Comparison of lateral flow assay, kidney inhibition swab, and liquid chromatography-tandem mass spectrometry for the detection of penicillin G residues in sow urine

Authors: Shelver, Weilin; CHAKRABARTY, SHUBHASHIS - Orise Fellow; Smith, David

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2017
Publication Date: 2/16/2017
Publication URL: http://handle.nal.usda.gov/10113/5635960
Citation: Shelver, W.L., Chakrabarty, S., Smith, D.J. 2017. Comparison of lateral flow assay, kidney inhibition swab, and liquid chromatography-tandem mass spectrometry for the detection of penicillin G residues in sow urine. Journal of Agricultural and Food Chemistry. 65:1778-1783. doi:10.1021/acs.jafc.6b05049.

Interpretive Summary: Penicillin G is used for treatment of a number of bacterial infections in a variety of food-animal species. The US Food and Drug Administration, Center for Veterinary Medicine has not established a tolerance for penicillin residues in swine tissues. As a consequence, any detectable penicillin G residue in any edible tissue of swine is considered to be violative. Previous study indicated urine would be a very useful indicator for on-farm or pre-slaughter on-site Kidney Inhibition Swab (KISTM) test (~ 4 hours assay time) with which veterinarians or pork producers could predict the presence of kidney penicillin G residues. The purpose of this study was to determine the accuracy of simple, rapid, and inexpensive penicillin-G lateral flow assays to detect penicillin residues in swine urine collected previously during the conduct of a large (126 sows) residue depletion study. Because the samples were collected in 2012 and we performed the lateral flow assay experiments in 2015, we also conducted studies to verify penicillin stability under our storage conditions and to determine the repeatability of the KISTM assay after prolonged matrix storage. Results of the KISTM test, re-run on samples after 3 years storage in ultra-cold temperature (-80 °C) were in excellent agreement with original analyses. Lateral flow immunoassay results were highly correlated with both the KISTM test and the instrumental LC-MS/MS results and could be obtained in under 5 minutes. Data obtained from this study suggest that lateral-flow assays could be used to quickly and efficiently to screen penicillin-treated sows for the presence of tissue residues prior to slaughter.

Technical Abstract: Sows (n=126) were administered penicillin G procaine at 5x the label dose for 3 consecutive days. Eighteen sows were slaughtered on each withdrawal days, 5, 10, 15, 20, 25, 32, or 39 d after treatment. Urine samples were collected at slaughter and were frozen at -80 °C until screening as positive or negative for penicillin G residues using a kidney inhibition swab (KIS™) test, with an approximate 4 h testing time and by a lateral flow immunoassay with a 5 min testing time. Screening results were confirmed or refuted using LC-MS/MS analysis. Because urine samples were stored frozen for approximately 1200 days, the stability of penicillin in urine was verified by comparing to previous LC-MS/MS analyses. Quantitative results were well correlated (R2 =0.98) indicating only a minimal (~10%) decrease in penicillin concentration after approximately 3 years of storage. Results of the KISTM test, re-run on samples after 3 years storage (-80 °C) were in excellent agreement with original analyses. Lateral flow immunoassay results were highly correlated with both the KISTM test and the LC-MS/MS results and could be obtained in under 5 minutes. Data obtained from this study suggest that lateral-flow assays could be used to quickly and efficiently screen penicillin-treated sows for the presence of tissue residues prior to slaughter.