Table 1 Zone diameter interpretive standards and equivalent MIC breakpoints for H. influenzae and H. parainfluenzae
|  | CLSI 2004–2011 | EUCAST 2012–2014 | |||||||
|---|---|---|---|---|---|---|---|---|---|
MIC breakpoints (μg/mL) | Disk content (μg) | Zone diameter breakpoint (mm) | MIC breakpoints (mg/dL) | Disk content (μg) | Zone diameter breakpoint (mm) | ||||
Antibiotic | Sensitive ≤ | Resistant ≥ | Sensitive ≤ | Resistant > | |||||
Sensitive ≥ | Resistant ≤ |  | Sensitive ≥ | ||||||
Ampicillin | 1 | 4 | 10 | 22 | 18 | 1 | 1 | 2 | 18 |
Piperacillin | 1 | 4 | 10 | 22 | 18 | 1 | 1 | 2 | 18 |
Ampicillin + Sulbactam | 2 | 2 | 10 + 10 | 20 | 19 | 1 | 1 | 10 + 10 | Not available |
Piperacillin + Sulbactam | 1 | 2 | 10 + 10 | 20 | 19 | 2 | 2 | 10 + 10 | Not available |
Piperacillin + Tazobactam | 1 | 2 | 100 + 10 | 21 | – | 2 | 2 | Susceptibility inferred from ampicillin susceptibility | |
Cefuroxime | 4 | 16 | 30 | 20 | 16 | 1 | 2 | 5 | 17 |
Cefotaxime | 2 | – | 30 | 26 | – | 0.125 | 0.125 | 5 | 25 |
Ciprofloxacin | 1 | – | 5 | 21 | – | 0.5 | 0.5 | 1 | 28 |
Levofloxacin | 2 | – | 5 | 17 | – | 1 | 1 | 1 | 26 |
Erythromycin | – | – | – | – | – | 0.5 | 16 | 5 | 50 |