While new research conducted in the Netherlands found that antibiotic resistance factors were more likely to be shared among people than between livestock and people, it said animal agriculture should continue efforts to minimize the release of antibiotic resistance factors into the environment (since these factors can circulate within livestock populations and reduce the effectiveness of animal health protocols).

At an industrial scale, compost, such as manure, is produced by mixing plant and animal waste. Manure, however, is likely to contain antibiotic-resistant genes if animals have been treated with antibiotics during their lifetime.

While antibiotic resistance genes are not harmful in and of themselves, they limit the effectiveness of antibiotics for treating bacterial infections and pose a serious threat to global public health.

Scientists at the University of York in the U.K., in partnership with Fujian Agriculture & Forestry University in China, have now shown that using a method called hyperthermophilic composting -- an industrial-scale process that heats the compost mixture from within to a temperature of 90°C -- can kill bacteria carrying antibiotic resistance genes.

Dr. Ville Friman from the University of York's department of biology said, "In modern animal husbandry, animals are reared in high density to maximize food production. However, in these circumstances, diseases can spread very easily.

"Antibiotic resistance genes are then transferred to the feces of the animal, which is later used as manure in compost that is spread on fields to fertilize crops. Antibiotic resistance is a significant global health issue, so we need to find ways of reducing the likelihood of these genes entering the food chain," Friman said.

The research shows that bacteria that carry antibiotic resistance genes are unlikely to survive high temperatures. Hyperthermophilic composting, therefore, has the potential to make composting end products safer by reducing the abundance of unwanted antibiotic resistance genes.

Friman said, "Developing safer ways to manufacture organic fertilizers can reduce our dependence of traditional chemical fertilizers while at the same time ensuring that they do not impact on human health by enriching antibiotic resistance genes in agricultural environments."

The hyperthermophilic composting process is similar in cost to traditional composting methods and has proved to work successfully with large compost volumes, making it a feasible approach at an industrial scale in the near future, according to the University of York.

The research was published in the journal Environmental Science & Technology.