Maryn McKenna

Journalist and Author

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.

New 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

“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.

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 Spain and 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.”

Food and ag policy sites: New in the blogroll

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Folks, when I was writing the last post (regarding Scott Weese’s blog), I had to stop and look up several sites. In mid-click, I realized how silly that was, because they are sites I visit all the time — and you should too, if you’re concerned about the veterinary, zoonotic, agricultural and food-policy issues that we discuss here so frequently.

So I’ve created a new category in the blogroll to the right, showcasing food and ag-policy sites that I think are worth reading. Among them you’ll find:

If you have other recommendations, please send them!

Restricting antibiotics in animals: Start by restricting access

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Constant readers, those of you who follow the pressing issue of MRSA in animals will know the work of J. Scott Weese, DVS, associate professor of pathobiology at the University of Guelph in Ontario and supervising author of many crucial papers on MRSA in food and companion animals, including the first finding of MRSA in pigs and pig farmers in North America.

You may not know that Weese and his postdoc Maureen Anderson publish an excellent blog on veterinary and zoonotic diseases called Worms and Germs (in the blogroll at right). This weekend they have an important post that deserves wider attention: Antibiotics: A Dose of Common Sense. In it, they propose that one way to reduce the overuse of drugs in food animals is to make animal antibiotics prescription-only. It’s worth taking the time to read it.

Those of you in the cities may not know this, but out here in the Great Flyover, antibiotics for veterinary use are surprisingly easy to buy (as I discovered when I stumbled into a farm-related store in search of a Carhartt jacket against the Minnesota winter). They’re not even over-the-counter — they’re on the shelf, or stacked on the floor with the implements and feed, or blended into the feed itself. And as Weese points out in this post, they are also available without prescription over the Internet (as human antibiotics are too).

It’s a potentially controversial proposal: I don’t think I have any farming readers, but I would imagine their response would start with an objection to the extra cost of hiring a veterinarian to assess whatever situation might require the drugs. And since most farmers (NB: not the overarching ag-biz companies, but the farmers themselves) exist on razor-thin economic margins, they would have a point. But as we know from the excellent work of Extending the Cure and the Center for a Livable Future, unnecessary antibiotic use comes with a cost as well — one that is borne by all of us when antimicrobial resistance prevents antibiotics from working.

MRSA and pets

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It’s been a while since we’ve focused on the presence of MRSA strains in pets, and the complications that can cause for the pets’ human owners/custodians/companions (or, in the view of my own two cats, abject servants. No, I will not post their pictures. I have some shreds of pride).

The problem with MRSA and pets is not the same as the problem of MRSA ST398 in food animals. Rather, pets tend to carry human strains, passed to them by their owners. The carriage is usually asymptomatic, but not always; there are cases in the medical literature of cats and dogs suffering serious skin and soft-tissue infections from community-strain MRSA, usually USA300. But the emerging consensus seems to be that pets carry the bug transiently — not long, but long enough to reinfect the person who passed the bacterium to the pet in the first place. (This can be, but is not always, the source of recurrent infections in humans: The human takes antibiotics and recovers, but the animal holds onto the bug long enough to pass it back to the now-clear human.)

For anyone who needs to go deeper on this, the current issue of Lancet Infectious Diseases has a good overview of the problem that community MRSA strains pose to pets and their humans. There’s a thorough review of the major papers:

  • Cefai, 1994: hospital outbreaks traced to two nurses and through them to their dog
  • Simoons-Smit, 2000: household epidemic of three humans, one cat, one dog
  • Manian, 2003; dog is source for owner’s recurrences
  • Vitale, 2006: owner is (apparently) source of cat’s MRSA.

(This is a good place to say that this entire history, including personal stories of human and animal infection, is covered in a chapter of SUPERBUG. Publication date coming soon!)

The Lancet paper incorporates reminders of some powerful and troubling trends. As with MRSA ST398, one thing can distinguish MRSA that has been in an animal is a resistance pattern that is slightly different from what we expect but that has arisen because the animals receive different drugs. In the case of pigs and ST398, the intriguing marker is tetracycline resistance; humans don’t usually get tetracycline for MRSA, but pigs do. In the case of companion animals, it tends to be fluoroquinolone resistance; pets are more likely to get that class of drugs for a skin/soft-tissue infection. But, the authors caution, that may mean that pets serve as a breeding ground for multi-drug resistant MRSA, with their fluoroquinolone treatment adding another resistance factor into the bug’s already potent arsenal.

