Alia Ahmed, “Lateral Flagella of Aeromonas Species Strongly Associate With Bacterial Adhesion to Human Colonic Epithelial Cells”
Mentor: Troy Skwor, Biomedical Sciences
Poster #214
Globally, millions of people are afflicted with bacterial gastroenteritis. Pathogens involved in these illnesses are successful due to their ability to invade mucosal linings, bind to host epithelial cells and produce various toxins. Gram-negative Aeromonas species are bacteria that have been identified as emerging opportunistic pathogens capable of causing gastroenteritis. To cause disease, this genus carries an arsenal of virulence factors such as enterotoxins, degradative enzymes, as well as both polar and lateral flagella. Considering colonization is one of the first steps of pathogenesis, the purpose of our study was to (i) establish a bacterial adhesion assay to examine binding to human colonic epithelial cells (HT-29) and (ii) determine if encoding the lateral flagella gene lafB is associated with increased binding to human epithelial cells. To examine adhesion, bacteria were incubated with HT-29 monolayers at a ratio of 100:1 for 90 minutes and subsequently washed to remove non-adherent bacteria. To quantify bound bacteria, human cells were lysed with Triton X-100, followed by plating serially diluted bacteria to determine colony forming units. To establish the adhesion model, a clinical uropathogenic Escherichia coli strain was utilized as a positive control due to encoding genes previously associated with binding: fimH and afa. The negative control was an E. coli lab strain, DH5-a. To examine the role of lateral flagella (lafB) in colonization, PCR was used to identify its presence amongst clinical and environmental Aeromonas populations. Our findings show both clinical and environmental lafB+ strains consistently colonized HT-29 cells at one log or higher rates than four other clinical and reference lafB- strains. One clinical, multi-drug resistant strain of Aeromonas hydrophila had over two logs more bacteria bound than lafB- clinical strains. Such findings may aid in future utilization of lafB as a potential vaccine or drug target to combat severe gastrointestinal infections.