Assessing the Efficacy of Selected Wastewater Treatment Technologies to Reduce Dissemination of Environmental Antibiotic Resistance

The widespread occurrence and proliferation of antibiotic resistant bacteria (ARBs) continues to be a global concern. Wastewater treatment plants (WWTPs) are known to be hotspots for ARBs and antibiotic resistant genes (ARGs) because of high nutrient concentrations, presence of antibiotics that promote selective pressure, and a plethora of diverse bacteria populations, which can promote dissemination of ARG via horizontal gene transfer. WWTPs can potentially discharge ARBs and ARGs through aqueous and solid effluents, which raises concern about the role WWTPs play in disseminating ARBs and ARGs into the natural environment.
This dissertation assesses the behavior and fate of a model ARB, carbapenem-resistant Enterobacterales, and its corresponding ¬¬ARG, blaKPC, as they flow from a hospital via wastewater into a typical municipal WWTP and, from there, into the natural environment via its receiving waters. This research also examines the efficacy of selected conventional WWTP technologies in deactivating the model ARB and ARG via laboratory-scale experiments of chlorination and ultraviolet (UV) radiation using traditional methods used in previous literature studies. This dissertation then describes an effects-based assay to assess the potential of gene transfer from treated wastewater effluents to microbial communities in the downstream receiving water. The results of this dissertation contribute to the knowledge of the role of WWTPs in dissemination of antibiotic resistance. They also highlight the usefulness of microcosm experiments as a novel, effects-based assay for evaluating the potential for antimicrobial dissemination from WWTPs, which has not yet been well-described in existing literature.