ERP Micro December 2019

Table I: Method Comparison Results (1)

Reference Method

Test kit

Test Kit Performance

MPN /25g a

No. test portions for each method

Inoculating organism

Presumptive Positive c

Confirmed Positive d

Relative Sensitivity f

False negative g

False positive h

Lab

Matrix

Test Portion

Positive b

χ 2e

Individual

3.75 0.75

20 20

17 17

15 15

15 15

0.61 0.61

88%

0 0

0 0

Listeria monocytogenes ATCC 13932

Turkey Deli Meat

Pooled Control

- -

0

5

0

0

0

-

-

-

Individual

1.85 0.37

20 20

15 15

16 16

16 16

0.14 0.14

107%

0 0

0 0

Soft Cheese Listeria welshimeri ATCC 35897

Pooled Control

- -

0

5

0

0

0

-

-

-

Individual

NA NA NA NA NA NA NA NA NA NA NA NA

20 20

11 11

10

10 10

0.10 0.88

91%

0

0 0

Stainless Steel

Listeria ivanovii ATCC 19119

Pooled Control

8 0 3 3 0

- -

20%

5

0 5 5 0

0 3 3 0

-

-

-

Sponsor

Individual

20 20

0.61 0.61

60%

0 0

0 0

Listeria seeligeri ATCC 35967

Ceramic

Pooled Control

- -

5

-

-

-

Individual

20 20

14 14

13 13

13 13

0.11 0.11

93%

0 0

0 0

Listeria innocua ATCC 33090

Plastic

Pooled Control

- -

5

0 5 5 0 0 0 0

0 7 7 0

0 7 7 0

-

-

-

Individual

20 20

0.46 0.46

140%

0 0

0 0

Listeria innocua and E. faecium 2 Listeria monocytogenes ATCC 19112

Plastic

Pooled Control

- -

5

-

-

-

Individual

0.38

20 20

15 13

18 19

23.4 18.8

(15/0)

17% 32%

0 0

Turkey Deli Meat

Pooled Control

0.076

- -

0

5

0

0

-

-

-

Independent

NA NA

Individual

20 20

15 15

13 12

13 12

0.46 1.71

87%

0

0

Stainless Steel

Listeria ivanovii BAA-139

Pooled Control

- -

8%

13%

0

5

0

0

0

-

-

-

a Most Probable Number : Colony Forming Units in a 25 g sample. Pooled MPN calculated by dividing Individual MPN by five. b Number of Positive samples as determined by the applicable reference culture method c Number of Positives given by the Test Method d Number of confirmed Positives from the Test Method e Mantel-Haenszel Chi Square for comparison to reference samples f Number of Confirmed positives (d) divided by the number of Reference method positives (b) g Number of Test Kit Presumptive negatives that were confirmed positive divided by the total number of confirmed positives h Number of Test Kit Presumptive positives that were confirmed negative divided by the total number of confirmed negatives NA=Not applicable