Abstract
Antibiotic resistance is a growing threat to public health, and environmental factors, including metals in drinking water distribution systems, are increasingly recognized as contributors to the spread of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Zinc orthophosphate, a common corrosion inhibitor, and copper corrosion products (CuO and Cu(2)O) are frequently present in drinking water systems. While each has been shown to increase ARB and ARGs individually, their combined effects remain unknown. The objective of this study was to evaluate the combined impact of copper corrosion products and the corrosion inhibitor zinc orthophosphate on antibiotic resistance. Two sets of lab-scale microcosms were used, in which CuO and Cu(2)O were added with and without zinc orthophosphate, and impacts on ARB abundance, ARG abundance, and microbial community structure were assessed. Overall, the combined addition of copper corrosion products and corrosion inhibitor increased ARB and ARGs, coinciding with changes to the microbial community's β-diversity. In most cases, the coaddition of the corrosion product with the corrosion inhibitor resulted in greater changes in antibiotic resistance abundance than the addition of the corrosion product alone. This research improves our understanding of how the coexistence of metal corrosion products and corrosion inhibitors in drinking water pipes can impact antibiotic resistance.