noting the choice, the Lancet editorialized: “Resistance has joined the front rank of global health concerns.”

On the day, the WHO and some other agencies and organizations will be announcing plans and strategies. I’ll cover those tomorrow. For today, a scene-setter: Why you should care.

Having spent the last couple of years immersed in antibiotic resistance (because, you know, I wrote a book about it), I’m often puzzled why it doesn’t excite more alarm. I’ve concluded our situation is similar to the overused analogy of the frog in the slowly warming water: We don’t realize how bad things have gotten, even when we’re in imminent danger of death.

So here’s a round-up to remind us, drawn just from recent news.

In hospitals: Very large hospital systems are using more broad-spectrum last-resort drugs. Last weekend, representatives of the Veterans Health Administration disclosed that over 5 years, vancomycin use has gone up 79 percent, and carbapenem use, 102 percent. Vancomycin is the only affordable drug of last resort for MRSA; carbapenems are the drugs of last resort for gram-negative infections such as Klebsiella. The use of those drugs is growing because organisms are becoming multi-resistant to less-powerful drugs, but they are becoming resistant to the big guns too. Carbapenem resistance in Acinetobacter, a bacterium that afflicts ICU patients and gravely wounded military members, rose from 5 percent of isolates in US hospitals in 2000 to 40 percent in 2009. Israeli scientists reported this month that carbapenem-resistant Klebsiella pneumoniae (CRKP, subject of my Scientific American article this month) caused a nationwide outbreak in 2007 and 2008, sickening 1,275 patients in 27 hospitals before it was brought under control. [Read more…]

Update: The French case — not MRSA but so interesting

By Leave a Comment

I’m flattered to have as a regular reader Dr. Peter Davies, a professor of swine health and production in the University of Minnesota’s Department of Veterinary Population Medicine. (Disclosure: I worked part-time at U Minn from mid-2006 to mid-2010, but in a different school.) In a comment on my previous post, he points out — perils of reading on a smartphone — an important point where I erred: The staph strain involved in the death of the French 14-year-old was not MRSA, but MSSA, drug-sensitive staph, that had picked up a resistance factor.

Unpacking that a bit: At a minimum, MRSA is resistant to all beta-lactam antibiotics — penicillin, the semi-synthetic penicillins (including methicillin, what the M in MRSA stands for), several generations of cephalosporins, monobactams, and carbapenems. It is also separately, but variably, resistant to macrolides (such as erythromycin), lincosamides (clindamycin), aminoglycosides (gentamicin), fluoroquinolones (ciprofloxacin) and tetracycline.

Livestock-associated MRSA, known as ST398 for its performance on a particular test (multi-locus sequence typing) was first identified as having a tie to pig-farming because it was also resistant to tetracycline, which was being given to the pigs on the farms where the first human carriers worked. (Hence its jocular name, “pig MRSA,” though it’s since been found in other animals.)

The ST398 strain involved in the French girl’s death does not have that broad array of resistance. Chiefly, it was not resistant to beta-lactams, and so can’t be considered MRSA. On analysis, it was resistant to the macrolides, of which the best-known are erythromycin and azithromycin (Zithromax or Z-Pak). Here’s something else intriguing: On another test (spa typing), the ST398 strain in the French girl was one known as t571; the ST398 that has spread from pigs to humans in the European Union, and subsequently to Canada and the United States, is usually t034.

Here’s why this is all so interesting: MSSA ST398 t571 was reported just a few years ago in New York City, in a Bronx community that has close ties to the Dominican Republic, and also in the towns in the Dominican Republic where those Bronx residents come from and visit. (Here’s my initial post on that finding from a medical meeting, and subsequent post when the paper was published.) In that case, the ST398 was fully drug-sensitive — and there was no visible link to pigs, though the authors speculated that livestock, perhaps poultry, might be playing a role on either side of the “air bridge” connecting the two communities.

In the paper (Bhat, Dumortier, Taylor et al., EID 2009, DOI: 10.3201/eid1502.080609), the authors expressed concern that, given staph’s promiscuous ability to acquire resistance — and the fact that ST398 is not regularly surveilled for —  the ST398 in New York could become an undetected resistant strain:

Given ST398’s history of rapid dissemination in the Netherlands, its potential for the acquisition of methicillin resistance, and its ability to cause infections in both community and hospital settings, monitoring the prevalence of this strain in northern Manhattan and the Dominican Republic will be important to understand more about its virulence and its ability to spread in these communities.

And now it appears it has become resistant — but in France, not New York City or the Dominican Republic, and to macrolides, not  beta-lactams. It’s one more reminder of staph’s genius at acquiring genetic defenses, and of how our lack of attention to its mutability and spread continues to allow it to take us by surprise.

Hospitals want patients to eat antibiotic-free meat

By Leave a Comment

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.)

Antibiotic use in animals: The feds move, a little

By Leave a Comment

(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.

