Table 4.
Truncations, frameshift mutations, insertion, deletions, and amino acid exchanges identified in the rdxA, frxA, gyrA, and 23S rRNA genes of sequenced H pylori isolates
| Genes | Mutation type (Position) | No. of H pylori strain (s) | References |
|---|---|---|---|
| rdxA | Nonsense (50) | 4 | Truncations in rdxA suggested to lead to metronidazole résistance 23 |
| Nonsense (86) | 1 | ||
| Fragmented | 1 | Fragmentation in rdxA suggested to be responsible for metronidazole résistance 31 | |
| Frameshift (146) | 1 | These frameshift, deletions have not been previously reported in the literature | |
| deletion of 35 bps N‐terminal region | 1 | ||
| deletion of 18 bps between codon 91 to 97 of N‐terminal region | 1 | ||
| R16C | 1 | R16C occurs only in metronidazole‐resistant H pylori strains 24 , 25 , 26 | |
| K64N | 7 | K64N occurs solely in metronidazole‐resistant H pylori strains 27 | |
| P106S | 5 | P106S occurs solely in metronidazole‐resistant H pylori strains 27 | |
| frxA | Frameshift (18) | 5 | Frameshifts in frxA suggested to confer metronidazole resistance 31 |
| Frameshift (106) | 1 | ||
| Nonsense (73) | 2 | This nonsense mutation has not been previously reported in the literature | |
| Insertion (45 543 bp) | 1 | This insertion in frxA has not been previously reported in the literature | |
| gyrA | 5‐ amino acid N‐terminal extension (MQDNS) | 5 | 5‐amino acid N‐terminal extension suggested to confer fluoroquinolone resistance 31 |
| D91G | 2 | Amino‐ acid exchanges in QRDR of GyrA suggested to confer resistance to fluoroquinolone 31 | |
| D91N | 1 | ||
| R295C | 1 | Amino acid exchange at 295 suggested to be responsible for fluoroquinolone resistant in H pylori 31 | |
| 23S rRNA | G2224A | 1 | G2224A mutation in 23S rRNA occurs solely in clarithromycin‐resistant H pylori strain 31 |