Maryn McKenna

Journalist and Author

MRSA in meat: How much? Which? And more bad news.

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(Sorry for the radio silence, constant listeners. It’s been a challenging few weeks at Casa Superbug, with a death in the family and the chaos afterward of catching up to the rest of life. But back now, with some interesting stuff planned for later this week.)

Last week was the General Meeting of the American Society for Microbiology (ASM). This is the conference at which, several years ago, Tara Smith’s team at the University of Iowa first announced they had found MRSA ST398 in pigs in the United States, so it always bears watching for new MRSA news, and this year it didn’t disappoint.

First: I’ve complained persistently because the federal system that monitors antibiotic-resistant bacteria in animals and food, NARMS (National Antimicrobial Resistance Monitoring System) doesn’t include MRSA among the pathogens that it tracks. It is possible that might be changing — because at ASM, a team from the Food and Drug Administration reported the results of a pilot study that looked for MRSA in retail meat in the US and found it.

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Drug-resistant bacteria in bedbugs

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Being Scary Disease Girl, I seem to have earned a reputation for never wincing in the face of weird disease threats.

But this, I admit, makes me go squick:

Researchers in Vancouver, BC have found bedbugs there carrying drug-resistant staph, MRSA, and vancomycin-resistant enterococci, VRE.

(Deep breath.)

(Another deep breath.)

OK, details: [Read more…]

Farm Antibiotics: 'Pig Staph' in a Daycare Worker

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

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

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Turning grief into action: Moms and antibiotic misuse

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In December 2007, I flew to Chicago to meet the team of researchers who spotted the first known cases of community-associated MRSA in the US in the mid-1990s, and who have been agitating ever since for recognition and action to beat back the rising tide of antibiotic resistance. It was grey and snowy outside their shabby suite of offices, carved out of University of Chicago’s long-replaced children’s hospital. I sat in a green-tinged conference room piled with stacks of articles while Everly Macario — a Harvard-trained ScD in public health, the daughter and sister of physicians — described how MRSA killed her toddler son Simon in less than 24 hours.

“We have no idea where he got it,” she told me. “We have no idea why he was susceptible.”

Simon Sparrow was 17 months old in April 2004, a big, sturdy child with no health problems except a touch of asthma. The day before he died, he woke up feverish and disoriented, startling his parents with a cry unlike anything they had heard from him before. It was a busy morning — his older sister had a stomach virus — but they got him to the pediatric ER, got him checked, and brought him home when doctors found nothing unusual going on.

A few hours later, Everly was working at home, watching both kids, and Simon’s breathing changed. Her husband James, a history professor, had driven a few hours away to give a speech. She called a friend who is a pediatrician, held the phone up to Simon’s nose and mouth so she could hear, and then got back on the line.

“Hang up,” her friend said. “Call 911.” [Read more…]

Bacterial music-video festival (tornado edition)

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We had scary-bad weather in the Southeast the past two days. Thankfully, there was no serious damage where I am, but the devastation to the north and west is appalling, with about 180 300 deaths so far. Please spare a thought for them.

It’s going to take me a while to haul my working materials back out from the storm shelter, and by storm shelter, I mean first-floor closet under the stairs behind the washing machine, which was about the only place that would have been protected from shattering glass and flying roof materials.

So in the meantime: This morning, Twitter tossed up a UK hospital’s attempt to energize its staff to wash their hands more frequently. It’s sweet, funny, and — apologies to the participants — unavoidably snark-inducing. Have a look: [Read more…]

World Health Day: Time to tackle resistance

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

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

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

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

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

Farm worker infections with MRSA — the first numbers

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Since the first identification in 2004 of MRSA ST398, also known as “pig MRSA” or livestock-associated MRSA (archives of posts here and here), that drug-resistant organism has been found being carried asymptomatically by farm workers and veterinarians, and causing illness in health care workers, hospital patients, and people with no known ties to agriculture. One of the persistent data gaps, though, has been whether farm workers themselves have been made sick by it.

