Use of Kidney Inhibition Swab Test to Evaluate Antimicrobial Residues in Pork Kidney from a Market Survey in Fargo, North Dakota

Introduction: The USDA-Food Safety and Inspection Service (FSIS) recently changed the on-site antimicrobial screening method to the Kidney Inhibition Swab (KIS™) test to be used at all livestock slaughter establishments.  Although the newly adapted screening method can detect different classes of antibiotics, the test is most sensitive towards penicillin.  Penicillin is one of the most commonly found tissue residue violations in annual USDA-FSIS surveys of pork.   Previously, our study indicated that sows treated with label dose of penicillin G and slaughtered at the proper labeled-indicated withdrawal day tested positive when kidney was monitored with the KIS™ test. 

Purpose: The purpose of this study was to determine the extent of antimicrobial residues detected by the KIS^TM test in pork kidney obtained from local markets.    

Methods: Pork kidneys were purchased from four grocery stores including two ethnic specialty stores every 2-4 weeks to ensure that the kidneys obtained were from different lots. Although kidneys were obtained from local grocery stores, the pork samples were from suppliers located throughout the mid-western region of North America. The KIS™ test were performed and color changes of the tests were recorded after prescribed incubation time at 64 ± 2 °C.  A purple/blue color indicated antibiotics were present in the samples while yellow/green color indicated no/low antibiotics present in the samples.  A “caution” indicates a sample contains antibiotics below the “positive” threshold. 

Results: Two samples returned “caution” from our market survey.  One “positive” sample was identified, but was not confirmed with the follow up tests. 

Significance: Our findings indicate that pork kidney in the market for human consumption contained low/no antibiotics using the newly adapted USDA-FSIS antimicrobial screening test.