MICROCOCCUS NEOFORMANS 769 



2. Micrococcus neoformans. 



Doyen has found in all malignant growths and in many benign growths a coccus 

 which he has named the Micrococcus neoformans. This organism appears to be the 

 " habitiial parasite " of rapidly-growing tumours in man. Doyen has also found 

 the same organism in a rat (renal carcinoma), in a mouse and in a bitch (cancers of 

 the mammary gland). 



The coccus of Doyen, the specificity of which is more than doubtful, can also be 

 found on the healthy skin and in glandular lesions not of a cancerous nature. Borrel 

 has isolated it several times from cases of tuberculous mammitis. 



Detection of the parasite. Doyen sows small pieces of tumours in a broth made 

 with cow's udder and prepared in the same way as ordinary peptone broth, using 

 500 grams of minced cow's udder freed from fat in place of meat. 



From a non- ulcerated tumour remove with the necessary aseptic precautions 

 small pieces of tissue and sow them in tubes containing about 1 c.c. of udder broth : 

 the culture grows best when the tissue is not completely immersed in the culture 

 medium. The coccus grows in 16-18 hours at 37 C. but it is not an uncommon 

 experience to find that no growth is visible until about the fifth day. 



Morphology. Jf. neoformans is a very small coccus (0'5-2M in diameter), some- 

 times arranged singly, sometimes grouped in motile diplococci (Isaza), occasionally 

 forming triads, tetrads or chains of 4 to 9 irregular elements. 



It stains well with the basic aniline dyes and is gram-positive (at least in young 

 forms). 



It is a facultative aerobe. On sloped agar it produces a moist whitish streak 

 which becomes glairy and ropy after 2 or 3 days. It liquefies gelatin, liquefaction 

 commencing about the fourth day at 20 C. (In this it is differentiated from the 

 pleomorphic coccus of the skin which does not liquefy gelatin.) 



Experimental inoculation. Inoculation of M. neoformans sets up in most mice 

 and in white rats after 2 or 3 months lesions of a neoplastic nature which terminate 

 fatally (Gobert). The lesions experimentally produced are indifferently of meso- 

 dermic or epithelial origin (lipomata, sarcomata, enchondromata, adenomata, 

 papillomata). 



It is best to inoculate into the peritoneal cavity : the lesions produced affect 

 especially the lung, occasionally the liver and lymphatic glands. In a bitch, Doyen 

 produced two sub -cutaneous lipomata in the region of the mammary glands. 



To obtain these results Doyen inoculated an emulsion made with fragments of 

 tumours which had been cultivated in broth for 6 or 7 days and the product from 

 scraping agar tubes sown with this broth (Gobert). It was therefore not a pure 

 culture which was inoculated but a mixture of a pure culture and ground-up cancer 

 tissue. 



Borrel has noticed bronchial proliferations, similar to those described by Doyen, 

 in rats which had died spontaneously with pulmonary abscess. 



Toxin. The inoculation of filtered glycerin- broth cultures into persons suffering 

 from cancer is followed by a reaction similar to that which tuberculin produces in 

 tuberculous persons (Doyen). 



Isaza proposes that this toxin should be used in the treatment of cancer. 



Doyen has prepared a vaccine with M. neofoimans and speaks favourably of the 

 results obtained in the treatment of human cancer. [Sir Almroth Wright endorses 

 Doyen's opinion as to the use of vaccines and thinks they relieve pain.] 



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