Heavy Metal Resistance Genes Are Associated with bla NDM-1 - and bla CTX-M-15 -Carrying Enterobacteriaceae.

The occurrence of heavy metal resistance genes in multiresistant Enterobacteriaceae possessing bla NDM-1 or bla CTX-M-15 genes was examined by PCR and pulsed-field gel electrophoresis with S1 nuclease. Compared with clinical susceptible isolates (10.0% to 30.0%), the pcoA , merA , silC , and arsA genes occurred with higher frequencies in bla NDM-1 -positive (48.8% to 71.8%) and bla CTX-M-15 -positive (19.4% to 52.8%) isolates, and they were mostly located on plasmids. Given the high association of metal resistance genes with multidrug-resistant Enterobacteriaceae , increased vigilance needs to be taken with the use of heavy metals in hospitals and the environment.