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Characterizing the hemolytic activity of Staphylococcus aureus clinical isolates

Description

Abstract:
Staphylococcus aureus is a gram-positive antibiotic-resistant pathogen that poses a growing global health threat. Bacteria produce virulence factors, including hemolysins, and can form biofilm matrices that render first-line treatments ineffective. As available treatments have the limitation of causing host cell damage despite reducing bacterial burden, there is a need to establish a translatable infection model in vitro to bolster the development of a therapeutic. The goal of this thesis is to explore the hemolytic activity of 10 clinical isolate strains, both in planktonic and biofilm states, in various growth conditions to observe the relationship of hemolysis and growth media. These experiments consisted of quantitative hemolysis assays in which planktonic and biofilm strains were grown in various media environments, and the hemolytic activity of these bacterial supernatants was observed in 5% (v/v) rabbit red blood cells. Our findings reveal that bacterial biofilms have greater hemolytic activity per 1 log colony forming unit per milliliter (CFU/mL) of bacteria than their planktonic counterparts across all media tested. These results suggest that the hemolytic activity of bacterial biofilms is not dependent on the media in which they are cultured. In contrast, planktonic bacteria hemolytic activity data suggest a dependence on the media environment. The 9/10 of the planktonic strains tested had the greatest hemolytic activity when grown in BHI compared to other growth media. Future studies should investigate the relationship of other virulence factors produced by S. aureus and media environments to better understand the circumstances of bacterial pathogenicity in vitro.
Notes:
Thesis (Sc. M.)--Brown University, 2023

Citation

Carneiro, Olivia, "Characterizing the hemolytic activity of Staphylococcus aureus clinical isolates" (2023). Biology and Medicine Theses and Dissertations, Biotechnology. Brown Digital Repository. Brown University Library. https://repository.library.brown.edu/studio/item/bdr:y2epf7rb/

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