Fig 1.

Silver resistance genes and IncHI plasmids in pathogenic isolate EN-373. (A) PCRs of four genes of the sil resistance determinant in strains EN-373, a clinical outbreak strain, and 501R3, a plant isolate. Plasmid MG101 was used as a positive control; E. coli strain DH5α was the negative control (NK). The hsp60 PCR was used as control PCR. (B) PCR of repA, a marker gene for IncHI-1 and IncHI-2 plasmids. 501R3 and E6, two plant isolates, were negative in the repA PCR, suggesting that they did not carry IncHI-1 or -2 plasmids. EN-373 was PCR positive, confirming the presence of an IncHI-1 or -2 plasmid, presumably carrying the silver resistance genes.