Evaluation of VIDASReg. Listeria species Xpress (LSX) immunoassay method for the detection of Listeria species in foods: collaborative study.

摘要

In a multilaboratory study, the effectiveness of an alternative method for rapid screening of Listeria species compared to traditional reference methods was demonstrated in a variety of food products. A collaborative study was conducted to compare the VIDASReg. Listeria species Xpress (LSX) method and standard cultural methods for the detection of Listeria species in foods. 6 food types were tested: vanilla ice cream, cheddar cheese, raw ground beef, frozen green beans, deli turkey and cooked shrimps. Each food, inoculated with a different Listeria strain at 2 levels and uninoculated test portions, was analysed by each method. A total of 15 laboratories representing government and industry participated. 1134 tests were subjected to statistical analysis. There were 490 positives by the VIDAS LSX method using the sample boiling step, 483 positives by the VIDAS LSX method using the Heat and Go system and 439 positives by standard culture methods. Overall, the Chi-square result for the VIDAS LSX method with boiling for all foods was 7.25, indicating a significant statistical difference between the VIDAS method and the standard methods (P < 0.05). For the VIDAS LSX method with the Heat and Go system, the Chi-square result for all foods was 5.37, indicating a significant statistical difference between the VIDAS LSX assay with the Heat and Go system and the standard methods at the 5% level of significance. In both cases, the VIDAS method was more sensitive than the standard methods. The LSX method detected Listeria species in foods with negative or presumptive positive results in a minimum of 30 h compared to at least 5 days for the cultural methods. Based on the results of this collaborative study, it is recommended that the VIDAS LSX method be adopted as an AOAC Official MethodSM for the detection of Listeria species in dairy products, vegetables, seafood, raw meats and poultry and processed meats and poultry.