Bacillus Rhusiopathiae Suis, Pasteur (1882). 



HOG EEYSIPELAS; EOUGBT (J'r.); SCHWEINBKOTHLAUF ((^erm.). 



Origin. — In the blood, internal organs, etc., of swine infected 

 with, the disease. 



Form. — In the body it occurs as very small, narrow rods resem- 

 bling needle-shaped crystals. On some media, as glycerin agar, the 

 slender rods may be quite long, and may show a slight bend. Are: 

 usually single, but may occur in pairs and even in threads. 



Motility.— It has no motion. 



Sporulation. — Spore formation is not known. 



Anilin dyes.— Stain readily. Gram's method, excellent results.. 



Growth. -Is rather slow but extremely characteristic. 



Plates.— Oa gelatin plates the colonies are very characteristic and appear as diffuse 

 clouds' patches which are sometimes difiScult to see. Little or no surface growth. No- 

 liquefaction. 



Siai culture. ~ In gelatin is likewise very characteristic. The growth develops- 

 along the line of inoculation as a delicate, cloud-like radiating column. As the culture be- 

 comes old a depression forms at the top, due to slow liquefaction and corresponding evap- 

 oration. Sometimes liquefaction can be observed. The vitality is maintained longest in 

 gelatin cultures. ^ 



Streak culture.— Ovi agar&nA on blood-serum it forms a scarcely visible thin film or 

 group of colonies. Glycerin agar is best and on this the vitality is prolonged. No 'growth 

 on potato except under anaerobic conditions. 



Bouillon.— k very delicate diffuse cloudiness forms which can best be seen on slight 

 agitation. Resembles the bouillon culture of the tetanus bacillus. No indol is formed. 



Oxygen requikemunts. — Is a facultative aerobe. Best growth 

 under anaerobic conditions, which, moreover, preserve the virulence. 

 Temperature. — Grows slowly at ordinary temperature. Best at 36°. 

 Behavior to gelatin. — Does not perceptibly liquefy gelatin. 



Aerogenesis. — Produces hydrogen sulphide in pure cultures, and 

 in the body. This gas is also produced by the anaerobic bacteria and 

 to a less extent by nearly all pathogenic bacteria. 



Attenuation. — Old cultures become attenuated; this result can 

 also be obtained by growing the virulent germ at high temperatures, 

 about 42°, for some time (Pasteur). Passage through rabbits attenu- 

 ates; whereas passage through pigeons increases the virulence with 

 reference to swine. 



Immunity.— By inoculation with attenuated culture — first and 

 second vaccine of Pasteur — perfect immunity can be produced. One 

 attack of the disease confers immunity. The serum of immunized 

 animals is anti-infectious. 



Pathogenesis. — Swine, rabbits, pigeons, white mice, rats andi 

 house mice are susceptible. Death in 3 to 5'days. Field mice, guinea- 

 pigs, dogs, cats, chickens and dupks are insusceptible. Bacilli distri- 

 buted throughout the organism (septicemia). They are very numerous 

 in the blood: single or in pairs; 'very often can be seen to be enclosed 

 in leucocytes. 



Infection.— Occurs naturally in swine through the food. The 

 bacillus is always present in the feces. 



Diagnosis. — The bacillus can be readily detected in the blood and 

 especially in the spleen by Gram's method. The cultural character- 

 istics will distinguish it from all other organisms except that of 

 mouse septicemia. Inoculation of mouse or rabbit. 



378 



