Examination of the glycocalyx of four species of Staphylococcus by transmission electron microscopy and image analysis.

The coagulase-negative staphylococci have become important pathogens in human infections involving foreign bodies. The bacterial glycocalyx is a major mediator of attachment of these organisms to medical devices, but the glycocalyx is sometimes difficult to demonstrate. A combination of the techniques of transmission electron microscopy (TEM) and image analysis enabled investigators to reveal the glycocalyx which was previously indiscernible. Eight strains of coagulase-negative staphylococci, including Staphylococcus epidermidis, S. hominis, S. lugdunensis, and S. schleiferi subspecies schleiferi, were grown, treated with anti-staphylococcal serum to stabilize the glycocalyx, and examined by TEM. Image analysis of negatives was then used to enhance the visual images which showed far more glycocalyx than previously seen by TEM alone.