Bacillus Anthracis, Davaine, PoUender (1849). 



ANTHRAX, SPLENIC FEVEE (in cattle): WOOL-SORTEE'S DISEASE, 



MALIGNANT PUSTULE (in man); MILZBRAND (Oerm.); 



QHARBON, SANG DE RATE {Fr.). 



Origin. — Pound in the blood and tissues in anthrax. 



Form. — Larg-e, clear, homogeneous rods, with slightly rounded 

 ends; size varies with different media, but the length is less than the 

 diameter of a blood cell. Occurs in blood in short threads of 2-4-6 

 cells, which may show slightly swollen ends. In bouillon and on agar 

 it forms long threads. Involution forms develop on potato at 16°. 



Motility. — It has no motion. 



Sporulation. — Forms median, oval spores, without enlargement 

 of cell. After long cultivation it may lose the property of forming 

 spores — asporogenic variety. In such cases, growth on peptonless 

 agar, or the addition of i-1 drop of Ca(OH)3 to an agar tube, favors 

 spore formation. Optimum temperature, 30°. Not formed below 16° 

 or above 42°, or within the body. Spores possess variable resistance. 



Anilin dyes. — It stains readily, also by Gram's method. 



Growth. — Is rapid. 



Gelatin plates. — Deep colonies form round, granular, yellowish-brown masses, with 

 irregular borders. Surface colonies are very characteristic, and according to the consis- 

 tency of the gelatin the border is fibrillated or shows very wavy strands of threads — Medusa 

 head. This typical colony is readily obtained on agar plates grown at 37°, Liquefaction. 



Stab culture. — Short threads radiate from the line of inoculation into the surrounding 

 gelatin, imparting a brush-like appearance. Cup-shaped liquefaction forms on top and 

 gradually extends till the contents are wholly liguefied. The mass of bacteria settles to 

 the bottom and leaves a perfectly clear solution above, without scum. 



Streak culture.— Qa agar, it forms a dry, grayish-white, slightly folded growth. On 

 potato, the growth is abundant, white, cream-like and rather dry, and is rich in spores (37°); 

 or in involution forms (16°). 



In bouillon, a thick gelatin ring forms on the surface. Milk is coagulated, the cas- 

 ein is then peptonized. Acid production on lactose media. 



Oxygen requirements.— It is aerobic, but can grow in the body as 

 a facultative anaerobe. 



Temperature.— Growth at 12 — 45°. The optimum is about 37°. 



Behavior to gelatin. —Liquefies slowly. 



Attenuation.— By heating for 10 minutes at 55°; i-1 minute at 

 100°. By growing at 42.5° for four weeks. By action of chemicals as 

 mercuric chloride, carbolic acid, etc. By insolation. By growth un- 

 der pressure. In the body of immune animals, as frogs. 



Immunity. — Obtained with- attenuated cultures, 1st and 2nd vac- 

 cine of Pasteur; with sterilized cultures; with purified toxin. Blood 

 of anthrax animals heated to 55° protects. The blood-serum of an ani- 

 mal vaccinated against the bacillus is preventive, and to some extent 

 curative. 



Pathogenesis. — White mice, guinea-pigs, rabbits, sheep, cattle, 

 horses and man are susceptible. Dogs, old white rats, cats, Algerian 

 sheep, birds and frogs are insusceptible. Young animals, as dog or 

 rat, are more susceptible than old ones. Subcutaneous application 

 kills guinea-pigs in 24^48 hours. Post-mortem examination shows sub- 

 cutaneous edema and enlarged spleen. Bacilli everywhere; leave 

 body in bloody discharges from the nose, intestine, urine, etc. 



Infection. — (1) Through the food, presence of spores. — Intestinal 

 anthrax in sheep and cattle. (2) Through wounds,- Inoculation an- 

 thrax in man (malignant pustule). (3) Through the air, — Lung an- 

 thrax in man, the wool-sorter's and possibly rag-picker's disease. 



Diagnosis. -Microscopical examination of spleen, blood, or of con- 

 tents of pustule; isolation of pure culture. Characteristics of the lat- 

 ter and eflect on white mouse or guinea-pig. It does not appear in 

 the blood until shortly before death. It is present in the "rusty " or 

 dark-colored sputum of the "wool-sorter's disease." 



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