Table 3.
Fractional inhibitory concentration (FIC) and FIC index (FICI) of combination between tylosin and EFNTE.
| Tylosin | EFNTE | FICI | Interpretation | ||
|---|---|---|---|---|---|
| Conc (μg/mL) | FIC of drug A | Conc (μg/mL) | FIC of drug B | (FIC of A + FIC of B) | |
| 1024 | MIC of A | 0 | MIC of A | MIC of A | MIC of A |
| 1024 | 1 | 6 | 0.0077 | 1.008 | IND |
| 1024 | 1 | 12 | 0.0154 | 1.015 | IND |
| 1024 | 1 | 24 | 0.0307 | 1.031 | IND |
| 512 | 0.5 | 49 | 0.063 | 0.563 | ADI |
| 256 | 0.25 | 98 | 0.125 | 0.375 | SYN |
| 256 | 0.25 | 195 | 0.25 | 0.499 | SYN |
| 128 | 0.125 | 391 | 0.5 | 0.626 | ADI |
| 64 | 0.0625 | 391 | 0.5 | 0.563 | ADI |
| 0 | MIC of B | 781 | MIC of B | MIC of B | MIC of B |
EFNTE: ethyl acetate fraction of N. tetragona 50% methanol extract; Conc: concentration; drug A: tylosin; drug B: EFNTE; SYN: synergistic effect; ADI: additive effect; IND: indifferent effect; MIC: minimum inhibitory concentration. The FICI was interpreted as follows: synergistic effect (0 < FICI ≤ 0.5), additive effect (0.5 < FICI ≤ 1), and indifferent effect (1 < FICI ≤ 4).