AOAC-RI ERP Book MICRO Sept 2016.pdf

Document 2 of 2 – 3M Petrifilm Salmonella Express PTM Study Report

Table 26. 3M Petrifilm SALX Method Comparison POD Results for Dry Dog Food and Stainless Steel (Internal Data) 1

3M Petrifilm SALX Method

Reference Method

MPN a / 325g or CFU 100cm 2

X c

N b

95% CI g

d

e

95% CI

x

95% CI

dPOD C f

Strain

Matrix Time Point

POD C

POD R

Dry Dog Food

-0.43 – 0.43 -0.17 – 0.35 -0.43 – 0.43 -0.17 – 0.35 -0.43 – 0.43 -0.32 – 0.23 -0.43 – 0.43 -0.32 – 0.23

0

5

0

0

0.00 - 0.43

0

0

0.00 - 0.43

0

Salmonella

18 Hr Primary Enrichment 24 Hr Primary Enrichment 18 Hr Primary Enrichment

Vs. FDA/BAM

0.03 (0.01- 0.68)

20

16

0.8 0.58 - 0.92

14

0.7 0.48 - 0.85 0.1

Poona

0

5

0

0

0.00 - 0.43

0

0

0.00 - 0.43

0

ATCC

0.03 (0.01- 0.68)

20

16

0.8 0.58 - 0.92

14

0.7 0.48 - 0.85 0.1

4840

Stainless Steel

0

5

0

0

0.00 - 0.43

0

0

0.00 - 0.43

0

Salmonella

Vs. FDA/BAM

51

20

6

0.3 0.15 – 0.52

7

0.35 0.18 – 0.57 -0.05

Kahla

0

5

0

0

0.00 - 0.43

0

0

0.00 - 0.43

0

ATCC

17980 24 Hr Primary Enrichment a MPN = Most Probable Number is based on the POD of reference method test portions across labs using the AOAC MPN calculator with 95% confidence interval b N = Number of test potions c x = Number of positive test portions d POD C = Candidate method confirmed positive outcomes divided by the total number of trials e POD R = Reference method confirmed positive outcomes divided by the total number of trials 51 20 6 0.3 0.15 – 0.52 7 0.35 0.18 – 0.57 -0.05

f dPOD C = Difference between the candidate method confirmed results and candidate method confirmed result POD values g 95% CI = If the confidence interval of a dPOD does not contain zero, then the difference is statistically significant at the 5% level

2 3 4 5 6 7 8 9 10