Threat of antimicrobial resistance calls for more cuts in antibiotic use in farm animals


22
May 2016

In 2014 two people died in Denmark of LA-MRSA – an antibiotic resistant bacteria that originates from pigs. Since 2003, LA-MRSA (livestock associated methicillin-resistant staphylococcus aureus) has emerged worldwide, adding to the growing concern over the threat of antimicrobial resistance (AMR) to human health. What many question is whether intensive livestock farming acts as an incubator for AMR due to the large, and often unfettered, use of antibiotics to promote growth and prevent illness in farm animals; calling into question whether intensive farming requires a rethink.

The deaths in Denmark from an antibiotic resistant bacterial clone are not the first nor will they be the last. AMR in livestock to different types and classes of antibiotics have actually been identified since the late 1950s (Food and Environment Reporting Network), and new forms are emerging all the time. MRSA-LA is one of the most recent, along with ESBL E.coli, the latter being resistant to most types of third generation antibiotics (Soil Association). What is concerning about these newer forms of AMR microbes is that they are resistant to ‘last line’ antibiotics – those used as a last resort to fight infection.

LA-MRSA found on 50% of all Danish pig farms.

LA-MRSA is considered widespread among Danish pigs; the Danish Pig Research Centre estimates that the bacterial clone is found on more than 50% of all Danish pig farms. In the Netherlands, Germany, Spain and Italy, all pig farms are considered infected with LA-MRSA, and have been so for several years.

According to Denmark’s Statum Serums Institut (SSI), as a share of all MRSA human infection cases in Denmark, LA-MRSA now represents 30.7% (643 out of a total of 2,094 MRSA cases) in 2013. This increasing trend is expected to have continued into 2014 (data still not available). Out of these cases, a total of 87% were found in persons with direct contact with pigs or in household members to these persons. It is also clear that LA-MRSA is expanding among persons with contact to swine and in areas characterised by intensive farming.

Denmark is taking steps to ensure that infections in humans caused by AMR are kept to a minimum. Since 2012 new guidelines were drawn up by the Danish Ministry of Food and Agriculture stating that all ‘persons working with pigs and household members of such persons must now be tested for MRSA upon admission to hospital’ (SSI). To minimise the spread of the infection outside of farms, since 2014 certain farms are expected to implement a biosafety protocol (SSI). But these recent policies are not tackling the real issue, which is how to prevent AMR from developing in the first place.

Some steps have been taken (DANMAP)*: Back in 2001 Denmark made it compulsory for all farmers to register use of specific antimicrobial medicines; in 2002 use of fluoroquinolone was restricted; in 2010 a voluntary ban on the use of cephalosporins was established (to tackle ESBL – extended beta-lactamase resistance) and finally since 2011 legal action can be taken against farmers with high antimicrobial medicine use (see timeline for sources). But regardless of these actions MRSA-LA infections are increasing. (*Danish Programme
for surveillance of antimicrobial consumption and resistance in bacteria from animals, food and humans.)

To understand what more needs to be done to significantly curb the problem one needs to look at the Netherlands. Denmark today is where the Netherlands was in 2004! And actually, LA-MRSA is likely to have originated from intensive pig-farming in the Netherlands. What the Dutch government did to tackle the threat was significant – in 2008/9 they implemented a strategy to cut antibiotic use in livestock by 50% by 2013 (Ministry of Economic Affairs, Netherlands)! By 2012 veterinary antimicrobial sales had drop 50%, and the following year data showed that resistant bacteria in pigs, veal, chickens and dairy cattle was on the decline.

On the whole the use of antimicrobials in pigs is still increasing, up 6% in 2013.

Denmark now has a comprehensive monitoring system in place to keep a close watch on AMR. This and restrictive policies have resulted thus far in low use of critically important antimicrobials. However, on the whole the use of antimicrobials in pigs is still increasing, up 6% in 2013 (DANMAP Annual report 2013). And the emergence of LA-MRSA, and its transfer to humans, indicates that action needs to be taken sooner, more cuts need to be made in antibiotic use and farming practises need to ultimately change to more sustainable methods!

