LA-MRSA and the pig industry – sorting fact from fiction

The pig industry, ‘unnoticed by consumers’, is manipulating and re-manufacturing the meat we eat to maximise profit – ‘leaving a legacy of problems that we are only now starting to understand’.

Foremost among those is LA-MSRA, the Daily Mail told millions of readers on October 22, under the extraordinary headline:
“The sick truth about our meat revealed: Pork pumped full of antibiotics. Chickens with E.coli and supermarket meat with MRSA”

The article seeks to link poor animal husbandry and overuse of antibiotics on farms to the discovery of Livestock Associated MRSA (LA-MRSA) CC398 in the UK.
With human deaths already associated with the bug in Denmark, the article pondered: “Many will ask how on earth have we got to a point where the food supposed to sustain us could actually be killing us?”

As Pig World went to press there had been no significant follow-up to the story, which contained little that was not already in the public domain.

However, the article was symptomatic of a campaign – led by the Alliance to Save our Antibiotics (ASOA), a coalition of organisations, including Compassion in World Farming and the Soil Association – to draw the public’s attention to LA-MRSA and antibiotic use on farms.

It is a subject that is not going away. But how concerned should pig farmers be about their reputation – and their health?

What is LA-MRSA?
Methicillin resistant Staphylococcus aureus (MRSA) refers to any strain of common bacteria, S. aureus, that is resistant to certain antibiotics.
Livestock associated (LA) is a relatively recently-discovered strain of MRSA that has been identified in livestock in various countries worldwide.
It was first identified in livestock in the Netherlands in 2004 and has been found most commonly in pigs as well as in cattle, horses, chickens and turkeys.

How big a problem is it in livestock?
It is a bigger problem in some countries than others. For example, studies carried out in Denmark in 2014, found approximately two-thirds of all pigs were carrying the bacteria. Virtually none was identified in an earlier survey in 2008.

The bug has been found in the UK in pigs, poultry and cattle but in very small numbers. The first case was identified on a turkey farm in East Anglia in 2013 and the first in pigs was in Northern Ireland the following year. In 2015, the bug was found on a farm in East Anglia, resulting in the death of a number of pigs.

Sampling might yet reveal more cases. However, currently, UK incidence remains relatively low.
One reason the issue has raised its head recently is the discovery of LA-MRSA CC398 in samples of pork and poultry in well-known supermarkets.

Three packets of pork mince – two from Asda, one from Sainsbury’s – were found to contain LA-MRSA CC398, after sequence typing by ASOA on 97 samples of pork products from major British supermarkets. The pork was from UK pigs, according to ASOA.

The bacterium in all three packets were resistant to tetracyclines, used widely in pig farming for various infections, while the pork from Sainsbury’s was also fluoroquinolone-resistant.

How many humans have been affected?
Campaigners fighting to reduce antibiotic use on farms point to figures in Denmark to suggest the extent of the health risk.

The Bureau of Investigative Journalism reports that at least 12,000 people are estimated to have contracted the bug in the past decade in Denmark, including 1,276 cases in 2014 and 1,172 last year. Six people are known to have died after contracting it, the bureau reported.

There have only been three confirmed human cases in the UK, according to Public Health England (PHE).

What is the risk?
Despite the Danish figures, the UK authorities are adamant the risk posed by LA-MRSA remains low, although agricultural workers are advised to take precautions.

The bug can pass between animals and humans in either direction, by direct contact or via dust in the environment of animals carrying the bacteria. It can survive in dust for a long time.

If it is passed to humans, it does not usually cause any problems, although occasionally it can cause infections, according to a Government-industry advisory leaflet targeting farm workers.

It adds: “Infections from this are very rare in people in the UK. It usually lives in the nose or on the skin without causing any signs or symptoms.
“If it is able to get into the body, for example via a wound, it can cause a local skin infection, usually resulting in boils or wound infections, but occasionally it can cause disease such as pneumonia or a blood stream infection.”

What do the
experts say?

