TABLE 5.
Effects of cysteine addition on Amd resistance of clinical isolatesa
| Strain | Relevant phenotype | Growth on MM |
Amd MIC (mg/liter) |
|||
|---|---|---|---|---|---|---|
| M9 | M9 + Cys | No Cys | 0.3 mM Cys | 0.75 mM Cys | ||
| DA5438 | Cys+ | Yes | Yes | 0.125 | 0.125 | 0.125 |
| DA28439 | Cys−b | No | Yes | 24 | 2 | 0.25 |
| DA14704 | Cys− | No | Yes | 32 | 0.125 | 0.125 |
| DA14709 | Cys− | No | Yes | 4 | 2 | 0.38 |
| DA14710 | Cys− | No | Yes | 64 | 8 | 0.125 |
| DA14712 | Cys− | No | Yes | 32 | 16 | 0.5 |
| DA14713 | Cys− | No | No | 64 | 4 | 0.125 |
| DA14715 | Cys− | No | Yes | 16 | 2 | 0.19 |
| DA14718 | Cys− | No | Yes | 32 | 8 | 0.38 |
| DA14719 | Cys− | No | Yes | 16 | 0.5 | 0.094 |
| DA24678 | Cys− | No | Yes | 48 | 16 | 0.38 |
| DA24686 | Cys− | No | Yes | 32 | 16 | 0.19 |
| DA24690 | Cys− | No | Yes | 32 | 24 | 0.125 |
| DA24692 | Cys− | No | Yes | 48 | 6 | 0.19 |
a
Shown are growth on M9 glucose minimal medium (MM) with or without cysteine added and Amd Etest MICs on MH plates with different concentrations of cysteine. DA5438 is E. coli MG1655, DA28439 is a constructed cysB knockout strain, and all of the other strains are Amdr clinical E. coli isolates with cysB mutations.
b
cysB knockout.