Assessment of the effect of small colony variant bacteria on wound healing
Cardiff Metropolitan University
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Small colony variants are novel sub-population of bacteria that are better able to persist mammalian cells and are more resistant to antibiotics than their wild-type progenitor. Those features allow them to cause latent and recurrent infections, especially in burn wounds. Aim of the project was to find out how different sub-populations from same strain affect wound healing, secreted bacterial factors or biofilm formation are more pathogenic to the wound, and what immune response different sub-populations awoke in the skin. In vitro analysis, including Scratch assay, was done using spontaneously immortalised, human keratinocyte cell line HaCaT. Cells were scratched with a fine pipette and 5:1 ratio of HaCaT and bacterial samples were fused to measure the effect on healing. Scratch assay was followed by two ELISA experiments. ELISA kits were used to measure the concentrations of Interleukin-1β and Interleukin-8 being excreted after 48h lasting Scratch assay. Results of the experiments revealed that there is no significant difference in healing whether Wild-type or SCV population was present, but interestingly, supernatant was proven to contribute as a virulence tool more than biofilm formation. We therefore hypothesise that SCVs allow bacteria to survive within a host by attenuation of virulence and by provoking a diminished immune response and when environmental conditions are favorable, they revert to a more virulent phenotype. It is possible that by this mechanism, recurrent infection post-antimicrobial treatment could occur. For example, in an infected wound treated with topical antimicrobial treatment the SCV phenotype could arise, upon cessation of symptoms, treatment is stopped but SCVs remain subsequently reverting to a WT-like phenotype (R) and causing re-current infection.
BSc (Hons) Biomedical Science
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