Heavy Metal Resistance Genes Are Associated with <i>bla</i> _NDM-1 - and <i>bla</i> _CTX-M-15 -Carrying Enterobacteriaceae

Abstract

The occurrence of heavy metal resistance genes in multiresistant <i>Enterobacteriaceae</i> possessing <i>bla</i>_NDM-1 or <i>bla</i>_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 <i>pcoA</i>, <i>merA</i>, <i>silC</i>, and <i>arsA</i> genes occurred with higher frequencies in <i>bla</i>_NDM-1-positive (48.8% to 71.8%) and <i>bla</i>_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 <i>Enterobacteriaceae</i>, increased vigilance needs to be taken with the use of heavy metals in hospitals and the environment.