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Access Type

Open Access Thesis

Document Type


Degree Program

Food Science

Degree Type

Master of Science (M.S.)

Year Degree Awarded


Month Degree Awarded



An increase in antimicrobial resistance bacteria has endangered our ability to treat infectious diseases. Lack of good in-vivo model has made it difficult to study antimicrobial resistance. In this study, we have used an inexpensive and short life span in-vivo model namely, Caenorhabditis elegans (C. elegans) to study antimicrobial treatment using pathogenic Escherichia coli O157:H7, a multidrug resistance bacterium that causes life threatening infection in humans.

We have investigated the influence of live vs. heat killed non-pathogenic E. coli OP50 (OP50) as a food source on the growth and survival of infected C. elegans mutant AU37 with E. coli O157:H7 in the presence and absence of antibiotics. This is analyzed using a liquid-based C. elegans-E. coli O157:H7 infection assay. C. elegans was synchronized and grown on a lawn of live OP50 till they reached L4-young adult stage. L4-young adults were transferred to liquid medium where the C. elegans was infected with live E. coli O157:H7 or live non-pathogenic OP50 for 24 hours. After infection, C. elegans were fed live or heat killed OP50 depending on the experiment, and the life span and levels of E. coli O157:H7 were monitored, with and without ampicillin treatment in a 96 well transwell plate.

Our results indicate that live OP50 is an ideal food source for C. elegans growth and survival to study antimicrobial treatment. C. elegans growth rate and survival decreased in presence of heat killed OP50, which makes heat killed OP50 as a non-ideal food source for antimicrobial assay. Moreover, using live OP50 we have discovered that the ampicillin dose 8mg/ml, 16mg/ml, and 32mg/ml are effective in increasing the survival of C. elegans infected with E. coli O157:H7. However, treatment on C. elegans infected with acid stressed E. coli O157:H7 is controversial.


First Advisor

Lynne A. McLandsborough

Second Advisor

Yeonhwa Park

Third Advisor

David A. Sela