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 2
Incidence rate ratio of Escherichia coli 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 | 2.50% CI | 97.50% CI | p value |
---|---|---|---|---|
Intercept |
1.5740809 |
1.3050913 |
1.8985113 |
2.09 × 10-6† |
Production system (referent comparison factor: conventional) | ||||
Antimicrobial-free‡ |
1.0275338 |
0.9170807 |
1.1512897 |
0.63969 |
Ideal disinfection method (referent comparison factor: no use of ideal method) | ||||
Use of ideal disinfection |
1.0133377 |
0.9418401 |
1.0902627 |
0.722652 |
Continuous variables of antimicrobial use (mg/kg) | ||||
Injections (in ovo or subcutaneous§) | 1.3588476 | 0.9911794 | 1.8628985 | 0.056785 |
Through feed | 1.0015582 | 1.0008262 | 1.0022907 | 2.99 × 10-5† |
Through water |
1.0032516 |
1.0019576 |
1.0045473 |
8.23 × 10-7† |
Sample collection year (referent comparison year: 2013) | ||||
2014 | 0.8881768 | 0.7850343 | 1.0048707 | 0.05972 |
2015 | 0.9555537 | 0.8431346 | 1.0829621 | 0.476499 |
2016 | 0.9458207 | 0.8349598 | 1.071401 | 0.381178 |
2017 | 0.9144284 | 0.8066086 | 1.0366604 | 0.162256 |
2018 | 0.8545609 | 0.7523902 | 0.9706058 | 0.015553† |
2019 |
0.7705043 |
0.6770116 |
0.8769079 |
7.81 × 10-5† |
Province (referent comparison province: Alberta) | ||||
British Columbia | 1.2229891 | 1.0173109 | 1.4702509 | 0.032138† |
Ontario | 0.9922909 | 0.8315428 | 1.1841136 | 0.931604 |
Québec | 1.3924895 | 1.1564315 | 1.6767333 | 0.000477† |
Saskatchewan | 0.4997466 | 0.3844197 | 0.649672 | 2.20 × 10-7† |
*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.