It’s a difficult question to answer for a nested set of reasons: First, in most of the states, MRSA (methicillin-resistant Staphylococcus aureus, or drug-resistant staph) is not a reportable disease; that is, a doctor who diagnoses it in a patient is under no obligation to tell any public health authority about that patient’s case. And second, the testing required to distinguish livestock-associated MRSA from community-acquired or hospital-acquired is not something that primary-care medical personnel have access to; you have to go to a state laboratory or an academic medical center to do the appropriate molecular typing. Those tests are expensive to perform, and their results primarily are useful to public health, not to individual medical practitioners. So finding out where that nascent epidemic is going has been unusually challenging.

Comes now a team from the University of Iowa — the same team that first identified ST398 in pigs and pig-farm personnel in the United States — to start to fill the gap. [Read more…]

News break: First guidelines for treating MRSA

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For my book SUPERBUG: The Fatal Menace of MRSA (came out last March; paperback will be out in February), I spent several years talking to about 100 victims of antibiotic-resistant staph, and family members of victims who did not survive their infections. There were some striking things about their stories.

One was the variability of the bug, which can cause anything from mild one-time skin infections to lethal necrotizing pneumonia, adding up to almost 19,000 deaths, 369,000 hospitalizations and possibly 7 million medical office visits a year. The other was the variability of the patients’ treatment. Some had the good luck to find physicians who knew about the bug, understood the layers of testing needed to determine the best antibiotics to use, and were sensitive to the possibilities of over- and under-treatment. Others were not so lucky: They went to doctors who didn’t recognize the infection, didn’t prescribe drugs that worked, didn’t have anything to offer when the infection recurred — a whole panoply of errors.

It was a lesson for me in how long it can take news of a new medical development to percolate through the clinical community, especially to primary-care practitioners — people who don’t have a channel for new news because they don’t work for an academic medical center or belong to a specialty society that puts out a journal or at least a substantial newsletter. But it was also a lesson on how few agreed-upon standards of practice there were for treating MRSA. For many presentations, there was no evidence refer to; clinicians were thrown back onto poring through the literature, or on making educated guesses based on their past experience.

As of this week, that should change. The Infectious Diseases Society of America has publshed the first-ever clinical practice guidelines for treating MRSA in adults and children. It’s a substantial document, 38 pages (in the advance access section of Clinical Infectious Diseases) and should be a tremendous resource for patients and their physicians. (I know of one patient who printed it out yesterday and took it to an office visit — only to find the physician had just downloaded a copy himself.) [Read more…]

"Pig MRSA": New human infections in France

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It’s one of the touchiest topics under the broad category of antibiotic resistance: Whether the drug-resistant organisms that emerge on farms as a result of antibiotic use stay on farms, or pose a risk to humans who have no connection to agriculture.

That drug resistance emerges under any selective pressure is basic biology: Resistance is an inevitable process. That they emerge on farms when antibiotics are used broadly — that is, in growth-promoting or prophylactic ways, not to treat disease in individual animals — really isn’t in dispute any more. It’s now a question of economics and politics, not science. (See this bibliography, stretching back to 1969; and the news I broke yesterday of FDA’s estimate of US farms using almost 29 million pounds of antibiotics last year.)

So the argument over farm antibiotic use now tends to focus on whether the resistant organisms that emerge on farms are only an issue within a farm’s confines, or rather pose a broader human health threat — and that’s where the continuing story of the “third epidemic” of MRSA becomes so important. Recapping, this is a strain known as MRSA ST398 that emerged in pigs and passed to pig farmers in the Netherlands in 2004, subsequently spread across the European Union, and crossed to Canada and then to the United States. (Key posts on ST398: here, here, here and this archive at my old site. Yes, it will be moved soon, promise.)

