Table 3.
Calf-level effect of antimicrobial drug treatment on the number of nonsusceptible fecal Escherichia coli cultured from a calf
| Antimicrobial drug treatment | Nonsusceptible E. coli, no. | Enrofloxacin treatment1
|
P-value | Odds ratio2 | |
|---|---|---|---|---|---|
| Tx, % (n = 42) | NoTx, % (n = 437) | ||||
| Nalidixic acid | 0 | 55 | 94 | <0.0001 | Reference |
| 1 | 2 | 4 | |||
| 2 | 5 | 1 | |||
| 3 | 38 | 1 | 41.0 (10—172) | ||
| Ciprofloxacin | 0 | 62 | 96 | <0.0001 | Reference |
| 1 | 3 | 2 | |||
| 2 | 4 | 1 | |||
| 3 | 31 | 0.5 | 92.0 (14—613) | ||
1
Calves with farm records with at least one treatment with enrofloxacin from birth to fecal sampling (Tx) or calves with a farm record with no treatment with enrofloxacin from birth to fecal sampling.
2
Odds ratio in case of 3 nonsusceptible isolates from a calf compared with 0 nonsusceptible E. coli isolates (reference) when a calf received at least one antimicrobial treatment of enrofloxacin. The 95% confidence interval is in parentheses.