But this approach is a hard sell to farmers. Basically, those in the agricultural profession will argue that curbing antibiotic use in farming will be detrimental to their profits. But experiences in Denmark and that of the Netherlands counter this argument:

“To compensate for the loss of the antibiotics they (Dutch pig farmers) used routinely—not just for growth promotion, but for prevention, to protect pigs from crowded farm conditions—farmers there have changed their raising standards: altering feed recipes, increasing barn temperatures, allowing their animals more space, keeping them with their mothers longer. That sounds expensive, and a rise in farming costs is something that American agriculture has always feared would happen if farm drugs were relinquished. But Dutch farmers say their bottom line hasn’t altered. In some cases, they’re making more money.”

Rising costs due to changes in farming practises is a concern in Denmark, especially as pig farming is a huge export industry – 85% of pig-products are exported. Pig meat exports accounted for more than 42% of all agricultural exports and 5% of all goods and services exported from Denmark (Pig Research Centre).

Evidence suggests that pig densities together with human population density is a key risk factor for contracting LA-MRSA, but the trend in Denmark is ever larger pig farms and more pigs (a trend mirrored across the world). There were around 4,600 pig farms in Denmark in 2011, with a population of 18.9 million pigs. The trend is moving towards fewer and bigger farms; it is projected that an average sow farms will consist of 1,000 sows and an average finisher producer will produce 11,000 pigs annually in 2020 (Agriculture and Food).

Higher welfare and less intensive production systems has the potential to reduce the use of antibiotics in agriculture significantly.

Considering this trend, farmers are unlikely to want to give pigs ‘more space’! But according to the Soil Association we need less intensive production systems to prevent AMR from getting out of control: ‘It should be recognized that a move towards higher welfare and less intensive production systems has the potential to reduce the use of antibiotics in agriculture significantly.’

This line of thinking is mirrored by many scientists, agriculturalists and environmentalists. Even in the UK where policy is minimal in the wake of AMR, a government commissioned report, the Foresight Report, on the Future of Food and Farming, recommended a more ‘sustainable intensification’ approach to farming which would require prudent use of antimicrobials.

We have been aware of and exposed to AMR for some time, what makes it a more urgent threat is due to several issues:  New forms of antimicrobial resistance are emerging all the time (and some showing multiple resistance); emergence can originate from anywhere in the world and get past on through trade of animals (Environmental Health Perspectives); our development of new antibiotics is flat-lining; finally there is concern that livestock associated AR will produce more virulent forms and spread via indirect routes such as through the purchasing, handling and cooking of meat products.

…[there is] a global consensus that antimicrobial resistance poses a profound threat to human health.

This week an action plan on AMR is being presented at the Sixty-eighth World Health Assembly. WHO states: ‘The development of this draft global action plan on antimicrobial resistance reflects a global consensus that antimicrobial resistance poses a profound threat to human health‘. But the problem of AMR has been recognised internationally, political intervention is still inadequate in major economies such as the US, UK and China (producer of 50% of all pigs!). This political inertia is economically driven, due to lobbying pressure from the agricultural sector. Even with success stories such as The Netherlands, giving up the uncontrolled use of antibiotics is not going to happen without serious political will and interjection because farmers are simply not going to give up such a jammy scenario.

Although there is now a drive to develop new antibiotics internationally, which will at least keep us ahead of AMR, this is not a sustainable solution. If the use of antibiotics in livestock is the cause of the problem, we need to find a different solution! Changing farming practises to more sustainable and less intensive means is going to be hard to sell but honestly if it works without economic detriment to the farmer, and with potentially positive ancillary benefits for our environment, it sounds like a viable option. And alongside changes in farming practises, a change in consumer meat eating habits would be welcome too, and in the long run, will probably be necessary (see Guardian and ICIS articles). No?

It is argued that because in Denmark there have only been four deaths up to August 2014 that can be associated with LA-MRSA (compared with 700 people who died from other staphylococci infections) there is no risk! And because there are so few cases of contraction outside of direct contact with livestock, that the risk is minimal. This is a short-sighted stance. Looking outside, to for example the Netherlands, it is clear that Denmark needs to face this problem head on with more drastic measures – whether farmers like it to not!

If the world acts as the Netherlands acted we can at least manage the problem better and minimise the risk. Whether it is enough to prevent emerging and future cases of AMR that remains to be seen but for now it is a role model worth copying.