Capnocytophaga: new genus of gram-negative gliding bacteria. II. Morphology and ultrastructure.

Gram-negative, anaerobic gliding bacteria were isolated from normal supragingival plaque and from periodontal lesions. Isolates could be divided into two size classes: small 2.4-4.2 micrograms x 0.38-0.5 microgram and large 4.8-5.8 micrograms x 0.42-0.6 microgram cells. The outer membrane was either loose-fitting and wavy, or taut, and of variable thickness. An electron-dense fuzz was discernible on several of the isolates. The periplasmic region was of variable electron-density. The genus Capnocytophaga has been proposed for these organisms based on morphological and cultural characteristics.