In a joint study, researchers at the Johns Hopkins Bloomberg School of Public Health and Arizona State University found evidence suggesting that a class of antibiotics previously banned by the U.S. government for poultry production is still in use. Results of the study were published March 21 in Environmental Science & Technology.
The study, conducted by the Bloomberg School's Center for a Livable Future and Arizona State's Biodesign Institute, looked for drugs and other residues in feather meal, a common additive to chicken, swine, cattle and fish feed. The most important drugs found in the study were fluoroquinolones - broad spectrum antibiotics used to treat serious bacterial infections in people, particularly those infections that have become resistant to older antibiotic classes.
The banned drugs were found in eight of 12 samples of feather meal in a multi-state study. The findings were a surprise to scientists because fluoroquinolone use in U.S. poultry production was banned by the U.S. Food and Drug Administration (FDA) in 2005.
This is the first time investigators have examined feather meal, a byproduct of poultry production made from poultry feathers, to determine what drugs poultry may have received prior to their slaughter and sale.
The rendering industry, which converts animal byproducts into a wide range of materials, processes poultry feathers into feather meal, which often is added as a supplement to poultry, pig, ruminant, and fish feeds or sold as an "organic" fertilizer. In a companion study, researchers found inorganic arsenic in feather meal used inretail fertilizers.
The discovery of certain antibiotics in feather meal strongly suggested the continued use of these drugs, despite the ban put in place in 2005 by the FDA, David Love, the lead author of the report, said.
A primary reason for the 2005 FDA ban on the use of fluoroquinolones in poultry production was an alarming increase in the rate of the fluoroquinolone resistance among Campylobacter bacteria.
In conducting the study, researchers from the Johns Hopkins Bloomberg School of Public Health and Arizona State University analyzed commercially available feather meal samples, acquired from six U.S. states and China, for a suite of 59 pharmaceuticals and personal care products. All 12 samples tested had between two and 10 antibiotic residues. In addition to antimicrobials, seven other personal care products, including the pain reliever acetaminophen (the active ingredient in Tylenol), the antihistamine diphenhydramine (the active ingredient in Benadryl)and the antidepressant fluoxetine (the active ingredient in Prozac), were detected.
When researchers exposed several strains of E. coli bacteria to the concentrations of antibiotics found in the feather meal samples, they also discovered the drug residues could select for resistant bacteria.
The scientists strongly believe that the FDA should monitor what drugs are going into animal feed. Based on what they learned, they are concerned that the new FDA guidance documents, which call for voluntary action from industry, will be ineffectual.
Source: Johns Hopkins Bloomberg School of Public Health