The Public Health Significance of the Fibrinogen-binding MSCRAMMs of Staphylococcus aureus

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The Ohio State University

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Infective endocarditis (IE) is a bacterial infection that has existed for multiple centuries and is a disease that has been constantly evolving. Recently, cases of IE caused by Staphylococcus aureus have been increasing gradually. To add to the problem, little is known about the mechanism in which S. aureus causes the heart infection. This study examined four different receptor proteins within the microbial surface components recognizing adhesive matrix molecules (MSCRAMM) family (ClfA, ClfB, FnbpA, FnbpB), that are present on the cell wall of S. aureus to understand each of their role when binding to fibrinogen (Fg), a key ligand in human hosts. The differences in binding to Fg for 7 different clinical isolates of S. aureus were analyzed using a 96-well microtiter plate apparatus. The binding to Fg for 5 reference strains of S. aureus (Newman strains and 8325-4) were also examined in the study. It was determined that the Newman strain that lacked ClfA had lower absorbance readings, indicating lower binding, than ones with ClfA and ones that lacked ClfB. In addition, clinical isolates, with an exception of one, exhibited comparably higher absorbance readings, indicating enhanced binding, relative to the Newman strains. The results pointed out that ClfA plays a critical role when binding to Fg, and both FnbpA and FnbpB are also equally important. Furthermore, it was discovered that the origin of the clinical isolates impacted binding to Fg. S. aureus specimens from the nasal cavity had lower absorbance readings compared to isolates that originated from the bloodstream of human patients.



Infective endocarditis, S. aureus, MSCRAMM, fibronectin binding protein, clumping factor, fibrinogen