ACTINOMYCES GROUP 



377 



There is no gas- or acid-production. A brown to black pigment 

 may be produced. 



Pathogenesis. Experimental Evidence. In the great majority 

 of cases experimental inoculation is without result. Many animals 

 have been used cattle, sheep, swine, dogs, cats, rabbits, and 

 guinea-pigs. In relatively a few cases significant lesions have 

 been developed. Musgrave, Clegg, and Polk have produced 

 extensive suppurative lesions by intraperitoneal inoculation of the 

 monkey, the infection terminating fatally in about three weeks. 

 The common lack of pathogenesis may be due to differences in 

 resistance, to a diminution 

 of virulence due to cultiva- 

 tion, or to the manner of 

 inoculation. In cattle it 

 may gain entrance with a 

 grass awn, and this may 

 protect it from the de- 

 structive agencies of the 

 tissues until its pathogen- 

 icity is well established. 



Character of Disease and 

 Lesions Produced. A swell- 

 ing or tumor-like mass de- 

 velops in cattle at the site 

 of infection. This softens 

 and ultimately discharges 

 thick, yellowish pus. The 

 discharge after the lesion has opened may become intermittent 

 in character. When the tongue is the primary seat of infection 

 it becomes swollen, indurated, and protrudes from the mouth in 

 some cases. The bones of the jaw are often attacked. The 

 infection is chronic. Animals rarely die from immediate effects. 

 In a few instances metastatic infection of other parts of the body 

 than the head and neck have been reported. 



In man the disease usually attacks the softer tissues, progresses 

 more rapidly than in cattle, and is apt to terminate fatally from 

 metastatic infection. Whether or not the organism isolated from 

 human actinomycosis is the same as that found in cattle is uncer- 



Fig. 163. Actinomyces bovis (strepto- 

 thrix actinomyces), stained mount from cul- 

 ture-medium (Musgrave, Clegg, and Polk, 

 in " Philippine Journal of Science "). 



