Maryn McKenna

Journalist and Author

"Pig MRSA" causing human infections

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Hi, everyone. Apologies for dropping out of sight! As SUPERBUG’s publication draws closer (and it’s very close now), I keep finding new tasks that I have do to. Last week’s was to go to New York to shoot a video for the Simon & Schuster website — and while there, I got caught in Snowpocalypse, got delayed coming home, and picked up a nasty cold. So I’m a bit behind.

But there’s exciting news tonight to start us up again: “pig MRSA,” ST398, causing human infections in Canada and Denmark.

“Infections” is important, because up til now, most evidence for  the spread of MRSA ST398 in humans has been through detection of colonization, the symptomless carriage of MRSA on the skin and in the nostrils. The first finding of ST398 in the Netherlands was via colonization; so was its first identification in humans in Canada, and also in the United States just about a year ago.

[Read more…]

Antibiotics and farming — how superbugs happen

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Constant readers: There’s an important new paper that’s been out for a week that I haven’t gotten to you. I apologize; it’s been busy. (Let’s not even talk about the important paper that’s been out for two weeks. Maybe over the weekend…)

We’ve talked for ages now about the potential dangers of unrestricted antibiotic use in agriculture, and how it’s analogous to the inappropriate antibiotic use that human health authorities disapprove of in humans. The main culprits, in farming, are subtherapeutic dosing, also known as growth promotion — that’s giving routine smaller-than-treatment doses to animals to increase their weight — and prophylactic dosing, which is giving a treatment dose to an entire herd or flock either routinely, if there is thought to be a disease threat, or when there is known to be disease in some members of the herd/flock. In either case, animals are getting antibiotics when they do not need them — when they are not sick. And just as in humans who take antibiotics when they are not sick, or take too-low doses when they are sick (such as not finishing a prescription), these practices in animals encourage the development of resistant bacteria.

(Necessary comment here: No one, to my knowledge, objects to giving the appropriate doses of antibiotics to animals that are sick. Why would you?)

[Read more…]

New film on organic farming (for European readers and Francophones)

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This is a little outside our usual subject matter, but:

What looks like a marvelous new documentary exploring environmental damage and human illness from pesticides and other farming chemicals is coming out in France, but needs assistance to get onto the international festival circuit. It’s called Nos enfants nous accuseront (Our Children Will Hold Us Responsible), and among other things, looks at the efforts of a French village to make all the food served in its schools organic — which, even in food-centric France, is much harder than it sounds.

You can view the trailer here. The more clicks, the more the film will be taken to have support, and the higher its rankings will go for festival consideration.

It comes well-recommended by friends of mine in Paris, so I hope you’ll take a look.

Farming and antibiotics – and voices from the ag side

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The whole issue of how antibiotics get used in agriculture — as growth promoters, as prophylatic treatment to prevent spread of infection within a farm, or as true treatment — is intensely controversial. For a sense of how farmers feel embattled, read the comments to this entry at FairFoodFight on whether there is a distinction between “Big Ag” and “small ag.” and consider that the PAMTA legislation I posted about in December, which would require veterinarian oversight of farm use of antibiotics,  has been strongly opposed by agricultural interests every time it has been introduced. (Large-farm use of antibiotics, let me remind you, has been concluded to be the driver behind the emergence of “pig MRSA” ST398.)

But I recently ran across two pieces online that I want to draw your attention to, because they demonstrate that thinking in agriculture about antibiotic use is not monolithic, and may be changing. Both were posted on the same site, the Illinois-based Agri-News Online.

[Read more…]

Back again to MRSA in animals, and spreading to humans

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There are two new reports out regarding new findings of “pig MRSA” ST398 (about which we have talked a lot; archive of posts here.)

First, researchers from the Complejo Hospitalario Universitario de Vigo and Complejo Hospitalario de Pontevedra, both in Pontevedra in northwest Spain, report that they have identified that country’s first human cases of infection with ST398. (It was only last fall that Spain reported the first identification of the strain in animals.)

The age of the three patients was 59, 82, and 83 years, respectively. Two patients owned pigs and the other a calf. Two patients were diabetic and were hospitalized because they developed skin and soft-tissue infections by MRSA ST398. The third patient had bronchitis and the strain was isolated from a respiratory secretion submitted to the laboratory from an outpatient clinic. The three patients had had multiple hospital admissions in the last 12 months.

Tellingly, the researchers spotted these particular isolates (out of 44 analyzed at the two hospitals in 2006) because they were resistant to tetracycline. Tetracycline resistance is not common among community strains of MRSA, because the drug isn’t the first-line choice for skin and soft-tissue infections; and when it is given, it’s usually for a short course, so the drug does not exert much selection pressure on the bug. But tetracycline is a very common animal antibiotic, and tetracycline resistance is a hallmark of ST398; it is one of the factors that led the Dutch researchers who first identified the strain to take a second look at the bug.

Second, researchers from several institutions in Italy report a very troubling case of ST398 infection that produced necrotizing fasciitis — better known as flesh-eating disease. [Read more…]

Warning on ST398: Monitor this now

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Drawing your attention: I have a story up tonight at CIDRAP on a new paper by Dr. Jan Kluytmans, a Dutch physician and microbiologist and one of the lead researchers tracking “pig MRSA,” ST398. (All past stories on ST398 here.) It’s a review paper, which is to say that it summarizes key existing findings rather than presenting original research.

