140 

 BACILLUS DIPHTHEBIJE. Klebs, Loffler (1883). 



BACILLUS OF DIPHTHERIA. 



Origin. Found in diphtheritic pseudo-membranes, and in 

 very small numbers in the spleen, liver, etc., of diphtheria. 



Form. Rather large thick rods which are straight or slightly 

 bent and have rounded ends. The form is subject to considerable 

 variation, and rods with swollen, club-shaped ends are frequently 

 met with involution forms. 



Motility. Has no motion. 



Sporulation. Spores have not been observed. Tne bacillus 

 is very susceptible to desiccation, or to heat of 50 and above. 



Anilin Dyes. Dimple anilin dyes react poorly. Can be best 

 stained with carbolic-fuchsine, or with Loffler's alkaline methylene 

 blue (30 c. c. of cone, alcoholic solution of methylene blue + 100 c.c. 

 of a 0.01 per cent, solution of potassium hydrate). Is also stained 

 by Gram's method. 



Growth. Is very rapid at higher temperatures and on special 

 media as glycerine agar and blood serum. 



Plates. On gelatin plates left at about 24 C. forms very small, round, 

 white colonies wh'ich have granular contents and irregular borders; do not 

 liquefy gelatin. Cn glycerine agar plates, kept in the incubator, excellent 

 colonies form in 24-48 'hours The deep colonies are round, or oval, coarsely 

 granular. The surface colonies are flat, grayish white, glistening, with irregu- 

 lar borders and coarsely granular contents. 



Rl.ich Cultures. In gelatin a very limited, scarcely preceptible growth 

 of small, round, white dots marked involution forms present. 



Streak Cultures. On glycerine agar show a thin, grayish, spreading, 

 adherent film, which is quite characteristic. On potato the growth is invisible 

 or forms a dry, thin glaze irregular forms of the bacillus are numerous. On 

 blood-serum it forms a thick white, opaque growth. 



Bouillon. Becomes diffusely clouded and the growth eventually sub- 

 sides on the sides of the tube and on the bottom. A pellicle may form on the 

 surface. 



Oxygen requirements. Is a facultative anaerobe, but grows 

 best in presence of oxygen. 



Temperature. Very slight growth at 20-25 C. The maxi- 

 mum is about 42 and the optimum 35-37 C. 



Behavior to Gelatin. Does not liquefy. 



Attenuation. Cultures directly isolated from membranes 

 show frequently marked variation in virulence. By artificial cul- 

 ture the virulence is still further diminished. Cultures can be at- 

 tenuated by growth at 40 in a current of air. 



Immunity. Is produced by filtered bouillon cultures heated 

 to 60-70 C. Also by injections of thymus bouillon cultures prev- 

 iously heated to 65-70. Partial results with iodine trichloride. 



Pathogeiiesis. Mice and rats are wholly immune. Finches, 

 sparrows, doves, chickens, rabbits, guinea-pigs and cats are suscep- 

 tible. Subcutaneous inoculation in guinea-pigs produces death in 

 24-48 hours. Pseudo-membranous masses form at point of inocula- 

 tion ; an extensive hemorrhagic oedema forms under the skin and 

 exudates occur in the pleural cavity. Inoculation in the trachea of 

 cats, chickens, doves, rabbits, etc., is followed by pseudo-membrane 

 formation, and by death. In some animals as rabbits typical diph- 

 theritic paralysis of the extremities can be observed. The highly 

 poisonous toxalbumin. 



Infection. Exact mode of infection is not known, but un- 

 doubtedly occurs through the air. 



NOTE. Make glycerine agar Petri dishes of the diphtheria bacillus. 



