Chapter XI 



ACTINOMYCETES AS CAUSATIVE AGENTS 

 OF HUMAN AND ANIMAL DISEASES 



Etiology of Infections:— It has now been definitely established that 

 certain diseases are caused by actinomycetes, the anaerobic and aerobic 

 types; the latter comprises both acid-fast and non-acid-fast forms. 



The specific nature of the organisms that are capable of causing acti- 

 nomycotic infections in animals and man has aroused considerable dis- 

 cussion and has often been the cause of much confusion. Despite the 

 fact that an animal pathogen, A. hovis, was among the first actinomy- 

 cetes ever described and has given the very name, Actinomycetales, to 

 the order of the organisms, and despite the very extensive literature that 

 has accumulated on the pathogenic nature of certain actinomycetes, the 

 identities of the specific agents that cause actinomycotic diseases in man 

 and in animals have been the subject of much disagreement. No at- 

 tempt will be made here to review this literature, an early summary' of 

 which was made by Musgrave et al. (310). Attention will merely 

 be directed to some of the more recent investigations. 



Wright (519) made a detailed study of the cultural characteristics 

 of a number of isolates of disease-producing strains of actinomycetes 

 from animals and from man. He came to the conclusion that onlv a 

 single anaerobic species was involved. He believed that the reported 

 isolations by Bostroem and others of aerobic forms responsible for 

 disease conditions were merely contaminations. These conclusions 

 were drawn by many other investigators. The very extensive literature, 

 however, on JSlocardia asteroides definitely pointed to the fact that ac- 

 tinomycetes causing infections in man and in animals comprise both 

 anaerobic and aerobic organisms. The existence of various types of 

 clinical actinomvcosis has been emphasized. This is brought out, for 

 example in the work of Naeslund, as summarized in Table 44. 



Henrici (169) recognized three well-defined types of infection in 

 man and in animals caused by actinomycetes: (n) the lumpy jaw type, 

 which is the most common infection and is produced by an organism 

 belonging to A. hovis, first isolated by Israel; (I?) the madura foot type, 

 caused by an aerobic form which is usually designated as Nocardia ma- 

 durae (438); (c) the rare infection type, comprising N. asteroides 

 (109), which is found most frequendy in man, and N. farcinica (324), 

 which occurs in cattle. 



