Intensive and extensive antibiotic use leads to the establishment of a pool of antibiotic resistance genes in the environment. Both pathogenic bacteria and organisms that do not cause disease may become resistant to antibiotics, and bacteria of human and animal origin can serve as reservoirs for resistance genes. Scientists are now trying to evaluate the odds that exposure to these genes will transfer antibiotic resistance to other populations of bacteria, animals, even humans. Research studies have shown that antibiotic resistant pathogens and possibly bacterial genes are transmitted from animals to humans through food, water, and by direct contact.
The transmissibility of antibiotic resistant bacteria or genes among animals and humans and the transfer of genes from antibiotic resistant bacteria to other kinds of bacteria associated with animals raise serious concerns about the use of antibiotics in agriculture. The concerns are three-fold: (1) that antibiotic resistance genes are amplified in the environment because of antibiotic use in agriculture; (2) that antibiotic resistance genes negatively impact public health; and (3) that antibiotic resistance genes negatively impact animal health and production.