Table 2

Intra- and Inter-assay variabilities of C. coli and C. jejuni real-time PCR assays for the standard curves generated with purified genomic DNA of C. coli CIP 70.81 and C. jejuni NCTC 11168, ranging from 101 to 108 genome copies per PCR reaction (genome copy number) and with DNA extracted from Campylobacter-negative pig faecal samples spiked with different amounts of C. coli and C. jejuni ranging from 2 × 102 to 2 × 107 CFU/g of faeces including the DNA extraction procedure (CFU/g of faeces)

Intra-assay 1

Inter-assay 2


C. coli

C. jejuni

C. coli

C. jejuni


Genome copy number

CVc (%)

Ct range

CVj (%)

Ct range

CVc (%)

Ct range

CVj (%)

Ct range


108

2.27

14.18-15.25

5.63

14.18-17.15

4.89

13.86-16.11

1.94

14.30-15.01

107

1.33

16.63-17.71

0.95

17.55-18.21

4.69

16.33-17.88

0.83

17.86-18.27

106

1.99

20.05-20.78

1.13

21.02-21.81

3.42

19.29-21.80

1.37

21.15-22.04

105

1.60

23.32-24.63

0.57

24.15-24.69

4.08

23.22-25.55

0.67

24.01-24.48

104

0.81

26.92-28.07

0.35

26.56-26.91

1.52

26.23-28.48

2.65

26.64-28.30

103

1.28

30.44-31.28

0.53

30.11-30.69

1.90

29.70-31.37

1.99

28.60-30.85

102

1.22

33-37-34.82

0.40

33.66-34.05

2.46

33.80-35.78

1.39

33.62-34.60

101

0.87

37.29-38.66

2.21

35.65-37.77

3.10

37.10-38.91

2.21

36.11-37.43


CFU/g of faeces

CVc (%)

Ct range

CVj (%)

Ct range

CVc (%)

Ct range

CVj (%)

Ct range


2 × 108

3.23

17.22-18.35

2.28

18-74-19.81

-

-

-

-

2 × 107

1.33

20.60-21.15

2.53

20.57-22.02

0.75

19.54-19.88

1.21

21.65-22.27

2 × 106

1.89

24.08-24.97

0.91

24.13-24.62

2.37

23.51-24.85

0.70

24.15-24.60

2 × 105

1.15

27.23-28.38

1.40

27.02-28.45

0.57

26.40-26.79

1.46

27.04-28.69

2 × 104

2.20

28.28-29.75

1.98

30.13-31.80

2.58

28.00-29.90

2.10

30.7-32.31

2 × 103

4.40

32.20-33.77

1.62

34.61-35.96

2.07

32.00-33.22

1.80

34.48-36.45

2 × 102

4.38

34.61-37.78

1.76

38.04-39.37

1.64

35.35-36.56

1.92

37.34-39.03


The coefficients of variation (CV) of the threshold cycles values (Ct) were evaluated for the C. coli real-time PCR (CVc) and for the C. jejuni real-time PCR (CVj). For each CVc and CVj, the range of Ct (Ct range), which corresponds to the smallest and the highest values of the Ct found among the ten, was indicated for each dilution for both intra-and inter-assay testings.

1 Results of intra-assay testing: ten replicates of each sample were tested in one PCR run

2 Results of inter-assay testing: one replicate of each sample was tested once in each of ten different PCR runs

Leblanc-Maridor et al. BMC Microbiology 2011 11:113   doi:10.1186/1471-2180-11-113

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