368 BACTERIA PATHOGENIC TO MAN 



that should never be neglected in differentiating this organism from 

 others which are morphologically similar. 



Biology. Grows best at blood temperature; the limits being roughly 

 25 and 40 C. It is a facultative anaerobe. It is not motile and produces 

 no spores. 



Culture Media. The gonococcus requires for its best growth the ad- 

 dition to nutrient agar of a small percentage of blood serum or some 

 equivalent. The following media have proven of value : 



1. Human blood from the sterilized finger streaked on common 

 nutrient agar. 



2. Human-blood serum, 1 part added to and mixed with 2 parts 

 melted 5 per cent, glycerin nutrient, 1.5 per cent, agar having a tem- 

 perature of 55 to 60 C. The whole after mixing being poured into 

 a Petri dish or cooled slanted in a tube. The same proportions of 

 nutrient broth and serum make a suitable fluid media. 



3. Human ascitic, pleuritic or cystic fluid in same proportions as blood 

 serum. One per cent, glucose may be added. 



4. Swine serum nutrose media. Wasserman strongly recommends 

 this mixture. (See under Media.) In our hands it has given good results. 



5. Nutrient or 5 per cent, glycerin agar. When considerable pus is 

 streaked on simple agar media a good growth of gonococci is usually 

 obtained. After continued cultivation gonococci cultures frequently 

 grow on media containing no serum. Some strains grow on ordinary 

 glycerin or glucose nutrient agar from the start. 



Viability. Cultures frequently die in forty-eight to seventy-two 

 hours when kept at room temperature. In the ice-box they may live 

 for several weeks. Most cultures require the serum media for the 

 later cultures, 



Appearance of Colonies. A delicate growth is characteristic. At the 

 end of twenty-four hours there will have developed translucent, very 

 finely granular colonies, with scalloped margin. The margin is some- 

 times scarcely to be differentiated from the culture medium. In color 

 they are grayish- white, with a tinge of yellow. The texture is finely 

 granular at the periphery, presenting punctated spots of higher refrac- 

 tion in and around the centre of yellowish color (Fig. 113). 



SURFACE STREAK CULTURE. Translucent grayish-white growth, 

 with rather thick edges. 



Resistance. The gonococcus has but little resistant power against 

 outside influences. It is killed by weak disinfecting solutions and by 

 desiccation in thin layers. In comparatively thick layers, however, as 

 when gonorrhoeal pus is smeared on linen, it has lived for forty-nine 

 days, and dried on glass for twenty-nine days (Heiman). It is killed 

 at a temperature over 42 C. 



Occurrence of Gonococci. Outside of the human body or material 

 carried from it gonococci have not been found. 



Pathogenesis. Non-transmissible to all animals. Both the living 

 and dead gonococci contain toxic substances which cause death or 

 injury when injected in large quantities. 



