378 COCCI PATHOGENIC FOR DOMESTIC ANIMALS AND MAN 



DIPLOCOCCUS PNEUMONIA OF FRANKEL-WEICHSELBAUM. 



In a great majority of cases this organism is the cause of croupous 

 or lobar pneumonia in man ; it also causes inflammatory and suppu- 

 rative processes in the middle ear, the joints, the pleura, the peri- and 

 endocardium, and sometimes cerebrospinal meningitis. It is also 

 called Diplococcus lanceolatus, and was probably first seen by Sternberg 

 and Pasteur. The typical shape of the organism, when seen singly 

 and in pairs, is the elongated coccus. The diplococci show par- 

 ticularly often in the shape of candle lights, hence the name Diplo- 

 coccus lanceolatus, which means lancet-shaped. In pathologic 

 exudates the organism frequently appears in short chains in which 

 the subdivision into diplococci is generally well marked, and it almost 

 invariably shows a distinct, quite large capsule, because of which it is 

 known also as the capsule coccus of pneumonia. As a rule, the capsule 

 is not shown on artificial culture media, but sometimes it appears on 

 sterile sputum or in sterile fluid blood serum or milk. The diplo- 

 coccus of pneumonia does not form spores, is not motile, and possesses 

 no flagella. It is Gram positive. The organism, after a number of 

 transplants, often forms longer chains, and the individual cocci 

 become perfectly round and lose the lancet-shape entirely. It grows 

 rather poorly on artificial culture media and only at blood temperature, 

 both aerobically and anaerobically. The superficial cultures on agar 

 are thin films, quite transparent. The deeper colonies are very small, 

 and when examined with a low power of the microscope appear light 

 yellow or light brown, and finely granular. The growth on gelatin 

 plates kept at 24 C. is scanty and poor. In agar stick cultures there 

 is very little growth on the surface, but more along the stick where a 

 band-like strip is formed. On agar or blood-serum slants a fine veil 

 composed of small dewdrop-like colonies is formed. Nutrient 

 bouillon and fluid blood serum become cloudy, and a scanty, loose, 

 whitish sediment is formed at the bottom. The growth on potatoes is 

 practically invisible, and is only revealed by microscopic examination 

 of material taken from the surface. Milk becomes coagulated. 

 The addition of glycerin and glucose to the media is favorable to the 

 growth. The reaction of the culture soils must be faintly alkaline. 

 The best medium is a serum agar prepared of two parts of agar to which 

 one part of human-blood serum has been added. The organism 

 generally dies out rapidly in artificial cultures. Sometimes a second 

 generation fails. It is always necessary to make frequent transplants. 

 The coccus perishes so quickly in pure cultures because it rapidly 

 forms acid in the presence of which it cannot live. The virulency 

 shown by different stems in first cultures varies greatly; it is lost 

 rapidly in subsequent transplants. It appears from Rosenou's w r ork 

 that virulent diplococci are unaffected by phagocytosis, avirulent types 

 alone are engulfed and destroyed by leukocytes. While pneumonia 



