AOAC-RI ERP Book Micro Jan 19 2017

“confirmation stage” results were both positive for a particular sample (POD C ). The difference in POD for the two values at each level of inoculation were calculated (dPOD C ) along with its corresponding 95% confidence interval. As noted above, if the 95% confidence interval of a dPOD C value does not contain zero, then the difference between the POD C of the candidate method and the POD R of the reference method at that level of inoculation is statistically significant at the 5% level. 3.0 RESULTS The objective of this study was to validate the 3M™ Molecular Detection Assay (MDA) for the detection of E. coli O157:H7 in three different food matrices. The inoculum concentration of E. coli O157:H7 in each food matrix was determined from Most Probable Number analysis, along with the 95% confidence intervals, as shown in Table 1. All data obtained for the candidate met hod testing of spinach, ‘screening stage’ and ‘confirmation stage’ (200 g spinach analyzed by the 3M TM MDA) is provided in Table 2. All data obtained for the reference method testing of spinach (200 g spinach analyzed by the FDA Bam Ch. 4A) is provided in Table 3. The number of true positives (samples with a positive ‘screening stage’ and a positive ‘confirmation stage’), true negatives (samples with a negative ‘screening stage’ and a negative ‘confirmation stage’), false positive (samples with a positive ‘screening stage’ but a negative ‘confirmation stage’) and false negatives (samples with a negative ‘screening stage’ but a positive ‘confirmation stage’ ) for the candidate method testing of spinach is provided in Table 4. As described in Section 2.7, the results presented here were statistically analyzed according to the POD methods of the 2012 version of the AOAC International Methods Committee Guidelines for Validation of Microbiological Methods for Food and Environmental Surfaces document (1). The POD CP , POD CC , dPOD CP , POD C , POD R , and dPOD C values calculated at each level of inoculation for the candidate method and the reference method testing of spinach, and their corresponding 95% confidence intervals, are provided below in Table 5. All data ob tained for the candidate method testing of sprouts, ‘screening stage’ and ‘confirmation stage’ (25 g sprouts analyzed by the 3M TM MDA) is provided in Table 6. All data obtained for the reference method testing of sprouts (25 g sprouts analyzed by the FDA Bam Ch. 4A) is provided in Table 7. The number of true positives (samples with a positive ‘screening stage’ and a positive ‘confirmation stage’), true negatives (samples with a negative ‘screening stage’ and a negative ‘confirmation stage’), false positive (samples with a positive ‘screening stage’ but a negative ‘confirmation stage’) and false negatives (samples with a negative ‘screening stage’ but a positive ‘confirmation stage’ ) for the candidate method testing of sprouts is provided in Table 8. As described in Section 2.7, the results

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