title: Effect In Vitro of Antiparasitic Drugs on Microbial Inhibitor Test Responses for Screening Antibiotic Residues in Goat's Milk.
abstract: Microbial inhibitor tests are widely used to screen antibiotic residues in milk; however, these tests are nonspecific and may be affected by various substances capable of inhibiting the growth of the test microorganism. The objective of this study was to determine the effect of antiparasitic drugs in goat's milk on the microbial inhibitor test response. Raw antibiotic-free milk from Murciano-Granadina goats was supplemented with eight concentrations of seven antiparasitic substances (albendazole, 10 to 170 mg/kg; closantel, 1 to 140 mg/kg; diclazuril, 8 to 45 mg/kg; febendazole, 10 to 140 mg/kg; levamisole, 40 to 440 mg/kg; diazinon, 8 to 45 mg/kg; and ivermectin, 40 to 200 mg/kg). Twelve replicates for each concentration were analyzed with three microbial inhibitor tests: BRT MRL, Delvotest SP-NT MSC, and Eclipse 100. The results were interpreted visually (negative or positive). Using a logistic regression model, the concentrations of the antiparasitic drugs producing 5% (IC5), 10% (IC10), and 50% (IC50) positive results were determined. In general, the Eclipse 100 test was less sensitive to the effect of antiparasitic substances; the inhibitory concentrations of almost all the drugs assayed were higher than those for other tests. Conversely, the BRT MRL test was most affected, with high levels of interference at lower antiparasitic drug concentrations. Closantel and diazinon interfered with all microbial tests at lower concentrations than did other drugs (IC5 = 1 to 26 and 12 to 20 mg/kg, respectively), and higher concentrations of levamisole and diclazuril (IC5 = 30 to 240 and 50 to 117 mg/kg, respectively) were required to produce 5% positive results. These findings indicate that microbial inhibitor tests can be affected by elevated concentrations of antiparasitic drugs in goat's milk.
authors: Instituto de Ciencia y Tecnología Animal, Universitat Politècnica de València, Camino de Vera S/N, 46022 Valencia, Spain.
authors: T
authors: T
authors: Romero
authors: Instituto de Ciencia y Tecnología Animal, Universitat Politècnica de València, Camino de Vera S/N, 46022 Valencia, Spain.
authors: M C
authors: MC
authors: Beltrán
authors: Institute for Agricultural and Fisheries Research, Technology and Food Science Unit, Brusselsesteenweg 370, 9090 Melle, Belgium.
authors: W
authors: W
authors: Reybroeck
authors: Instituto de Ciencia y Tecnología Animal, Universitat Politècnica de València, Camino de Vera S/N, 46022 Valencia, Spain. pmolina@dca.upv.es.
authors: M P
authors: MP
authors: Molina
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis*; D000977:Antiparasitic Agents / Q000737:chemistry*; D004350:Drug Residues / Q000032:analysis*; D005506:Food Contamination / Q000032:analysis*; D006041:Goats; D020128:Inhibitory Concentration 50; D016015:Logistic Models; D008826:Microbial Sensitivity Tests; D008892:Milk / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D000977:Antiparasitic Agents