Bacillus Diphtheriae, Klebs, Loffler (1883). 



BACILLUS OF DIPHTHERIA. 



Origin. — Found in diphtheric pseudo-membranes, and in very 

 :small numbers in the spleen, liver, etc., of diphtheria; rarely in the 

 throats of healthy children. 



- Form. Rather large, thick rods which are straight or slightly 

 bent or wedge-shaped and have rounded ends. The form is subject to 

 considerable variation, and fods with swollen, club-shaped ends are 

 frequently met with; likewise branching forms— involutions. Usually 

 single; length variable. 



Motility.— It has no motion. 



Sporulation.— Spores have not been observed. The bacillus is 

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



Anilin dyes. — Simple anilin dyes react poorly. Round polar 

 bodies and transverse bands. Can be stained best with carbolic 

 fuchsin, or with Loffler's alkaline methylene blue.' It is also stained 

 by Gram's method. 



Growth. — Very rapid, especially on glycerin agar and blood-serum. 



Plates.— On gelatin plates kept at about 24° it forms very small round, white colonies, 

 which have granular contents and irregular borders; do not liquefy gelatin. On glycerin 

 agar plates, kept in the incubator, excellent colonies form in 24 hours. The deep ccuonies 

 are round, or oval, coarsely granular. The surface colonies are fiat, grayish white, glisten- 

 ing, with irregular borders: coarsely granular contents. 



Stab culture. — In gelatin the growth spreads over the surface while along the punc- 

 ture only a very limited, scarcely perceptible 'growth of small, round, white dots occurs. 

 Marked involution forms present. Vitality is retained best in gelatin. 



Streak culture. — On glycerin agar 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; branching forms may be present, especially if the medium is soft. 



Bouillon. — Ma^, or may not be diffusely clouded; the growth rapidly subsides, form- 



ing a granular deposit on the sides of the tube and on thejjottom. A pellicle usually forms 



:id, c 

 5uga 

 produced. Milk is not altered^ 



on the surface and the liquid becomes perfectly clear. The reaction becomes acid, owing 

 to the presence of muscle sugar; in a few days becomes alkaline. No gas or indol is 



Oxygen requirements. — Facultative anaerobe; grows best in air. 



Temperature.— Very slight growth at 20°. The maximum is 

 about 42° and the optimum is at 35-37°. 



Behavior to.gelatin.— It does not liquefy. 



Attenuation. — Cultures isolated direct from membranes show 

 marked variation in virulence. By artificial culture, especially if 

 transplanted infrequently, the virulence is still further diminished. 

 Attenuated by growth at 40° in a current of air; by desiccation. 



Immunity.— This is produced by filtered bouillon cultures heated 

 to 60-70°. or unheated, Also by injections of thymus bouillon cultures 

 previously heated to 65-70° . Partial results with ICI3. Living cultures 

 can be used. Serum of artificially immunized animals is antitoxic. 



Pathogenesis. — Mice and rats are wholly immune. Finches, spar- 

 rows, doves, chickens, rabbits, guinea-pigs and cats are susceptible. 

 Likewise, horses, cattle, dogs and goats. Subcutaneous inoculation 

 in guinea-pigs usually produces death in 24-48 hours. Pseudo-mem- 

 branous masses form at point of inoculation; an (extensive hem- 

 orrhagic edema 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 diphtheric paralysis of the extremities 

 can be observed. Local swelling and scar, in prolonged cases. The 

 filtered bouillon culture contains a highly poisonous toxin (p. 84). 



Infection.— This undoubtedly occurs through the air, or by con- 

 tact with infected articles. Diagnosis.— See p. 334. 



1 This is prepared by adding 30 c.c. of cone. ale. solution of methylene blue to 100 c.c. 

 ■of a 0,01 per cent, solution of potassium hydrate. 



332 



