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Table 4 Detailed results from the external validation study.

From: Validation of a same-day real-time PCR method for screening of meat and carcass swabs for Salmonella

Salmonella serotype

Inoculation level (cfu/25 g)

Real-time PCRa

Salmonella BAX

Detection System

  

Ct-value for Salmonella

Ct-value for IAC

Final result

Final result

Infantis

1000

20.05

27.89

Positive

Positive

 

100

21.66

29.09

Positive

Positive

 

10

27.14

28.68

Positive

Positive

 

10

30.59

28.95

Positive

Positive

 

10

24.92

28.89

Positive

Positive

 

5

29.42

29.09

Positive

Positive

 

5

26.57

28.81

Positive

Positive

 

5

26.29

27.66

Positive

Positive

 

5

26.63

28.79

Positive

Positive

 

2

27.70

28.42

Positive

Positive

 

2

25.68

28.08

Positive

Positive

 

2

27.86

28.56

Positive

Positive

 

2

27.20

28.90

Positive

Positive

Agona

1000

22.47

28.97

Positive

Positive

 

100

24.70

27.93

Positive

Positive

 

10

> 36

29.21

Negative

Negative

 

10

> 36

29.07

Negative

Negative

 

10

26.04

28.93

Positive

Positive

 

5

28.47

28.76

Positive

Positive

 

5

32.93

28.53

Positive

Negative

 

5

29.84

28.92

Positive

Positive

 

5

32.17

27.90

Positive

Positive

 

2

> 36

28.76

Negative

Positive

 

2

> 36

29.07

Negative

Negative

 

2

33.22

28.77

Positive

Positive

 

2

30.61

27.96

Positive

Positive

Infantis

1000

19.59

29.01

Positive

Positive

 

100

23.74

28.86

Positive

Positive

 

10

25.55

28.45

Positive

Positive

 

10

24.85

28.40

Positive

Positive

 

10

26.82

28.36

Positive

Positive

 

5

29.82

29.10

Positive

Positive

 

5

29.03

28.16

Positive

Positive

 

5

24.77

28.28

Positive

Positive

 

5

> 36

> 40

Inconclusive

Positive

 

2

28.61

27.88

Positive

Positive

 

2

26.24

28.79

Positive

Positive

 

2

26.02

28.82

Positive

Positive

 

2

> 36

28.63

Negative

Negative

  1. Results from 39 pork meat samples inoculated with salmonella at different levels and analyzed in parallel on-site using the real-time PCR and the Salmonella BAX methods.
  2. a Samples with a Ct value > 36 is considered negative if the Ct value for the IAC is < 40 and inconclusive if a Ct > 40 is obtained for the IAC. According to the Method Directive for the PCR method, re-analysis of the extracted DNA by PCR is then needed.