Characterization of virulence phenotypes in shiga-toxin producing Escherichia coli O157:H7 and O113:H21 serotypes

Sebastian, Eliza A.
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Shiga toxin-producing Escherichia coli (STEC) is a deadly human pathogen that causes gastrointestinal infections worldwide. The main virulence factor of STEC is the production of Shiga toxins (Stx), which is associated with life threatening complications, such as hemolytic uremic syndrome and hemorrhagic colitis. The toxin is prevalent in three allelic variants Stx1, 2 and 2c and is located in the genomes of temperate bacteriophages. Determination of serotype-specific and shared pathogenic traits that underlie severe human diseases in two STEC O157:H7 and O113:H21 serotypes remain to be elucidated. In order to gain further insight into the effect of the antibiotic, ciprofloxacin and mitomycin C was observed on bacterial growth and a series of growth curves were recorded for both O157:H7 and O113:H21 serotypes. This was conducted in order to determine both optimal time points and antibiotic concentrations for virulence assays. Reversed passive latex agglutination assays (RPLA) and Enzyme-linked immunosorbent assay (ELISA) were also used to determine Stx2 toxin production. Further studies are needed to understand O113:H21 serotypes, such as determining Stx2-specific phage mobilization and Stx2 transcript levels post antibiotic treatment. The characterization of Stx virulence phenotypes can serve as direct indicator of human disease severity.

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E. coli, Shiga toxin
Integrative Biology