Antibiotic resistance a problem but economics dictate use

COLUMBUS, Ohio — Antimicrobial resistance is a global issue affecting public, animal and plant health.

Before the 1960s, antibiotics were expensive and were not widely used in livestock production, said Wondwossen Gebreyes, executive director of Global One Health Initiative at Ohio State University.

However, there are economic benefits to using antibiotics in livestock production.

A study from the University of Kentucky found the total benefit per pig was $3.98.

“There is huge incentive to use antibiotics and when you withdraw them there are huge consequences,” he said at the National Institute of Animal Agriculture annual meeting held April 3-6 in Columbus, Ohio.

In 2000, Denmark phased out the use of growth promoting antibiotics but their medication prescriptions have increased substantially.

Use is difficult to track, but the United States International Trade Commission reported 48 percent of antibiotics were sold for human use and 52 percent were sold for animal use.

It is estimated that several million people are affected after developing a bacterium resistant to treatment. Most are in sub -Saharan Africa and Asia. About 390,000 patients died in Europe and 321,000 were affected in North America.

There is a push for new antibiotics but it takes eight to 12 years to develop new animal health products and up to 15 years to develop a human product.

“In 1998, everybody was looking for new antimicrobials,” he said, but very few companies are seriously looking at new products.

More research into antibiotic alternatives is needed, said Cyril Gay of the Agricultural Research Service agency within the United States Department of Agriculture.

Antibiotics are one of the greatest inventions of the modern world but the possibility of resistance was understood early on, he said.

“It is not anything new. We already knew when we used antibiotics, some would mutate and some would evolve,” he said.

In 2013, a global symposium on the responsible use of antimicrobials for animals recommended more relevant research to improve understanding of the efficacy of current antimicrobial agents, as well as finding alternatives for animal production.

There is a perception that products used in livestock production could cause added bacterial resistance to drugs used in human medicine.In addition, medically important antibiotics are being lost and no replacements are coming. Veterinarians want to preserve antibiotics as well, he said.

Vaccination is the quintessential alternative to antibiotics, said Gay.

“Yet we actually have a lot of vaccines that are not that good.”

More research is needed to im-prove vaccine efficacy.

“There is a need to invest in some of this basic research to understand mechanisms of immunity and mechanisms of protection,” he said.

Scientists know a lot about mouse and human immunology but are challenged in their understanding of livestock immunology.

Vaccine research could look at knowledge gaps like understanding maternal colostrum interference, cross protection or inclusion of relevant strains in vaccine formulations or innovative ways to deliver mass vaccinations.

Alternatives to antimicrobials for treatments of parasites, bacteria and viruses are needed. Antibiotic alternatives are very distinct molecules with different effects, doses and mechanisms of action and need to be developed accordingly.

More research is needed to find alternatives with defined mechanisms of action that are also safe and effective.

Other possibilities include nutraceuticals or herbal products. This is a multibillion-dollar industry on the human side but research is needed to see if they actually work and if they would be useful to livestock.

More work could be done on bacteriostatic agents that stop bacteria from reproducing.

Gene sequencing to produce animals with disease resistance is another area for development.

Probiotics need more work and antimicrobial peptides should be investigated.

Interferon, a naturally occurring type of protein that can attack bacteria, viruses, parasites and tumours, deserves renewed attention.

“The discoveries are mind boggling,” he said.

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