THE FRIEDLANDER GROUP 675 



The smooth type is capsulated ; the rough type is not. It might therefore be thought 

 that virulence depends on capsule formation. Toenniessen (1914) discusses this possibility, 

 but concludes that the association between capsule formation and virulence is fortuitous. 

 He isolated, for example, one variant which, though non- capsulated, was highly virulent. 

 He states that old cultures of the smooth type, in which the capsules have largely become 

 autolysed, have just the same virulence for mice as fresh young capsulated cultures. More- 

 over, Julianelle's Friedlander Type C strains, though capsulated, were non-vii-ulent. It 

 would appear, therefore, that capsule formation is often associated with, but is not essential 

 to virulence. 



After subcutaneous injection of a very small dose — about 0-0000001 ml. of a 24-hours' 

 broth culture of a virulent strain — into mice, the animals die in 12 to 72 hours. Post 

 mortem, there is a local exudate, the focal glands are swollen, and the spleen is enlarged. 

 Capsulated bacilli are found in the blood and viscera (Pfeiffer 1889, Fricke 1896, Toenniessen 

 1914). 



Guinea-pigs are refractory to subcutaneous, but succumb to intraperitoneal injection, 

 death occurring in 12 to 72 hours. The fatal dose is about 001 ml. of a 24-hours' broth 

 culture. Post mortem, there is a viscous exudate in the peritoneum ; the spleen may be 

 enlarged, and the suprarenals hsemorrhagic. The bacilli are found in large numbers in 

 the blood and viscera. 



Rabbits appear to be more resistant, but they succumb after intravenous or intra- 

 peritoneal injection with a dose of about 01 ml. of a broth culture. Intraperitoneal 

 inoculation is likewise fatal to pigeons. 



Classification. — The demarcation of this group from other groups of capsulated 

 bacilli, and the subdivision of the group itself, are both in a very unsatisfactory state. 

 In the first place it is doubtful what relation capsulated organisms of the aerogenes 

 and intermediate type have to Friedlander's bacillus. It is usual to regard Bad. 

 aerogenes as a saprophyte of grains, the intermediate types of coliform bacilli as 

 saprophytes of soil, and the Friedlander-ozaena-rhinoscleroma group as parasites 

 of man and animals. But the fact that most Friedlander strains of respiratory 

 origin are indistinguishable from strains of intermediate I type (see C'hapter 92), 

 and that many strains found in cystitis appear to be identical with Bad. aerogenes, 

 renders dangerous any attempt to separate these organisms on the basis of 

 habitat alone. It is difficult to avoid the conclusion that all these organisms 

 should be classified in a single group, but whether that group should be called 

 Aerobacter, Encapsulatus, or Klebsiella is very doubtful. For the moment we 

 prefer to keep them within the wide Baderium genus. 



Attempts to make subdivisions within the group must necessarily await the 

 definition of the group itself. Though Goslings (1934) and Wielenga (1937) are 

 convinced of the value of biochemical tests in distinguishing between the scleroma, 

 ozaena, and pneumoniw types, it is clear from a careful study of their papers that, 

 apart perhaps from the scleroma group, there is so much variation between the 

 different members within each group as to make the classification of any individual 

 strain of unknown origin often impossible. At the moment a study of antigenic 

 structure seems to hold out the only promise of throwing any light on this problem. 

 A careful comparison of adequate niimbers of freshly isolated strains from different 

 sources is urgently called for. Until this is done, it will be impossible to decide 

 whether ozsena and rhinoscleroma strains are specifically distinct from strains of 

 Friedlander, or whether they are merely types of the same species differing in the 

 polysaccharide constituents of their capsule. Any such attempt should include 

 a thorough study of intermediate and aerogenes strains. 



