Isolation of L Type Growth from a Strain of Bacteroides funduliformis. ∗ †

Abstract

It has been described in a previous note that in cultures of certain bacterial strains belonging to various species tiny colonies, similar to young colonies of the pleuropneumonia group of organisms develop. 1 During the last year these colonies were isolated in pure culture from a strain of flavobacterium and one of Bacteroides funduliformis respectively. The colonies isolated from the flavobacterium always died out after 2 or 3 transplants; those isolated from the funduliformis apparently can be indefinitely maintained in cultivation. Colonies resembling those of the organism of pleuropneumonia bovis were first isolated by Klieneberger from cultures of Streptobacillus moniliformis. 2 She designates them with the letter L. Recently she described the isolation of similar cultures from a Gram negative streptobacillus causing suppurative lesions in guinea pigs. 3 The characteristics which differentiate these L type colonies from the usual bacterial colonies are the following:

The colonies are very tiny. The growth extends not only on but beneath the surface of the medium. The growing elements of the colonies are tiny pleomorphic granules and fine filaments which swell up and may form large round bodies of 5 to 10 micra. The pleomorphism of the cultures is accentuated by the softness of the elements. They are disfigured by the slightest tearing and for this reason are not recognizable in dry smears. The colonies have a marked tendency to autolyze.

A strain of funduliformis was isolated from a case of generalized peritonitis. Immediately after isolation the bacterium was similar in many respects to Streptobacillus moniliformis. It grew in the form of Gram negative segmented filaments which in fully developed colonies became pleomorphic and many of the bacteria swelled up into large round bodies.