Super bugs

Pigs and bacteria

In Denmark, there are more than twice as many pigs as humans, and twice as many antibiotics given to the animals as well. A perfect breeding ground for resistant bacteria – to which politics have failed to respond.

von Nils Mulvad

© Ivo Mayr

In November 2013, a 63-year-old man with diabetes and end-stage kidney got fever because of inflammation. Samples of blood grew the resistant pig-bacteria, methicillin-resistant Staphylococcus aureus, MRSA, CC398. Three weeks later the man died.

By analyzing the specific type of the bacteria, doctors identified the cause of the infection. It was another man. Someone carrying the same type of bacteria, staying in the same outpatient clinic at Odense University Hospital; a nasal and pharyngeal MRSA-carrier.

The dead man is proof that bacteria of animal origin now transmit directly between humans in Denmark. It does not need pigs anymore – but can jump directly from one human to another. The man from the Odense hospital is one out of two cases described May 2016 by Danish doctors in the journal Emerging Infectious Diseases.

In Denmark, the focus on resistant bacteria for some years has been especially high on MRSA coming from pigs. In humans, it can be present on the skin, commonly in the nose, without causing harm. Yet when it enters the wound of a weakened patient, as it happens after surgery, it can lead to threatening infections.

“We see a picture of an epidemic that is out of control. Authorities have done remarkably little and seem at all levels perplexed“, wrote a leading researcher in human disease treatment, Hans Jørn Kolmos from the Department of Clinical Microbiology, Odense University Hospital in late September 2013.

“The Danish Veterinary and Food Administration has now, seven years after the problem was documented, still no overview of the epidemic, and has done nothing to halt the spread of infection“, Kolmos writes.

Highest pig-man ratio in the World

Denmark has the highest pig-man ratio in the World. The country with 5.7 million inhabitants has an average population of 12.7 million pigs. The use of antibiotics in the country reflects this. In 2014, humans in total in Denmark got 53 tons of active antibiotics, while pigs got 86 tons.

In 2007, the first case of presence of humans carrying a strain of MRSA coming from pigs was recorded. Yet little was done to stop the spread of the bacteria. MRSA usually does not harm pigs.

The authorities followed the amount of affected meat at the slaughterhouses, but they did not demand farms to get their pigs tested. Then, farmers could not warn employees and visitors of the potential risk.

Today farmers and authorities say every pig should be regarded as colonized, and then workers, visitors, and neighbors should take their own precautions, washing hands and changing clothes. Hospitals should also take their own precautions, regarding humans in contact with pigs as a health risk factor.

This has consequences for the whole of Europe. According to Eurostat, Denmark is the leading pig exporter. In 2013, more than half of young pigs in Europa came from Denmark, meaning the rest of Europe can also get MRSA from the Danish pigs.

Proposal from task force denied

After growing public awareness of the problems since 2010, the Minister of Agriculture at that time, Mette Gjerskov, established a task force to propose several initiatives to stop the spread.

The main proposal was to closely follow the spread in pig farms and establish an MRSA-free trade way. Per Henriksen, head of the Danish Veterinary and Food Administration, rejected the plan silently. Instead, the authorities sat up some minor initiatives based on a strategy of accepting all pigs as carriers.

The Danish Veterinary and Food Administration and the Ministry of Agriculture rejected to disclose which farm had MRSA-carrying pigs. Only after a FOI-case and later a court-case, the authorities were forced to give out this information in March 2016.

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A main problem is that only around one in ten farms are being tested, so there is still no information on the status of MRSA in most of the farms and there is no MRSA-free trade way. Investigative Reporting Denmark has published an exclusive investigation into the numbers.

Antibiotic use on every farm

When the public awareness of MRSA rose in 2010, the Danish parliament also decided to introduce a system warning and fining farmers, when their use of antibiotics was too high. The authorities set up a system for gathering data on antibiotic use and the number of pigs on each of all 4000 pig farms in Denmark.

Since the introduction of the scheme, 130 farmers have received a warning, yet none has been fined, according to information received by „Investigative Reporting Denmark“ in September 2014.

After getting the data, „Investigative Reporting Denmark“ presented a method to calculate the amount of antibiotic used on every farm in Denmark.

Fighting six years for data

A system called Vetstat has been used to surveil antibiotic on stable-level in Denmark for more than 20 years. It is regarded as a success, because the use of antibiotics was reduced by 16 percent since 2009. The recent Danish minister of Agriculture, Esben Lunde Larsen hopes the Danish system will be part of a new EU-initiative to prevent development of resistant bacteria.

Yet the data in Vetstat is not publicly available. A request for data was delivered in 2006. The data was received for the first time six years later, in 2012. The data showed all the pigfarms with heavy use of antibiotics and was later the background for the warning system.

In 2014, the Danish Audit Agency started an investigation on the Ministry of Food and Agriculture and The Danish Veterinary and Food Administration because of a case with swine-MRSA. In October 2015, this investigation finished with a heavy critique.

The ministry administrated MRSA in pigs nearly only looking on the cost of the production of pigs, not taking care of the implications for the society – especially the health sector, concluded the agency.

MRSA in pigs has been the main focus point in Denmark for years. Another issue has been a growth in MRSA from Danish people visiting foreign countries. MRSA from pigs now count for four out of ten cases of MRSA-infection, MRSA originating from foreign countries count for less than two out of ten. Today doctors calculate 12,000 Danes are carrying pig-MRSA 398 – most without knowing.

The new superbugs

In recent years, health authorities have identified two more serious threats from antibiotic resistance in Denmark, VRE and CPE.

Vancomycin-resistant enterococci (VRE) are a type of bacteria called enterococci that have developed resistance to many antibiotics, especially vancomycin. If they become resistant to antibiotics, they can cause serious infections, especially in people who are ill or weak. Common infections include the intestines, the urinary tract, and wounds.

In 2015, VRE was found in 382 Danish patients, seven time as many as in 2012.

Carbapenemase-producing enterobacteriaceae (CRE) are bacteria that are nearly resistant to the carbapenem class of antibiotics, considered a drug of last resort. The bacteria can kill up to half of patients who get bloodstream infections. In 2014, CRE were found in 29 Danish patients – twice as many as the year before. Often these patients had been hospitalized in a foreign country before getting back to Denmark.

Both for VRE and CPE there are no screening of patients, so the total number might be much higher, warns Dr. Robert Leo Skov from Statens Serum Institut.