The authors also remind us that MRSA can come from animals much more directly than through silent carriage: that is, in a bite. Both dog and cat bites have been found infected with MRSA, due to bacterial contamination of the wound either from the pet or from colonization on the human’s skin.

The cite is: Oehler RL et al. Bite-related and septic syndromes caused by cats and dogs. The Lancet Infectious Diseases, 9(7):439 – 447, July 2009. doi:10.1016/S1473-3099(09)70110-0.

Antibiotics in water supplies

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Via the journal Environmental Health Perspectives comes an important, comprehensive review article by scientists from Environment Canada and the Universite de Montreal on the presence of antibiotics in water supplies and waste water.

The news is not good. If you are concerned about the possibility that antibiotic residues in the environment create another setting in which resistance can develop, it is worth reading. It is long (10 pages in pdf) but has a comprehensive bibliography. Also, it’s open-access.

Where do these antibiotic residues come from? From us, in some cases: We urinate out up to 90% of some drugs, wash off topical formulations, flush old prescriptions down the toilet. Sometimes from industrial residues, or from leaky hospital sewage, or from sewage treatment plants, or — of course — from industrial-scale agriculture administration and run-off.

And where do they go? According to the paper, over more than 20 years of research, 126 different antibiotics and anti-infectives have been identified in processed waste water, natural surface water and groundwater, and drinking water supplies. Among them are all the antibiotics that we are concerned about here: the drugs that MRSA is already resistant to (beta-lactams, lincosamides, macrolides) and the drugs that still work, for community MRSA at least (sulfonamides, trimethoprim, tetracycline).

Moreover, the trend is expected to get worse, the authors warn: because of increased urbanization; because many urban areas are consciously setting water-saving policies, reducing the volume of wastewater and therefore increasing the concentration of drugs in the water that remains; and because, well, CAFOs aren’t exactly going away right now, are they? As they say:

…even if our results show that high concentrations … of anti-infectives in these waters are more the exception than the rule, the existence of a few locations where these concentrations can be reached are enough to contribute to the global spreading of anti-infective resistance. Given that large populations of bacteria are being exposed to a selective pressure, environmental waters and especially wastewaters become ideal settings for the assembly and exchange of mobile genetic agents encoding for resistance in bacteria. … Anti-infectives, the miracle drugs of the 20th century, have become environmental contaminants of emerging concern in the 21st.

The cite is: Segura PA et al. Review of the Occurrence of Anti-infectives in Contaminated Wastewaters and Natural and Drinking Waters. Environmental Health Perspectives, 117 (5) May 2009.

H1N1 flu and swine surveillance – more relevance for MRSA

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Constant readers, you probably know that yesterday the World Health Organization declared the first flu pandemic in 41 years. I want to point out for you a side issue in the H1N1 story that has great relevance for MRSA, especially ST398.

As described in this article I wrote last night for CIDRAP, three medical journal articles have now pointed out that the virus, or its major components, could have been recognized in swine months to years ago. We missed it, though, because there is so little regular surveillance in pigs for diseases of potential importance to humans. As the authors of the most recent article, in Nature, said yesterday: “Despite widespread influenza surveillance in humans, the lack of systematic swine surveillance allowed for the undetected persistence and evolution of this potentially pandemic strain for many years.”

This is important for our purposes because we know that we are in the same situation with MRSA ST398: The strain was first spotted in France, and has been a particular research project in the Netherlands, but has been found pretty much wherever researchers have looked for it, throughout the European Union, in Canada, and most recently in the United States. All told, though, the scientists concerned with it are still a small community; there is no broad surveillance looking for this bug.

And that’s a problem, for MRSA, for influenza, and for any number of other potentially zonotic diseases: We cannot anticipate the movement of pathogens from animals to humans if we don’t know what’s in the animals to start with. That’s the argument behind the “One Health” movement, which has been arguing for several years now for including veterinary concerns in human health planning. (The human health side would probably say that the animal health side just wants more money. This is also true, which does not make it unimportant.)

To understand the need to look at animal health in order to forecast threats to human health, you can’t do better than the map I’ve inserted above (because Blogger, annoyingly, won’t let me put it below). It has appeared in various forms in various publications for about 10 years but originates I think from the IOM’s Emerging and Reemerging Diseases report in the early 90s. (This iteration comes from the One Health Initiative website.) It depicts the movement of new diseases from animals to humans over about 30 years. It’s up-to-date through SARS and through the 2003-05 movement of H5N1 avian flu around the world. I’m sure H1N1 will be added soon. How many of those outbreaks could we have shortcircuited if we had been warned of their threat in good time?

