Report bleak on antibiotic resistance

antibiotic resistance in farm animals

A report to the United Nations paints an alarming picture of rapidly emerging antimicrobial drug resistance with agriculture among industries being called on to invest more in developing alternative treatments and to collaborate with the human health sector.

Antibiotics are typically the main antimicrobial drug class used against bacterial infection. The high-level report produced by the UN’s antimicrobial resistance group demands ambitious and immediate action on an issue it says will lead to a disastrous crisis. It documents increasing evidence of resistance among bacteria to antimicrobial treatments, with 35% of common human infections already resistant to medicines.

That number is as high as 80-90% in some lower to middle income countries. Worryingly, the authors say growing resistance to last-line defence drugs is expected to double in only 20 years. They attribute the overuse or misuse of antibiotics to promote growth and prevent disease in otherwise healthy animals and crops as major contributors to resistance development. Estimates are drug resistance already contributes to at least 700,000 deaths globally a year and that could increase to apocalyptic levels of 10 million by 2050 under its worst-case scenario. A quarter of those deaths will be in high-income countries like New Zealand. Left unchecked, resistance development will have an impact comparable to that of the global financial crisis of 2008. NZ is ranked as a high user of antibiotics for human treatments but low in terms of use in animal production systems and farms. Human consumption is seventh highest in the world but third lowest for animals.

Veterinary Association’s antimicrobial resistance committee chairman Mark Bryan, a Southland vet, said the link between human resistance and use of antimicrobials in animals remains a thin one. “And the level of resistance in animal diseases to antimicrobial treatments has shifted very little over the past 20 years. About 37% of pathogens cultured exhibit a level of resistance. There’s been a slight increase but not a significant one.” While NZ has been on the front foot with a low level of use in animals more work has to be done in getting better data specific to use and farm type, helping provide better surveillance and understanding of use. “I could see NZVA being the umbrella organisation for this, given vets are at the front end of administration but we are not resourced to do it and it would require funding through MPI to achieve that. To be fair, MPI has had a lot on their plate. “We have some regional data for Southland and Canterbury but it would be good to be able to pull this data together from around the country.” The dairy industry accounts for about 40% of antibiotics used and mastitis treatment accounts for 29% of the total.

Dry cow therapy in dairy cows is one of the most significant areas where antimicrobial treatments are used on NZ farms. Bryan believes farmers’ attitudes to using such treatments have changed significantly in recent years thanks, in part, to vets’ efforts to educate about the impact of antimicrobial resistance. Farmers are being offered alternative non-antimicrobial treatment regimes, including teat sealants. In 2015 the association set the target to reduce antimicrobial treatments by 2030 to a level the country does not need them to maintain animal health and wellness. Chemical users’ group Agcarm chief executive Mark Ross said NZ ranks alongside countries like Iceland, Lithuania and Sweden for low levels of antimicrobial use in animals.

Those countries report use of about 9t of antimicrobials per 1000t of biomass compared to countries like Hungary or Germany sitting at well over 200t per 1000t. Italy and the United States rank among the highest users for both animal and human use. “It is often the case that high use reflects intensive farming systems for the likes of poultry,” Ross said. The UN report calls for countries to have established national antimicrobial resistance action plans, something NZ did in 2017. It requires optimised use of antimicrobial medicines in human, animal health and agriculture.

Richard Renni, Farmers Weekly


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