Table 1 Breakpoints used for susceptibility testing of Salmonella species.
Class | Agent | Range (mg/L) | nWTa | Clinical Breakpointb | |
|---|---|---|---|---|---|
CS | CR | ||||
Aminoglycosides | Gentamicin | 0.25–16 | 2 | ≤4 | >8 |
Streptomycin | 2–64 | 16 | ≤32 | >32 | |
β-lactam/β-lactam inhibitor combination | Amoxicillin-Clavulanate (2:1 ratio) | 1–32 | — | ≤8 | >16 |
Cephems | Cefoxitin | 0.5–32 | 8 | ≤8 | >16 |
Ceftiofur | 0.12–8 | 2 | — | — | |
Ceftriaxone | 0.25–64 | — | ≤1 | ≥4 | |
Fluoroquinolones | Ciprofloxacin | 0.015–4 | 0.06 | ≤0.06 | >0.5 |
Quinolones | Nalidixic acid | 0.5–16 | — | — | — |
Folate pathway inhibitors | Trimethoprim-Sulfamethoxazole (1:19) | 0.12–4 | 1 | ≤2 | >2 |
Macrolides | Azithromycin | 0.12–16 | — | — | — |
Penicillins | Ampicillin | 1–32 | 8 | ≤8 | >16 |
Phenicols | Chloramphenicol | 2–32 | 16 | ≤8 | >16 |
Tetracyclines | Tetracycline | 4–32 | 8 | ≤4 | >8 |