Still, it’s important reading because Kluytmans is one of the few scientists who have some history with this bug and understand how quickly and unpredictably it has spread across borders and oceans, from pigs to other livestock, to pig farmers and veterinarians, into health care workers and hospital patients who have no known livestock contact, and now into retail meat in Europe, Canada and the United States.

Take-away: A plea and warning for better surveillance, so that we can track not only the bug’s vast range, but also its evolution as it moves into new ecological niches — including humans who are buying that retail meat and possibly becoming colonized with it as they prep it for cooking in their home kitchens.

To honor fair use (and in hopes you’ll kindly click over to CIDRAP), I won’t quote much, but here’s the walk-off:

Because the novel strain has spread so widely and has already been identified as a cause of hospital outbreaks, it should not be allowed to spread further without surveillance, Kluytmans argues.”It is unlikely that this reservoir will be eradicated easily,” he writes. “Considering the potential implications of the reservoir in food production animals and the widespread presence in meat, the epidemiology of [MRSA] ST398 in humans needs to be monitored carefully.”

The cite is: Kluytmans JAJW. Methicillin-resistant Staphylococcus aureus in food products: cause for concern or case for complacency? Clin Microbiol Infect 2010 Jan;16(1):11-5. The abstract is here.

Questioning meat-raising and meat-eating — in eat-everything France

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Happy New Year, constant readers. I’m honored and flattered to have had the chance to spend the past few years with you here. 2010 is going to be a big year — not just because SUPERBUG will be published, but because the issue of antibiotic resistance really, really is gathering force in the public mind. I not only believe that, I see it in the news that flows through my computer everyday. The wind is shifting.

Here’s one excellent example. In France of all places, a culture that embraces meat-eating and finds the idea of animal rights quixotic, a book has been published that questions the environmental and moral effects of modern factory farming. It’s called Bidoche, L’industrie de la viande menace le monde (“Bidoche” is a slangy, dismissive term for meat), and it has made enough of a splash that the newspaper Le Monde ran both an article on the book and a readers’ Q&A with the author, journalist Fabrice Nicolino. (The article ran two days before Christmas but was called out on Twitter today by Paula Crossfield of CivilEats.com, who spotted it while on holiday, and to whom hat/tip.)

Sadly, the article is behind a paywall; you can see the first 100 words or so here. The Q&A is open though. It’s titled, “To save the planet, should we eat less meat?”and makes fascinating reading (GoogleTranslate into English here), as do the comments, some of which raise the issue of the use of antibiotics in agriculture. But what’s most striking to me is that the conversation is taking place at all, actively and in a public forum, in a place where only a few years ago the local culture would not have been open to the debate. Things are changing indeed.

MRSA in pets – a closer look

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From the research team at the University of Guelph Ontario Veterinary College — who have probably done more than any other group to elucidate MRSA in companion animals — comes a look at MRSA infections in dogs.

In order to get better data, the team used a study model that is much-employed in human epidemiology — and has often been used for MRSA — but under-employed in veterinary medicine: a case-control study matching MRSA infections against MSSA, or drug-sensitive staph. Studies matching MRSA against MSSA have been able, for instance, to show that certain (human) MRSA infections have higher death rates, keep patients in the hospital longer, and cause more healthcare expense.

The Guelph team used the same method to compare the presentation and outcome for 40 MRSA-infected dogs and 80 dogs with MSSA who were seen between 2001 and 2007 in three veterinary hospitals, in Guelph, Philadelphia and Boston. Their verdict:

MRSA is an emerging problem in dogs, and the risk factors for MRSA infections are similar to those in humans, particularly the use of IV catheters and both beta-lactam and fluoroquinolone antibiotics.

The researchers were not able to say whether MRSA in dogs causes more deaths than MSSA, because the infections that were recorded by the hospitals were mostly superficial ones in skin and ears:

Infection types for which death would be a more realistic possible outcome were limited… Comparison of mortality rates between patients with MRSA or MSSA infections would be best performed among on ly those with invasive infections and should be considered for future studies. Here, mortality rate information was obtained retrospectively and only recorded up to the time of discharge. Therefore, whether dogs died from their infections after discharge from the referral hospital, causing an underestimate of deaths, is unknown.

Dr. Scott Weese, senior author of this paper and chief of the Guelph group, has an excellent blog on infections in companion animals, called Worms and Germs. (It’s in the blogroll.) And if you are looking for further information on MRSA in pets, the best resource I know of is the UK-based, but international, Bella Moss Foundation, named for a dog that died of a MRSA infection.

Antibiotics in chickens, and links to human infections

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From the January issue of Emerging Infectious Diseases, published by the CDC (and therefore free. Must I keep urging you to read it? Go, already), here’s a roundup of bad news about bad bugs.

