CHAPTEE XXIII. 



BACILLUS OF TETANUS. 



Occurrence and Animals Susceptible. Tetanus, or lockjaw, is a 

 disease of man and some of the lower animals, which has been 

 known for a long time. It is, in fact, mentioned by Hippocrates, and 

 it had been noticed that it frequently follows lacerated, deep-seated 

 contaminated wounds. The disease is characterized by clonic and 

 tonic convulsions of the voluntary muscles, but it has no charac- 

 teristic anatomic or histopathologic lesions, and a diagnosis of 

 tetanus cannot be made from a ^postmortem examination unless it 

 is combined with a bacteriologic examination, including animal inoc- 

 ulation experiments. The clinical symptoms, however, are so charac- 

 teristic that it is easy to diagnosticate a case of typical tetanus in man 

 or animals. The disease, as a rule, follows wound infection; the wound 

 so infected may be the umbilicus of the newborn or the uterus after 

 parturition. Man and the horse are most susceptible to natural infec- 

 tion, but cattle, sheep, and hogs are likewise subject to tetanus. The 

 dog is only slightly susceptible, likewise the cat. Of experimental 

 animals, mice, guinea-pigs, and rabbits are susceptible. Tetanus may 

 develop in exceptional cases as a cryptogenetic infection, i. e., one of 

 hidden, secret origin, from the intestinal tract; this manner of origin, 

 however, does not occur in the horse. 



Historical. The first investigator to succeed in producing artificial 

 experimental tetanus was Nicolaier in 1885. He inoculated mice, 

 rabbits, guinea-pigs, and dogs with garden earth, and* by this means 

 produced tetanus in the three former animals but not in the dog. At 

 the point of inoculation he found slender bacilli, but in his experiments 

 he failed to obtain them in pure cultures. Rosenbach, in 1887, saw 

 identical bacilli in man in a gangrenous wound which had led to 

 the development of lockjaw. Finally, in 1889, Kitasato succeeded 

 in obtaining the tetanus bacillus in pure culture by raising it under 

 strictly anaerobic conditions. 



Morphology and Staining Properties. The tetanus bacillus when 

 obtained from a gelatin culture is a slender rod 2 to 4 micra long, 

 0.3 to 0.5 micron wide. It has slightly rounded ends. In addition 

 to individual bacilli, chains of several rods, forming slender filaments, 

 are found; the older the culture the more numerous are the latter. 

 In older cultures raised on gelatin at room temperature many spore- 

 bearing bacilli are seen. Young tetanus bacilli show a slight motility, 

 which can be best demonstrated on a warm stage. The bacilli 



