Volume 27, Number 9—September 2021
Research
Reduction in Antimicrobial Use and Resistance to Salmonella, Campylobacter, and Escherichia coli in Broiler Chickens, Canada, 2013–2019
Table 1
Incidence rate ratio of Salmonella nC from LASSO-penalized generalized mixed-effects Poisson model in a study of antimicrobial use and in broiler chickens, Canada, 2013–2019*
Variable | Incidence rate ratio | 2.5% CI | 97.5% CI | p value |
---|---|---|---|---|
Intercept |
0.224851 |
0.1326975 |
−0.3810016 |
2.92 × 10-8† |
Production system (referent comparison factor: conventional) | ||||
Antimicrobial-free‡ |
1.456588 |
0.9917592 |
2.1392781 |
0.05514 |
Disinfection system (referent comparison factor: no use of the ideal method of disinfection) | ||||
Use of ideal disinfection |
0.8947851 |
0.6969602 |
1.1487606 |
0.38316 |
Continuous variables of antimicrobial use (mg/kg) | ||||
Injections (in ovo or subcutaneous§) | 3.3926736 | 1.1860941 | 9.704318 | 0.02271† |
Through feed | 1.0030552 | 1.0004128 | 1.0057047 | 0.02341† |
Through water |
1.0005486 |
0.9947253 |
1.006406 |
0.85389 |
Sample collection year (referent comparison year: 2013) | ||||
2014 | 0.9904373 | 0.6355585 | 1.5434709 | 0.96614 |
2015 | 1.0475486 | 0.6851365 | 1.6016635 | 0.83021 |
2016 | 1.0912259 | 0.7028907 | 1.6941097 | 0.69726 |
2017 | 0.9097193 | 0.5821923 | 1.4215049 | 0.67777 |
2018 | 0.9869455 | 0.6351112 | 1.5336864 | 9.53 × 10-1† |
2019 |
1.548854 |
1.0091025 |
2.3773092 |
0.04534† |
Province (referent comparison province: Alberta) | ||||
British Columbia | 1.6846635 | 1.1510546 | 2.465644 | 0.00728† |
Ontario | 1.8199429 | 1.2502213 | 2.6492848 | 0.00177† |
Québec | 3.7534112 | 2.4943597 | 5.6479808 | 2.24 × 10-1† |
Saskatchewan | 1.9772529 | 1.1775379 | 3.3200878 | 0.00994† |
*nC, number of antimicrobial classes to which each isolate was resistant. †Statistically significant (p<0.05). ‡Antimicrobial-free flocks were not exposed to medically important antimicrobials through any route of administration. §Subcutaneous route in young chicks at the hatchery.