RESUMO
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 VIDAS Listeria species Xpress (LSX) method and the standard cultural methods for the detection of Listeria species in foods. Six food types were tested: vanilla ice cream, cheddar cheese, raw ground beef, frozen green beans, deli turkey, and cooked shrimp. Each food, inoculated with a different Listeria strain at two levels and uninoculated test portions, was analyzed by each method. A total of 15 laboratories representing government and industry participated. In this study 1134 tests were analyzed in the 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 the 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 at the 5% confidence. 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 detects 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 Method for the detection of Listeria species in dairy products, vegetables, seafood, raw meats and poultry, and processed meats and poultry.
Assuntos
Ensaio de Imunoadsorção Enzimática/métodos , Microbiologia de Alimentos/métodos , Listeria/isolamento & purificação , Animais , Técnicas Bacteriológicas , Bovinos , Comportamento Cooperativo , Laticínios/microbiologia , Ensaio de Imunoadsorção Enzimática/instrumentação , Microbiologia de Alimentos/instrumentação , Humanos , Listeria/patogenicidade , Carne/microbiologia , Produtos da Carne/microbiologia , Aves Domésticas/microbiologia , Produtos Avícolas/microbiologia , Alimentos Marinhos/microbiologia , Verduras/microbiologiaRESUMO
A multilaboratory study was conducted to determine the limit of detection (LOD) of Staphylococcal enterotoxins (SET) in 5 foods. Cooked chicken, ham, potato salad, pasteurized liquid whole milk, and canned mushrooms were each spiked with a different enterotoxin (A, B, C1, D, or E), and tested at 0.25 and 0.5 ng/g SET levels to determine the LOD of the assay for those foods in a collaborative study. Unspiked controls were also included. A total of 19 laboratories representing government and industry participated. In this study, 1674 test portions were analyzed, of which 1638 were used in the statistical analysis. Of the 1638 test portions used in the statistical analysis, 1104 were spiked test portions, of which 1073 were positive by the VIDAS Staph enterotoxin II (SET 2) method. The detection rates at the 0.25 ng/mL level were cooked chicken, 98.2%; ham, 99.0%; potato salad, 99.1%; liquid whole milk, 85.2%; and canned mushrooms, 100%. The detection rates at the 0.5 ng/mL level were cooked chicken, 97.4%; ham, 98.1%; potato salad, 100%; liquid whole milk, 99.0%; and canned mushrooms, 100%. The data indicate that the SET 2 method is capable of detecting SET at 0.25 ng/g in cooked chicken, ham, potato salad, and canned mushrooms and at 0.5 ng/g in pasteurized liquid whole milk.
Assuntos
Enterotoxinas/análise , Microbiologia de Alimentos , Imunoensaio/métodos , Staphylococcus/isolamento & purificação , Staphylococcus/patogenicidadeRESUMO
A multilaboratory study was conducted to compare the VIDAS LIS immunoassay with the standard cultural methods for the detection of Listeria in foods using an enrichment modification of AOAC Official Method 999.06. The modified enrichment protocol was implemented to harmonize the VIDAS LIS assay with the VIDAS LMO2 assay. Five food types--brie cheese, vanilla ice cream, frozen green beans, frozen raw tilapia fish, and cooked roast beef--at 3 inoculation levels, were analyzed by each method. A total of 15 laboratories representing government and industry participated. In this study, 1206 test portions were tested, of which 1170 were used in the statistical analysis. There were 433 positive by the VIDAS LIS assay and 396 positive by the standard culture methods. A Chi-square analysis of each of the 5 food types, at the 3 inoculation levels tested, was performed. The resulting average Chi square analysis, 0.42, indicated that, overall, there are no statistical differences between the VIDAS LIS assay and the standard methods at the 5% level of significance.
Assuntos
Análise de Alimentos/métodos , Contaminação de Alimentos , Microbiologia de Alimentos , Imunoensaio/métodos , Listeria/metabolismo , Animais , Queijo/microbiologia , Técnicas de Química Analítica/métodos , Fabaceae/microbiologia , Reações Falso-Negativas , Reações Falso-Positivas , Alimentos Congelados/microbiologia , Sorvetes/microbiologia , Carne/microbiologia , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Tilápia/microbiologia , Verduras/microbiologiaRESUMO
The 3M Petrifilm Staph Express Count plate method was compared with AOAC Official Method 975.55 for the enumeration of Staphylococcus aureus in selected foods. Five foods--ice cream, raw milk, yogurt, whey powder, and cheese--were analyzed for S. aureus by 12 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample, a low inoculation level, a medium inoculation level, and a medium inoculation level with background flora, each in duplicate. The mean log10 counts for the methods were comparable for all 5 foods. The repeatability and reproducibility variances of the 24 h Petrifilm Staph Express Count plate method were similar to those of the 72 h standard method.
Assuntos
Contagem de Colônia Microbiana/métodos , Laticínios/microbiologia , Staphylococcus aureus/isolamento & purificação , Animais , Queijo/microbiologia , Contagem de Colônia Microbiana/instrumentação , Sorvetes/microbiologia , Laboratórios , Leite/microbiologia , Proteínas do Leite , Reprodutibilidade dos Testes , Proteínas do Soro do Leite , Iogurte/microbiologiaRESUMO
The 3M Petrifilm Staph Express Count plate method was compared with AOAC Official Method 975.55 for the enumeration of Staphylococcus aureus in selected foods. Five foods--frozen lasagna, custard, frozen mixed vegetables, frozen hashbrowns, and frozen batter-coated mushrooms--were analyzed for S. aureus by 13 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample, a low inoculation level, a medium inoculation level, and a medium inoculation level with background flora, each in duplicate. The mean log10 counts for the methods were comparable for all 5 foods. The repeatability and reproducibility variances of the 24 h Petrifilm Staph Express Count plate method were similar to those of the 72 h standard method.
Assuntos
Contagem de Colônia Microbiana/métodos , Microbiologia de Alimentos , Staphylococcus aureus/isolamento & purificação , Agaricales , Contagem de Colônia Microbiana/instrumentação , Manipulação de Alimentos , Conservação de Alimentos/métodos , Congelamento , Reprodutibilidade dos Testes , Verduras/microbiologiaRESUMO
A multilaboratory study was conducted to compare the VIDAS Listeria monocytogenes II (LMO2) immunoassay and the standard cultural methods for the detection of Listeria monocytogenes in foods. Five food types-vanilla ice cream, brie cheese, cooked roast beef, frozen green beans, and frozen tilapia fish-at 3 levels were analyzed by each method. A total of 26 laboratories representing government and industry participated. In this study, 1404 test portions were analyzed of which 1152 were used in the statistical analysis. There were 448 positive by the VIDAS LMO2 assay and 457 positive by the standard culture methods. A chi2 analysis of each of the 5 food types, at the 3 inoculation levels tested, was performed. The resulting chi2 value, 0.36, indicates that overall, there are no statistical differences between the VIDAS LMO2 assay and the standard methods at the 5% level of significance.