Antibiotic resistance in food — some governments pay attention

By Leave a Comment

Folks, I told you Tuesday about a Congressional hearing on antibiotic resistance, featuring NIAID Director Dr. Anthony Fauci and CDC Director Dr. Thomas Frieden. Not much new was said, but it’s encouraging that the hearing was held at all. (Fauci testimony here, Frieden here.)

Coincidentally, constant reader Pat Gardiner of the UK alerted me to a gathering being held on the same day in Ireland, by the quasi-government agency SafeFood—which reports to the North-South Ministerial Council of Ireland, which deals with whole-island issues under the Good Friday agreement, which is more about the Irish political structure than you probably ever wanted to know.

The conference was titled Antimicrobial resistance and food safety and featured government officials and academic researchers from across Ireland. Here’s the agenda, and here’s the press release with the names of key speakers. Even more important, here are links to a report on antibiotic resistance in food that Safefood released in advance of this conference: executive summary and whole thing.  I especially recommend from p.25 in the big report for an accessible discussion of the connections between ag antibiotic use and human health. Key quote among many:

The majority of the evidence acquired through outbreak and epidemiological investigations of sporadic infections, field studies, case reports, ecological and temporal associations and molecular sub-typing studies support the causal link between the use of antimicrobial agents in food animals and human illness. A few papers have questioned this but these have not survived detailed scrutiny.

It’s refreshing to see a government body engage seriously with this emerging issue, which we’ve been talking about for, well, years now, on this blog (sometime this month we passed our 3-year anniversary). I wish, wistfully, that the government doing the discussing was ours.

A blog reaction so perfect I want to print the whole thing…

By Leave a Comment

(…but I won’t, because it’s not fair use or good blogger behavior. But I want to!)

Melissa Graham of Chicago had a great corporate life — and then she re-evaluated, became a chef and caterer, and began organizing in Chicago for sustainable local food, farmers’ markets, and a family-friendly food system. She blogs at the food and food-policy blog The Local Beet. And she’s written a reaction to SUPERBUG that not only completely gets the book, but is emotional and thoughtful and moving besides.

She says, in part:

Before reading Superbug, the question of confinement raised animals was an ethical one for me – whether the misery inflicted upon animals and, for that matter, the humans working in those facilities by the putrid conditions outweighed the need to eat cheap meat. Even the environmental degradation resulting from the inevitable careless management of CAFOs seemed a distant and intangible casualty. For me, Superbug has changed the argument from one of ethics to a moral imperative. In every hamburger of unknown origin, I see Tony Love’s face or even worse that of Carlos Don IV.

Carlos was another healthy kid who left on a school trip to the mountain and returned with a 104°F fever. The first doctor diagnosed Carlos with walking pneumonia so his mother kept him home bundled and hydrated until she realized that he was beginning to hallucinate. She rushed Carlos to the hospital and the doctor’s ultimately diagnosed his condition as MRSA. A long slow death march ensued during which Carlos’s lungs dissolved and clotting choked off the blood to his lower intestines, legs and arms. In two weeks, he was dead.

After reading Carlos’s story late in the evening, I woke a bewildered little locavore from a dead sleep to scrub his hands clean. I hugged him as tightly as I could.

…[recently] I had the pleasure to hear Ruth Reichl speak and she implored the audience to stop eating confinement raised animals. As she put it, if everyone stopped buying them and eating them, the practice would be history. Knowing what I now know, I think it’s our moral duty.

To give the post the traffic it deserves, please go here.

Catching up to MRSA news (not about me)

By Leave a Comment

Constant readers: I’m looking forward to having the breathing space to get back to in-depth blogging. Meanwhile, though, news is zipping by — so here’s a quick list of recent things worth reading.

“Cows on Drugs” — a superb history of the 30-year-old fight to get unnecessary antibiotics out of food animals. Note, written by a former commissioner of the Food and Drug Administration, not exactly a wild-eyed radical:

More than 30 years ago, when I was commissioner of the United States Food and Drug Administration, we proposed eliminating the use of penicillin and two other antibiotics to promote growth in animals raised for food. When agribusiness interests persuaded Congress not to approve that regulation, we saw firsthand how strong politics can trump wise policy and good science.Even back then, this nontherapeutic use of antibiotics was being linked to the evolution of antibiotic resistance in bacteria that infect humans. To the leading microbiologists on the F.D.A.’s advisory committee, it was clearly a very bad idea to fatten animals with the same antibiotics used to treat people. But the American Meat Institute and its lobbyists in Washington blocked the F.D.A. proposal.

Antibiotic resistance in your kitchen, playroom, car... — After years of begging from health advocates, the FDA and EPA are taking a second look at the chemical compound triclosan, an antibacterial that is put into, well, almost anything you can name: soaps, hand sanitizers, cutting boards, toys. Triclosan is suspected of interfering with hormone regulation in the body, and also increases resistance in organisms in our environment. (When I ask you to use hand sanitizers that contain only alcohol or salts, not antibacterials, triclosan is one of the things I’m thinking of.) The FDA will report its findings in a year. I’d rather see it happen sooner, but it’s a great move.