In Canada, researchers from that country’s Public Health Agency have found a “strong correlation” between the use of ceftiofur, a third-generation cephalosporin, in chickens; the rates of a resistant strain of Salmonella in chickens; and the appearance of that same strain in humans. The strain is Salmonella enterica serovar Heidelberg, one of the most common salmonella strains in North America, and one which can be nasty: It may cause mild illness, but also causes septicemia and myocarditis and can kill. Quebec created an unplanned natural experiment: Hatcheries there were broadly using ceftiofur until 2004, backed off from its use in 2005 and 2006, and then began using it again in 2007 in response to a growing problem with a particular infection. When the drug was withdrawn, resistant infections in birds and humans plunged; when it was reintroduced, they rose again. (Look at the black and red lines in the graph above left.)

Meanwhile, broiler chickens in Iceland are passing fluoroquinolone-resistant E. coli to humans there. Researchers at the University of Iceland were puzzled by an earlier finding that bacteria resistant to fluoroquinolones (a family that includes the human drug Cipro) were increasing among chickens raised in Iceland, despite strict controls on antibiotic use in food animals and stringent disinfection in chicken batteries after cohorts of birds were sold for slaughter and removed. They have two findings: The source of the resistant bacteria in the birds appears to be feed contaminated with resistant E. coli; and resistant bacteria in Iceland residents are microbiologically indistinguishable from those in the birds. Because E. coli is a very diverse organism, the very close resemblance between the isolates from chickens and the isolates from humans pins chickens as the likely source.

And just to make clear we’re not blaming every microbiological evil on farming: Seagulls in Portugal have been found carrying multi-drug resistant E. coli in their feces. The public health concern here is obvious: Just think back to the last time you were at a beach, or anywhere else seagulls frequent, and envision a seagull perch — and the masses of seagull droppings streaking it. Now imagine those droppings transmitting antibiotic-resistant E. coli into the surrounding environment: the boardwalk, the beach, the towels… Additional problem: Seagulls are migratory birds, so the resistant bacteria easily cross borders and oceans.

Antibiotics in animals – a warning from the poultry world

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Constant reader Pat Gardiner guided me to an enlightening post at the website of the agricultural magazine World Poultry that questions the routine use of antibiotics in food animals. It’s written by Wiebe van der Sluis, a Netherlands journalist from a farming background, founder of World Poultry and also the magazines Pig Progress and Poultry Processing.

The Netherlands, let’s recall, is the place where MRSA ST398 first emerged, and also the place where that livestock-MRSA strain has caused the most serious human cases and triggered the largest changes in hospital infection-control practices. In the Netherlands, swine farmers and veterinarians are considered serious infection risks because of their exposure to animals, and are pre-emptively isolated when they check into hospitals until they can be checked for MRSA colonization.

Van der Sluis takes seriously the tie between the use of antibiotics in animals and the emergence of MRSA:

Although most of the time MRSA is linked to pig production, it is also related to the veal and poultry industry. The industry, therefore, cannot shrug its shoulders and move on if nothing was wrong. In this case it would be wise to redefine the term prudent use of antibiotics. Time is up for those who use antibiotics to cover up bad management, poor housing conditions or insufficient health care. The standard rule should be: Do not use antibiotics unless there is a serious health issue and no other remedy applies. Veterinary practitioners, who usually authorise producers to use antibiotics, should also take responsibility and prevent unnecessary antibiotic use and the development of antibiotic resistance in animals and humans.

It’s unusual in the US context so hear someone so immersed in agriculture speak so candidly about antibiotic use. It’s refreshing.

Wednesday a.m.: Congressional briefing on antibiotics in livestock – live-tweeted!

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Folks: On Wednesday 2 December, at 9:30 a.m. EST, Rep. Louise Slaughter (D-NY) will host a Congressional briefing about antibiotic use in food animals. As a reminder, Rep. Slaughter is an MPH and Congress’s only microbiologist, and the chief sponsor of PAMTA, the Preservation of Antibiotics for Medical Treatment Act that proposes restricting antibiotic use in animals to therapeutic uses under the guidance of a veterinarian and phases out “growth promotion” with sub-therapeutic doses, which consumes millions of pounds of antibiotics every year, many of them close analogs to human drugs.

Appearing at the briefing along with Rep. Slaughter are leaders of efforts that have produced an important string of reports on antibiotic overuse — the Pew Commission on Industrial Farm Animal Production and the Extending the Cure project of Resources for the Future:

  • Michael Blackwell, DVM, MPH–former Vice Chair, Pew Commission on Industrial Farm Animal Production; Assistant Surgeon General, USPHS (ret.); Former Dean, College of Veterinary Medicine, University of Tennessee, Knoxville, TN.
  • Robert Lawrence, MD–Director, The Johns Hopkins Center for a Livable Future, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD.
  • Ramanan Laxminarayan, PhD, MPH–Senior Fellow, Center for Disease Dynamics, Economics, and Policy, Resources for the Future, Washington, DC
  • Robert Martin–Senior officer, Pew Environmental Group; former Executive Director, Pew Commission on Industrial Farm Animal Production, Washington, DC
  • Lance Price, PhD– Director, Center for Metagenomics and Human Health, Translational Genomics Research Institute, Flagstaff, AZ

Here’s a post explaining the importance of this issue from the blog of the Center for a Livable Future, a Johns Hopkins University research group that has produced some of the most mportant papers on leakage of antibiotic-resistant bacteria and antibiotic residues from CAFOs (“confined” or “concentrated” “animal-feeding operations” — very, very large-scale farms). And here’s some video on the issue from last summer from Lou Dobbs Tonight.

