Table 2. Time associated odds ratio quantifying the change in the probability of obtaining a response equal to or lower than each MIC level measured for each antimicrobial per year obtained using a cumulative logistic regression model (values below 1 indicate a decreasing probability of finding isolates with lower MIC values).
| Antimicrobial | Swine | Cattle | ||||
|---|---|---|---|---|---|---|
| Model | OR (p-value) | 95% CI | Model | OR (p-value) | 95% CI | |
| Ampicillin | P(Y ≤ MICj|yeari) | 1.007 (<0.001) | 1.042–1.114 | P(Y ≤ MICj|yeari) | 0.921 (0.13) | 0.921–1.010 |
| Ceftiofur | P(Y ≤ MICj|yeari) | 1.050 (0.001) | 1.020–1.081 | P(Y ≤ MIC1|yeari)a | 1.126 (<0.001) | 1.061–1.195 |
| P(Y ≤ MIC2:j|yeari)a | 0.927 (0.002) | 0.883–0.973 | ||||
| Enrofloxacin | P(Y ≤ MICj|yeari) | 0.721 (<0.001) | 0.681–0.764 | NA | NA | NA |
| Florfenicol | P(Y ≤ MICj|yeari) | 1.068 (<0.001) | 1.037–1.099 | P(Y ≤ MIC1:2|yeari) b | 1.045 (0.11) | 0.991–1.103 |
| P(Y ≤ MIC3:j|yeari) b | 0.951 (0.040) | 0.905–0.998 | ||||
| Gentamicin | P(Y ≤ MICj|yeari) | 1.009 (0.56) | 0.978–1.041 | NA | NA | NA |
| Neomycin | P(Y ≤ MICj|yeari) | 1.020 (0.21) | 0.989–1.052 | P(Y ≤ MICj|yeari) | 1.089 (0.002) | 1.030–1.151 |
| Oxytetracycline | P(Y ≤ MIC1|yeari) c | 0.719 (0.18) | 0.444–1.162 | P(Y ≤ MIC1|yeari) d | 1.691 (<0.001) | 1.242–2.301 |
| P(Y ≤ MIC2:j|yeari) c | 1.113 (<0.001) | 1.060–1.169 | P(Y ≤ MIC2:j|yeari)d | 0.968 (0.17) | 0.924–1.014 | |
| Spectinomycin | P(Y ≤ MIC1|yeari) e | 0.954 (0.66) | 0.775–1.175 | P(Y ≤ MICj|yeari) | 1.236 (<0.001) | 1.178–1.296 |
| P(Y ≤ MIC2:j|yeari) | 1.056 (<0.001) | 1.024–1.089 | ||||
a MIC1 = ≤0.5 μg/ml; MIC2:j = 1, 2, 4 and 8 μg/ml.
b MIC1:2 = ≤1 and 2 μg/ml; MIC3:j = 4 and 8 μg/ml.
c MIC1 = ≤0.5 μg/ml; MIC2:j = 1, 2 and 4 μg/ml.
d MIC1 = ≤0.5 μg/ml; MIC2:j = 1, 2 and 4 μg/ml.
e MIC1 = ≤16 μg/ml; MIC2:j = 32 and 64 μg/ml.