Table IV.
Unconditional associations between herd management and antimicrobial use practices and antimicrobial resistance in at least 1 E. coli isolate from a composite fecal sample collected from 20 cows per herd at fall pregnancy testing (n = 96 herds).
| Resistant to at least 1 antimicrobial | Resistant to at least 2 antimicrobials | Resistant to sulfisoxazole and streptomycin | Intermediate or resistant to tetracycline | |||||
|---|---|---|---|---|---|---|---|---|
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| OR (95% CI) | P-value | OR (95% CI) | P-value | OR (95% CI) | P-value | OR (95% CI) | P-value | |
| Sample collection date | 0.11 | 0.35 | 0.44 | 0.11 | ||||
| November: Octobera | 0.22 (0.02 to 1.5) | 0.16 | 0.41 (0.03 to 3.9) | 0.61 | 0.64 (0.04 to 9.5) | 0.99 | 0.22 (0.02 to 1.5) | 0.16 |
| December: October | 0.14 (0.003 to 1.4) | 0.13 | 0.26 (0.005 to 3.6) | 0.49 | 0.41 (0.01 to 8.1) | 0.88 | 0.14 (0.003 to 1.4) | 0.13 |
| January and February: October | 0.81 (0.06 to 6.2) | 0.99 | 1.5 (0.11 to 15) | 0.99 | 2.3 (0.14 to 36) | 0.78 | 0.81 (0.06 to 6.2) | 0.99 |
| Samples collected after weaning | 0.85 (0.17 to 5.5) | 0.99 | 0.59 (0.11 to 4.1) | 0.74 | 0.47 (0.07 to 3.4) | 0.57 | 0.85 (0.17 to 5.5) | 0.99 |
| Producer age (years) | 1.0 (0.96 to 1.1) | 0.60 | 1.0 (0.95 to 1.1) | 0.73 | 1.0 (0.95 to 1.1) | 0.64 | 1.0 (0.96 to 1.1) | 0.66 |
| Produces purebred cattle for sale | 1.5 (0.23 to 7.4) | 0.82 | 0.46 (0.01 to 3.9) | 0.82 | 0.54 (0.01 to 4.9) | 0.99 | 1.5 (0.23 to 7.4) | 0.82 |
| Total cows calved 2014 > 300 | 0.22 (0.005 to 1.7) | 0.23 | 0.29 (0.01 to 2.5) | 0.44 | 0.35 (0.01 to 3.1) | 0.59 | 0.52 (0.05 to 2.9) | 0.68 |
| Number of cows to calf in 2014 | 0.996 (0.989 to 1.000) | 0.17 | 0.997 (0.989 to 1.001) | 0.25 | 0.997 (0.988 to 1.001) | 0.30 | 0.998 (0.992 to 1.001) | 0.30 |
| Calves retained after weaning | 0.04 (0.06 to 3.7) | 0.86 | 0.22 (0.005 to 1.8) | 0.25 | 0.26 (0.01 to 2.3) | 0.37 | 0.69 (0.11 to 3.3) | 0.88 |
| Feedlot operation | 0.65 (0.00 to 4.6) | 0.71 | 0.83 (0.0 to 6.2) | 0.88 | 0.97 (0.0 to 7.3) | 0.98 | 1.1 (0.02 to 9.9) | 0.99 |
| Calving started before March 2014 | 1.6 (0.34 to 7.5) | 0.70 | 1.6 (0.27 to 9.1) | 0.79 | 1.2 (0.16 to 7.3) | 0.99 | 1.0 (0.20 to 4.7) | 0.99 |
| Calf mortality > 5% | 3.8 (0.68 to 19) | 0.14 | 5.8 (0.94 to 36) | 0.06 | 7.8 (1.2 to 61) | 0.03 | 2.2 (0.32 to 12) | 0.49 |
| Antimicrobials provided to cows in feed | 2.9 (0.42 to 15) | 0.32 | 2.1 (0.19 to 14) | 0.66 | 0.97 (0.02 to 9.1) | 0.99 | 4.9 (0.87 to 25) | 0.07 |
| Injectable antimicrobials used on cows | 0.98 (0.13 to 8) | 0.99 | 0.76 (0.10 to 8) | 0.99 | 0.65 (0.08 to 8) | 0.99 | 0.98 (0.13 to 8) | 0.99 |
