Morphological and Cultural Studies of the Genus Fusiformis

Abstract

A study of the morphological and cultural characteristics of fusiform bacteria is presented. 104 strains of fusiform bacteria were isolated from the oral cavity and grown in pure culture. Isolation was accomplished on 5% rabbit blood agar containing gentian violet 1 part in 5,000 or on 10% potato extract agar containing gentian violet 1 part in 10,000. 67 of these strains were studied in detail, including tests for saccharolytic activity, indol production, acid production, resistance to environmental changes and motility. No evidence was found to support the possibility of a generic relationship between the cultivated fusiform organisms and oral spirochetes. On the basis of the findings, it appears useful for the present to divide the fusiform bacteria into 3 "species"; Fusiformis nucleatus (p.520), F. polymorphus (p.522), and F. dentium (p.523). This differentiation into "species" is based on well-defined cultural and morphological differences.