Gram - positive coagulase-negative staphylococci, clinically relevant species implicated in latent infection of prosthetic biomaterials, produce a polysaccharide glycocalyx, or slime. Slime is a known virulence factor, enhanced by the presence of a foreign body. It appears critical to adhesion, proliferation and perhaps antibiotic resistance. Traditional aldehyde/osmium. tetroxide fixation approaches do not visualize slime. Preservation and/or staining of slime has been improved by the use of the cationic staining of slime has been improved by the use the cationic lysine. However, the fibrous outer slime often appears partial (as for example in Figure 31) Cells and Materials 1993 3 (3) p. 332) and rarely surrounds the cell body completely (as shown for example in Figure 2B or 3F Cell and Materials 1993 3: 327-336). The latter is thought to be more representative of the cell in situ. Thus confirmation of the structures seen by alternative methodologies is desirable. High pressure freezing followed by freeze substitution and LR White processing would provide an alternative of cryo-fixed cells in vitreous ice without the formation of damaging ice crystals. If successful, this approach could be used to explore the action of ruthenium red and alcian blue as well as the impact of antibiotics on slime. Further work could include the adhesion and proliferation of these organisms, in the presence or absence of antibiotics, on prosthetic biornaterials.
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