The more we use antimicrobials on our livestock the more resistant pathogens there are. This poses a risk for human health because there are more human infections with superbugs for which there might eventually be no effective medication, researchers from the National Food Institute in Denmark reported today in Student BMJ (British Medical Journal).

Jørgen Schlundt and team stress that profitable livestock farming is possible with considerably lower routine use of antimicrobials. They call for stricter regulations and closer monitoring of antimicrobial use in farm animals.

Antimicrobials include:

  • Antibiotics – to fight bacterial infections
  • Antifungals – to fight fungal infections.
  • Antivirals – to fight viral infections.
  • Antiparasitics – to fight infections by parasites.

Antibiotics are crucial for the treatment of bacterial infections in both humans and animals. Huge quantities are used in modern livestock farming. However, their routine use can promote the evolution of bacteria that become resistant to antibiotics.

Humans can acquire resistant bacteria from animals through physical contact, as in abattoirs (slaughterhouses), and through the food chain.

Examples of recently emerging infections that now affect humans and came from animals include:

Experts and organizations around the globe would like to see a number of measures taken to protect primarily human health, and also animal health, including restricting antimicrobial use in livestock of medications which are critically important for humans.

The European Union has started monitoring drug resistance in livestock – often termed food animals. All EU member states now have to monitor antimicrobial usage.

Denmark has had strict regulations regarding monitoring animals and medication usage for livestock since 1995.

The authors explain that more stringent regulations do not mean a farmer’s productivity drops. Pig farmers in Denmark use less than one-fifth of what their equivalents in the USA use – antimicrobial agents per kilogram of pork produced. However, productivity in Denmark has never been so high; it is the largest exporter of pork on the planet.

According to Norwegian data on fish farm management, the introduction of effective vaccines has reduced antimicrobial usage by more over 95%.

The authors write:

“We have major tasks ahead for global containment of resistance, in relation to both veterinary and human medicine. Antimicrobials are too precious to be wasted, and both sectors have plenty of room for improvement.

(conclusion) Substantial reduction of antimicrobial use in livestock is feasible and necessary if we want to preserve the power of antimicrobials for future generations of both animals and humans.”

Drug resistance refers to the loss of effectiveness of a medication, such as an antimicrobial or antineoplastic (chemotherapy cancer drug) in treating a condition or disease. The term today is commonly used to refer to resistance acquired by pathogens, such as bacteria.

A multi-resistant pathogen has developed resistant to two or more drugs.

MRSA (methicillin-resistant Staphylococcus aureus) refers to some strains of Staphylococcus aureus, a type of bacteria that have become resistant to several antibiotics. The media often refer to them as superbugs.

Staphylococcus aureus live on the surface of the skin and inside the nose of humans. Usually they pose no health risk and carriers are unaware. UK health authorities estimate that up to 30% of the country’s population carries these bacteria. They spread easily form human-to-human through contact.

Problems occur when the bacteria enter the human through the skin, via a cut or wound. The majority of healthy individuals would have no problems; their immune systems would fight off the infection and they would experience mild symptoms or none at all. Those with weakened immune systems, however, are vulnerable to serious and sometimes life-threatening complications, such as heart-valve problems, toxic shock syndrome, septic wound, impetigo, abscesses and boils.

Patients with MRSA complications need antibiotics to help them fight the infection. The problem is that very few medications now work.

Bacteria are forever evolving, their genes are constantly changing and adapting. When exposed to an antibiotic some may survive because they have adapted genetically. That is why it is important to complete your course of antibiotic, to make sure all the bacteria are destroyed.

In farming, it is common practice to routinely give animals low-dose antibiotics. The problem here is the low dosage – a much larger number of bacteria survive, and they have adapted. The offspring of these bacteria will then adapt further, and in large numbers.

If antimicrobials were only used for sick animals, and if each course of antibiotics on a sick animal was completed, the risk of drug resistance evolving would be considerably smaller.

The World Health Organization would like to see the use of antibiotics as growth promoters in animal feeds banned.

The FDA (Food and Drug Administration) estimates that 70% of all antibiotic production in the USA is given to animals. There are currently two federal bills in America aimed at phasing out the non-therapeutic use of antibiotics in the country’s food-animal production (S. 549 and H.R 962).

Many diseases and infections today are becoming increasingly difficult to treat, such as malaria, candida infection, gonorrhea, tuberculosis, influenza, HIV infections, and staphylococcal infection.

There is today serious concern among experts that one day we might have no drugs at all to treat some infections.

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Written by Christian Nordqvist