PLAGUE 95 



The bacillus is oval, Gram negative, shows bipolar staining, somewhat resembles 

 B. influenzae and grows only on uncoagulated serum media, as blood or ascites agar. 

 The original cultures are very scanty so that the colonies are difficult to recognize. 

 In subcultures the growth is more flourishing. The organism is only found in white, 

 thick, leukocyte abounding sputum, of the beginning of the disease. Hence per- 

 tussis is probably contagious only at the onset. 



Complement binding and agglutination reactions have been obtained. For 

 diagnosis stain the sputum. Remember that pertussis gives a mononuclear leuko- 

 cytosis of 15 to 50 thousand. 



GRAM NEGATIVE BACILLI GROWING ON ORDINARY MEDIA. 



Bacillus pneumonias (Friedlander, 1882). This organism is 

 responsible for about 5% of the cases of pneumonia. It is usually 

 termed the pneumobacillus to distinguish it from the pneumococcus; 

 at other times Friedlander's bacillus. The name of Fraenkel attaches 

 to the pneumococcus. Morphologically, it is a short, thick bacillus, 

 and in pathological material, as sputum, shows a wide capsule. It is 

 nonmotile and Gram negative. The colonies on agar are of a pearly 

 whiteness and are markedly viscid. On potato it shows a thick viscid 

 growth containing gas bubbles. The characteristic culture is the nail 

 culture of a gelatin stab. The growth at the surface is heaped up like a 

 round-headed nail, the line of puncture resembling the shaft of the nail. 

 It does not liquefy gelatin. It does not produce indol, and does not 

 produce gas in lactose bouillon differences from the colon bacillus 

 with which it may be confused in cultures, as it does not then possess a 

 capsule. If in doubt, inject a mouse at the root of the tail. Death 

 from septicaemia occurs in two days. The peritoneum is sticky and 

 numerous capsulated bacilli are present in the blood and organs. The 

 organisms which have been isolated from rhinoscleroma and ozcena 

 are practically identical with the B. pneumonias. This group of organ- 

 isms is generally referred to as the Friedlander group. Similar organ- 

 isms have been isolated from the discharges of middle-ear diseases and 

 in anginas. Cases have been reported where the B. pneumonias was 

 the cause of septicaemia in man. 



Bacillus pestis (Kitasato, Yersin, 1894). This is the organism of 

 plague. It is primarily a disease of rats. It is the member of the group 

 of haemorrhagic septicaemias (Pasteurelloses), from which man suffers. 



Other Pasteurelloses are chicken cholera, swine plague, mouse septicaemia and 

 rabbit septicaemia. This is a widely distributed group and may include saprophytic 

 organisms as well as those noted for their virulence. 



