Table 3.
Interaction of selected bactericidal HsrA inhibitors with first-line antibiotics against H. pylori ATCC 700392.
| Antibiotic 1 | HsrA Inhibitor | FICantibiotic | FICinhibitor | FICI 2 | Interaction 3 |
|---|---|---|---|---|---|
| CLR | I | 1 | 1 | 2 | Neutral |
| IV | 1 | 1 | 2 | Neutral | |
| V | 0.5 | 0.06 | 0.56 | Additive | |
| VIII | 0.5 | 0.03 | 0.53 | Additive | |
| XI | 0.25 | 0.5 | 0.75 | Additive | |
| XII | 0.25 | 0.5 | 0.75 | Additive | |
| MTZ | I | 0.125 | 0.5 | 0.625 | Additive |
| IV | 1 | 1 | 2 | Neutral | |
| V | 0.125 | 0.5 | 0.625 | Additive | |
| VIII | 0.5 | 0.125 | 0.625 | Additive | |
| XI | 0.5 | 0.063 | 0.563 | Additive | |
| XII | 0.25 | 0.25 | 0.5 | Synergism | |
| LVX | I | 1 | 1 | 2 | Neutral |
| IV | 1 | 1 | 2 | Neutral | |
| V | 1 | 1 | 2 | Neutral | |
| VIII | 1 | 1 | 2 | Neutral | |
| XI | 1 | 1 | 2 | Neutral | |
| XII | 0.5 | 0.5 | 1 | Neutral |
1 CLR, clarithromycin. MTZ, metronidazole. LVX, levofloxacin. 2 The fractional inhibitory concentration index (FICI) is calculated as: FICA (MICA in the presence of B/MICA alone) + FICB (MICB in the presence of A/MICB alone). 3 According to the FICI value, the interaction between two compounds against a particular bacterial strain can be classified as synergism (FICI ≤ 0.5), additive (FICI > 0.5 to ≤1), no interaction or neutral (FICI > 1 to ≤4), and antagonism (FICI > 4). FIC, fractional inhibitory concentration. MIC, minimal inhibitory concentration. A and B refer to antimicrobial A and antimicrobial B.