A recipe for MRSA

March 2013

Milk production. Photo by Farm Sanctuary on Flickr

At the end of 2012, the media reported that MRSA 'ST398' had been found in British milk for the first time.

This antibiotic-resistant 'superbug' has been a problem in many countries for some years and is now spreading through UK farms too.

In milk, the bacteria will, of course, be destroyed during routine pasteurisation before sale to the public. However in the animals, such bugs will still be transmitted by dairy-hands, vets, abattoir staff and meat.

Although ST398 doesn't seem to be among the most virulent of MRSA strains (but see Note below), it can infect a wide range of species including all our main food animals (pigs, cattle, poultry), horses, rats and humans, and carries a wide range of antibiotic-resistance genes. These features combine to make ST398 life-threatening to vulnerable members of the population, such as those with compromised health, the young and the elderly, because the infection risk is high and treatment options extremely limited.

Note. Researchers surveying the genes found in common strains of MRSA commented that the lack of recognised virulence-enhancing genes in ST398 coupled to its obvious ease of dissemination “might suggest the (strain) harbours novel virulence determinants”. In other words, ST398 may pose a much greater risk to health than scientists have so far been able to identify.

At about the same time as the news broke about ST398's arrival in the UK, the results of an equally sinister scientific investigation were published.

A survey of six major rivers in China found bacteria with resistance to the antibiotic ampicillin in every one. The gene conferring this drug-resistance was found to be a synthetic version constructed in a laboratory.

This particular gene has been inserted into many commercialised GM crops to enable the identification of successful transformation. 

(OUR COMMENT These genes are unnecessary in the final GM plants, and could have been eliminated at a later stage, but the biotech industry has never gone to the trouble and expense of doing so, and indeed has never been required to do so by regulators, even when their presence is outlawed as in the EU.)

Besides ampicillin-resistance, this gene confers resistance to a wide range of therapeutic antibiotics including penicillin derivatives, cephalosporins, monobactams and carbapenems. Pathogens with resistance to all these drugs are a major public health concern.

What's driving the emergence of all this antibiotic-resistance?

The biggest recognised culprit is the modern practice of intensive livestock rearing: cramped conditions are a breeding ground for disease, and antibiotics are part and parcel of the system, while constant exposure to antibiotics is a breeding ground for antibiotic-resistant bacteria. Driving this practice is the price pressure imposed by the big supermarket chains and a cheap-food-is-good culture.

Over-prescribing of antibiotics by vets expands the problem. Although sick dairy-cows given medication have to be withdrawn from the supply chain until the drugs have cleared from their system, the unsellable milk they produce is fed to calves which become a further breeding ground of antibiotic-resistant microbes.

Over-prescribing of antibiotics by doctors extends the problem outside the farmyard.

A second culprit, denied and dismissed for decades, is the antibiotic-resistance genes in GMOs disseminating through the environment and being passed from microbe to microbe (not necessarily related to each other). The huge monocultures of biotech crops leave debris (and genes) all over the place, before, during and after being trucked across the globe to be fed to animals. China has been precautionary about GM food crops, but most of its cotton crops are GM. Add to this, GM biofuel fermentation, GM microbes used in environmental remediation, and laboratories which create GM cells as experimental models all of which contribute to the artificial gene pool available to bacteria in the environment.

Soil run-off, gut contents, industrial effluent, and laboratory waste all tend to end up in waterways. The Chinese researchers found the artificial ampicillin-resistance gene present in between 21.9% and 36.4% of samples from their rivers. This is clear evidence that the 'vanishingly small' possibility of horizontal gene transfer declared by the biotech industry and accepted for decades by regulators has never been anything but wishful thinking.

So far, only the dissemination of antibiotic-resistance genes lying outside the bacterial chromosome has been ascertained. Other artificial genes have not been investigated, nor DNA which doesn't express a protein but can alter gene expression, nor the presence of man-made DNA inserted into the bacterial chromosome itself where it presents a more permanent and evolutionary risk.

Dr. Ignacio Chapela has pointed out a more sinister implication of the Chinese river study. 

 “... the antibiotic resistance is not at all the most important point of this paper (even when the authors themselves seem to think it is). Looking for antibiotic resistance was the easiest feasible way to do this work and it also has the obvious medical implications, but this is only a fraction of the many other sequences of transgenic DNA which must be expected out there in the environment, from all kinds of origins, with all kinds of possible functions. This paper is the equivalent of the proverbial sighting of the iceberg's tip. A Polaroid photo of a small part of what must be a very large and relevant phenomenon.”

Indeed, attached to the ampicillin-resistance gene was a range of synthetic DNA sequences added in to aid the production, insertion and expression of the gene.

OUR COMMENT

In light of the above, rogue, promiscuous viral promotors generating “novel virulence determinants” in MRSA STD 398 aren't such a far-fetched idea.

A global campaign is underway to reign in the use of antibiotics in livestock. To do this we need first to cut back on how intensively we farm animals. Next, we need to eliminate GM crops with antibiotic-resistance genes, stop naively accepting industry's baseless and blandly reassuring risk-assessments, and return to good old-fashioned composting of manure which will destroy harmful bacteria before they get a chance to swap parts.

There's no reason to believe that Chinese rivers are the only ones awash with antibiotic-resistant bacteria. Tell the Government and supermarkets that the risk to your health and life from the horizontal gene transfer of antibiotic-resistance genes and other active artificial DNA elements into gut microbes inside you or food animals is unacceptable.

SOURCES:

• Jeremy Laurance, MRSA found in British milk 'not a risk to consumers', Independent 26.12.12
• Dorota M. Jamrozy et al., 2012, Comparative Genotypic and Phenotypic Characerisation of Methicillin-Resistant Staphylococcus aureus ST398 Isolated from Animals and Humans, PLoS ONE 7:7
• Superbug MRSA ST398 found in British cattle, Soil Association, 21.12.12
• Dr. Eva Sirinathsinghji, GM Antibiotics Resistance in China's Rivers, Institute of Science in Society Report 13.02.13
• J. Chen et al., 2012, A survey of drug resistance Bla genes originating form synthetic plasmid vectors in six Chinese rivers, Environment Science and Technology, Dec. 18, 46(24)
• Dr. Ignacio Chapela comment, New study finds antibiotic resistance from GMOs in microbes in rivers, GM Watch 7.01.13
• Cotton http://www.gmo-compass.org