Most of the identifications of MRSA ST398 in humans, including those first identifications above, were colonizations, the term for symptomless carriage of staph in the nostrils and on the skin; in other words, it wasn’t making people sick. News of actual illnesses has been rare — especially illnesses among people who have no contact with farming, such as the post-surgical infections found in Canada earlier this year.

But they’re getting a little less rare, as demonstrated by a letter just posted ahead-of-print to the journal Clinical Infectious Diseases. It recounts the finding, via annual surveys of bloodstream infections, of four cases of ST398 in four different hospitals in France. One may have been due to animal exposure. Three were hospital-acquired.

Examination of patient histories revealed exposure to animals in 1 case, a fatal idiopathic community-acquired bloodstream infection in an 84-year-old man who lived on a farm at which 1 pig was being raised. The remaining cases were hospital-acquired and included 1 case of catheter-associated infection observed in a 58-year-old man with advanced multiple myeloma, 1 case following elective digestive tract surgery in a 69-year-old woman, and 1 case following cardiac surgery in a 68-year-old man.

There’s an especially interesting thing about these cases. In Europe and the US, ST398 has particular characteristics: It is resistant to tetracycline (the drug most commonly given to pigs) and does not manufacture the toxin Panton-Valentine leukocidin or PVL, which is suspected to be a cause of community-strain MRSA’s uncommon virulence. (See this story, from the book SUPERBUG, of how PVL-positive pneumonia almost killed a toddler.) The strain in the French cases, though, does manufacture PVL, and shares some virulence characteristics with the dominant community strain, USA300. It is less like the European strain of livestock-associated MRSA and more like a livestock-associated strain that appears to be emerging in China, ST9 (more on that here).

The argument against the significance of these cases is likely to be that they are, again, just one data-point, and may be just rare and random. That is worth considering. But it is also worth considering that they continue to be found.

And, also, that the community epidemic of MRSA was first flagged in a discovery of 25 cases in children in Chicago back in 1998, a finding that was also dismissed at the time as rare and random — and that grew into an epidemic of millions of cases a year.

(H/t to constant reader Pat Gardiner for flagging this paper for me.)

Cite: van der Mee-Marquet N et al. Emergence of Unusual Bloodstream Infections Associated with Pig-Borne–Like Staphylococcus aureus ST398 in France. Clin Infect Dis. (2011) 52 (1): 152-153. doi: 10.1093/cid/ciq053

Image via Flickr user johnmuk under CC

Alarm over "pig MRSA" — but not in the US

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There’s some new news out — along with a fair amount of public reaction — regarding “pig MRSA” or, to use the technical term, MRSA ST398, the “third epidemic” strain that emerged in pigs in the Netherlands in 2004 and has since appeared, in animals, retail meat, and humans, across the European Union, in Canada, and in the United States. (My last post on it is here, and a long archive of my posts on it starts here.)

I wish I could say the attention to ST398 was being paid in the United States, where there is almost certainly more MRSA in livestock than has been recorded, given that the only published surveillance, from 2009, covered only Iowa and Illinois. Unfortunately, there is still no indication that federal agencies have any intention to test for the presence of the organism in animals or in meat. In fact, the major surveillance mechanism for drug-resistant organisms in meat animals, retail meat and meat-eaters in the US, the National Antimicrobial Resistance Monitoring System or NARMS, doesn’t test for MRSA at all; it handles only enteric or gut-borne bacteria such as Salmonella and Campylobacter. (NARMS IS shared among three agencies: the CDC handles drug-resistant foodborne bacteria in humans, the FDA looks for the same bacteria in food, and the USDA looks for those bacteria being carried by livestock.)

Instead, as so often seems to happen with antibiotic resistance, the country paying attention is in Scandinavia — in this case, Denmark. The annual report from Denmark’s surveillance scheme, DANMAP (Danish Integrated Antimicrobial Resistance Monitoring and Research Programme) is out. Denmark does surveil for MRSA, and here’s what they found: 13% of pigs, at slaughter, were positive for MRSA ST398.
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