Abstract
The production of experimental pneumonia in dogs by means of intra-bronchial insufflation of bacterial cultures has now been carried out in several series of investigations. In the first series Lamar and Meltzer produced lobar pneumonia by insufflation of cultures of a virulent pneumococcus. In a second series we produced lobular pneumonia by insufflation of a virulent streptococcus and of the influenza bacillus. Besides the differences in the gross appearances of the lesions both pneumonias offered the following distinguishing points: In the lobar pneumonia of the virulent pneumococcus there was a mortality of about 16 per cent.; even in the non-fatal cases there was bacteremia present in the first twenty-four hours; the exudate was rich in fibrin and the framework of the lungs was invariably free from leucocytic infiltration. In the cases of broncho-pneumonia produced by the streptococcus or by the influenza bacillus there was no mortality; at no time was there a bacteremia; the exudate contained very little fibrin, but the framework of the lungs was invariably and often very intensely infiltrated with leucocytes.
In a third series of experiments, which has not yet been published, we studied the effects of insufflation of a non-virulent pneumococcus. This organism also caused the development of a lesion which macroscopically resembled the lesion of lobar pneumonia produced by the virulent pneumococcus. However, there was no mortality, no bacteremia, and an exudate comparatively poor in fibrin; the framework of the lung was here again practically free from leucocytic invasion.
The results obtained with the non-virulent pneumococcus led us to a study of the intra-bronchial insufflation of such a nonpathogenic organism as the B. megatherium. Ten experiments were made. The insufflation brought on a definite pneumonic lesion in every case.
Get full access to this article
View all access options for this article.