TABLE 1.
CLSI interpretive criteria for disk diffusion and broth microdilution for Mannheimia haemolytica, with interpretation indicated as susceptible (S), intermediate (I), and resistant (R)
| Susceptibility breakpoints | ||||||
|---|---|---|---|---|---|---|
| Antimicrobial | Disk zone interpretive criteria (mm) | Broth dilution interpretive criteria (μg/mL) | ||||
| S | I | R | S | I | R | |
| FLOR | ≥19 | 15‐18 | ≤14 | ≤2 | 4 | ≥8 |
| CEF | ≥21 | 18‐20 | ≤17 | ≤2 | 4 | ≥8 |
| PEN | – | – | – | ≤0.25 | 0.5 | ≥1.0 |
| OXY | – | – | – | ≤2 | 4 | ≥8 |
| ENR | ≥21 | 17‐20 | ≤16 | ≤0.25 | 0.5‐1 | ≥2 |
| DAN a | ≥22 | 18‐21 | ≤17 | ≤0.25 | 0.5 | ≥1 |
| TIL | ≥14 | 11‐13 | ≤10 | ≤8 | 16 | ≥32 |
| TUL | ≥18 | 15‐17 | ≤14 | ≤16 | 32 | ≥64 |
Abbreviations: CEF, ceftiofur; CLSI, Clinical Laboratory Standards Institute; DAN, danofloxacin; ENR, enrofloxacin; FLOR, florfenicol; OXY, oxytetracycline; PEN, penicillin; TIl, tilmicosin; TUL, tulathromycin.
a
Interpretive criteria for intermediate and resistant ranges were not established at the time Kirby‐Bauer susceptibility was performed.