February 7, 2022

Research finds feedlots may contribute to antibiotic resistance

Researchers from the University of New England (UNE) have found evidence that feedlot manure carries antibiotic-resistant bacteria that could be contributing to antibiotic resistance in both human and animal health.

Fadhel Abbas, a UNE PhD student, discovered that farm soils where feedlot manures have been spread include drastically increased bacteria levels resistant to antibiotics, compared to untreated soils.

This discovery that antibiotic bacteria may have evolved under feedlot conditions could significantly affect human and animal health.

Dr Nick Andronicos, one of Abbas' supervisors at UNE and a senior lecturer in Biochemistry and Immunology, said the issue of feedlot manure contributing to human antibiotic resistance is worsened due to the use of the same classes of antibiotics for humans and animals.

Abbas also wrote in his findings that conditions in the feedlot could be hastening the evolution of antibiotic resistant microbes, as livestock raised in a limited area could enhance bacteria transmission through direct contact with other livestock or ingesting polluted water and food in faeces.

Abbas' findings were discovered in bacteria-soil interactions at UNE's research feedlot, Tullimba. 11 types of antibiotics were assessed by growing colonies of bacteria harvested from fresh manure, soils treated and not treated with feedlot manure, as well as exposing the colonies to a standard then double dose of each antibiotic.

Higher populations of antibiotic-resistant bacteria were found in fresh feedlot manure compared to treated and untreated soils and stored manure. Between 30%-75% of the antibiotic-resistant bacterial load in fresh manure was discovered in soil treated with fresh manure, depending on the class of antibiotic.

-      University of New England