Further Observations on the L Organism of Klieneberger

Abstract

The L organism which Klieneberger 1 isolated from the cultures of Streptobacillus multiformis and more recently directly from pathological lesions of rats presents many characteristics which are not observed in bacteria. It has a marked similarity to a group of microörganisms, the main representative of which is the causative agent of pleuropneumonia bovis. The relation of this group to the well characterized classes of microörganisms is obscure. The L organism starts to grow in very small units which pass readily through a coarse bacterial filter. Later the small forms develop into large yeast-like bodies. Probably the small bodies are reproduced by the disintegration of the large forms. In all stages of development the organism is very fragile and its form can be seen only by using special technic. Since pleuropneumonia-like organisms occur in different animals 2 and probably also free in nature, 3 their occurrence in rats is not unexpected. However, it is very surprising to find such organisms regularly in the cultures of a bacillus.

Klieneberger regards the connection between the L organism and streptobacillus as a symbiosis. The two main arguments in favor of this supposition are: (1) the striking differences between the L organism and the bacillus; (2) the constancy of the properties of the L organism which in several years of cultivation never reverted to bacterial forms. The occurrence of L organisms without bacteria in animal lesions and the observation that the L organism forms mixed cultures with bacillus tetanus and certain other bacteria, give further support to the hypothesis that the L organism is a symbiont of the bacillus.

The observations which are here reported do not agree with this supposition. In the colonies of the streptobacilli the characteristic swollen forms do not develop as a separate growth admixed with the bacteria but are produced by the swelling up and transformation of the streptobacilli themselves. These large forms persist for a while or soon degenerate, but neither in the original cultures nor in transplants do they show any signs of multiplication. A transplant from a colony consisting mostly of the large forms gives a pure culture of the bacilli.