Why is antibiotic resistance an ecological problem?

When humans and animals are treated with antibiotics, approximately 80-90% of the ingested drugs are not broken down but are released as waste into the environment. These antibiotics retain the ability to affect bacteria and can promote antibiotic resistance after they enter the soil or water as a waste product. The fate of new antibiotic-resistant bacteria in the environment remains largely unknown. Find out more about the use of antibiotics as growth promoters in food animals.