Browsing by Subject "staphylococcus aureus"
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Item Blood Serum Affects Polysaccharide Production and Surface Protein Expression in S. Aureus(2017-03-03) Islam, Nazrul; Hossain, Khwaja G.; Ross, Julia M.; Marten, Mark R.Background: S. aureus biofilm serves a major role in pathogenesis. Two of the major components of bacterial biofilm are Polysaccharides intercellular adhesions (PIA) and surface proteins. It is not known how PIA and surface proteins expressions are affected in presence of blood serum. Analyses of surface proteins expressions will provide more effective biomarker discovery that might lead to development of antimicrobial therapeutics to meet the challenges of biofilm-related infections. Method: Secondary cultures of S. aureus Philips, a biofilm-forming bacterium, were generated by inoculating 1 ml of overnight culture into 50 ml of TSB. Bacteria were cultured at several concentrations of blood serum and found that 12.5% supplemented blood serum provide s similar growth curve as normal TSB (100%). One and 2 D SASPAGE were used to separate proteins and the differentially expressed proteins were identified by nano-LC/MS. Results: Polysaccharide intercellular adhesions production was significantly increased due to the addition of blood serum in the media. We also identified two serum proteins, apolipoprotein and globulin (Fc and Fab), that remained attached with the membrane fraction of bacterial proteins. Conclusion: These results have strongly demonstrated that blood serum influences the exopolysaccharide expression in S. aureus.Item Proteomic analysis of Staphylococcus aureus biofilm cells grown under physiologically relevant fluid shear stress conditions(BioMed Central Ltd, 2014-04-30) Islam, Nazrul; Kim, Yonghyun; Ross, Julia M.; Marten, Mark R.Background: The biofilm forming bacterium Staphylococcus aureus is responsible for maladies ranging from severe skin infection to major diseases such as bacteremia, endocarditis and osteomyelitis. A flow displacement system was used to grow S. aureus biofilms in four physiologically relevant fluid shear rates (50, 100, 500 and 1000 s−1) to identify proteins that are associated with biofilm. Results: Global protein expressions from the membrane and cytosolic fractions of S. aureus biofilm cells grown under the above shear rate conditions are reported. Sixteen proteins in the membrane-enriched fraction and eight proteins in the cytosolic fraction showed significantly altered expression (p < 0.05) under increasing fluid shear. These 24 proteins were identified using nano-LC-ESI-MS/MS. They were found to be associated with various metabolic functions such as glycolysis / TCA pathways, protein synthesis and stress tolerance. Increased fluid shear stress did not influence the expression of two important surface binding proteins: fibronectin-binding and collagen-binding proteins. Conclusions: The reported data suggest that while the general metabolic function of the sessile bacteria is minimal under high fluid shear stress conditions, they seem to retain the binding capacity to initiate new infections.Item Quantitative analysis of the accumulation, architectural organization, detachment and reseeding of Staphylococcus aureus biofilms under physiological fluid shear conditions(2009-01-01) Ymele-Leki, Patrick; Ross, Julia M.; Chemical, Biochemical & Environmental Engineering; Engineering, Chemical and BiochemicalStaphylococcus aureus is an opportunistic gram- positive pathogen responsible for a wide variety of animal and human infections. In humans, it is associated with both superficial and invasive cases of infections, including bacteremia, endocarditis, osteomyelitis, septic arthritis, keratinitis, pneumonia and catheter- related infections. The prevalence of S. aureus as a human pathogen has been attributed to its ability to form specific bonds with a wide variety of extracellular matrix ( ECM) proteins. These binding events contribute significantly to the molecular mechanisms of S. aureus virulence. Additional virulence properties incur from its capacity to colonize surfaces in organized biofilm communities and from the occurrence of secondary metastatic infections caused by bacterial cells detaching from biofilms growing under shear stress. Microbial biofilms have also been associated with the spread of community- acquired bacterial infections and the emergence of resistant bacterial variants. The treatment of biofilm- associated infections costs over $ 1 billion annually in the United States. As a result, the study and characterization of microbial biofilms is rapidly gaining interest in the scientific community. The overall ambition of this project was to investigate the effects of physiologically relevant hydrodynamic forces on the accumulation and proliferation of S. aureus biofilms onto biotic substrates. Additionally, we evaluated the ability of sodium metaperiodate to inhibit the growth of S. aureus biofilms in vitro under both static and dynamic conditions. In the course of these studies, we demonstrated that: 1) hydrodynamic forces and nutrient availability modulate the rate of growth and the internal structure of early S. aureus biofilms grown on biotic surfaces; 2) through the process of erosion, S. aureus biofilms grown under physiologically relevant hydrodynamic conditions release planktonic cells with reduced adhesion avidity to ECM proteins; 3) these eroded planktonic cells demonstrate the potential to initiate secondary biofilm formations; and 4) under hydrodynamic conditions, S. aureus biofilms can withstand antimicrobial challenges that would otherwise be detrimental to sessile cultures grown under static conditions and to individual cells grown in suspension. The current research extended our understanding of the physiological effects of fluid shear forces on the development of S. aureus biofilms. It is essential to establish the principal factors leading to the multilayered accumulation of staphylococcal biofilms in vivo in order to design alternative therapeutic approaches to treating S. aureus infections.