CHAPTER XXVI 



Animal Inoculation 



TI 1 E inoculation ol animals with material from patients lor the purpose 

 of diagnosis is seldom resorted to if a superficial infection is suspected. 

 Direct microscopic examination and a cultural study are preferable. For 

 patients with a deep mycosis, a positive diagnosis may he difficult; in such 

 instances the inoculation ol animals susceptible to the infection ma\ he 

 advisable. The kind of animal to be used may depend on the infecting 

 micro-organism, since there is variance in susceptibility. Animal inoculation 

 has also been used to determine pathogenicity when a new fungus is iso- 

 lated or when a fungus which is usually saprophytic is under suspicion. The 

 results must here be interpreted with caution, as differences in suscepti- 

 bilities of different laboratory animals show that human beings may like- 

 wise respond in an individual manner. At times, contaminating bacteria 

 and fungi crowd out the pathogenic growth on the agar slant. If the ma- 

 terial is injected into a suitable laboratory animal, the pathogenic- fungus 

 nia\ invade susceptible tissues and organs from which it may be cultured 

 in pure form. When a fungus becomes pleomorphic, its original appearance 

 may sometimes be restored by passage through a laboratory animal. Further- 

 more, the recovery and recognition of characteristic spore tonus may be 

 difficult from the cultural growth, whereas such forms may develop in 

 laboratory animals. 



(aiinea-pigs, rats, mice and rabbits are usualK employed, (aits (espe- 

 cially kittens) may be used for cutaneous inoculation. In the first group, 

 inoculations may be cutaneous, intraperitoneal or testicular. The inoculum 

 is usually a saline suspension freshly prepared from the cultural growth on 

 dextrose agar or from finch ground fresh tissue. The animal is examined 

 frequently for evidence of the infection. DeLamater and Benham described 

 the course of the infection in animals successfully inoculated with a ring 

 worm fungus. It is sufficient here to note that the response is confined to the 

 epidermal structures of the animal. When a "take" occurs alter inoculation 



2f>7 



