LYSINE EFFECT ON RUTHENIUM RED AND ALCIAN BLUE PRESERVATION AND STAINING OF THE STAPHYLOCOCCAL GLYCOCALYX

The effect of lysine on ruthenium red (RR) and alcian blue (AB) preservation and/or staining for transmission electron microscopy of glycocalyces was evaluated for three species of the gram-positive, coagulase-negative staphylococci. A RR and an AB procedure were compared with and without lysine included in the glutaraldehyde prefixation. Minimal or no glycocalyx was preserved or stained by glutaraldehyde fixation only. For all species, the inclusion of lysine increased visualization of fibrous material. RR treatment without lysine, results in sparse or limited fibrous material or artifactual condensations which contrasts with enhanced fibrous material seen when lysine is included with RR. The effect of lysine is also to enhance the visualization of staphylococcal glycocalyx by AB. Without lysine, condensed curved structures are consistently seen following AB processing. In contrast, extensive and elaborate glycocalyces are observed with inclusion of lysine with AB. Thus, ultrastructural visualization by RR and AB of the staphylococcal glycocalyx in the species studied was enhanced by use of lysine.