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Antibiotic resistance: the role of animal production (2 de 2)

Why has antimicrobial resistance become more important over the last few years? Which is the responsibility of animal production? Is it possible to transfer antimicrobial resistance from animals to humans and vice versa? Can meat contain resistance even without having antimicrobial residues?

Why has antimicrobial resistance become more important over the last few years?

It is due to multiple factors. It was only a matter of time; in our laboratory, we have been fighting antimicrobial resistance for more than ten years. The use, abuse and misuse of antibiotics, both in human and veterinary medicine over the last decades, has promoted a fast increase of the resistance levels, as well as the emergence of new mechanisms and multi-resistant bacteria that can even be resistant to all known antibiotics. At the same time, and due to several circumstances, the industry has not focused its efforts on searching for new antibiotics in the last decades.

This phenomenon results in more than 25.000 deaths in the EU every year and related costs of approximately 1,5 billion Euros. In 2014, it was already recognized as one of the main threats to human health worldwide, and in September 2016, the UN unanimously declared antimicrobial resistance one of the main health alerts worldwide.

Which is the responsibility of animal production?

The responsibility of the animal production industry is difficult to quantify. What we do know, is that antibiotics will always select bacteria resistant to them. Following this axiom, the reduction of antimicrobial use is the way to delay the appearance of resistance to them. This is being done in some countries, both in human and veterinary medicine. The time to point fingers has ended, and it’s given way to a time where all the agents involved in the use of antibiotics are fighting together. The world of animal production must commit to reducing the use of antibiotics, using them more efficiently and promoting practices that improve animal health and welfare as well as biosecurity measures at the farms.

Is it possible to transfer antimicrobial resistance from animals to humans and vice versa?

Of course, and that is why is so important to fight together. Only reducing the use of antibiotics, will we reduce the risk. In April 2017 we published an article that described, for the first time in the world, the presence of a human pathogen that has adapted to living in dogs and that is resistant to Tigecycline, an antibiotic used as a last resort in human medicine and that is not used in veterinary medicine. This highlights the importance of fighting together, as veterinary practice —in both farm animals and pets—, indirectly affects human medicine and in the same way medical practice affects animals. It is necessary to point out that human beings are responsible for the proper use of both the antibiotics we prescribe and the antibiotics that are prescribed to us, and that animals depend on our decisions.

Flow diagram of antibiotic resistance determinants among the different reservoirs. Blue indicates points of antibiotic administration. http://www.effort-against-amr.eu/
Flow diagram of antibiotic resistance determinants among the different reservoirs. Blue indicates points of antibiotic administration. http://www.effort-against-amr.eu/

Can meat contain resistance even without having antimicrobial residues?

Most food is not sterile and, therefore, contains bacteria with DNA, which can encode for antimicrobial resistance genes. As regards meat, it will depend on the handling it’s been subjected to during the production process, always taking into account the risk factor derived from the potential high levels of resistance present at the source farms. Regarding quantification, we are currently working on that. In the EFFORT project we are analyzing meat samples from different origins to study bacteria levels and the resistance genes they contain. This will provide the necessary information to estimate the potential presence of resistance genes in food.

What is the probability of resistance being transmitted to humans?

We still need to gain more knowledge and carry out further research to obtain more data, which will allow us to determine the transmission levels. It will mainly depend on specific cases and individual susceptibility. It will also depend on the microorganism that carries the resistance factors, its virulence or ability to colonize and adapt.

Is it possible that the use in animals of antimicrobials that are not used in human medicine could favour resistance to antibiotics in human pathogens and vice versa?

It will depend on every case. As regards enrofloxacin, for instance, there is no doubt: bacteria resistant to enrofloxacin are also resistant to the fluorquinolones used in humans, such as ciprofloxacin or levofloxacin, which are widely used in human medicine to treat complex urinary or respiratory infections. Despite the large amount of antibiotics available, they can be classified in a small number of families that share, amongst other things, their main structure and mode of action. Antimicrobial resistance genes can be grouped in resistance groups against the different families; it is common that one single gene provides resistance against a large number of antibiotics belonging to the same family. For example, third generation cephalosporins used in hospitals favour resistance to other members of the beta-lactam family such as amoxicillin and penicillin, frequently used in veterinary medicine. In the same way, the use of enrofloxacin, a fluorquinolone, in pigs can favour the increase of resistance against ciprofloxacin.

How can antimicrobial resistance be reduced?

The strategic plans defined by several medicine agencies clearly reflect the 6 main pillars of the fight against antimicrobial resistance:

  • The level of antibiotic consumption must be known.
  • Transparency first and foremost.
  • The level of resistance must be known.
  • Research is essential to find new ways to fight against antimicrobial resistance.
  • Alternatives to the use of antibiotics must be promoted, clearly improving farm management.
  • Finally, training professionals and raising awareness in society is a key factor to tackle, all together, this pandemia.

There has been a turnaround in the way the problem is perceived in many of the countries where pig production is a relevant industry. Some countries have started taking measures to reduce antimicrobial resistance. It is expected that in the short, medium term, specific requirements by retailer, processors, etc. to reduce the use of antibiotics will increase. The commitment of the pig industry will definitely be a key element to improve this parameter. Taking into account the professionalism of the industry, and how important everything related to food safety is for the consumer, an important progress in reducing antimicrobial resistance will, no doubt, be made.

Article Comments

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David Burch27-Jun-2017 (27 days ago)

I have spent some time over the last couple of years trying to quantify the transmission of resistance from food animals to man and the attribution to pigs, chickens and cattle. Pigs appear to play a relatively minor role in comparison with chicken meat and eggs still. Visit www.octagon-services.co.uk if you wish to find out more.

Thomas27-Jun-2017 (27 days ago)

75% of all antibiotics are used in animal farming. Biggest problem is the system, that uses antibiotics in prophylactic way. The big mega farms (1000 mother sows and more) can not work without antibiotics. Most pig farmers do not believe that medium and big farms can work without antibiotics. We work already 6 years without antibiotics (500mothersows til fattening) and have not met comparable farms with comparable results. Animal care knowledge is today on a very poor practical level. Poor payment, little animal care knowledge ... now that antibiotics stops working, the system will collapse ... a system that produces only cheap meat. Meat must become expensive again to get quality not quantity and to stop all the problems related to the quantity production of animal farming (ecology destroyed, people eat too much meat, because it is so cheap and retail suggest that eating meat around the clock is normal, but it's not) The Meat industry is by far too concentrated. Full circle farms with max. up to 600 mother sows and no antibiotic use, no super fertile mother sows (with 35 and more piglets - which then are brought up with all the artificial milk and medicaments) will be the future of animal farming. Quality meat 2-3times a week is healthy and enough. Quality meat can be only produced with minimum of antibiotics (max. 5% of all piglets produced per year get once a medication). Currently big farms use up to 500 times more (with every feed change prophylactic use). Good farmers or animal producers are only those who work with almost no antibiotics, so basically there are currently only a few good pig producers left.

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