BACILLI 423 



BACILLUS OF TETANUS 



(Bacillus tetani] 



LIQUEFIES GELATINE | 



Authority. Nicola,iei\ Deutsclie med. Viochenschrift, 1884, No. 52. Kitasato. 

 ' Ueber den Tetanusbacillus,' Zeitschrift f. Hygiene, vol. vii., 1889, p. 225. 

 Kitt, 'UeberTetanusimpfungenbeiHausthieren,' Centralblatt fiirBakteriologie, 

 vol. vii., 1890, p. 297. 



Where Found. In soil, in air, in water, and in pus from tetanus wounds. 



Microscopic Appearance. Straight bacilli with rounded ends, somewhat 

 longer but scarcely broader than the bacillus of mouse septicaemia. It occurs singly, 

 also in long threads. Forms spores in about thirty hours at 37 C., which are 

 round and broader than the bacillus and are situated at one end. At 20 to 25 C. 

 spore formation does not take place under seven days. In moist surroundings 

 the spores will resist one hour's exposure to 80 C., but are killed by five 

 minutes' exposure to 100 C. in the steam steriliser. The spores when dried on 

 silk threads or mixed with soil retain their vitality and virulence for several 

 months. It is slightly motile, but the spore-carrying bacilli are motionless. It 

 can be easily stained with all the usual aqueous solutions of aniline colours, and 

 it is also stained by Gram's method. 



Cultures. 



GELATINE PLATES. When grown in an atmosphere of hydrogen the colonies 

 at first resemble those of the hay bacillus (see p. 417). The centre is dense, 

 and the periphery consists of a circle composed of fine short hair-like extensions 

 of equal length. Liquefaction proceeds very slowly. Older colonies appear 

 to be composed entirely of numerous isolated radial extensions, recalling the 

 appearance of a mould. 



GELATINE TUBES. It is strictly anaerobic. In the depth of the gelatine a 

 cloudy growth appears from which radial extensions penetrate the adjacent 

 gelatine in all directions. Slow liquefaction ensues and gas is liberated. 



AGAR-AGAR. Grows rapidly when 1'5 to 2 per cent, of grape sugar is added 

 to the agar. 



BLOOD SERUM. At from 34 to 38 C. soft circular depressions appear in the 

 serum, due to a transparent and almost invisible delicate and colourless growth. 

 After being kept at 37 C. for from six to ten days the serum becomes hori- 

 zontally cleft. (Kitt.) 



BROTH. Renders it very turbid. 



Remarks. It grows better at 87 C. than at 18 to 20 C., and no growth takes 

 place below 14 C. It is very important that all media used for its cultivation should 

 be quite freshly prepared (see p. 12). All the cultures emit an offensive odour. 

 The bacillus may he isolated from tetanus-pus by inoculating portions of the latter 

 on to agar-agar, and subsequently keeping the cultures at 36 to 38 C. for forty-eight 

 hours, and then exposing them to a temperature of 80 C. for from three-quarters to 

 one hour in a water-bath. The tetanus spores are then usually found in a pure con- 

 dition, and may be inoculated on to fresh material and kept in an atmosphere of hydro- 

 gen. It is pathogenic to mice, rats, guinea-pigs, and rabbits, whilst more recently 

 Kitt has found it fatal to horses, sheep, and dogs. For the action of light on tetanus 

 filtrates see p. 385. 



