Diphtheria (Corynebacterium diphtheriae) Corynebacteria are Gram-positive, aerobic, nonmotile, rod-shaped bacteria related to the Actinomycetes. They do not form spores or branch as do the actinomycetes, but they have the characteristic of forming irregular shaped, club-shaped or V-shaped arrangements in normal growth. They undergo snapping movements just after cell division which brings them into characteristic arrangements resembling Chinese letters. The genus Corynebacterium consists of a diverse group of bacteria including animal and plan ....