TABLE 1.
Antibiotic-resistant isolates form a ΔacrAB ΔacrE straina
| Antibiotic-resistant isolate(s) (culture no.) | MIC of Nov/Ery (μg/ml) | Efflux pump dependence | Gene affected in resistant mutants (allele) | Mutation (aa change) |
|---|---|---|---|---|
| WT | 64–128/128 | NA | NA | NA |
| ΔacrAB ΔacrE | 1/2 | NA | NA | NA |
| TolC− | 0.5/1.0 | NA | NA | NA |
| 1, 2 (1) | 2/16 | MdtEF | hns | IS1::224 |
| 3 (1) | ND | MdtEF | hns | IS1::193 |
| 4 (2) | ND | MdtEF | hns | T399C (F133S) |
| 5 (3) | ND | MdtEF | hns | T90C (L30P) |
| 6, 7 (3) | 2/8 | MdtEF | hns | IS5::268 |
| 8 (4) | ND | MdtEF | hns | IS1::141 |
| 9 (4) | 16/4 | MdtABC | baeS (baeS51) | C310T (R104C) |
| 10 (4) | 16/2 | MdtABC | baeS (baeS52) | T104A (F35Y) |
| 11 (4) | ND | MdtABC | rpoB (rpoB53) | G1361T (R454L) |
| 12 (5) | 2–4/8–16 | MdtEF | likely cyaA | ? |
| 13 (5) | ND | MdtABC | rpoB (rpoB55) | T1295G (L432R) |
| 14 (6) | ND | MdtABC | rpoB (rpoB57) | A443C (Q148P) |
| 15 (6) | 4/4–8 | MdtABC | rpoB (rpoB58) | G1346T (G449V) |
| 16 (6) | 16/2 | MdtABC | baeS baeS59 | T895C (S299P) |
| 17 (6) | 32/4 | MacAB | ? | ? |
| 18 (7) | 8–16/2 | MdtABC | baeS (baeS61) | A76C (S26R) |
| 19 (7) | 2/8 | MdtEF | crp | G41A (W14stop) |
| 20 (7) | 16/2 | MdtABC | baeS (baeS63) | A1285G (N429D) |
a
ND, not determined; NA, not applicable; Nov, novobiocin; Ery, erythromycin; aa, amino acid; ?, mutation or affected gene is not revealed. Numbers after insertion sequence (IS) designation represent the hns nucleotide number at the insertion site.