Farm animals and antibiotics – a new campaign

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I was gobsmacked to discover today, a few days late, that the Pew Campaign on Human Health and Industrial Farming (authors of the report discussed here) have launched a marvelously in-your-face series of ads in Washington DC, aimed at bringing the issue of antibiotic use in farm animals to people who might not think about it.

The ads have been placed in the Capitol South and Union Station Metro stops, which are the stops that bracket Capitol Hill, and in Metro cars on the red and blue/orange line trains, which are the main commuter trains down to the Hill. In other words, they’ve been made to be the morning reading of the people most engaged in the health reform debate right now — and if you think those folks are not thinking about healthcare spending and the growth of antibiotic resistance, well, umm, oh never mind.

The campaign says:

The American Medical Association, the American Academy of Pediatrics and other leading medical groups agree that the growth of bacterial infections resistant to antibiotic treatment is a looming public health challenge. The groups also agree the misuse of antibiotics on industrial animal farms plays a significant role in this crisis. While antibiotics are prescribed to people for short-term disease treatment, these same critically important drugs—like tetracycline, erythromycin and ciproflaxin—are fed in low doses to large herds or flocks daily, often for the lifespan of the animal. This creates ideal conditions for the breeding of new and dangerous antibiotic-resistant bacteria.

For statistics and arguments, along with more images — cows! chickens! pills! — go to the site of the commission’s campaign, Save Antibiotics.

MRSA in pig-farm workers – very high rates

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Let’s go back for a moment to what I think of as the “third epidemic” of MRSA: ST398 and the other strains that reside in animals and cross to humans. (In my personal taxonomy, the first and second epidemics are hospital-acquired and community-associated.)

Via Emerging Infectious Diseases, the open-access journal published by the CDC (Do I have to keep telling you to read it? It’s free. It’s good. Your tax dollars pay for it.), comes a report of surveillance for MRSA colonization of pig-farm workers, conducted in Belgium by researchers from Erasmus Hospital of the Free University of Brussels, and the Veterinary and Agrochemical Research Centre of Brussels. The group persuaded 127 farm workers on 49 farms to be tested for colonization, or asymptomatic carriage, of MRSA; at the same time, they tested 30 randomly selected pigs on each farm.

They found very high rates of colonization, higher than have been found in patients in hospitals or residents of nursing homes: 38% of the farm workers carried MRSA ST398, the pig strain (plus, an additional 17% carried various strains of MSSA, drug-susceptible staph). There was a clear association between colonized farmers and colonized pigs: Out of 1500 pigs sampled, 44% carried ST398 — and half of the workers on farms with colonized pigs were colonized also, compared to only 3% of workers on farms where pigs did not carry the bug.

In a bit of good news, the researchers found only one farm worker who had suffered any MRSA disease from ST398, a man with a lesion on his hand. There was no invasive disease, though ST398 has been associated in the past with pneumonia and endocarditis.

Workers were more likely to acquire the bug if they had regular contact with pigs, dogs or horses, which makes intuitive sense. But in an odd finding, their odds of acquiring ST398 did not go down if they wore protective clothing — which is to say, aprons, gloves and masks did not protect them from picking up the bug, leading the researchers to wonder whether airborne spread or contaminated surfaces are playing a role in transmission.

So what does this mean? The lack of invasive disease in this population must be good news; and it’s consistent with a number of papers that have reported low rates of disease from ST398 even when colonization is present. But to me, the high rate of colonization must be bad news. The more of this bug there is (and every researcher who looks for it seems to find it), the more chance there is of the bug adapting in an unpredictable — potentialy more resistant, potentially more virulent — way. If that did happen, it could well go undetected for a while — because as swine flu has been teaching us, disease surveillance in animals is patchy at best, and new pathogens can and do arise and ciruclate for years before being detected.

For more on the paucity of surveillance in animals, see my CIDRAP colleague Lisa Schnirring’s story here. For a complete archive of posts on “pig MRSA” ST398, go here.

The cite is: Denis O, Suetens C, Hallin M, Catry B, Ramboer I, Dispas M, et al. Methicillin-resistant Staphylococcus aureus ST398 in swine farm personnel, Belgium. Emerg Infect Dis. 2009 Jul; [Epub ahead of print] DOI: 10.3201/eid1507.080652.

