Microbial System for Identification of Antibiotic Residues in Milk

[EN] The aim of this study was to evaluate the ResScreen (R) microbiological system for the identification of antibiotic residues in milk. This microbiological system consists of two methods, the BT (betalactams and tetracyclines) and BS (betalactams and sulfamides) bioassays, containing spores of G. stearothermophilus subsp. calidolactis, culture media and indicators (acid-base and redox). The detection limits of 29 antimicrobial agents were calculated using a logistic regression model. Both methods detect residues of penicillin-G, ampicillin, amoxicillin, cloxacillin, oxacillin, cephalexin, cefoperazone and ceftiofur (R) at levels close to their Maximum Residue Limits (MRL). The BT bioassay also presents good sensitivity to tetracycline and oxytetracycline residues, whereas the BS bioassay detects sulfadiazine, sulfamethoxazole and sulfathiazole residues in milk. The simultaneous use of both bioassays identifies betalactam, tetracycline and sulfamide residues in milk. Neomycin, tylosin and lincomycin residues can also be detected, but these molecules arc positive with the BT and BS bioassays, e.g., betalactams, given the microorganisms' sensitivity to these molecules.This research work has been carried out as part of the CAI+D'09/11 Project (No. 033-173 Res.C.D. No. 100/09) and supported by financial assistance from the Universidad Nacional del Litoral (Santa Fe, Republica Argentina).Nagel, OG.; Molina Pons, MP.; Althaus, RL. (2011). Microbial System for Identification of Antibiotic Residues in Milk. Journal of Food and Drug Analysis. 19(3):369-375. http://hdl.handle.net/10251/8098136937519