MIC data for polymyxin analogues 7a–f, 8a–f, and 9a–f. Values are expressed in μg mL−1 (backgrounds of all strains used are provided in Table S3†).
| E. coli | K. pneumoniae | A. baumannii | P. aeruginosa | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Lipid | Position 3 residue | ATCC 25922 | 1313 | NCTC 13846a | ATCC 13883 | JS-123 | NCTC 13443 | ATCC 19606 | ATCC 17978 | MDR | 2018–006 | ATCC 27853 | NRZ 08418 | NRZ 03961 | |
| Polymyxin B | Dab | 1 | 0.125 | 4 | 0.25 | 0.25 | 0.5 | 0.25 | 0.25 | 0.5 | 0.125 | 1 | 1 | 1 | |
| 7a |
|
d-Ser | 2 | 1 | 8 | 1 | 1 | 1 | 0.25 | 1 | 1 | 0.5 | 4 | 4 | 4 |
| 7b | Gly | 2 | 0.5 | 8 | 1 | 0.5 | 1 | 0.5 | 0.5 | 1 | 0.5 | 2 | 2 | 4 | |
| 7c | d-Dap | 2 | 0.5 | 4 | 1 | 1 | 1 | 0.5 | 1 | 1 | 0.5 | 2 | 2 | 2 | |
| 7d | Dap | 1 | 0.5 | 2 | 1 | 0.5 | 1 | 0.5 | 1 | 1 | 0.5 | 2 | 2 | 2 | |
| 7e | d-Dab | 2 | 0.5 | 4 | 1 | 1 | 1 | 0.5 | 1 | 1 | 0.5 | 2 | 2 | 2 | |
| 7f | Dab | 1 | 2 | 8 | 1 | 2 | 2 | 0.5 | 1 | 1 | 0.5 | 2 | 4 | 4 | |
| 8a |
|
d-Ser | 2 | 0.5 | 16 | 0.5 | 0.5 | 1 | 0.25 | 0.25 | 0.5 | 0.5 | 4 | 8 | 8 |
| 8b | Gly | 2 | 0.25 | 16 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 4 | 4 | 4 | |
| 8c | d-Dap | 2 | 0.5 | 8 | 0.5 | 0.5 | 0.5 | 0.25 | 0.25 | 0.25 | 0.25 | 1 | 4 | 2 | |
| 8d | Dap | 1 | ≤0.125 | 4 | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | 1 | 1 | 1 | |
| 8e | d-Dab | 2 | 0.25 | 8 | 0.5 | 0.25 | 0.5 | 0.25 | 0.25 | 0.5 | 0.25 | 1 | 2 | 2 | |
| 8f | Dab | 1 | ≤0.125 | 8 | 0.5 | 0.25 | 0.5 | 0.5 | 1 | 1 | 0.5 | 1 | 1 | 2 | |
| 9a |
|
d-Ser | 2 | 0.5 | 8 | 1 | 0.25 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 4 | 4 | 8 |
| 9b | Gly | 2 | 0.25 | 8 | 1 | 0.5 | 0.5 | 1 | 1 | 1 | 1 | 4 | 4 | 4 | |
| 9c | d-Dap | 2 | 0.5 | 16 | 0.5 | 2 | 8 | 0.5 | 0.5 | 0.5–1 | 0.5 | 1 | 0.5 | 2 | |
| 9d | Dap | 2 | ≤0.125 | 2 | 0.5 | 0.5 | 2 | 0.5 | ≤0.25 | 8 | 2 | 4 | 2 | 2 | |
| 9e | d-Dab | 2 | 0.5 | 4 | 1 | 0.5 | 0.5 | 0.5 | 1 | 1 | 0.5 | 2 | 2 | 2 | |
| 9f | Dab | 1 | 0.125 | 4 | 0.5 | 0.25 | 0.25 | 1 | 1 | 4 | 2 | 4 | 2 | 1 | |
a
Multi-drug resistant strain, mcr-1 positive, making it intermediate resistant to polymyxin B.