Table 4.
Logistic regression model of variables associated with the presence of S. enterica in samples collected from the floor(s) of commercial broiler chicken barns in Ontario that were disinfected during the rest period (n = 336 samples from 17 b; random effects for barn, visit, and floor; α = 0.05).
| Variable | OR | 95% CI | P value |
|---|---|---|---|
| Sampling point1 | |||
| Baseline (n = 112) | Referent | ||
| 2 d After sanitation (n = 112) | 0.17 | 0.04–0.61 | 0.007 |
| 6 d After sanitation (n = 112) | 0.09 | 0.02–0.40 | 0.002 |
| Flooring type1 | |||
| Concrete (n = 204) | Referent | ||
| Wood (n = 132) | 1.58 | 0.60–4.17 | 0.356 |
| Season2 | |||
| Summer/Fall (n = 144) | Referent | ||
| Winter/Spring (n = 192) | 0.005 | 0.0001–0.20 | 0.005 |
| Variance components | Variance | SE | ICC3 |
|---|---|---|---|
| Barn | 10.16 | 7.14 | 0.73 |
| Visit | 0.42 | 0.90 | 0.76 |
| Floor | 3.57 × 10−33 | 9.45 × 10−17 | 0.76 |
Overall P value for the model: 0.0021.
Abbreviations: CI, confidence interval; OR, odds ratio; SE, significance of error.
Included regardless of significance because it was an a priori variable of interest.
Fall: September 21st to December 20th; winter: December 21st to March 20th; spring: March 21st to June 20th; summer: June 21st to September 20th.
ICC: intraclass correlation coefficient calculated using the latent variable technique (variance at sample-level = π2/3 = 3.29).