CHAPTER XXXIV 



The bacillus of malignant edema is commonly present in garden soil, 

 barnyard manure and in river silt. 



Morphology. It is a large bacillus, 3 to 10 n long, 0.5 to i.o /x wide, has 

 slightly rounded ends, occurs singly and in chains and under anaerobic conditions 

 is slightly motile. 



Staining occurs readily with the usual anilin dyes and it is Gram positive. 



Growth. -The bacillus of malignant edema is an obligate anaerobe and 

 grows at temperatures between i5C. and 4iC., best at 37C. 



Bouillon shows cloudiness in 12 to 18 hours; after 24 to 48 hours a heavy, 

 whitish sediment forms and the bouillon above becomes clear. 



Agar. Colonies develop on the surface in several days; they are small, 

 round, elevated and grayish. 



Stab Cultures in Agar show growth in i or 2 days. It appears at first as 

 a white line along the stab and then extends laterally, giving the medium a 

 grayish cloudy appearance and forming gas, which splits the agar. 



Gelatin. Growth on gelatin has the same appearance as on agar. The 

 medium is rapidly liquefied. 



Blood serum is liquefied. 



Milk is slowly coagulated. 



Potato shows slight, if any, growth. 



The bacillus of malignant edema produces indol and forms spores. 



Resistance. Bacilli are destroyed in a moist state in less than an hour at 

 7oC. They are more resistant to chemical germicides than the typhoid bacillus. 

 Spores are very resistant to all germicidal agents and require boiling for at least 

 i hour to kill them. 



Toxin. The bacillus of malignant edema forms a small amount of a weak 

 intracellular toxin. 



Agglutinins. Specific agglutinins occur in the blood of immunized animals. 



Pathogenesis. This organism rarely infects man. Being an obligate 

 anaerobe infection is most apt to occur in puncture and deep lacerated wounds 

 and has been most frequently observed in severe compound fracture wounds 

 grossly contaminated with dirt. 



Most of the domestic and laboratory animals are susceptible to the bacillus 

 of malignant edema. 



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