Antimicrobial resistant bacteria found in organic and conventional dairy farms
A two-year survey of dairy farms in Canterbury has revealed a number of isolates resistant to multiple antibiotics.
4 February 2025
1 minute read
By: Lincoln University PhD graduate, Dr Omega Amoafo, carried out the work between 2017 and 2018, isolating more than 800 strains of Escherichia coli (E. coli) from farms using either organic or conventional practices to manage their dairy cows.
Although just 3.7% of the strains were found to be resistant, many of the antibiotics tested are used in hospitals to treat infections and most strains were resistant to multiple antibiotics.
There was a trend for antibiotic resistance to be more common in farms managed with conventional methods compared to those using organic procedures.
“Even though our numbers are small, the fact is that we have found E. coli in dairy farms that are resistant to clinically used antibiotics,” Professor Stephen On, Dr. Amoafo’s principal PhD supervisor, said. “The World Health Organisation is on record saying that antimicrobial resistance is one of the major threats to human health, so it is important to establish the risks of contamination from different sources."
“Our risks from dairy seem low but they are not zero. It would be worthwhile establishing the risk profile across the country to better estimate the threat,” Professor On said.
