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Table 5 Univariable models of associations between antimicrobials, number of treatments, age, time and antimicrobial resistance LCA classes for 546 commensal E. coli isolated from fecal samples obtained from 140 calves

From: Antimicrobial use policy change in pre-weaned dairy calves and its impact on antimicrobial resistance in commensal Escherichia coli: a cross sectional and ecological study

Risk factors

Cross tabulations

Resistance classes (odds ratio & 95% CI)

TET

XNL+

NAL+

CIP + NAL + XNL+

XNL+

NAL+

CIP + NAL + XNL+

Enrofloxacin

 Untreated

123

95

71

69

   

 Treated

51

19

52

64

0.5 (0.3–0.9)

1.8 (1.1–2.9)

2.2 (1.4–3.6)

Sulfonamide

 Untreated

28

34

4

7

   

 Treated

146

80

119

126

0.5 (0.3–0.8)

5.7 (1.9–16.7)

3.5 (1.5–8.2)

β-lactams

 Untreated

71

56

24

40

   

 Treated

103

58

99

93

0.7 (0.4–1.4)

2.8 (1.7–4.9)

1.6 (1.0–2.6)

No. of treatments

 ×1

56

35

15

35

   

 0

23

31

4

7

2.2 (1.1–4.3)

0.6 (0.2–2.2)

0.5 (0.2–1.3)

 ×2

58

20

41

34

0.6 (0.3–1.1)

2.6 (1.3–5.3)

0.9 (0.5–1.7)

 ×3

24

19

47

36

1.3 (0.6–2.6)

7.3 (3.4–15.5)

2.4 (1.2–4.7)

 ×4–6

13

9

16

21

1.1 (0.4–2.9)

4.6 (1.8–11.6)

2.6 (1.1–5.8)

Age (5 categories)

 57 - 80d

63

14

17

14

   

 43 - 56d

44

16

36

10

1.6 (0.7–3.7)

3.0 (1.5–6.1)

1.0 (0.1–0.4)

 29 - 42d

28

11

52

20

1.8 (0.7–4.4)

6.9 (3.4–13.9)

3.2 (1.4–7.3)

 15 - 28d

15

21

14

57

6.3 (2.6–15.2)

3.5 (1.4–8.5)

17.1 (7.6–38.5)

 1 - 14d

24

52

4

32

9.7 (4.6–20.7)

0.6 (0.2–2.0)

6.0 (2.7–13.1)

Age (2 categories)

 29 - 80d

135

41

105

44

   

 1 - 28d

39

73

18

89

6.2 (3.7–10.4)

0.6 (0.3–1.1)

7.0 (4.2–11.6)

Sampling period

 Nov 15 – Jan

97

54

30

64

   

 Sep – Nov 15

55

34

67

42

1.1 (0.6–1.9)

3.9 (2.3–6.8)

1.2 (0.7–1.9)

 May – Aug

22

26

26

27

2.1 (1.1–4.1)

3.8 (1.9–7.7)

1.9 (1.0–3.5)

  1. OR and 95% confidence intervals that exclude the null value of 1 are highlighted in bold