Date of Award

Spring 2020

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Ocean Science and Engineering

Committee Chair

Wei Wu

Committee Chair School

Ocean Science and Engineering

Committee Member 2

D.Jay Grimes

Committee Member 2 School

Ocean Science and Engineering

Committee Member 3

Eric Saillant

Committee Member 3 School

Ocean Science and Engineering

Committee Member 4

Robert J. Griffitt

Committee Member 4 School

Ocean Science and Engineering

Abstract

As antibiotic resistance genes in aquatic environment have been increasing across the world, affecting water quality and public health, many studies documented concentrations of antibiotic resistance genes and some studies discussed their potential drivers. However, systematic and quantitative reviews that link antibiotic resistance genes (ARGs) to anthropogenic and environmental factors are limited. Nevertheless, this information will be important for developing regulation policy on controlling antibiotic use and therefore reducing potential risks to antibiotic resistance. I conducted meta-analysis of ARGs concentration at a global scale using Bayesian inference to explore climatic and socio-economic factors as drivers. I found local-scale climatic variables played a more important role in predicting concentrations of ARGs than the country-scale socio-economic variables. More specifically, the concentrations of ARGs increased with precipitation, and there existed an optimal temperature where the concentrations of ARGs reached a maximum. Then I initialized the study on antibiotic resistance bacteria in bottlenose dolphins Tursiops truncatus in relation to oil contamination following the 2010 BP oil spill in the northern Gulf of Mexico. Bacterial communities and antibiotic resistance prevalence were compared between Barataria Bay (BB) and Sarasota Bay (SB) by applying the rarefaction curve method, and linear mixed models. Finally, I collected surface water samples at upstream, outflow, and downstream of a WWTP at lower Pascagoula River in southeastern Mississippi from February to November in 2016. I then tested and quantified antibiotic resistance of bacteria in the water samples to three commonly used antibiotics: sulfamethazine, tetracycline and ciprofloxacin using both cultural and molecular methods. I was able to detect and quantify three different ARGs commonly found in the natural environment: Suf1, Suf2, and Int1. The lowest relative concentrations of all three ARGs occurred in the summer, and the highest relative concentrations occurred in February or April. The findings showed that anthropogenic pollutions increased ARB or ARGs in the aquatic systems, meanwhile climatic factors played an important role in affecting antibiotic resistance. The impact of temperature on antibiotic resistance shows large spatial variability at the country and local scales. Further research is required in order to understand how antibiotic resistance will change under global warming.

Available for download on Thursday, May 14, 2020

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