Purpose: An independent study was conducted at ADRIA, to validate this new method in comparison to the ISO 16654 standard, as part of the NF VALIDATION approval process and according to the ISO 16140 standard.
Methods: The 3M™ Molecular Detection Assay E. coli O157 (including H7) test protocol includes a single enrichment step in pre-warmed Buffered Peptone Water (ISO) at 41.5°C. After lysis, DNA amplification is performed in the 3M™ Molecular Detection Instrument.
Results: 185 samples were analyzed for relative accuracy, sensitivity and specificity study. The results demonstrate equivalent performances between the 3M Molecular Detection Assay E. coli O157 (including H7) and the ISO 16654 methods. Depending on the tested (matrix/strain) pairs, the relative detection limits of the 3M Molecular Detection Assay E. coli O157 (including H7) method vary from 0.2 to 1.0 CFU/25 g, those of the ISO standard vary from 0.2 to 1.3 CFU/25 g. The selectivity and the specificity of the alternative method were assessed by tested 50 target strains and 31 non target strains. The 3M Molecular Detection Assay E. coli O157 (including H7) method was also evaluated in a ring trial involving 12 laboratories. The results of the calculated accuracy, accordance, concordance and odds ratio clearly show that the 3M Molecular Detection Assay E. coli O157 (including H7) method precision is equivalent to the ISO 16654 standard.
Significance: The alternative method is a reliable method for Escherichia coli O157 (including H7) detection in raw beef meats, raw dairy products, raw fruits and vegetables, and offers important economic savings by reducing time to result and handling time.