Impact of zinc and copper on antibiotic resistance and conjugative plasmid transfer in bacteria isolated from wastewater treatment plants

The rapid emergence of antibiotic resistance is leading to a global public health crisis. The purpose of this study was to examine zinc and copper, two environmentally and clinically relevant heavy metals that have shown potential at promoting resistance, as influencers on antibiotic resistance profiles and conjugative plasmid transfer in bacteria isolated from wastewater treatment plants (WWTPs). A total of 47 bacterial cultures isolated from WWTPs were examined to determine the effect of zinc and copper on their antibiotic resistance profiles and whether the metals had an impact on the transfer of plasmids carrying antibiotic resistance genes. It was found that only a few isolates were affected by zinc or copper. Sub-inhibitory levels of copper were found to have no significant effect on plasmid transfer between two environmental strains of Escherichia coli (E.coli). It is important to control the spread of antibiotic resistance and reinstate efficacy of antibiotics.