786 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



Gonorrhoea has been known from the very earliest times. In 1879 

 the diplococcus was pointed out by Neisser as the probable cause. 

 Bumm in 1885 first cultivated it on coagulated human placental serum. 



The microorganisms can be easily stained in the typical early dis- 

 charges where it occurs in pairs and for the most part within cells 

 (Fig. 166). 



For isolation, sterile human blood, blood-serum or ascitic fluid should be added 

 to melted nutrient agar at about 45. Thompson's plasma glucose agar and Wasser- 

 mann's swine-serum-nutrose medium are also good. The Gonococcus is about o.6ju 

 to o.S/x in diameter. It is usually seen in pairs; where the adjacent sides of the 

 cocci are flattened the long diameter of the pair reaches as much as i.6/x; non-motile, 

 and forms neither spores nor capsules. It stains readily with the aniline dyes and 

 is Gram-negative. The temperature range is 30 to 38.5 with an optimum of 37.5. 

 Aerobic conditions are preferred with a reaction about 0.6 per cent, acid to phenol- 

 phthalein, but Ruediger reports luxuriant growth in air-tight-tubes of special neu- 

 tral serum agar. On serum agar or similar suitable media, colonies appear in 

 twenty-four hours as fine slightly elevated, translucent or opalescent spots frequently 

 referred to as "dew-drop" colonies. They possess a faint bluish or grayish white 

 color with a slightly marked concentric or radial striation with a scalloped margin 

 and finely granular center. In serum broth there may occasionally be a uniform 

 clouding though, as a rule, there is a finely granular, somewhat slimy sediment with 

 clear fluid above. Only in exceptional cases has growth been observed in gelatin 

 because of the unfavorable temperature. On inspissated blood serum growth may 

 sometimes be observed as discrete pale yellowish or brownish colonies. Dextrose 

 is changed with the development of acid but no gas. Alkali is not formed in any 

 medium by typical strains. No gas, indol or pigment are formed. The toxins are 

 intracellular and quite thermostable. Resistance is very slight toward external 

 influences. Cultures undergo rapid autolytic changes and die out at room tempera- 

 ture, often within forty-eight hours. A temperature of 41 to 45 will kill in a few 

 hours. To light and drying they are also very sensitive, and are rapidly killed by 

 the ordinary disinfectants. 



Animals inoculated subcutaneously or intraperitoneally show symp- 

 toms of poisoning with suppuration and necrosis locally and may 

 succumb. 



The virulence of the organism is variable. They may apparently lie 

 dormant or rather, may remain very slightly active in chronic conditions 

 in one individual but set up an acute gonorrhoea when transferred 

 to a second person. 



The organism gains entrance to the urethral mucosa or conjunctiva 

 usually by direct contact and it is doubtful if the disease could be 

 carried by any infected article later than twenty-four hours. 