Because the event Wednesday is an informational briefing, not a hearing, I can’t find any link for a live webcast. (I’ll update if I find one.) But the hearing will be live-tweeted by the staff of the Center for a Livable Future (@LivableFuture) at the hashtag #CLF09. BLOGGERS: They will take tweeted questions toward the end of the hearing, ~10:45 a.m. — use the hashtag.

"Pig MRSA" in the EU – long-awaited survey

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It’s not very likely that people will be eating much pork today — OK, maybe some pancetta in the Brussels sprouts — and that’s good, because there’s lots of news today about MRSA in pigs.

(In fact, there’s a ton of news just this week. Make it stop.)

The European Food Safety Authority has published a long-awaited, European Union-wide survey looking for the presence of MRSA in pigs. Here’s the key points: Investigators found MRSA on 1 out of 4 farms where pigs were being raised and in 17 of the 24 EU states. (Two non-member states were included in the analysis.)

Strictly speaking, this is not a survey of MRSA in pigs; the study samples not the pigs themselves, but the dust in pig-raising sheds. The sites were 1,421 breeding farms and 3,176 farms where pig are raised to slaughter age. By far the most common strain was MRSA ST398, though other strains were detected, including some known human strains. The prevalence in various countries went from a low of 0 to as high as 46% of farms. (Highest, in descending order: Spain, Germany, Belgium, Italy, Portugal. The Netherlands, where St398 was first identified, had a prevalence of 12.8%. Countries reporting no MRSA: Bulgaria, Cyprus, Denmark, Estonia, Finland, Hungary, Ireland, Latvia. Lithuania, Luxembourg, Sweden, the United Kingdom, Norway and Switzerland.)

The report closes by recommending comprehensive monitoring of pigs for MRSA, as well as monitoring of poultry and cattle.

About the potential of ST398 crossing to humans, it has this to say:

In humans, colonisation with MRSA ST398 originating from pigs has been identified as an occupational health risk for farmers and veterinarians and their families. Although MRSA ST398 represents only a small proportion of the total number of reports of human MRSA infections in the EU… in some countries with a low prevalence of human MRSA infection, CC398 is a major contributor to the overall MRSA burden.
In most cases, colonisation with MRSA ST398 in humans is not associated with disease, although clinical cases associated with MRSA ST398 have been reported. MRSA ST398 can be introduced into hospitals via colonised farmers and other persons in a region with intensive pig farming. Therefore, MRSA ST398 may add substantially to the MRSA introduced in health care settings. However, it seems that the capacity for dissemination in humans (patient-to-patient transmission) of livestock-origin MRSA, in particular ST398, is lower as compared to hospital-associated MRSA).
… Food may be contaminated by MRSA (including ST398), however there is currently no evidence for increased risk of human colonisation or infection following contact or consumption of food contaminated by ST398 both in the community and in hospital.

Britain’s Soil Association, which pressed for the study to be done, has released a statement quoting the food safety agency warning that the testing method may have underestimated MRSA’s presence on farms, and warning that if ST398 is not yet in England, it is certainly soon to arrive. Germany’s Federal Institute for Risk Assessment also released a statement, admitting that ST398 in German pig stocks is “widespread.”

The report is here, executive summary here, and press release here. All well worth reading.

New MRSA pig strain in China

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Via Emerging Infectious Diseases comes the full version of a piece of research I posted on in September that was presented at the London conference Methicillin-resistant Staphylococci in Animals: Veterinary and Public Health Implications. A new MRSA variant — not ST398 — has been spotted in pigs in China.

Luca Guardabassi and Arshnee Moodley of the University of Copenhagen and Margie O’Donoghue, Jeff Ho, and Maureen Boost of the Hong Kong Polytechnic University report that they found a pig-adapted MRSA strain in 16 of 100 pig carcasses collected at 2 wet markets in Hong Kong. By multi-locus sequence typing, the strain is ST9, previously found in pigs in France; by PFGE, they fall into categories that tend to carry the community-strain cassettes SCCmec IV and V.

Here’s the bad news: This strain possesses resistance factors that resemble human hospital-associated MRSA more than they do ST398.

Twelve isolates displayed a typical multiple resistance pattern, including resistance to chloramphenicol, ciprofloxacin, clindamycin, cotrimoxazole, erythromycin, gentamicin, and tetracyline. The remaining 4 isolates were additionally resistant to fusidic acid. … All isolates were negative for Panton-Valentine leukocidin and susceptible to vancomycin and linezolid.

The further bad news, of course, is that this is being found in Hong Kong, adjacent to China, which is the world’s single largest producer of pork, raising tens of millions of tons of pig meat per year. Most of the pigs sold in Hong Kong come from the Chinese mainland, not from the SAR. Pig surveillance for MRSA in China is practically non-existent (which is not much of a criticism since it does not exist in the United States, either). A human infection with ST9 has already been recorded in Guangzhou, the province adjacent to Hong Kong.

