504 A MANUAL OF BACTERIOLOGY 



coagulated serum there is little or no liquefaction. 1 

 None of the alcohols, carbohydrates or glucosides is 

 fermented. The odour of cultures is characteristic ; it is 

 not putrefactive, but is more like that of stable manure. 

 The spores retain their vitality for years in the dry 

 state. 



B. tetani is extremely difficult to isolate in a pure state. 

 Contaminating organisms are usually of the type of 

 B. sporogenes. 



Agglutinins. The injection of washed and heated 

 organisms intra-venously into rabbits is followed by the 

 development of agglutinins specific for the tetanus 

 bacillus. 



By means of the agglutination test strains of the 

 tetanus bacillus can be divided into four serological 

 groups, 2 known as Types I, II, III, and IV. 



Type I is the standard U.S.A. bacillus, and is the 

 organism which appears to have been usually employed 

 in laboratories in Europe prior to 1914 for the preparation 

 of tetanus antitoxin. 



Of 100 strains of B. tetani obtained from cases of 

 tetanus studied by Tulloch, Type I bacillus was obtained 

 in forty-one instances, the mortality being 13 per cent. ; 

 Type II bacillus in twenty -two, mortality 27 per cent. ; 

 Type III bacillus in thirty-three, mortality 35 per cent., 

 and Type IV bacillus in four, mortality nil. All these 

 cases had received a prophylactic dose of antitoxin. Of 

 twenty-five strains of B. tetani isolated from wounds the 

 subjects of which showed no signs of tetanus, 76 per cent, 

 were of Type I. 



These differences of serological type are not correlated 



1 There is some variation in the descriptions given of the changes produced 

 in serum and milk by B. tetani, probably owing to the use of impure cultures, 

 for even old laboratory strains may prove to be mixed cultures. 



2 Tulloch, Journ. of Hygiene, vol. xviii, 1919, p. 103. 



