Evaluation of penicillin G residues by kidney inhibition swab tests in sow body fluids and tissues following intramuscular injection

Authors: Shelver, Weilin; Lupton, Sara; NEWMAN, DAVID - North Dakota State University; LARSEN, STEVEN - National Pork Board; Smith, David

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/15/2013
Publication Date: 9/9/2013
Citation: Shelver, W.L., Lupton, S.J., Newman, D.J., Larsen, S., Smith, D.J. 2013. Evaluation of penicillin G residues by kidney inhibition swab tests in sow body fluids and tissues following intramuscular injection [abstract]. SafePork 2013 Proceedings Book. 2013. pp. 35-38.

Interpretive Summary: In 2011, the USDA-Food Safety and Inspection Service (FSIS) changed the method used for screening swine tissues for antimicrobial residues to the Kidney Inhibition Swab (KIS(TM)) from the Fast Antimicrobial Screen Test. A high dose of penicillin G procaine relative to a label dose is commonly used to treat bacterial infections in heavy sows. Such off-label use is legal in the United States under the Animal Medicinal Drug Use Clarification Act when label routes or doses are ineffective at treating disease. Here, we describe the use of KIS(TM) for the detection of penicillin G procaine residues from kidney, liver, plasma, urine, and skeletal muscle of heavy sows following extra-label, high dose penicillin-G procaine administration. Heavy sows (n=126; 228 +/- 30.1 kg) were administered intramuscular (IM) doses of penicillin-G procaine (33,000 U/kg bw; 5x the label dose) for 3 consecutive days using 3 different administration patterns. Within treatment, six sows each were slaughtered after 5-, 10-, 15-, 20-, 25-, 32-, or 39-day withdrawal periods. The intramuscular administration pattern had no discernible effect on penicillin G procaine depletion from kidney, skeletal muscle, serum, urine or liver. Residues were depleted most rapidly from liver and skeletal muscle and more slowly from kidney and urine. While kidney residues were a poor predictor of penicillin G residues in skeletal muscle, it was the most sensitive target tissue for detecting penicillin G residues in carcasses, with two positive results even after a 39-day withdrawal period. The most suitable ante-mortem matrix to replace FSIS on-site tests using kidney was urine. Serum, another ante-mortem matrix predicted muscle residue well albeit showing more positives than muscle. These data support a 15-day withdrawal period suggested by Food Animal Residue Avoidance Databank for extra-label penicillin G treated heavy sows with the caveat that kidney tissues be excluded from human consumption.

Technical Abstract: In 2011, the USDA-Food Safety and Inspection Service (FSIS) changed the method used for screening swine tissues for antimicrobial residues from the Fast Antimicrobial Screen Test to the Kidney Inhibition Swab (KIS(TM)). Here, we describe the use of KIS(TM) test for the detection of penicillin G residues in kidney, liver, plasma, urine, and skeletal muscle of heavy sows following the administration of a 5x label dose of penicillin G procaine. Such off-label use is legal in the United States under the Animal Medicinal Drug Use Clarification Act (AMDUCA) when label routes or doses are ineffective at treating disease and is commonly used to treat bacterial infections in heavy sows. Heavy sows (n = 126; 228 +/- 30.1 kg) were administered intramuscular (IM) doses of penicillin G (33,000 U/kg bw) for 3 consecutive days using 3 different administration patterns. Within treatment, six sows each were slaughtered after 5, 10, 15, 20, 25, 32, or 39 withdrawal days. The IM administration pattern had no discernible effect on penicillin G depletion from kidney, skeletal muscle, serum, urine or liver. Residues were depleted most rapidly from liver and skeletal muscle and more slowly from kidney and urine. While kidney residues were a poor predictor of penicillin G residues in skeletal muscle, kidney was the most sensitive target tissue for detecting penicillin G residues, with two positive results even after a 39-day withdrawal period. The most suitable ante-mortem matrix to replace FSIS on-site tests using kidney was urine. Serum, another ante-mortem matrix predicted muscle residue well albeit showing more positives than muscle. These data support a 15-day withdrawal period suggested by Food Animal Residue Avoidance Databank for extra-label penicillin G treated heavy sows with the caveat that kidney tissues be excluded from human consumption.