ELECTRON-MICROSCOPIC DEMONSTRATION OF EXTRACELLULAR STRUCTURE OF BURKHOLDERIA-PSEUDOMALLEI

The occurrence of latency and relapse in human melioidosis suggests ad aptations by Burkholderia pseudomallei that help to avoid the human im mune response. Ruthenium red-stained preparations of bacterial culture s viewed by electron microscopy revealed three morphologically distinc t variants; one with a very marked and another with a less electron-de nse layer surrounding the cell wall, and a third variety devoid of suc h a structure. This structure may be attributable to a layer of polysa ccharide, suggesting the presence of a glycocalyx that may aid in the survival of the organism during latency.