The question, for this strain as for all MRSA strains in pigs, is what is its zoonotic potential? Here again, the news is not good. According to Maureen Boost, who presented this research at the London conference, the isolates were obtained by the researchers from intact heads from butchered pigs; the researchers took the snouts to the lab and and swabbed them there. Pig snout happens to be a desirable meat in China; it is bought in markets, taken home and made into soup. Boiling in broth would probably kill MRSA bacteria — but home butchering of a pig snout could pass the bug on to the human cutting it up, or to that human’s kitchen environment, long before the snout ever got into the pot.

The cite is: Guardabassi L, O’Donoghue M, Moodley A, Ho J, Boost M. Novel lineage methicillin-resistant Staphylococcus aureus, Hong Kong. Emerg Infect Dis. 2009 Dec. DOI: 10.3201/eid1512.090378

 

Antibiotic misuse in animals – one example

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Via the Minneapolis Star Tribune and the excellent blog Fair Food Fight comes the story of two cows, from two Minnesota farms, that have been reprimanded by the US Food and Drug Administration for bringing cows to slaughter that turned out to have been massively overdosed with antibiotics.

From the Strib:

In a rare move, federal officials sent stern warning letters to two central Minnesota dairy farms, which were among only 30 farms nationwide reprimanded so far this year for violating the rules governing how animal drugs can be used.
J&L Dairy, in Clarissa, Minn., sent a dairy cow to slaughter in March, even though it was drugged with 129 times the amount of penicillin allowed under federal regulations.
Another farm, Evergreen Acres Dairy, LLC, in Paynesville, Minn., was warned by the FDA last month, after one of its cows was found to have more than four times the allowed amount for a certain type of antibiotic. Further inspection found that the farm had misused 10 other drugs. (Byline Lora Pabst)

From one of the FDA’s reprimand letters, to J&L Dairy of Clarissa, Minn.:

Our investigation … found that you hold animals under conditions that are so inadequate that medicated animals bearing potentially harmful drug residues are likely to enter the food supply. … Our investigation found that you routinely administered penicillin G procaine to dairy cows without following the daily dosage amount or dosage amount per injection site as stated in the approved labeling. Your extralabel use of penicillin G procaine was not under the supervision of a licensed veterinarian, in violation of 21 CFR 530.11 (a), and your extralabel use of penicillin G procaine resulted in illegal drug residue, in violation of 21 CFR 530.11(d).

From the other reprimand letter, to Evergreen Acres Dairy of Paynesville, Minn.:

Our investigation … found that you hold animals under conditions that are so inadequate that medicated animals bearing potentially harmful drug residues are likely to enter the food supply.
…The investigation … found that you adulterated the new animal drugs neomycin sulfate, sulfadimethoxine oral solution, oxytetracycline injection, oxytetracycline hydrochloride injection, ceftiofur hydrochloride, ceftiofur crystalline free acid, ceftiofur sodium, penicillin G procaine aqueous suspension, florfenicol, tetracycline hydrochloride soluble powder, and tylosin. Specifically, the investigation revealed that you did not use these drugs as directed by their approved labeling. Use of these drugs contrary to their approved labeling is an extralabel use.

There are some important points to make here.

As we’ve talked about before, many of the antibiotics used in food animals are effectively over-the-counter drugs; farmers can buy them in feed stores and administer them without a veterinarian’s supervision. (Putting an end to OTC animal antibiotics is the goal of Rep. Louise Slaughter’s legislation, the Preservation of Antibiotics for Medical Treatment Act (PAMTA), supported by the Obama Administration supports; post here.) Without such supervision, it is easier for a farmer to make a mistake in dosing, or to give the drugs too close to animal’s slaughter time, so that the drug’s don’t wash out of the animal’s system but remain in its meat after death.

A second important point is that we talk a lot here about the dangers of industrial-scale farming, in which antibiotics are given to animals that are not sick, either in small doses as growth promoters or in treatment-size doses to prevent illness spreading through a flock or herd. Antibiotic misuse has become linked in the public mind with the enormous animal-raising operations known as CAFOs. But both these reprimanded farms were family farms, not CAFOs. These reprimands underline that inappropriate antibiotic use is not a function of farm size — it’s a by-product of market pressure.

New reports on animals, food, MRSA ST398

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Well, constant readers, didn’t expect to be gone *that* long. Many apologies. There was a good reason — actually, several: I attended a journalism meeting, and spoke at a second meeting. But most important, I received, marked up, and returned the galleys of SUPERBUG. Yes, it’s really starting to look like a book now. There will be things to share, soon.

Meanwhile, I’ll try to roll out some of the many, many pieces of news and research related to staph that have emerged in the past few weeks. Today: News on animals, and our old opponent, MRSA ST398.

First: A team from the Universidad de La Rioja reports in the Journal of Antimicrobial Chemistry the first finding of MRSA ST398 (“pig MRSA,” archive here) in food in Spain. They tested 318 raw meat and wild-game samples (chicken, pork, veal, lamb, turkey, rabbit, game bird, wild boar, deer, hare) and found ST398 and other MRSA strains in 5 of them, an incidence of 1.6%. The authors write: “Although MRSA prevalence in raw food is low, the risk of its transmission through the food chain cannot be disregarded.”

