TABLE 2.
Sequence variations in CmeR-Box of ciprofloxacin-resistant C. jejuni isolates
| Type of variation | Sequence variant | Sequence of CmeR-Boxa | No. of strainsb | Percentage | MICs (μg/ml) (related expression levels of cmeA)c |
|
|---|---|---|---|---|---|---|
| Of tested strains | Average | |||||
| Conserved sequences | 1 | TGTAATTTTTATTACA | 6 (5) | 7.6 | 4 (0.82 ± 0.07), 4 (0.86 ± 0.11), 4 (0.79 ± 0.08), 8 (1.11 ± 0.14), 8 (0.93 ± 0.11) | 5.6 (0.90 ± 0.09) |
| 2 | TGTAATATTTATTACA | 20 (6) | 25.3 | 4 (1.04 ± 0.09), 4 (1.07 ± 0.04), 4 (1.21 ± 0.07), 8 (1.12 ± 0.11), 8 (1.37 ± 0.19), 8 (1.17 ± 0.21) | 6 (1.16 ± 0.09) | |
| Point substitution | 3 | TATAATTTTTATTACA | 17 (5) | 21.5 | 4 (1.32 ± 0.26), 16 (1.28 ± 0.17), 32 (1.37 ± 0.22), 64 (2.38 ± 0.19), 64 (2.11 ± 0.22) | 36 (1.69 ± 0.44) |
| 4 | TGTAGTTTTTATTACA | 6 (3) | 7.6% | 32 (2.43 ± 0.31), 32 (2.55 ± 0.18), 64 (3.43 ± 0.25) | 42.7 (2.80 ± 0.42) | |
| 5 | TGTAATTTTTATTATA | 5 (3) | 6.3 | 16 (3.21 ± 0.33), 64 (2.11 ± 0.31), 64 (2.73 ± 0.33) | 48 (2.68 ± 0.38) | |
| 6 | TATAATATTTATTACA | 4 (3) | 5.1 | 64 (3.14 ± 0.48), 64 (2.81 ± 0.32), 128 (4.22 ± 0.29) | 85.3 (3.39 ± 0.56) | |
| 7 | TATAATATTTATTACA | 1 (1) | 1.3 | 64 (2.12 ± 0.11) | 64 (2.12) | |
| 8 | TGTAATATTTATTGCA | 1 (1) | 1.3 | 32 (1.70 ± 0.24) | 32 (1.70) | |
| 9 | TGTAATATTTATTATA | 4 (3) | 5.1 | 8 (1.81 ± 0.22), 8 (2.28 ± 0.35), 16 (2.11 ± 0.31) | 10.7 (2.07 ± 0.17) | |
| 10 | TGTAATATCTATTATA | 2 (2) | 2.5 | 32 (3.49 ± 0.51), 32 (5.08 ± 0.83) | 32 (4.29 ± 0.79) | |
| Point deletion | 11 | TGTAAT-TTTATTACA | 12 (6) | 15.2 | 128 (13.32 ± 0.41), 128 (16.39 ± 0.93), 128 (15.67 ± 1.11), 128 (16.80 ± 0.68), 128 (9.71 ± 0.77), 128 (10.58 ± 0.38) | 128 (13.75 ± 2.54) |
| Point insertion | 12 | TGTAATATTTTATTACA | 1 (1) | 1.3 | 128 (8.08 ± 1.63) | 128 (8.08) |
a
The positions underlined indicate sequence variations in CmeR-Box.
b
The number of isolates randomly chosen for MIC and cemA expression level test are in parentheses.
c
Relative expression based on C. jejuni NCTC 11168 was calculated using the 2–-ΔΔCT method. 16S rDNA was used as the internal reference.