| Highest % of cows in which antimicrobials were used for any reason | 1.0 (0.99 to 1.0) | 0.31 | 1.0 (0.97 to 1.0) | 0.65 | 1.0 (0.94 to 1.0) | 0.99 | 1.0 (1.0 to 1.1) | 0.07 |
| Antimicrobials used in cows | ||||||||
| Aminoglycosides (not topical) | 8.6 (0.0 to 335) | 0.99 | 11 (0.0 to 429) | 0.99 | 13 (0.0 to 496) | 0.99 | 8.6 (0.0 to 335) | 0.99 |
| 1st generation cephalosporins | 2.2 (0.0 to 22) | 0.99 | 2.9 (0.0 to 29) | 0.99 | 3.3 (0.0 to 34) | 0.99 | 2.2 (0.0 to 22) | 0.99 |
| Ceftiofur | 1.0 (0.0 to 7.9) | 0.99 | 1.3 (0.0 to 10) | 0.99 | 1.5 (0.0 to 12) | 0.99 | 1.0 (0.0 to 7.9) | 0.99 |
| Florfenicol | 2.9 (0.60 to 14) | 0.22 | 4.9 (0.87 to 34) | 0.08 | 3.8 (0.59 to 28) | 0.19 | 2.9 (0.60 to 14) | 0.22 |
| Lasalocid | 9.0 (0.11 to 750) | 0.40 | 12 (0.14 to 986) | 0.32 | 14 (0.16 to 1163) | 0.29 | 9.0 (0.11 to 750) | 0.40 |
| Macrolides | 0.30 (0.0 to 2.0) | 0.26 | 0.39 (0.0 to 2.7) | 0.39 | 0.46 (0.0 to 3.3) | 0.49 | 0.30 (0.0 to 2.0) | 0.26 |
| Monensin | 2.8 (0.24 to 19) | 0.47 | 1.4 (0.03 to 14) | 0.99 | 0.97 (0.0 to 7.3) | 0.98 | 5.5 (0.74 to 34) | 0.10 |
| Penicillin | 1.9 (0.39 to 8.8) | 0.54 | 1.1 (0.15 to 5.8) | 0.99 | 1.3 (0.18 to 8.4) | 0.99 | 2.9 (0.64 to 15) | 0.20 |
| Polymyxinsb | 0.46 (0.0 to 3.2) | 0.49 | 0.6 (0.0 to 4.3) | 0.66 | 0.69 (0.0 to 5.1) | 0.76 | 0.46 (0.0 to 3.2) | 0.49 |
| Sulfa boluses (including intra-uterine) | 2.3 (0.04 to 26) | 0.86 | 3.0 (0.05 to 36) | 0.72 | 1.9 (0.0 to 16) | 0.99 | 2.3 (0.04 to 26) | 0.86 |
| Tetracyclines | 0.6 (0.13 to 4.1) | 0.76 | 0.43 (0.08 to 3.1) | 0.48 | 0.34 (0.05 to 2.6) | 0.35 | 0.62 (0.13 to 4.1) | 0.76 |
| Trimethoprim-sulfadoxine | 1.5 (0.03 to 15) | 0.99 | 1.9 (0.04 to 20) | 0.94 | 2.3 (0.04 to 25) | 0.84 | 1.5 (0.03 to 14) | 0.99 |
| Category-I drugs used in cow herdc | 0.26 (0.0 to 1.8) | 0.19 | 0.34 (0.0 to 2.4) | 0.32 | 0.40 (0.0 to 3.8) | 0.40 | 0.26 (0.0 to 1.8) | 0.19 |
| Category-II drugs used in cow herdc | 1.0 (0.21 to 4.7) | 0.99 | 0.58 (0.08 to 3.2) | 0.72 | 0.74 (0.10 to 4.6) | 0.99 | 1.6 (0.34 to 8.1) | 0.74 |
| Highest % of preweaned calf herd in which antimicrobials were used for any reason | 1.0 (1.0 to 1.0) | 0.10 | 1.0 (0.99 to 1.0) | 0.22 | 1.0 (0.98 to 1.0) | 0.54 | 1.0 (0.98 to 1.0) | 0.41 |
a
Samples collected in November compared to the samples collected in October (reference category).
b
Contained in intra-mammary preparation (Special Formula 17900-Forte Suspension).
c
Importance to human health as categorized by Health Canada (15). Category I includes drugs of very high importance to human health and Category II is of high importance.
OR — odds ratio; CI — confidence interval.
Values in bold signify factors where P < 0.20.