Table 3.
Genetic determinants of antibiotic resistance in H. pylori CHC155 and VN1291.
| Antibiotic | Minimum inhibitory concentration (mg/L) | Phenotype | Gene | Mutation site |
|---|---|---|---|---|
| (a) Strain CHC155 | ||||
| Amoxicillin | 0.06 | S | pbp1 (HP0597) | N.D |
| Clarithromycin | 4 | R | 2 copies of 23S rRNA | A2147G |
| Levofloxacin | 8 | R | gyrA (HP0701) | N87K |
| Metronidazole | 32 | R | rdxA (HP0954) | T31E, H53R, D59N, Q65* |
| frxA | N.D | |||
| Tetracycline | 0.12 | S | 2 copies of 16S rRNA | N.D |
| (b) Strain VN1291 | ||||
| Amoxicillin | 0.5 | R | pbp1 (HP0597) | F366L, S414R, K464insE, D473E |
| Clarithromycin | 4 | R | 2 copies of 23S rRNA | A2147G |
| Levofloxacin | 0.5 | S | gyrA (HP0701) | N.D |
| Metronidazole | > 256 | R | rdxA (HP0954) | Frameshifted, insertion/deletion at approximately position 1,114,371 |
| frxA | N.D | |||
| Tetracycline | 0.125 | S | 2 copies of 16S rRNA | N.D |
S Susceptible, R resistant. Determined by cut off value according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) clinical breakpoint (2021-01-01). S is equal to or less than the cut-off value and R is more than the cut-off value. The cut offs (mg/L) were; amoxicillin (0.125), levofloxacin (1), clarithromycin (0.25), tetracycline (1), and metronidazole (8). N.D. not detected.