650 NEISSERIA 



Neisseria gonorrhoeae 



Synonym. — Gonococcus. 



Isolation. — -First described by Neisser in 1879; first cultivated by Bumm (I8860, b), 

 and Leistikow and Loeffler (Leistikow 1882). 



Habitat. — Strict parasite of man. Found in genito-urinary system of patients suffering 

 from gonorrhoea. 



Morphology. — Oval or spherical coccus ; 0-8 fi X 0-6 /i, frequently arranged in pairs, with 

 adjacent sides flattened or slightly concave, resembling a pair of kidney beans ; 

 long axis of oval lies at right angles to axis joining the two cocci. In cultures 

 great variation in size and in depth of staining occurs, due to autolysis ; in the 

 body the cocci are more regular, and are generally intracellular. Non-motile, 

 non-capsulated. Gram-negative. 



Serum Agar Plate. — 24 hours, 37° C. Round, convex, or slightly umbonate, greyish- 

 white, translucent, amorphous colonies, 0-5-1 mm. in diameter, with smooth, glisten- 

 ing surface and entire edge ; consistency butyrous or slightly viscid ; fairly easily 

 eraulsifiable. Later, colonies increase in size, and may develop a roughened surface 

 and a crenated edge. 



Serum Agar Slope. — 24 hours, 37° C. Rather poor, partly confluent, raised, greyish- 

 yellow growth with smooth surface ; edge entire or formed of single colonies. 

 Consistency often viscid. 



Oelatin Stab. — No growth. 



Serum Broth. — 24 hours, 37° C. Very poor growth with little or no turbidity, and a slight 

 granular deposit, partly disintegrating on shaking. 



Resistance. — Highly susceptible to inimical agencies. When dried, the cocci succumb in 

 an hour or two. Killed by moist heat at 55° C. in less than 5 minutes, and at 42° C. 

 in 5-15 hours (Carpenter et al. 1933). In serum cultures they are killed by 1/4000 

 AgNOg in 7^ minutes, and in pus in 2 minutes. Sealed cultures kept at 37° C. 

 may live for 4 or 5 weeks ; when kept at room temperature, they die in a day or two. 



Metabolism. — Optimum H-ion concentration for growth is pH 7-5. Optimum tempera- 

 ture for growth is 37° C. ; no growth under 30° C. or over 38-5° C. Fails to grow 

 on plain agar as a rule ; requires the presence of serum, blood, ascitic fluid, or 

 hydrocele fluid ; glucose is not beneficial. Aerobic, but growth is said to be 

 improved by a lowered oxygen pressure, by presence of — SH groups, and by 

 10 per cent, of CO2 in the atmosphere. Little or no growth under strictly anaerobic 

 conditions. 



Biochemical. — Produces acid, no gas, in glucose. No change in litmus milk. Catalase-|-. 

 M.B. reduction— . M.R. — ; V.P. — ; indole — ; HgS — . 



Antigenic Structure. — No clear definition into separate serological tjrpes ; most strains 

 appear by agglutination and absorption of agglutinins to belong to one or other of 

 two main groups ; numerous other less important groups. 



Pathogenicity. — Responsible for gonorrhoea and ophthalmia neonatorum in man. Experi- 

 mentally, it proves fatal to mice, guinea-pigs, and rabbits, if injected in large doses 

 intraperitoneally ; there is little or no multiplication of the organisms in the body. 



Differentiation of the Gonococcus from the Meningococcus. — Morphologi- 

 cally the two organisms are very similar. In the body, both occur chiefly in 

 pairs situated intracellularly. It is sometimes stated that the adjacent sides of the 

 meningococci are flattened, whereas those of the gonococci are concave, thus 

 leaving an oval space between the two organisms. Possibly the meningococcus 

 is slightly larger than the gonococcus in the body, though smaller in a 24-hours' 

 culture in the laboratory (Wollstein 1907). Culturally the gonococcus is more 

 dysgonic ; it grows more slowly, forms smaller colonies, and grows on a narrower 

 range of media than the meningococcus ; the colonies are slightly viscous and do 