Importantly, one of the other strains found in the meat of these animals is an uncommon variant, ST125-t067, that has already been implicated in large numbers of hospital infections in Spainand is resistant to ciprofloxacin (Cipro), erythromycin and a third antibiotic, tobramycin, in addition to the usual suspects. The other non-ST398 strain is ST217, which is a variant of a long-known hospital strain, and is also resistant to Cipro, a very valuable drug for skin and soft-tissue infections. So it appears the contamination may cross both ways, from animals, and to animals as well.

No link, but the cite is: Lozano, Carmen, et al. Detection of methicillin-resistant Staphylococcus aureus ST398 n food samples of animal origin in Spain. Journal of Antimicrobial Chemistry. e-pub Oct. 21 2009 AOP doi:10.1093/jac/dkp378

Next: If the prevalence of ST398 is so low in food, why do we care? We care because of where those organisms go next — into hospitals, among other places. A Dutch/German team that includes the original identifier of ST398 in humans are reporting that they have found an association between the density of pig-farming in parts of Germany and the probability that patients admitted to hospitals will be carrying ST398 with them, creating a possible source for nosocomial infections. R. Kock and colleagues screened 1,600 pigs on 40 German farms, and also reviewed screening results for every MRSA-positive patient admitted to the University Hospital-Munster from 2005 through 2008. They found ST398 on 70% of the farms, and also found that ST398 represented 15% of the MRSA isolates at the hospital in 2005, rising to 22.4% in 2008. The key association: The patients carrying St398 were more likely to have contact with pigs in their daily lives, and also with cattle, than patients who had other forms of MRSA or no MRSA at all.

The cite for that paper: Kock, R. et al. Prevalence and molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) among pigs on German farms and import of livestock-related MRSA into hospitals. European Journal of Clinical Microbiology and Infectious Diseases, e-pub Aug 25, 2009. DOI 10.1007/s10096-009-0795-4

And finally: How do you stop the evolution and spread of antibiotic-resistant organisms in livestock? One good way is to stop giving teh livestock antibiotics in the first place. In a column at the Huffington Post, Laura Rogers, project director of the Pew Campaign on Human Health and Industrial Farming, takes on the oft-repeated assertion that you can’t farm without them without risking the lives and market place of your livestock, and offers the example of Denmark, which did ban antibiotics in animals, and which has healthier, more profitable livestock as a result:

American agribusiness often has criticized Denmark’s 1998 ban on antibiotics, calling it an outright failure. But compelling new research presented by a Danish scientist earlier this year showed the opposite, revealing that antibiotic use on industrial farms has dropped by half while productivity has increased by 47 percent since 1992. Danish swine production has increased from 18.4 million in 1992 to 27.1 million in 2008. A decrease in antibiotic-resistant bacteria in food animals and meat has followed the reduced use of these vital drugs.

New news on MRSA and animals

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Constant readers, I’ve been behind the Great Firewall of China for two weeks, unable to post. (Apparently Blogger is not always unavailable there, but access has tightened up in advance of the National Day celebrations on Oct. 1.) I left with a file of things to post in my spare time — and so now we’re way behind, with lots to catch up on.

Latest news first, though. A few days ago, an intriguing conference was held in London: Methicillin-resistant Staphylococci in Animals: Veterinary and Public Health Implications. It was co-sponsored by the American Society for Microbiology and the European Society of Clinical Microbiology and Infectious Diseases, and it was the first conference ever convened to examine the behavior in animals of MRSA and other staph species, including our old friend, ST398.

I have the abstracts (which have not otherwise been published), and wow, there was a ton of news.

Here’s the biggest: An investigation by a team at University of Iowa (the same group that first identified ST398 in pigs and pig farmers in the United States) found significant amounts of MRSA in pigs and in human workers on 4 out of 7 conventional farms, but no MRSA on 6 organic farms. MRSA was present — as a colonizing organism, not causing illness — in 23% of the 168 pigs sampled on the conventional farms, and 58% of 45 humans who worked on those farms. “These results suggest a significant number of U.S. swine may be colonized with MRSA, adding to the concern about domestic animal species as a reservoir of this bacterium,” the abstract says. “Furthermore, occupational exposure to these colonized pigs may spread the bacteria from the farm to the community via a high number of colonized swine workers.” (Author: Abby L. Harper, MPH, University of Iowa)

A partial list of the other findings announced:

