UBC Theses and Dissertations
Characterization and intervention of Campylobacter jejuni persistence and biofilm formation Feng, Jinsong
The hard-to-treat chronic bacterial infection is one of the most significant challenges to conventional antibiotic therapy. These chronic infections represent an elevated risk for the development of severe clinical consequences. Bacteria can form biofilms or persister cells to withstand harsh stresses and antibiotic treatment. In addition, both biofilm and persister cells can restore the bacterial population upon the removal of stresses and antibiotic treatment. Hence, biofilm and persister cells are proposed to be one of the major survival strategies that associate chronic bacterial infections. As one of the major causes of human gastroenteritis in the world, Campylobacter jejuni was frequently identified in food production as well as in the environment. However, how can this microaerophilic microbe survive in the aerobic environment and disseminate throughout the food chain to eventually cause campylobacteriosis is not fully understood yet. We argued that bacterial biofilm and persister cells be two particular survival state of C. jejuni that contribute to the prevalence of C. jejuni. In this dissertation, particular survival modes of C. jejuni, known as biofilm and persister cells, were characterized. We found that C. jejuni could form both mono- and multispecies biofilms and biofilm formation was significantly influenced by environmental stresses. The extracellular DNA was the factor that mediated this influence. In addition, we identified the presence of C. jejuni persister cells which accounted for ~ 0.01% of the total population. The transcriptome analysis of persister cells indicated that the low metabolic activity and bacterial dormancy could play an important role in the formation of persister cells. In the end, a synergistic treatment using ajoene and Al₂O₃/TiO₂ nanoparticles in a combined manner was applied to generate a significant antimicrobial effect against C. jejuni. In this study, we comprehensively investigated the two major bacterial survival strategies, namely biofilm and persister cells, and applied innovative antimicrobial treatment to inactivate C. jejuni. The knowledge from this study provides insight to understand the survival and distribution of C. jejuni and aids in the development of intervention strategies to reduce the prevalence of C. jejuni and other pathogens.
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