Sensitivity and specificity of the BAX((R)) for Screening/Listeria monocytogenes assay: Internal validation and independent laboratory study

In this study to certify the BAX((R)) for Screening/Listeria monocytogenes assay (DuPont Qualicon, Wilmington, DE), an internal evaluation was conduct ed on 16 food types that were simultaneously analyzed with the BAX system ( BAX), and the ISO method for the detection of L. monocytogenes (ISO). No st atistically significant difference in performance between the BAX and ISO m ethods was observed. Inclusivity/exclusivity testing showed that the BAX sy stem was able to detect 97 of 97 (100 %) of L. monocytogenes strains tested . None of 56 other Listeria species or non-Listeria tested gave a reproduci ble positive BAX result. Ruggedness testing demonstrated that performance o f the assay was not affected by reasonable variability in the operating par ameters. BAX was then submitted for independent laboratory validation. In t his phase, BAX was compared with standard culture methods for the detection of L. monocytogenes in chicken (USDA-FSIS), crab meat (BAM), and milk (AOA C). This study validated product claims of sensitivity and specificity > 98 % in accordance with AOAC Performance Tested Method(SM) requirements.