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Dupont BAX Salmonella Pre- Collaborative Study For Expert Review Panel Use Only Do Not Distribute

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Table 8. BAX® System Presumptive vs. Confirmed Results – Produce

95% CI f

dPOD CP e

BAX® Presumptive

BAX® Confirmed

Test Portions

MPN a

Sample Type

Media

X b POD CP c

95% CI f

X b POD CC d

95% CI f

Control

5

0 7 4 0 8 5 0 3 0 7

0

(0, 0.43)

0

0

(0, 0.43)

0 0 0 0 0 0 0 0 0 0

(-0.45, 0.45) (-0.14, 0.14) (-0.45, 0.45) (-0.45, 0.45) (-0.14, 0.14) (-0.45, 0.45) (-0.45, 0.45) (-0.14, 0.14) (-0.45, 0.45)

Peas (25 g)

LB

0.43 (0.23, 0.72)

20

0.35 0.80

(0.18, 0.57) 7

0.35 0.80

(0.18, 0.57) (0.38, 1.0)

1.8 (1.0, 3.0)

5 5

(0.38, 1.0)

4 0

Control

0

(0, 0.43)

0

(0, 0.43)

Peas (25 g)

MP media

0.43 (0.23, 0.72)

20

0.40

(0.22, 0.61) 8

0.40

(0.22, 0.61) (0.57, 1.0)

1.8 (1.0, 3.0)

5 5

1.0

(0.57, 1.0)

5 0

1.0

Control

0

(0, 0.43)

0

(0, 0.43)

Orange juice (25 mL)

UPB / BHI

0.17 (0.051, 0.34)

20

0.15

(0.05, 0.36) 3

0.15

(0.05, 0.36)

Control

5

0

(0-0.43)

0

0

(0, 0.43)

Orange juice (25 mL) MP media / BHI

0.17 (0.051, 0.34) (-0.14, 0.14) a MPN = Most Probable Number based on the POD of reference method test portions using the AOAC MPN calculator (with 95% confidence interval) 20 0.35 (0.18, 0.57) 7 0.35 (0.18, 0.57)

2 3 4 5 6 7 8 9

b X = Number of positive test portions

c POD CP = Candidate method presumptive positive outcomes divided by the total number of trials d POD CC = Candidate method confirmed positive outcomes divided by the total number of trials

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

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