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Table 8 Comparisons of identification of D. nodosus by the aprB2 rtPCR and culture/gelatinase gel test from subsets of presence/absence or both of foot lesions from the clinically affected flocks, consisting of 135 clinically affected sheep and 35 clinically healthy sheep

From: Assessment of a rtPCR for the detection of virulent and benign Dichelobacter nodosus, the causative agent of ovine footrot, in Australia

Flocks

Sheep clinical status (foot lesions)

No. sheep tested

aprB2 PCR Run and/or Cut-off

Culture Gelatinase Thermolabile (Benign) vs aprB2 PCR

Percentage positive results

Concordant results

Culture +ve

PCR + ve

p value

Kappa

Culture

aprB2 PCR

+ve

-ve

PCR -ve

Culture -ve

12 to 24

+ve

135

Run 1 / 40

7

108

2

18

0.0008

0.348

6.7%

18.5%

12 to 24

+ve

135

Run 1 / 35

7

110

2

16

0.0022

0.378

6.7%

17.0%

12 to 14

-ve

35

Run 1 / 40

0

33

0

2

0.4795

0

0.0%

5.7%

12 to 14

-ve

35

Run 2 / 40

0

34

0

1

1

0

0.0%

2.9%

12 to 14

-ve

35

Run 1 / 35

0

34

0

1

1

0

0.0%

2.9%

12 to 14

-ve

35

Run 2 / 35

0

34

0

1

1

0

0.0%

2.9%

12 to 14

-ve & + ve

72

Run 1 / 40

1

60

1

10

0.0159

0.112

2.8%

15.3%

12 to 14

-ve & + ve

72

Run 2 / 40

1

62

1

8

0.0455

0.143

2.8%

12.5%

12 to 14

-ve & + ve

72

Run 1 / 35

1

63

1

7

0.0771

0.163

2.8%

11.1%

12 to 14

-ve & + ve

72

Run 2 / 35

1

63

1

7

0.0771

0.163

2.8%

11.1%

12 to 24

-ve & + ve

170

Run 1 / 40

7

141

2

20

0.0003

0.336

5.3%

15.9%

12 to 24

-ve & + ve

170

Run 1 / 35

7

141

2

17

0.0013

0.376

5.3%

14.1%

  1. The p-value for McNemar’s test for independence between culture gelatinase thermostable (benign) and aprB2 PCR result is shown. Detection rates of both culture and rtPCR are presented as percentage positive results