MRSA in the House of Lords — the silly, the serious

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Thanks to constant reader Pat Gardiner, we have the transcript of the UK House of Lords discussion on community MRSA, called there PVL-MRSA after the toxin. (Go to the linked page, and click down to the time-mark 3.16 pm.) It’s encouraging to see some members of a government taking MRSA seriously. The members are asking for

  • better surveillance
  • better infection control
  • consideration of MRSA as a notifiable disease
  • and promotion of both vaccine research and point-of-care diagnostics.

Hear, hear to Baroness Masham of Ilton for bringing it up.

To get to that discussion, though, you’ll have to click down through some silliness (the ghost of Monty Python is never far from the British government, is it?): a discussion at time-stamp 3.07 p.m. of whether a House of Lords restaurant can afford to serve British bacon, rather than Dutch bacon, given that British bacon is almost twice as expensive and Dutch pigs are associated with MRSA ST398:

Lord Hoyle: My Lords, I thank the noble Lord for that reply, although there is more than a whiff of hypocrisy about it. After all, I and many others on all sides of the House have argued that it should not be a matter of price. We have urged the British consumer to buy British bacon because of the higher welfare standards that are applied in this country. Will the noble Lord also take into account the presence in Dutch bacon of a deadly form of MRSA, ST398, which can cause skin infection, heart trouble and pneumonia? Is he not putting people in this country at risk, particularly as the strain has passed from animals to humans? Indeed, when Dutch farmers go into hospital, they go into isolation. Why is he putting the British consumer and those who buy bacon in this House at risk in this way?

The discussion quickly devolves into foolishness about British Tomato Week — but if you read carefully, you’ll see that behind the silliness, there are serious issues at stake: animal welfare, farming standards, truth in labeling (the Lord Bishop of Exeter advances the very newsworthy claim that pork imported from other countries is subsequently labeled “British” only because it is packaged in the UK) and movement of zoonotic pathogens across national borders thanks to globalized trade.

Sadly, the leader of the discussion — the Chairman of Committees, AKA Lord Brabazon of Tara (no, really) — appears not to have been keeping up with the news, since he notes of ST398:

As far as MRSA is concerned, I read the article in, I think, the Daily Express a couple of weeks ago. I do not think that it has been followed up by anybody else.

Apparently the Lord’s staff have not been keeping up, since MRSA in pigs in the EU has been covered by the Daily Mail, the Independent, comprehensively by the Soil Association, and by, ahem, us.

While taking a flu break, a MRSA round-up

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Constant readers, the H1N1 (Virus Formerly Known as Swine) Flu story remains a bit intense. I’ve missed a few MRSA stories over the past few days, so here is a round-up.

First, though, if you’re curious about what the swine flu reaction says about our ability to handle a pandemic, you might take a look at this story I wrote Friday at CIDRAP. Quick version: Over-reaction on the part of the “worried well” — and people seeking testing and not knowing where to get it — put ERs into meltdown nationwide. If we were facing a virus that was not only fast-spreading but virulent, we could be in serious trouble.

On to MRSA:

  • Therapy animals as a vector: In a letter to the Journal of Hospital Infection, Drs. J. Scott Weese and Sandra L. Lefebvre of the Ontario Veterinary College at the University of Guelph report on two therapy dogs that became transiently colonized with C. difficile (on its paw pads) and MRSA (on its coat; found on the hands of its handler) after visiting health care facilities, demonstrating how easily bacteria can move in and out of hospitals. Constant readers will recognize Weese’s name: He is one of the most important investigators of MRSA in food animals and pets, and among other things has written infection-control guidelines for therapy animals.
  • In the Canadan Medical Association Journal, Drs. Anne G. Matlow and Shaun K. Morris of the University of Toronto and the Hospital for Sick Children caution that while hospitals may be getting better at infection control, there is not yet as much attention to it as there should be in ambulatory-care settings: urgent care centers, surgery centers and doctors’ offices. They offer a checklist of the minimal things that a physician practice should do.
  • And in the UK, Baroness Masham of Ilton, a member of the House of Lords, offers her online notes on serious infections with community MRSA, which the Brits are calling PVL-MRSA in recognition of the toxin that the strain produces. The notes are in advance of a series of questions that she intends to pose to government ministers during a Question Time on Wednesday.

More soon.