142 



MICROCOCCUS PNEUMONIA CROUPOS.2E. 

 Sternberg (1880). Frankel (1883). 



SYNONYMS: MICROBE OF SPUTUM SEPTIC^MIA, DIPLOCOCCUS PNEU- 

 MONIA, FKANKEL'S DIPLOCOCCUS. 



Origin. Occasionally in saliva of healthy persons; especially 

 in " rusty " sputum of pneumonia. The same organism or scarcely 

 distinguishable varieties, are present in cerebro-spinal meningitis, 

 pleuritis, peritonitis, pericarditis, etc. 



Form. Oval or lance-shaped diplococci, may form chains of 

 4-6 cells and resemble a streptococcus. Owing to its oval form it is 

 sometimes regarded as a bacillus. In the animal body it is sur- 

 rounded by large capsules. 



Motility. Has no motion. 



Sporulation. Unknown. 



Anilin Dyes. Stains readily, also by Grain's method. The 

 capsules remain colorless. 



Growth. Takes place somewhat slowly and only at higher 

 temperatures, and on alkaline media. 



Plates. On gelatin plates kept at 24 C. small, round, sharply denned, 

 tly granular, whitish colonies develop slowly. On agar plates in the in- 

 -cubator, in 48 hours, delicate, glistening, transparent drops form which under 



slightly granular, whitish colonies develop slowly. On agar plates in the in- 

 -cubator, in 48 hours, delicate, glistening, transparent drops form 

 the microscope are round, sharply bordered and finely granular. 



Stich Cultures. In. gelatin a row of small, white granules develop along 

 the line of inoculation. Does not liquefy. 



Streak Cultures. On agar, in the incubator, the growth develops as a 

 thin layer of delicate, glistening, almost transparent drops. Dies out rapidly. 

 On blood-serum forms a transparent film-like dew drops. No growth on 

 potato. 



Bouillon. Excellent growth occurs; vitality preserved for some time. 



Milk. Is a favorable culture medium, becomes coagulated. 



Oxygen requirements. Is a facultative anaerobe. 



Temperature. Growth occurs only between 24 and 42. Its 

 optimum is about 37 C. 



Behavior to Gelatin, Does not liquefy. 



Attenuation. Cultures from different sources show marked 

 difference in virulence. When grown on artificial media it rap- 

 idly attenuates and soon dies out, unless it is passed through a sus- 

 ceptible animal, as a rabbit, every few weeks. Rapidly attenuates 

 *it42O. 



Immunity. Intravenous injection of very small amount of 

 virulent culture ; injections of filtered cultures, especially when 

 heated to 00 C. ; blood serum of immune animals. Blood-serum 

 from pneumonic patients immunizes rabbits against the pure cul- 

 ture. 



Pathogenesis. Subcutaneous injection of 0.1 0.2 c. c. of 

 bouillon cultures in rabbits produces death in 24-48 hours. The 

 diplococcus is found in the blood and internal organs and is sur- 

 rounded by a capsule. Tracheal injections in rabbits produce true 

 pneumonia. Mice and rabbits are highly susceptible ; guinea-pigs, 

 sheep, dogs are less susceptible. Is the" recognized cause of croup- 

 ous pneumonia. 



NOTE. Make agar Petri dishes from the peritoneum exudate in a rabbit. 

 Make cover-glass preparations from the peritoneum, surface of intestines and 

 tieart-blood, and stain by simple and by Gram's method. 