Experts in the field have downplayed the stories of a great looming human health risk.
For example, Prof Mark Woolhouse, Professor of Infectious Disease Epidemiology at the University of Edinburgh, said: “Livestock acquired MRSA is a well-known, but rare, food safety risk. It has been found in food animals, in food and, occasionally, in people for many years. It must be taken seriously but it has shown no sign of causing a pandemic.”
Nicola Williams, Professor of Bacterial Zoonotic Disease at the University of Liverpool, said: “Current data does not suggest that LA-MRSA is common among UK pig herds. Even if herds are infected with significant levels of the bacteria, the extent of contamination of meat with MRSA will be much lower than compared to food-poisoning bacteria such as Salmonella, so the risk of transmission to people will be lower.”

Is the emergence of LA-MRSA linked to overuse of antibiotics?
The British Veterinary Association and Pig Veterinary Society have poured cold water on the narrative that the problem is a symptom of antibiotic use.
They have stated that ‘while antimicrobial use has played a role in the emergence of MRSA, its subsequent spread relates mainly to it being a successful bacterial species, not to antimicrobial use.’
Tellingly, LA-MRSA has been found in animals in which no antimicrobials have been used.

Are we at risk from imports?
A common theme in media reporting on the issue is the lack of rigour in preventing LA-MRSA in imported pigs from entering the UK pig herd. There is, for example, no mandatory screening for live breeding pigs leaving Denmark, prompting claims this leaves the UK dangerously exposed.
National Pig Association chief executive Zoe Davies said: “Defra and the NPA recommend that anyone importing breeding pigs to Britain should have them screened for LA-MRSA.
“The NPA Imports Protocol, which is a requirement under Red Tractor Assurance and was developed by the UK breeding companies themselves, sets out the tests that should be completed, and when.”

How is the industry responding to the publicity over LA-MRSA?
The NPA has responded to the Daily Mail article with a letter to the paper that accuses it of a lack of balance in its reporting; highlights inaccuracies in the article, such as claims 60 per cent of antibiotics are used in pigs and draws attention to expert opinion on the real risks posed by LA-MRSA.

The NPA, AHDB Pork and RUMA (the Responsible Use of Medicines in Agriculture) have also been discussing a coordinated response to the publicity around LA-MRSA and antimicrobial resistance (AMR) more widely.

Dr Davies said: “LA-MRSA is an issue we all take very seriously and we will continue to do all we can to keep the UK pig herd as free from it as possible.
“But in response to recent media reports, we as an industry need to put the issue in context, ensure there is balance in the debate and that the public understand the full story.

“LA-MRSA, as experts continue to advise, presents a very low risk to the public.
“Meanwhile we continue to advise farmers to use antibiotics responsibly, including entering usage data onto eMB-Pigs.”

How to minimise LA-MRSA risk
As a precaution, it is recommended anyone working with livestock follows as many of the steps below as possible:

  • Wash your hands regularly with soap, especially before eating, smoking and leaving the farm
  • Cover any cuts, grazes or areas of broken skin with a waterproof dressing
  • Wear protective outer clothing when working with animals. Remove the protective clothing on the farm and, if possible, have a shower before leaving
  • Wash all work clothes on farm or, if not possible, put them in a sealed bag to take them home for washing
  • Wash work clothes separately from other laundry and wash your hands after handling them
  • Footwear should be dedicated to working with livestock
  • Inform your doctor or dentist that you work with livestock as they may wish to test for LA-MRSA before carrying out any surgery or dental extractions
  • Members of your household should also let the doctor know they have an indirect connection to livestock.

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About The Author

Editor of Pig World and contributor to LBM’s other farming publications. Also National Pig Association webmaster. Formerly political editor at Farmers Guardian for many years. Enjoy a bit of media punditry. Brought up on a Leicestershire farm. Work from a shed in the garden in Oxfordshire. Under-9 football coach and big fan of Leicester City and Leicester Tigers. Occasional cricketer.