No progress on hospital-acquired infections — The Agency for Healthcare Research and Quality, part of the Department of Health and Human Services, has published its 2009 National Healthcare Quality Report. The news is not good. To quote the agency’s own language: “Very little progress has been made on eliminating health care-associated infections.” This is all hospital-acquired infections, not just MRSA, but MRSA is a leading organism. The ugly details:

  • Post-operative bloodstream infections up 8%
  • Post-operative catheter-associated urinary-tract infections up 3.6%
  • “Selected infections due to medical care” up by 1.6%
  • Bloodstream infections as a result of central lines unchanged.

(NB, three professional organizations — the Infectious Diseases Society of America, the Society for Healthcare Epidemiology of America, and the Association for Professionals in Infection Control — put out a statement in response to this report saying it “presents an outdated and incomplete picture on healthcare-associated infections (HAIs) in our healthcare system.” The gist of the statement seems to be that they’ve got better numbers coming… soon. When there’s actual data, I’ll let you know.)

SUPERBUG on Capitol Hill

By Leave a Comment

Constant readers, I’ve been shamefully absent from the blog, but with reason, since I’ve been traveling promoting the book. There was a pretty interesting opportunity this week that I wanted to tell you about: I was asked to be part of two Congressional briefings in Washington, DC Wednesday, addressing the overuse of antibiotics in agriculture and the contribution that makes to the emergence of resistant organisms such as MRSA. I went specifically to tell the story of the emergence of MRSA ST398, which we’ve been talking about for years here.

The briefings (FYI, “hearings” are for Congresspersons, “briefings” are for their staff) were cosponsored by the Pew Charitable Trusts, Union of Concerned Scientists, American Public Health Association, Infectious Diseases Society of America, and the nonprofit Keep Antibiotics Working.

Here’s Pew’s announcement, here’s the UCS version, here’s a write-up from the Washington Examiner, and here’s a longer one from the site Spectrum Science.

MRSA research round-up: hospitals, vitamins, pets

By Leave a Comment

Because I’ve been so behind, there’s so much to cover! So let’s dive in:

In today’s Archives of Surgery, researchers from Seattle’s Harborview Medical Center report that one simple addition to the routine of caring for trauma patients made a significant difference to the patients’ likelihood of acquiring a hospital-associated infection:
bathing them once a day with the antiseptic chlorhexidine (in an impregnated wipe). Patients who were bathed with the antiseptic wipe, compared with patients wiped down with an inert solution, had
one-fourth the likelihood of developing a catheter-related bloodstream infection and
one-third the likelihood of ventilator-associated MRSA pneumonia. Cite: Evans HL et al. Effect of Chlorhexidine Whole-Body Bathing on Hospital-Acquired Infections Among Trauma Patients.
Arch Surg. 2010;145(3):240-246.

How important are hospital-acquired infections? Here’s a piece of research from a few weeks ago that I sadly failed to blog at the time: Just
two categories of HAIs, sepsis and pneumonia, account for 48,000 deaths and $8.1 billion in health care costs in a single year. Writing in the Archives of Internal Medicine, researchers from the nonprofit project Extending the Cure analyzed 69 million hospital-discharge records issued in 40 states between 1998 and 2006. Hospital charges and number of days that patients had to stay in the hospital were
40% higher because of those infections, many of which are caused by MRSA — and all of which are completely preventable. Cite: Eber, MR et al. Clinical and Economic Outcomes Attributable to Health care-Associated Sepsis and Pneumonia.
Arch Intern Med. 2010; 170(4): 347-53.

 What else could reduce the rate of MRSA infections? How about Vitamin D? South Carolina scientists analyze data from the NHANES (National Health and Nutrition Examination Survey 2001-2004), a massive database overseen by the CDC, and find
an association between low blood levels of Vit. D and the likelihood of MRSA colonization. More than 28% of the population is Vitamin D deficient. MRSA colonization is increasing in the US. Can giving Vit. D decrease MRSA carriage? More research needed. Cite: Matheson EM et al. Vitamin D and methicillin-resistant Staphylococcus aureus nasal carriage.
Scand J Infect Dis
. 2010 Mar 8. [Epub ahead of print]

And finally: Who else carries MRSA? Some unlucky pet owners have found that animals can harbor human strains, long enough at least to pass the strain back to a human whose colonization has been cleared. So it makes sense to ask whether humans who spend time with pets are carrying the bug. Last month’s Veterinary Surgery reports that the answer is Yes.
Veterinarians are carrying MRSA in very significant numbers: 17% of vets and 18% of vet technicians at an international veterinary symposium held in San Diego in 2008. Cite: Burstiner, LC et al. Methicillin-Resistant Staphylococcus aureus Colonization in Personnel Attending a Veterinary Surgery Conference.
Vet Surg. 2010 Feb;39(2):150-7.