234 TETANUS 
Etiology. Tetanus is caused 
by a slender bacillus (B. tetani) 
2 to 44 in length. Jt forms 
spores which are at the end of the 
organism giving it somewhat the 
appearance of a pin. On this 
account it has been designated 
the “pin bacillus.”’ It is anaéro- 
bic. It was first observed by 
Nicolaier in 1884. Carle and 
Rattone showed that the disease 
could be transmitted from man 
to animals by inoculation with 
the pus from the local lesion. In 
1889, Kitasato isolated the bacillus and studied it in pure. culture. 
B. tetani stains readily with the aniline dyes, especially with carbol- 
fuchsin. It takes the Gram stain. It grows well in nutrient gelatin, 
agar or bouillon and on blood serum at the temperature of the body 
and in an atmosphere of hydrogen or in the absence of air as in deep 
agar cultures. The addition of a little grape sugar facilitates its 
growth. It has the distinction of producing the most powerful 
(poisonous) toxin of any known bacteria, 0.23 of a milligram being 
estimated as a fatal dose for a man of 175 pounds weight. In the 
infected animal the bacilli remain at the point of inoculation, 
Tetanus bacilli are found in the soil and in the larger intestine of 
horses and cattle. They have been found in hay dust, in the mortar 
of old masonry, in the dust in rooms, barracks and hospitals. It is 
reported that certain savages in Africa destroy their enemies by 
putting bits of broken glass mixed with certain soils in their shoes. 
The cause of death is tetanus. Mold rich in horse manure seems to 
be the most favorable abode for them. 
The tetanus bacillus is very resistant, especially in its spore form, to 
destructive agents such as drying and the ordinary disinfectants. 
Kitasato found that a 5 per cent. solution of carbolic acid applied 
for ten hours failed to kill the spores. Tizzoni and Cattani found 
that mineral and organic acids produced no effect upon the dried 
spores. Von Behring found that iodine trichloride possesses a strong 
antiseptic effect upon them. They are not affected by the gastric 
fluids. It has been noted by Kitt that the dried spores in pus have 
retained their virulence for sixteen months. They are destroyed 
Fig. 51. BACILLUS TETANI. 
