ABSTRACT
TRANSIA® PLATE Salmonella Gold is an ELISA that was validated by Association Française de Normalisation (AFNOR) in 2001 and as a Performance Tested MethodSM (PTM) by AOAC in 2006 (PTM No. 010602) as a two-step enrichment protocol requiring 48 h. A simple next-day enrichment protocol using modified Enterohemorrhagic Escherichia coli media was developed for the TRANSIA PLATE Salmonella Gold to improve the time-to-results and laboratory work flow. We tested 128 Salmonella strains, representing all serotypes from A though Z and 51-66. TRANSIA PLATE Salmonella Gold detected all 128 of these strains. None of the 50 non-Salmonella strains were detected by TRANSIA PLATE Salmonella Gold. Performance of TRANSIA PLATE Salmonella Gold using the new enrichment protocol was compared with U.S. Department of Agriculture Microbiology Laboratory Guidebook reference culture procedure for the detection of Salmonella in ready-to-eat poultry, ready-to-eat beef, and chicken carcass rinsate. In addition, TRANSIA PLATE Salmonella Gold performance was compared with U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) for the detection of Salmonella from raw spinach, raw almonds, raw pasta, and environmental surfaces (stainless steel, rubber, and plastic). There was no statistically significant difference in the numbers of positive results TRANSIA PLATE Salmonella Gold protocol compared with the appropriate U.S. Department of Agriculture Food Safety and Inspection Service or FDA-BAM reference methods for any of these matrixes. Robustness testing demonstrated that the introduction of small changes in the normal assay parameters had no impact on the method performance. This new enrichment protocol has been approved as a Third Level modification to Performance Tested Method 010602.
Subject(s)
Cell Culture Techniques/methods , Culture Media , Equipment Contamination , Food Microbiology/methods , Salmonella/isolation & purification , Animals , Antibodies/immunology , Cattle , Cell Culture Techniques/instrumentation , Chickens , Edible Grain/microbiology , Enzyme-Linked Immunosorbent Assay/methods , Plastics , Poultry/microbiology , Prunus dulcis/microbiology , Red Meat/microbiology , Rubber , Salmonella/immunology , Spinacia oleracea/microbiology , Stainless SteelABSTRACT
A total of 22 individuals participated in this benchmark study to characterize the thermodynamics of small-molecule inhibitor-enzyme interactions using Biacore instruments. Participants were provided with reagents (the enzyme carbonic anhydrase II, which was immobilized onto the sensor surface, and four sulfonamide-based inhibitors) and were instructed to collect response data from 6 to 36 degrees C. van't Hoff enthalpies and entropies were calculated from the temperature dependence of the binding constants. The equilibrium dissociation and thermodynamic constants determined from the Biacore analysis matched the values determined using isothermal titration calorimetry. These results demonstrate that immobilization of the enzyme onto the sensor surface did not alter the thermodynamics of these interactions. This benchmark study also provides insights into the opportunities and challenges in carrying out thermodynamic studies using optical biosensors.
