[Experimental erysipelas in different species as a model for systemic connective tissue disease. I. Systemic vascular...

The similarities between erysipelas in animals and rheumatic diseases in man have been discussed since the work of Nieberle (1931). The present work sets out to investigate the course of organ manifestations in pigs, rats, and mice using germ-free or specific pathogen-free experimental animals. Particular consideration will be given to the initial systemic vascular processes as well as to the significance of the erysipelas antigen.

In several experiments, a total of 166 pigs--partly gnotobiotic or specific pathogen-free animals--37 specific pathogen free Wistar rats and 57 albino mice were orally and/or parenterally infected with standardized erysipelas strains of serotype B. Clinical examination post infection were carried out with the EKG and by x-raying the joints of the extremities. All large parenchymatous organs, as well as heart valves, aorta and synovia were examined histologically in paraffin sections. In mice and rats, joints of the extremities were embedded in toto in metracrylate. Besides various histological staining methods, histochemical reactions were used to demonstrate mucopolysaccharides and fibrin. The myocardium, central nervous system and synovia of several joints were examined with the electron microscope. In the pig, immunohistological methods demonstrating the presence of fibrin, complement and IgG, as described by Seidler et al. (1971) and Trautwein et al. (1972), were used.

The most important changes in joints, heart valves heart musculature and blood vessels occur during the early bacteriemic phase. A distinct sticking effect develops in the mouse 3.5 hours p.i., in the rat 24 hours p.i., and in the pig 36 hours p.i. Simultaneously, hyaline thrombi occur in capillaries and venules; these are seen as parallel, loosely-packed fibrin fibers in the electron microscope. With the aid of immunofluorescence fibrin, IgG and complement C3 can also be demonstrated here. Exudates rich in fibrin develop parallel to the microthrombosis. In pigs and rats vascular and myocardial necroses develop to 3 days p.i. The mice do not survive the 3rd p.i. 39% of the pigs showed edema and mesenchymal activation of varying intensity in the heart valves between the 3rd and 8th day p.i. Besides the insudation of the valves, endocardial thromboses developed in 80% of the mice. Endocarditis, aand in addition large aortic thromboses were recognized in more than 50% of the rats. As early as the 4th day p.i., coagulopathy, angionecrosis and exudation led to acute arthritic symptoms..