MENINGOCOCCUS 69 



Plain bouillon is not a favorable medium upon which to cultivate the 

 meningococcus; when growth does occur it is scant and similar to that observed 

 in bouillon which contains serum or ascitic fluid. 



Serum Bouillon. Slight cloudiness in 24 hours; after 36 to 48 hours a scant 

 grayish-pellicle forms. 



Milk is neither acidulated nor coagulated. 



All cultures of the meningococcus die out in from 3 to 6 days, as a rule, but 

 those which have been cultivated for a long time may survive longer than a week 

 without transplanting. 



Glucose and maltose are the only sugars fermented by this organism. 



Resistance. Drying kills the meningococcus in several hours, low tempera- 

 tures and freezing kill in several days, i : 1000 bichloride and i per cent, phenol 

 solutions kill in less than 2 minutes. In the hot-air sterilizer iooC. for 15 

 minutes and in the moist state 6oC. for 10 to 15 minutes kills meningococci. 

 Their resistance outside the body is slight. 



Toxin. The meningococcus produces an intracellular toxin of much 

 virulence. 



Agglutinins appear in the blood of persons having meningococcus meningitis 

 and can be produced by injecting attenuated or killed cultures into animals. 

 Complement fixation tests are employed to differentiate between meningococcus, 

 gonococcus and micrococcus catarrhalis, but seldom in diagnosis. 



Antimeningococcus serum is the most valuable agent employed in the treat- 

 ment of meningococcus infections. 



Pathogenesis. In man the meningococcus causes meningitis, inflammation 

 of the naso-pharynx and throat. Some observers have reported finding the 

 organism in the blood of persons afflicted with meningitis. Conditions similar 

 to those occurring in man can be produced by inoculation into monkeys. The 

 organism is pathogenic for white mice, injected into the peritoneal cavity it 

 produces a fatal peritonitis with exudate that contains many organisms. 

 Other animals are immune or suffer from toxemia when inoculated. 



Recent investigations have shown there are numerous strains of meningo- 

 cocci and para-meningococci which fail to agglutinate with serum from animals 

 inoculated with the strains most commonly isolated from patients with menin- 

 gitis strains that are not acted upon by therapeutic sera on the market, hence 

 the desirability of polyvalent sera. 



Diagnosis. In carriers the meningococcus is present on the mucosa of the 

 naso-pharynx or throat. Suspected carriers are examined by passing a sterile 

 cotton swab over these surfaces and then planting several tubes of blood serum 

 and agar with the swab. Smears for microscopic examination are made from 

 the swab. 



When the disease is epidemic cases of naso-pharyngitis are examined as 

 carriers, for it is believed that the meningococcus first assaults these membranes. 

 Its activity may be confined to them or it may pass to the meninges and produce 

 meningitis. 



In cases of meningitis caused by the meningococcus the organism in nearly all 



