Defense Date
2024
Document Type
Thesis
Degree Name
Master of Science
Department
Biology
First Advisor
Rima Franklin
Abstract
The spread of antibiotic-resistant bacteria (ARB) associated with wastewater is a significant environmental concern, but little is known about the persistence and proliferation of these organisms in receiving water bodies after discharge. To address this knowledge gap, we performed a series of microcosm experiments in which river water was amended with either untreated or treated wastewater, and the abundance of viable ciprofloxacin-, Bactrim-, and erythromycin-resistant bacteria was monitored for 72 hours.
Both types of wastewater amendments increased the initial abundance of ARB compared to microcosms containing only river water. The increase was greatest with untreated wastewater, but that effect decreased steadily over time. In contrast, microcosms amended with treated wastewater saw a smaller initial increase and more complex temporal dynamics. Following a brief lag, ARB abundance bloomed for all three of the antibiotics that we considered. This suggests that ARB that survive wastewater treatment are particularly hardy and may proliferate in riverine conditions after a short recovery period.
To determine how interactions with the native river microbial community impacted the persistence of wastewater-associated ARB, an additional set of microcosms was prepared using filter-sterilized river water. Peak abundance in these microcosms was 1-2 orders of magnitude higher than in microcosms containing an intact river microbial community, which suggests that biotic interactions play a significant role in regulating the persistence and proliferation of ARB.
The data presented in this paper are among the first available that specifically consider the persistence of viable ARB and represent an important step toward understanding AR-related human health risks downstream from wastewater discharge points and following sewer overflow events. Additional studies that consider longer time scales and the interplay of biotic and abiotic variables are essential for modeling public health risks associated with wastewater inputs of ARB to rivers and other aquatic environments.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
5-5-2024