Recently, researchers at Johns Hopkins (Baltimore, MD) found evidence that houseflies collected near broiler poultry operations may contribute to the dispersion of drug-resistant bacteria and thus increase the potential for human exposure to drug-resistant bacteria. In fact, there is a great concern now about these resistant strains, and a lot can be learned about what not to do based on a study of the commercial poultry industry.
Dr. Robert Lawrence of the Center for a Livable Future (Johns Hopkins) believes that confined animal feeding operations—where thousands of birds are crowded together and fed antibiotics—create the perfect environment for new strains of bacteria that are resistant to antibiotics. Although he didn't state it in the release from JHU, I believe that this same issue is seen in commercial production of hogs and other animals as well.
“Antimicrobials are among the most important developments of the twentieth century in managing infectious diseases in people. We can’t afford to squander them by using them as growth promoters in industrial food animal production. The increase in antibiotic-resistant bacteria is a major threat to the health of the public, and policymakers should quickly phase out and ban the use of antimicrobials for non-therapeutic use in food animal production,” said Lawrence.
In the work done by Johns Hopkins, Graham and his colleagues collected flies and samples of poultry litter from poultry houses along the coastal region shared by Maryland, Delaware and Virginia, which has one of the highest densities of chickens per acre in the United States. The research team isolated antibiotic-resistant enterococci and staphylococci bacteria from both flies and litter. These flies, of course, have a large radius from where they are discovered, with lots of human interactions along the way.
“Flies are well-known vectors of disease and have been implicated in the spread of various viral and bacterial infections affecting humans, including enteric fever, cholera, salmonellosis, campylobacteriosis and shigellosis,” said lead author Jay Graham, PhD, who conducted the study as a research fellow at JHU. "Our study found similarities in the antibiotic-resistant bacteria in both the flies and poultry litter we sampled. The evidence is another example of the risks associated with the inadequate treatment of animal wastes.”