  • MRSA ST398, which emerged as an animal and human pathogen in the Netherlands, is now causing human colonization and illnesses in other countries. Denmark, which like the Netherlands has a very low background rate of MRSA, has detected 109 cases since 2003, 35 of them with actual infections. Two of the infections were very serious: one pneumonia in a newborn baby, and one septic arthritis in an adult that led to sepsis and multi-organ failure. (J. Larsen, National Centre for Antimicrobials and Infection Control, Denmark)
  • Meanwhile, the Netherlands — which conducts routine screening for MRSA carriage on hospital admission — has seen its annual count of MRSA detections rise from 16 per year between 2002 ad 2006 to 148 per year between 2006 and 2008, with 81% of the current cases due to ST398. (M. Wulf, PAMM Laboratory, the Netherlands) UPDATE: Coilin Nunan of the Soil Association in the UK corrects me (thanks, Coilin!): This study covers only the southeastern pig-farming areas, or about 40% of the MRSA cases in the country.
  • MRSA ST398 spreads from infected to uninfected pigs during transport to slaughterhouses and while being held at slaughterhouses. (E. M. Broens, Wageningen University, the Netherlands)
  • More than 15% of slaughterhouse workers who handle live pigs — but none of those who handled pig carcasses after slaughter — were carrying MRSA 398, and 25% of environmental samples such as dust taken from different parts of slaughterhouses were carrying the organism as well. (B. A. van Cleef, RIVM [National Institute for Public Health and the Environment], the Netherlands)
  • Along with the pig-origin ST398, recognized human strains of MRSA can also colonize pigs, according to a study on one Norwegian farm, but human strains are less successful at persisting in pigs and tend to die out after months. (M. Sunde, National Veterinary Institute, Norway)
  • Animal-origin MRSA is rising in China, the world’s largest producer of pork, but the problematic strain there is ST9, not ST398. That MRSA strain was found on 5 out of 9 farms in Sichuan province in mainland China, and in 33.5% of 260 pigs slaughtered in Hong Kong, where more than 90% of pork comes from the mainland. (J. A. Wagenaar, Central Veterinary Institute, the Netherlands; and M. V. Boost, Hong Kong Polytechnic University)
  • And an intriguing finding for those concerned about humane slaughter methods: Broiler chickens were significantly more likely to carry MRSA, and transmit it to slaughterhouse workers, if they were killed by the traditional method of electrical shock followed by throat-slitting, and less likely to carry or transmit the bug if they were killed by carbon dioxide asphyxiation, which has been held out as a more humane method of killing. (M. N. Mulders, RIVM [National Institute for Public Health and the Environment], the Netherlands)

UPDATE: I’m still a bit jet-lagged and forgot to mention that, of course, we have a long archive of coverage of ST398 and other strains in animals. Find them here.

Non-medical use of antibiotics: A whole new problem with ethanol

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Constant readers, we’ve talked frequently about the emerging recognition that the enormous use of antibiotics in agriculture is fueling the development of resistance, both directly in the case of specific organisms such as MRSA ST-398, and indirectly in that it pushes the evolution of resistance factors that bacteria then trade amongst themselves. (For a superb overview of the antibiotics/agriculture problem, see this article in the June issue of the Johns Hopkins (University) Magazine. Hopkins is the home of the Center for a Livable Future, which is doing excellent research on this issue.)

And we’ve also talked about the related issue of antibiotic residues elsewhere in the environment, in sewage and wastewater supplies.

But here’s a whole new peril: Antibiotic resistance generated by ethanol production, that vast corn-based industry that has been pitched as a homegrown biofuel alternative to foreign oil.

Food-policy blogger (and farmer and chef) Tom Philpott has been doggedly following this story for more than a year at Grist. And in a study published last month the Institute for Agriculture and Trade Policy brings some important numbers-based analysis. The gist of the problem is this:

  • Ethanol production uses yeast to convert corn starches into alcohol
  • Bacterial contamination, usually by lactobacilli, can hijack the process and covert the starches to unusable lactic acid instead
  • To prevent that from happening, ethanol producers dose their corn mash with antibiotics
  • Because contamination is frequent and persistent, producers use increasing amounts of antibiotics to overcome bacteria that have become resistant
  • After ethanol is extracted, the mash residue remains tainted with those resistant bacteria and with antibiotics — including penicillin, erythromycin and streptogramin (an analog of the human antibiotic Synercid)
  • The dried mash residue is sold to farmers as livestock feed, exposing livestock to resistant bacteria and dosing them with unsuspected additional antibiotics as well.

If there is any good news in this, it is that (according to the IATP), some of the faltering ethanol industry is aware of the problem and working on it, with about 45% of plants now working on non-antibiotic alternatives. The bad news is that 55% — more than 90 of the 170 ethanol facilities in the United States — are not.

Catching up on some reading: health care reform, food bugs, vaccine, MRSA+flu

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Folks, while I was caught in travel hell, some excellent stories and blogposts were released. Here’s a quick round-up of recommendations for a rainy weekend:

  • At Roll Call (covers Congress like a blanket), Ramanan Laxminarayan, PhD MPH, of the rational-use-of-antibiotics project Extending the Cure and infection-control physician Ed Septimus, MD make a strong argument for including control of hospital infections in health care reform. Hard to argue against when you realize that HAIs cost the United States more than $33 billion each year.
  • At Meat Wagon, a blog of the online magazine Grist, the always-excellent Tom Philpott digs into the ongoing outbreak of antibiotic-resistant Salmonella in hamburger meat. Key quote: “Outbreaks of [antibiotic-resistant foodborne illnesses] are really ecological markers — feedback that our way of producing meat is deeply unsustainable and really quite dangerous.”
  • The Associated Press reports that the long-in-development staph vaccine made by Nabi Pharmaceuticals may have received a second life: It’s been purchased by international pharma giant GlaxoSmithKline in a $46-million deal.
  • And finally and sadly, the Sacramento Bee reports that a California nurse who died of H1N1/swine flu also had MRSA pneumonia. Karen Ann Hays, 51, died despite being extremely healthy: she was a triathlete, skydiver and marathon runner. No one yet has been able to say whether she caught the flu — or MRSA — at work (though her partner believes that to be true), but her death has fueled disquiet among members of the California Nurses Association, who are protesting a lack of protective equipment for nurses.

