TABLE 3.
Enhancement of antibiotic effectiveness with quercetin expressed using the fractional inhibitory concentration (FIC) index.
|
FIC indexa |
||||||||
| Antibiotic |
E. coli strain |
|||||||
| ATCC25922 | GZP8-8 | GZP10-8 | 12a4 | 12e5 | GZP13-4 | II-119 | II-CX53 | |
| Tetracycline | 0.5 | 0.375 | 0.094 | 0.375 | 0.312 | 0.5 | 0.125 | 0.5 |
| Oxytetracycline | 0.265 | 0.5 | 0.265 | 0.254 | 0.258 | 0.281 | 0.187 | 0.252 |
| Chlortetracycline | 0.254 | 0.28 | 0.375 | 0.5 | 0.375 | 0.254 | 0.375 | 0.5 |
| Doxycycline | 0.5 | 0.156 | 0.187 | 0.5 | 0.25 | 0.281 | 0.187 | 0.258 |
| Ofloxacin | 0.75 | 1 | 2 | 1 | –b | 1 | 1.5 | 1 |
| Norfloxacin | 1 | 1.5 | 0.75 | 1.5 | 1 | 1 | 1.5 | 2 |
| Ciprofloxacin | 1.5 | 1 | 1.5 | 2 | – | 1 | 2 | 1 |
| Florfenicol | 1 | 1 | 1 | 1.5 | 0.75 | – | 1.5 | 0.75 |
| Cefquinome | 0.75 | 1.5 | – | – | – | 1 | 1 | 1 |
| Ceftiofur | 0.75 | 0.75 | – | – | 2 | 0.75 | 1 | 2 |
aFIC ≤ 0.5, synergism; 0.5 > FIC < 1, additive effect; 1 > FIC < 2, no effect; FIC > 2, antagonistic effect. bNot tested.