Date of this Version
Many antibiotics and medications used in the treatment of animals have a withdrawal time; residues are a concern for the meat industry. The most recently published 2009 USDA-FSIS Residue Program Data Report listed 135,389 Inspector-In-Charge-Generated (IICG) residue samples from 43,142,500 beef and dairy cattle inspected that year at harvest (USDA-FSIS 2009a). Of these samples, 1306 contained violative antibiotic residues and 327 violative flunixin meglumine residues. Two classes of antimicrobials comprised over half of the documented violative antimicrobial residues (beta-lactams that include ceftiofur and sulfa drugs that include sulfadimethoxine). While the violative residue rate seems small, violative residues are unacceptable. Management of carcasses that contain violative residues is costly to the USDA, the meat packing industry, and the producers involved.
There is no preharvest or ante-mortem screening test currently available that mirrors the antibiotic screening test used by the United States Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) in beef and swine packing plants (USDA-FSIS Notice 39-09). Adapting the test currently used by the USDA-FSIS to screen for antibiotic residues in tissue or used by the Food and Drug Administration (FDA) to screen for drug residues in milk would make it possible for producers and veterinarians to identify or predict livestock that might be considered a high risk for containing a violative antibiotic residue in tissue. In addition, there is no preharvest screening test currently available to detect violative residue levels of flunixin meglumine and ceftiofur in cattle prior to market (Damian, 1997).
A simple, cow-side test for the presence of drug residues in live animal fluids would provide useful information for tissue drug residue avoidance programs. This work describes adaptation and evaluation of rapid screening tests to detect drug residues in serum and urine. Medicated herd animals had urine, serum, and tissue biopsy samples taken during drug treatment. Samples were tested by rapid methods and high-performance liquid chromatography (HPLC). The adapted microbial inhibition method, kidney inhibition swab (KIS®) test, was useful in detecting sulfadimethoxine in serum and successfully predicted proper drug withdrawal in the kidney by HPLC, 5 to 6 days post treatment. The lateral flow (LF) screening method for flunixin and beta-lactams adapted for urine was useful in predicting flunixin in the liver detected by HPLC, 96 hours post-treatment. The same adapted methods were not useful to detect ceftiofur in serum or urine relative to the recommended tissue withdrawal time after ceftiofur treatment. These anti-mortem screening tests demonstrated that the selection of method used, and whether urine or serum are tested, will vary based on drug used and should be based on animal treatment history if available. The live animal tests demonstrated the potential to allow verification that an individual animal is free of drug residues before sale for human consumption.
Advisor: Dee Griffin