For those of us concerned about MRSA pneumonia — and we have been talking here since the start of the H1N1 pandemic about the danger of MRSA co-infection — that last item about Hays’ very sad death should underline a vital point. Public health authorities have been stressing that H1N1 is most deadly when the infected person has a pre-existing condition: pregnancy, heart disease, obesity, diabetes, cystic fibrosis. It is possible that MRSA infection is also a pre-existing condition that will put anyone infected with flu at risk of deadly complications.

If you have had MRSA, even a minor skin infection — and especially if you have experienced recurrent infections — you should probably discuss with your personal physician whether you should take the H1N1 vaccine when or if it becomes available. It could be the step that prevents a minor case of flu from tipping over into something much more serious.

Media round-up: recommending MRSA stories

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By chance — or is it because interest is really picking up? — a couple of worthwhile stories on MRSA have been published almost simultaneously:

  • For when the science gets wonky: Environmental Health Perspectives has an excellent lay-language explanation of how drug resistance emerges and spreads — with gorgeous graphics!
  • For when yet another drug doesn’t work: Scientific American covers development of new antibiotics, and even more important, development of new ways of creating antibiotics.
  • For yet more depressing news about MRSA in meat: Prevention adds to the discussion of MRSA in the food supply with a “special report” review. Constant readers who have been following along as we’ve drilled into this topic over the past two years won’t find a lot new, except for an intriguing account of an outbreak of MRSA in an Arkansas chicken plant (in which the bug went disappointingly untyped, so we don’t know whether it was a human strain or ST398). The story hits on issues we have talked about here: Surveillance for MRSA in animals is non-existent, practically speaking, and when the bug is found, investigation falls between human and animal health agencies. It’s a longer than usual story for Prevention, and should bring the knotty food-policy questions around MRSA in meat to a new audience.

Antibiotic overuse in animals: Obama administration comes out against

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For anyone who cares about the overuse of antibiotics in food animals, and the resistant bacteria that overuse has been shown to produce, this is important news.

In testimony today, new FDA Commissioner Dr. Joshua Sharfstein announced the administration’s opposition to the use of growth promoters: sub-therapeutic doses of antibiotics used not as disease treatment, but to encourage animals to put weight on rapidly. Further, he also came out against the administration of antibiotics in food animals without the involvement of a veterinarian — a common situation out here in farm country, where veterinary antibiotics are freely available over the counter. (We discussed Scott Weese’s proposal to end that practice here.)

Both of these practices have been repeatedly linked to antibiotic resistance, and for the administration to come out against them is highly significant — not just for the struggle against resistant bacteria, but also for the movement to reduce industrial-scale agriculture, which relies on antibiotics to keep food animals healthy while they are in the close confinement of CAFOs.

Sharfstein made the announcement while giving testimony on behalf of Rep. Louise Slaughter (D-NY)’s Preservation of Antibiotics for Medical Treatment Act of 2009, which has been introduced (and opposed into nonexistence) multiple times over the past decade. (Earlier post on the legislation, including its text, here.) He said:

To avoid the unnecessary development of resistance under conditions of constant exposure (growth promotion/feed efficiency) to antibiotics, the use of antimicrobials should be limited to those situations where human and animal health are protected. Purposes other than for the advancement of animal or human health should not be considered judicious use. …
Important factors in determining whether a prevention use is appropriate include evidence of effectiveness, evidence that such a preventive use is consistent with accepted veterinary practice, evidence that the use is linked to a specific etiologic agent, evidence that the use is appropriately targeted, and evidence that no reasonable alternatives for intervention exist. FDA also believes that the use of medications for preventino and control should be under the supervision of a veterinarian. …
FDA supports the treatment of ill animals according to appropriate veterinary practice within a valid veterinary-client-patient relationship.

Also on the docket at Slaughter’s hearing:

  • Margaret Mellon, PhD, of the Union of Concerned Scientists (who specifically discussed MRSA ST398): “As long as the massive use of antibiotics continues, animals … will remain a fountain of resistant pathogens, dangerous to both animals and humans. The straightforward solution to the problem is to reduce the use of antibiotics in animal production and thereby diminish the pool of resistant organisms and traits.”
  • Robert Martin of the Pew Environment Group (Pew Charitable Trusts): “The present system of producing food animals in the United States is not sustainable and presents an unacceptable level of risk to public health, damage to the environment, as well as unnecessary harm to the animals we raise for food.”
  • And statements of support from the Chipotle restaurant chain and the Bon Appetit Management Company (which operates catering services in corporations and universities).

Of note, the Pew Commission on Human Health and Industrial Farming, which supports Slaughter’s bill, said after the hearing that Sharfstein’s proposals are only necessary but not sufficient: ““The proposed FDA position does not go far enough in this regard and would allow the continuation of conditions that necessitate the improper use of antibiotics in the first place.”