The pleuropneumonia-like organisms: further comparative studies and a descriptive account of recently discovered types

Abstract

1. The four different L1 strains in the writer's possession isolated between 1933 and 1936 have been maintained for a further period without reverting to Streptobacillus moniliformis. The supposition that the L1 is a pleuro-pneumonia-like organism and lives in symbiosis with a bacterium in cultures of S. moniliformis is still maintained by the writer and the reasons for it are given.2. From a culture isolated from lesions in guinea-pigs and pathogenic for these animals called the “guinea-pig strain”, an L1-like organism of the pleuropneumonia group has been separated, but not yet been maintained for a long enough period to ensure irreversibility. The morphology of the “guinea-pig strain” shows that it is closely related to S. moniliformis though it can be distinguished from the latter by its cultural and pathogenic properties. The morphology of two other cultures, viz. a saprophytic coccus from the skin of a pig and the organism known as Fusobacterium nucleatum, have been described as possibly representing similar symbiotic associations of bacteria and pleuropneumonia-like organisms.3. Cultural and serological differences between the L4 causing arthritis, swollen glands and abscesses in rats, and the two other pleuropneumonia-like organisms from rats, L1 and L3, are recorded. It has been shown that the organisms occurring in the brains of mice, L5 and L6, and in the joint of a mouse, “M55”, are of aetiological significance for the condition in which they occur. At the same time they differ in their colony type, morphology and serological features.4. Morphological and serological studies of the saprophytic organisms of the pleuropneumonia group isolated by Laidlaw & Elford and Seiffert from water and soil show that Seiffert's organisms are closely related to Laidlaw & Elford's type “A”. In agreement with Laidlaw & Elford it was found that their type “B” is slightly different from “A” serologically, while “C” is distinct from “A” and “B” and may be regarded as a special type.These saprophytic types are not antigenically related to the parasitic varieties.