Table 8.
Logistic regression model of variables associated with the presence of qacEΔ1 in E. coli isolates from samples collected from the floor(s) of commercial broiler chicken barns in Ontario during the rest period (n = 338 isolates from 24 b; random effects for barn, visit, and floor; α = 0.05).
| Variable | OR | 95% CI | P value |
|---|---|---|---|
| Sanitation procedure1,2 | |||
| Dry cleaning (n = 214) | Referent | ||
| Disinfection (n = 124) | 0.40 | 0.16–0.98 | 0.044 |
| Sampling point1 | |||
| Baseline (n = 133) | Referent | ||
| 2 d After sanitation (n = 98) | 0.94 | 0.43–2.01 | 0.864 |
| 6 d After sanitation (n = 107) | 0.91 | 0.43–1.94 | 0.815 |
| Flooring type1 | |||
| Concrete (n = 198) | Referent | ||
| Wood (n = 140) | 7.23 | 2.13–24.47 | 0.001 |
| No. of times per yr the barn is disinfected | |||
| 0 or 1 (n = 116) | Referent | ||
| 2 to 4 (n = 84) | 1.67 | 0.44–6.42 | 0.452 |
| Every (n = 138) | 6.57 | 1.94–22.23 | 0.002 |
| No. of times per yr the barn is disinfected ∗ Flooring type | |||
| 0 or 1 ∗ Concrete (n = 78) | Referent | ||
| 2 to 4 ∗ Wood (n = 42) | 0.20 | 0.03–1.34 | 0.098 |
| Every ∗ Wood (n = 60) | 0.22 | 0.05–0.98 | 0.047 |
| Cycle length | |||
| 10 wk (n = 104) | Referent | ||
| 8 wk (n = 98) | 6.03 | 2.14–17.00 | 0.001 |
| 9 wk (n = 136) | 1.59 | 0.53–4.79 | 0.408 |
| Variance components | Variance | SE | ICC3 |
|---|---|---|---|
| Barn | 2.41 × 10−34 | 5.20 × 10−18 | 7.09 × 10−35 |
| Visit | 1.26 × 10−33 | 1.57 × 10−17 | 4.42 × 10−34 |
| Floor | 0.12 | 0.47 | 0.03 |
Overall P value for the model: <0.0001.
Abbreviations: CI, confidence interval; ICC, intraclass correlation coefficient; OR, odds ratio; SE, significance of error.
Included regardless of significance because it was an a priori variable of interest.
Dry cleaning: dry cleaning only; disinfection: dry cleaning followed by wet cleaning followed by disinfection.
ICC: intraclass correlations calculated using the latent variable technique (variance at sample level = π2/3 = 3.29).