23,00 people die as a direct result from these infections, while many more die from complications of the infections.6 2.3 Antibiotics in Agriculture In the 1950s, the farming industry changed forever when scientists discovered that adding antibiotics to livestock feed accelerated the growth of animals and was cheaper than then previous methods of growth enhancement. During the beginning of the twentieth century, American farmers could not keep up with the demand.17 The meat industry was steadily increasing prices, puzzling policy makers and angering consumers. In 1917, there were millions of boycotts throughout the United States to protest the prices of meats, which encouraged the USDA to fund research targeted at keeping the food supply on pace with the demand.27 It was known that diets that contained animal derived proteins like fishmeal or cod liver oil produced healthier animals that gained weight quicker. These animal derived protein additives were expensive; especially during World War II. The concentration to finding a solution was focused on finding a protein substitute, but the search quickly shifted to antibiotics when it was discovered that adding them to animal feed increased livestock’s growth.17 During administration of antibiotics in animals, an unforeseen side effect was observed: rates increased in growth of livestock. 7 Farmers were very quick to ditch the pricey animal’s proteins and switch to inexpensive antibiotics. Livestock reached a market weight much quicker and production costs for farmers dramatically dropped. This was an agricultural revolution for farmers running large operations and led to the reliance on antibiotics to promote growth and keep animal’s healthy.12
human infections back to livestock operations.27 In a study in 1976, by Stuart Levy showed the link between tetracycline resistant bacteria in a farm family whose animals were treated with antibiotics. Tetracycline resistant E.Coli bacteria appeared in chickens within a day that were fed tetracycline antibiotic in their feed.7 Five months from initial feeding the resistant E.Coli strain appeared in family members working on the farm that were not eating the chicken and not directly in contact with the tetracycline.10 Occupations that have direct contact with animals are at the most risk of acquiring and spreading antibiotic resistant strains. These jobs include workers on farms and slaughterhouse and veterinarians that come in close contact with infected animals. Workers become infected through handling animals, animal feed, and manure.8 Once the strain infects a worker it can easily and readily be transferred to family, friends, and the community. This is a limited transmission setting and although it is not initially a population level health threat, occupational workers and their families provide an initial entry of the resistance genes into the community.27 5.2 Food Consumption A more far reaching problem and more complex route of transmission is through the consumption of animal products.17 Over the course of a factory farm animal’s life, drug resistant bacteria build up in its intestines. When the animals are slaughtered and processed the bacteria is released and they can spread to the packaged meats that people are consuming. The drug resistant strains of bacteria then colonize in the consumer’s intestines and the genes can thrive there and cause harm by making new strains across bacterial species.7 In consumer report it was uncovered that 42% of broiler chicken at the supermarket were contaminated with campylobacter and 20% of these cases were the antibiotic strain of the disease.15 Thorough