Table 1.
Effects of complementation of wild-type MarR and YedSCH4 on carbapenem susceptibility in clinical and laboratory strains of E. coli
| Strain | Mutation(s) in marR | MIC (μg/ml)a |
||
|---|---|---|---|---|
| Imipenem | Meropenem | Ertapenem | ||
| CH4 | Gln42Arg, Gly103Ser, Tyr137His | >32 | 32 | >32 |
| CH4/pACT7/pET13a | >32 | 32 | >32 | |
| CH4/pACT7/pmarRwildtype | 0.25 | 0.38 | 0.25 | |
| CH4/pACT7/pyedSCH4 | 1.5 | 1.5 | 4.0 | |
| CH4/pAC-MarRwt | 0.25 | 0.38 | 0.25 | |
| BL21(DE3)/pET13a | Wild-type marR | 0.047 | 0.023b | 0.047 |
| BL21(DE3)/pyedSCH4 | 0.004 | 0.023b | 0.004 | |
a
MICs were determined using Etest (bioMérieux). CH4 cells were cultured on LB agar containing kanamycin (800 μg/ml) and spectinomycin (200 μg/ml) when carrying pET13a plasmids and pACT7 plasmids, respectively. BL21(DE3) cells were cultured on agar containing kanamycin (50 μg/ml) when carrying the pET13a plasmid. All cultures were induced with IPTG (0.5 mM).
b
Meropenem MICs were not affected by overexpression of YedS in BL21(DE3), most likely due to other factors in this strain which affect susceptibility to this carbapenem.