The spread of antibiotic resistance is a health care crisis of major proportions and requires a moratorium on the use of antibiotics in agriculture. The Centers for Disease Control (CDC) call antibiotic resistance “one of the world's most pressing public health problems.” Many bacterial infections are becoming resistant to the most commonly prescribed antibiotics, resulting in longer-lasting infections, higher medical expenses, and the need for more expensive or hazardous medications. The development and spread of antibiotic resistance is the inevitable effect of the use of antibiotics. Bacteria evolve quickly, and antibiotics provide strong selection pressure for those strains with genes for resistance.
In spite of the spread of antibiotic resistance, the antibiotics used in plant agriculture are both important for fighting human disease. Tetracycline is used for many common infections of the respiratory tract, sinuses, middle ear, and urinary tract, as well as for anthrax, plague, cholera, and Legionnaire's disease, though it is used less frequently because of resistance. Streptomycin is used for tuberculosis, tularemia, plague, bacterial endocarditis, brucellosis, and other diseases, but its usefulness is limited by widespread resistance.
Use of antibiotics on fruit trees can contribute to resistance to the antibiotic in human pathogens. The human pathogenic organisms themselves do not need to be sprayed by the antibiotic because movement of genes in bacteria is not solely “vertical” –that is from parent to progeny– but can be “horizontal” –from one bacterial species to another. So, a pool of resistant soil bacteria or commensal gut bacteria can provide the genetic material for resistance in human pathogens.
When bacteria on the plants and in the soil are sprayed with an antibiotic, those with genes for resistance to the chemical increase compared to those susceptible to the antibiotic. Resistance genes exist for both streptomycin and tetracycline, and spraying with these chemicals increases the frequency of resistant genotypes by killing those susceptible to the antibiotic and leaving the others. Those genes may be taken up by other bacteria by a number of mechanisms, collectively known as “horizontal gene transfer.”
The guts of humans and other animals provide efficient incubators for antibiotic resistance. Antibiotic resistance increases first in commensal bacteria—the bacteria that naturally live within our bodies—and may then be transferred to pathogens. Thus, the argument that human pathogens are not present in orchards sprayed with antibiotics is irrelevant to the actual development and spread of bacteria resistant to antibiotics. The number of bacteria in the gut is large – often more than 1014 bacteria of several hundred species—with a large gene pool offering many mechanisms of resistance, and every exposure to antibiotics offers new opportunities for selection for resistance.
Antibiotics from use on animals and crops are washed into waterways, where they find another environment perfect for encouraging the growth of antibiotic-resistant bacteria. Aquatic environments are rich in bacteria, providing another place where pathogens can obtain genes for resistance.
It is important to eliminate uses of antibiotics in agriculture that can contribute to antibiotic resistance in human pathogens. Instead, EPA has been increasing those uses and fails to count antibiotic resistance as a health risk to humans.
>>Tell EPA to save antibiotics for important medical uses and eliminate use as pesticides.