Fig. 3.

MTX and TMP MIC ofE. coliDH5α expressingdfrA1ordfrA12. The MTX (a) and TMP (b) MIC for the wild type (wt) E. coli DH5α (MP18–09) compared to the strain harboring the empty pBAD30 (MP18–10) expression vector as well as strains with pBAD30 with different dfrA genes expressed under the inducible expression control by the pBAD promotor (MP18–11 and MP18–12). The detection limit of the assay is 64 μg/mL for TMP and 32 mg/mL for MTX. For both drugs, the MIC of E. coli DH5α expressing dfrA12 (MP18–12) exceeded the detection limit whereas the strain expressing dfrA1 (MP18–11) has the same MICs as the wt strain. Showing that MTX and TMP resistance conferred by the pG06-VIM-1 plasmid is caused by the dfrA12 gene.