Table 3. Distribution of L. monocytogenes-positive samples and persistent pulsotypes in four slaughterhouses in Québec.
| Characteristics | Number of samplesa | Number (%) with persistent strains | Odds ratiosb | |
|---|---|---|---|---|
| Estimate | P-valuec | |||
| Slaughterhouses | ||||
| A | 58 | 33 (56.9%) | 14.4 | <0.001 |
| B | 54 | 32 (59.3%) | 5.4 | <0.01 |
| C | 97 | 12 (12.4%) | Ref | |
| D | 32 | 13 (40.6%) | 9.6 | <0.01 |
| Operation areas | ||||
| Lairage | 68 | 5 (7.4%) | Ref. | |
| Slaughtering and bleeding | 10 | 3 (30.0%) | 9.0 | 0.15 |
| Dehairing and evisceration | 51 | 13 (25.5%) | 6.7 | 0.02 |
| Chilling and hanging | 23 | 8 (34.8%) | 7.5 | 0.05 |
| Cutting and deboning | 89 | 61 (68.5%) | 36.5 | <0.001 |
Ref.: Reference category used for odds ratios.
a Only L. monocytogenes-positive samples from the 241 samples with at least one isolate characterized by PFGE were included (two samples were missing). One isolate per sample was randomly selected.
b Odds ratios from multi-level multivariable logistic regression model.
c P-value adjusted for multiple comparison (Tukey-Cramer).