PATHOGENICITY OF C. REN ALE AND C. MURIUM 461 



The differential characters of the two organisms are enumerated on p. 469 under 

 C. equi. 



Enderlen (1890-91) described a diphtheroid bacillus that he had isolated from the 

 pus from a cow suffering from pyelitis. This organism has been named C renale. 

 A similar organism was isolated by Ernst (1905, 1906) ; and Jones and Little (1925) 

 record an outbreak of infective cystitis and pyelitis in three dairy herds associated 

 with the constant presence of a diphtheroid bacillus. In this last instance, at least, 

 there would seem to be no reasonable doubt that the bacillus was setiologically 

 related to the disease ; though the same organism may often be isolated from 

 the genital tract of healthy calves (Jones and Little 1930). There are as far as 

 we know no records of the lesions produced by this organism in laboratory animals, 

 though Jones and Little have reproduced the disease in cattle. Ernst, indeed, 

 stated that the bacillus isolated by him produced no lesions in any animal, and he 

 therefore regarded it as devoid of pathogenic significance. No attempt has appar- 

 ently been made to ascertain whether it produces a filtrable toxin. Its claim to rank 

 as a separate species must rest in part on its predilection for the urinary tract in 

 cattle, but mainly on its behaviour in the laboratory. It is recorded as not produc- 

 ing a hsemolysin and not liquefying gelatin, in both of which characters it differs 

 sharply from C. pyogenes (Merchant 1935). 



C. murium, which was first described by Kutscher (1894), gives rise to a 

 natural disease in mice, and its pathogenic activity is apparently confined to 

 this small laboratory animal. It has been injected without effect into the guinea- 

 pig, rabbit, cat, dog, pigeon, hen, rat, goat, calf, sheep, cow and horse (Kutscher 

 1894, Bongert 1901), but Gundel, Gyorgy, and Pagel (1932) have recorded spon- 

 taneous infections in rats on a vitamin-deficient diet. We may give here a brief 

 description of the natural disease as well as of the results of experimental inoculation. 



The natural disease has been described by Kutscher and by Bongert, and has been 

 observed on many occasions by the present authors during necropsies on mice, though it 

 is certainly relatively infrequent. The most characteristic lesion in the naturally-occurring 

 disease is the presence of large, firm, caseous areas in the lung. In sections or films from 

 these lesions the bacilli are usually abundant. Caseous nodules may be found in the liver, 

 though they are less frequent. When present they project from the surface, in contra- 

 distinction to the necrotic areas seen in mouse typhoid. The lymphatic glands of the 

 axilla, neck, mediastinum and mesentery may be enlarged and caseous ; but the pulmonary 

 lesions are frequently the only obvious sign of disease. Occasionally the bacillus may be 

 isolated from a single caseous gland, found at necropsy without any other detectable lesion. 



The disease may readily be reproduced by inoculating mice with pure cultures of C. 

 murium, or by administration per os. The findings at necropsy depend largely on the 

 route of administration. After feeding, lesions develop in the mesenteric glands and in 

 the fiver. After intraperitoneal inoculation, which usuaUy leads to death within a week, 

 the peritoneum is found to be studded with minute tubercles, and there is a spreading 

 granulomatosis, of very varying extent, involving the regional lymphatic glands, the liver, 

 and less frequently the spleen. In our experience pulmonary lesions are much less frequent 

 in the experimental than in the natural disease, though they occasionaUy occur. Bongert 

 ( 1901) has caUed attention to the trivial lesions which may sometimes be found post mortem 

 after experimental infection. In animals dying after subcutaneous inoculation the only 

 detectable lesion may be a smaU caseous abscess at the site of inoculation. Seeking an 

 explanation for this fact, he inoculated mice with filtrates of broth cultures, or with cultures 

 killed by heat, and found that death resulted in every case, after about 10-14 days. No 

 obvious lesions of any kind were found at necropsy. Mice fed with filtrates died in about 

 the same time, and with the same absence of lesions. We can in part confirm these findings 



