TABLE 2.
Summary of disk diffusion antimicrobial susceptibility test results for 48 Mannheimia haemolytica isolates collected from 20 stocker calves before (Arrival, n = 26) and 10 to 14 days after (Revacc, n = 22) metaphylactic treatment with tulathromycin
| No. isolates (%) | ||||
|---|---|---|---|---|
| Antimicrobial | Occasion | Susceptible | Intermediate | Resistant |
| FLOR | Arrival | 26 (100%) | 0 | 0 |
| Revacc | 13 (59.1%) | 1 (4.5%) | 8 (36.4%) | |
| CEF | Arrival | 26 (100%) | 0 | 0 |
| Revacc | 22 (100%) | 0 | 0 | |
| ENR | Arrival | 26 (100%) | 0 | 0 |
| Revacc | 0 | 0 | 22 (100%) | |
| TIL | Arrival | 19 (73.1%) | 7 (26.9%) | 0 |
| Revacc | 0 | 0 | 22 (100%) | |
| GAM | Arrival | 26 (100%) | 0 | 0 |
| Revacc | 0 | 0 | 22 (100%) | |
| TUL | Arrival | 21 (80.8%) | 5 (19.2%) | 0 |
| Revacc | 0 | 0 | 22 (100%) | |
Abbreviations: CEF, ceftiofur; ENR, enrofloxacin; FLOR, florfenicol; GAM, gamithromycin; TIL, tilmicosin; TUL, tulathromycin.