Figure 1
The two most common types of lipid A modifications that lead to colistin resistance
Table 1
| K. pneumoniae | ||
|---|---|---|
| Type | m/z | Proposed structures |
| Native lipid A | 1824 |  |
| 1840 |  | |
| Native lipid A | 2062 |  |
| 2078 |  | |
| Chromosome-encoded resistance – L-Ara4N addition | 1971 (1840 + 131) |  |
| 2209 (2078 + 131) |  | |
| Plasmid-encoded resistance – pEtN addition | 1963 (1840 + 123) |  |
| 2201 (2078 + 123) |  | |
Table 2
P. aeruginosa native and modified lipid A structures and their corresponding m/z values (37)
| P. aeruginosa | ||
|---|---|---|
| Type | m/z | Proposed structures |
| Native lipid A | 1446 |  |
| 1462 |  | |
| Chromosome-encoded resistance – L-Ara4N addition | 1577 (1446 + 131) |  |
| 1593 (1462 + 131) |  | |
| 1708 (1446 + 262) |  | |
| Chromosome-encoded resistance – L-Ara4N addition | 1724 (1462 + 262) |  |
Table 3
| A. baumannii | ||
|---|---|---|
| Type | m/z | Proposed structure |
| Native lipid A | 1728 |  |
| Native lipid A | 1910 |  |
| Chromosome-encoded resistance – pEtN addition | 2033 (1910 + 123) |  |
Table 4
| E. coli | ||
|---|---|---|
| Type | m/z | Proposed structure |
| Native lipid A | 1796 |  |
| Chromosome-encoded resistance – L-Ara4N addition | 1927 (1796 + 131) |  |
| Both plasmid- and chromosome-encoded resistance | 1919 (1796 + 123) |  |
Table 5
| S. enterica | ||
|---|---|---|
| Type | m/z | Proposed structure |
| Native lipid A | 1796 |  |
| 1812 |  | |
| Native lipid A | 1876 |  |
| 2034 |  | |
| Native lipid A | 2050 |  |
| Chromosome-encoded resistance – L-Ara4N addition | 1927 (1796 + 131) |  |
| Chromosome-encoded resistance – L-Ara4N addition | 2165 (2034 + 131) |  |
| Plasmid-encoded resistance – pEtN addition | 1919 (1796 + 123) |  |
| Plasmid-encoded resistance – pEtN addition | 1935 (1812 + 123) |  |
| 2157 (2034 + 123) |  | |
| Plasmid-encoded resistance – pEtN addition | 2173 (2050 + 123) |  |