Of meat and microbes

Pig out : Nature : Nature Publishing Group

The spread of dangerous bacteria that are resistant to antibiotics is fuelled by overuse of the drugs — and not just in people. Farmers around the world routinely feed antibiotics to their animals, not only to prevent and treat infections, but also to make their animals grow faster. This leads to drug-resistant bacteria in the animals, and this resistance can spread to the bacteria that infect us.

The overuse of antibiotics in farm animals is a global issue. Human propensity for trade and travel ensures that resistant bacteria spread easily around the world, so as long as any one country pumps its pigs and poultry full of the drugs, everyone is at risk.

In 1998, the Danish poultry industry took the unusual step of volunteering to stop using antibiotics for the promotion of animal growth. Two years later, the country's pork farmers did the same. Denmark might be a small country, but it is the world's largest exporter of pork. And it didn't stop there, writes Frank Aarestrup in a Comment piece on page 465, Denmark went on to reduce its overall use of antibiotics in livestock by 60%. It achieved this by creating a comprehensive surveillance system to monitor overuse, and limiting the amount of money that vets could make from selling the drugs to farmers.

Many feared that the changes would cripple Denmark's pork production. Instead, production rose by 50%. “Any country trying to limit the use of antibiotics in livestock can learn from what my colleagues and I did in Denmark, adjusting what worked to local needs,” Aarestrup writes. These are encouraging words, but it is unlikely to be that simple.

The biggest obstacle is likely to be generating the political resolve and public support needed to crack down on the lucrative trade in antibiotics. This was possible in Denmark because there, perhaps uniquely, warnings from the medical community were picked up by the media, creating widespread public awareness of the problems caused by the overuse of antibiotics. People in other countries may not be so engaged, particularly when faced with the inevitable lobbying of the agricultural and veterinary sectors, which make big profits from selling antibiotics.

Also a problem is the fact that in many countries, farmers tend to work independently of each other. Almost all Danish farmers, by contrast, are members of the Danish Agriculture and Food Council, through which they frequently communicate and interact. This meant that they had a convenient forum in which to debate the issue and come to the decision to stop using antibiotics for growth. Denmark also has a detailed system in place to keep track of the effects of antibiotic use by farmers, which helps to enforce the regulations. In the United States, drug companies provide the Food and Drug Administration with data on the quantity of antibiotics sold to farmers, although they do not routinely say what types of animal the drugs are given to, or what the drugs are used for. The nation therefore has the necessary infrastructure and reporting system to monitor and regulate the use of antibiotics for animal growth, should it wish to do so, as do other countries. And the European Union has already banned such drug use.

The first step to building the case for tighter control is to obtain more specific data. Researchers should be able to survey ten farms in ten US states, for example, and extrapolate those data nationally to build up an accurate picture of antibiotic use. The drugs are almost certainly overused, and are almost certainly having a damaging impact on public health, so publishing the results would help in raising awareness of the problem and generating the necessary support. The people of Denmark deserve praise for their efforts, and other countries, and their people, should look more carefully at what their animals are being fed.

http://www.nature.com/nature/journal/v486/n7404/full/486440a.html