[Electron microscopic detection of spirochetes in dermatitis digitalis of cattle]

In typical Dermatitis digitalis (D.d.) lesions, spirochaete-like bacteria with variations in spiralization were revealed by electron microscopy. While, in the early stages of the disease, these are found to be associated with fibrillar material of keratocytes, they occur massively in vacuoles at more advanced stages. The spirochaetes carry one pair of endoflagella, originating with a hook from the poles of the bacteria. These flagellae are composed of coiled flagellating fibrils in the pole region, merging towards the centre of the bacterium. A coat of fibrils was found in association with the cytoplasmatic membrane. The winding of this coat follows and may influence the coiling of the protoplast, and is probably involved in the rapid motility of this spirochaetes, together with the flagella. Immuno-electronmicroscopy revealed an antigenic relationship with Borrelia burgdorferi, at least with regard to the regions of flagella and undulating membrane. The paper discusses: 1. The possible classification of these spirochaetes with the genus Treponema; 2. The layer of peptidoglycan occurring on the outer membrane; and 3. The keratolytic activity of spirochaetes in D.d.