The consumption of animal proteins presents a global and sustained increase, causing the expansion of intensive farming of pigs, poultry and cattle. The intensification of production in limited acreage environments has led to the massive introduction of antimicrobials to maintain animal health and productivity. The routine use of antibiotics (AMU, Anti Microbial Utilization) promotes the appearance of resistant strains (AMR, Anti Microbial Resistant), thus constituting a major threat to both human and animal health.

In an interesting study by Katie Tiseo y col, the evolution of the use of antimicrobials in 41 countries is analyzed. The data obtained in 2017 show that in these countries a total of 93,000 tons of active products were used as antimicrobials, a figure that represents 73% of the total used by medicine and veterinary medicine. In this period, the five countries with the highest consumption of veterinary antibiotics have been China, 40%, Brazil 7%, US 6%, Thailand 4% and India 2%.

It is widely believed, supported by solid data, that there is a relationship between the development of bacterial resistance in food animals and the emergence of resistant bacterial populations in humans.

Antibiotics are mainly used to treat bacterial infections and their administration to prevent disease is recommended only in very exceptional situations.

In Europe, the use of these drugs to promote the growth of animals has been totally prohibited since 2006. However, this is not the case in other regions of the world where they can still be added to the diet of healthy animals.

According to the WHO, the abuse and misuse of antibiotics in animals and humans are contributing to the increased threat posed by antimicrobial resistance. Some types of bacteria that cause serious human infections are already resistant to most or all available treatments, and there are very few promising alternatives under investigation.

These bacteria can be transmitted from animals to humans by different routes:

• By direct contact with animals.
• Through foods derived from animals
• Through the environment. Pharmaceutical residues can be strongly bound to soil particles through animal feces. The ones more soluble in water can be washed away by rain or melting snow and reach both groundwater and surface water streams.

What can be done to combat resistance?

• Surveillance of the use of antibiotics and resistant bacteria. WHO strongly recommends a general reduction in the use of all classes of medically important antibiotics in food-producing animals, including complete restriction of these drugs to promote growth and prevent undiagnosed disease. Also, knowing the type and quantity of antibiotics used and the class of resistant bacteria and the frequency with which they are detected provides us with very useful information from an epidemiological point of view. Among other things, it makes it possible to identify associations between consumption and the appearance of resistance, analyze trends and design effective measures to curb the problem.

• Promotion of prudent use through training activities for the sector and the preparation of prudent use guides. Recently, based on a report prepared by experts, the European Commission has proposed to categorize veterinary antibiotics according to the impact that their use may have on human health. Each of the four categories is accompanied by specific recommendations for use.

• Prevention of infections. Since healthy animals do not need to be treated, reducing possible infections will help reduce the use of antibiotics. Measures to achieve this include improving hygiene and biosafety in livestock farms, strengthening the immune system of animals and the implementation of specific health plans for each farm.

• New chemical structures. The development of easily degradable antibiotic molecules could help reduce contamination.

Finally, more research is needed to better understand the mechanisms by which resistance is generated, develop new diagnostic tools, as well as new alternatives to antibiotics and better disease control measures.

References

Tiseo, K., Huber, L., Gilbert, M., Robinson, T. P., & Van Boeckel, T. P. (2020). Global trends in antimicrobial use in food animals from 2017 to 2030. Antibiotics, 9(12), 918.

FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS. Drivers, dynamics and epidemiology of antimicrobial resistance in animal production. FAO, 2016.