AOAC-RI ERP Book Micro Jan 19 2017

Table 9. POD CP , POD CC , and dPOD CP Values for the Candidate Method (25 g Sprouts Analyzed via the 3M TM MDA) and POD R , POD C , and dPOD C Values for Candidate Method vs. the Reference Method (25 g Sprouts Analyzed via the FDA BAM Ch. 4A)

Method / Inoculation Level

Measure Value

95% CI

POD CP POD CC dPOD CP POD CP POD CC dPOD CP POD CP POD CC dPOD CP

0.800 (0.3755, 1.000) 0.800 (0.3755, 1.000) 0.000 (-0.469, 0.469) 0.500 (0.2993, 0.7007) 0.500 (0.2993, 0.7007) 0.000 (-0.284, 0.284) 0.000 (0.000, 0.4345) 0.000 (0.000, 0.4345) 0.000 (-0.434, 0.434) 1.000 (0.5655, 1.000) 0.800 (0.3755, 1.000) -0.200 (-0.624, 0.278) 0.350 (0.1812, 0.5672) 0.500 (0.2993, 0.7007) 0.150 (-0.146, 0.412) 0.000 (0.000, 0.4345) 0.000 (0.000, 0.4345) 0.000 (-0.434, 0.434)

Candidate Method Screening vs. Confirmation High Level Inoculation

Candidate Method Screening vs. Confirmation Low Level Inoculation

Candidate Method Screening vs. Confirmation Un-inoculated

POD R POD C

Reference Method vs. Candidate Method High Level Inoculation

dPOD C

POD R POD C

Reference Method vs. Candidate Method Low Level Inoculation

dPOD C

POD R POD C

Reference Method vs. Candidate Method Un-inoculated

dPOD C

POD CP , Probability of Detection for Candidate Method “Screening Stage” Positive Results; POD CC

, Probability of , Probability of

Detection for Candidate Method “Confirmation Stage” Results; dPOD CP Detection for Reference Method Confirmed Results; POD C

, POD CP

Minus POD CC

; POD R

, Probability of Detection for Candidate Method

Confirmed Results (i.e. Combined “Screening Stage” and “Confirmation Stage” Results); dPOD C , POD R Minus POD C . 95% Confidence Interval Values are Generated from the AOAC International POD Calculator.

4.0 DISCUSSION The purpose of this study was to validate the 3M™ Molecular Detection Assay (MDA) for detection of Escherichia coli O157:H7 in sprouts and spinach. This study followed the format for the validation of a candidate method using the experimental setup and Probability of Detection (POD) statistical analysis provided in the February 24, 2012 version of the AOAC International Methods Committee Guidelines for Validation of Microbiological Methods for Food and Environmental Surfaces document (1). Portions of spinach (200 g sample size) and sprouts (25

CONFIDENTIAL INFORMATION Page 14 of 17