Master's Theses



Degree Name

Master of Science (MS)


Antimicrobial compounds have been used by humans to counteract bacterial infections since 1910. Overuse of these compounds in clinical and agricultural applications has led to rapid evolution and global spread of antimicrobial resistance and rivers are the main receiving body for antimicrobials and resistant bacteria from urban effluents and agricultural runoff. When antimicrobial-resistant bacteria enter the aquatic environment, water acts as a physical pathway for their distribution. Subsequently, resistance genes become established in natural systems and pose threats to human health and ecological processes. Due to these potential threats, antimicrobial resistance in the aquatic environment should be closely monitored. To improve the understanding of antimicrobial resistance in two river systems in Kansas, intestinal contents from 20 Channel Catfish (Ictalurus punctatus) and water samples were taken at eight sites on the Arkansas and South Fork Ninnescah rivers during the spring of 2012. These samples were examined for resistance to six compounds representing major classes of antimicrobials and resistance was observed in 94 isolates. From these isolates, 39 bacteria species were identified by partial sequencing of the 16S ribosomal RNA gene. Resistant species included common isolates from the environment and pathogens of humans and fish. Minimum inhibitory concentrations were determined for bacteria resistant to azithromycin, ciprofloxacin, and tetracycline. Several isolates exhibited no zone of inhibition, indicating they were resistant to the maximum concentration of the assay. Multi-drug resistance was also observed in eight species.


Dr. William Stark

Date of Award

Spring 2014

Document Type



© 2014 Jordan R. Hofmeier


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