270 BACTERIOLOGY FOR NURSES 



by drying, and should first cultures be unsuccessful a second at- 

 tempt may be made by using the dried granules in the same manner 

 as the fresh ones. If after several days' incubation growth has 

 occurred in the inoculated tubes colonies appear as opaque white 

 nodules, most numerous about 7 or 8 mm. below the surface. A 

 characteristic colony may be cut out of the agar by means of a 

 platinum wire and transplanted into a fresh tube of melted glucose 

 agar. 



Resistance. The organisms show considerable resistance 

 to drying. On the walls of a test tube they may be found alive 

 after seven weeks and in cultures for a year or more. 



Pathogenesis. Only slight local lesions can be produced by 

 the inoculation of pure cultures into the smaller animals such as 

 guinea pigs and rabbits ; cattle, however, are very susceptible to 

 the disease and in a less degree horses and swine also. In cattle 

 there is usually an abundant growth of granulation tissue which 

 results in large tumor-like masses. The disease may remain local 

 or spread by continuity; it usually appears in the head or neck 

 and produces the condition known as " lumpy jaw." Lesions 

 may occur in the lungs, subcutaneous tissue, skin, liver, and other 

 organs. Death resulting from actinomycosis is due rather to the 

 mechanical action of the tumor in pressing upon or occluding the 

 respiratory or alimentary tract rather than to any toxic effect. 



In man the disease manifests itself in a similar manner save 

 that there is generally less production of new tissue and more 

 extensive suppuration. It may terminate fatally in a short time 

 through a secondary infection or it may take a chronic course 

 for years. Treatment with potassium iodide has effected cures 

 both in man and cattle although its method of action is still 

 unknown. 



Mode of Infection. Transmission by direct contact has not 

 been satisfactorily proven. Many cases in human beings have 

 been reported, in which so far as could be discovered no contact 

 with a previously existing case had occurred. The frequent local- 

 ization of the disease in the head and jaw has led to the supposi- 

 tion that the organism enters the body by way of the mouth, 



