Table 4.
Combinatory effect of DHPs with metronidazole and clarithromycin against two H. pylori-resistant strains.
| Strain | Combination Tested | FICantibiotic | FICDHP | FICI a | Interaction b |
|---|---|---|---|---|---|
| ATCC 43504 (MTZ-R) | MTZ + Nifedipine | 0.25 | 0.5 | 0.75 | additive |
| MTZ + Nicardipine | 1 | 1 | 2 | no interaction | |
| MTZ + Nisoldipine | 0.5 | 0.5 | 1 | additive | |
| MTZ + Nimodipine | 0.125 | 0.5 | 0.62 | additive | |
| MTZ + Nitrendipine | 1 | 1 | 2 | no interaction | |
| MTZ + Lercanidipine | 1 | 1 | 2 | no interaction | |
| ATCC 700684 (CLR-R) | CLR + Nifedipine | 0.5 | 0.5 | 1 | additive |
| CLR + Nicardipine | 0.25 | 0.5 | 0.75 | additive | |
| CLR + Nisoldipine | 0.5 | 0.5 | 1 | additive | |
| CLR + Nimodipine | 0.5 | 0.5 | 1 | additive | |
| CLR + Nitrendipine | 1 | 1 | 2 | no interaction | |
| CLR + Lercanidipine | 0.0625 | 0.5 | 0.56 | additive |
a Fractional inhibitory concentration index (FICI) could be calculated as: FICA (MICA in the presence of B/MICA alone) + FICB (MICB in the presence of A/MICB alone). b According to the FICI value, the interaction between two compounds against a particular bacterial strain can be classified as: synergism (FICI ≤ 0.5), additive effect (0.5 < FICI ≤ 1), no interaction or neutral (1 < FICI ≤ 4), or antagonism (FICI > 4).