CHAPTER XXXVIII 

 BACILLUS PRODIGIOSUS 



Bacillus prodigiosus occurs in soil, dust and water, and upon exposed food- 

 stuffs, especially those containing starch. 



Morphology. Bacillus prodigiosus is smaller than the typhoid bacillus, 

 but the difference is not sufficient to permit differentiation. It is motile and 

 possesses from six to eight lateral flagella. It is arranged singly, in pairs, short 

 filaments and in irregular groups. 



Staining. It stains readily with all the anilin dyes and is Gram negative. 



Growth. Bacillus prodigiosus is aerobic and facultative anaerobic. Under 

 aerobic conditions it produces a red pigment; this does not occur in an anaerobic 

 state. It grows best between 2oC. and 25C.; above 37.5^ pigment is not 

 formed. 



Bouillon becomes cloudy in 24 to 48 hours; under favorable circumstances 

 pigment forms and gives the medium a reddish tint; after several days a sediment 

 forms. 



Agar. Growth appears in 1 8 to 24 hours, as round, moist, glistening, whitish, 

 pin-head-sized colonies, which later coalesce and cover the surface with a red 

 pellicle. 



Gelatin is liquefied and a reddish sediment forms. 



Milk is acidulated and coagulated. 



Potato is the best medium upon which to observe pigment formation. 

 Growth covers the entire surface in 24 to 36 hours. At first it is bright red; as 

 the culture ages the pigment darkens until it becomes brown. 



Glucose is not acidulated, but occasionally gas is formed. Indol production 

 is variable. Bacillus prodigiosus does not form spores. 



Resistance. Bacillus prodigiosus is sterilized by an exposure of J hour to 

 i5oC. dry heat, or J^ hour at 8oC. moist heat; boiling kills it immediately. 

 It is slightly more resistant to chemical germicides than the typhoid bacillus. 



Toxin. Very old cultures are said to contain toxin. 



Agglutinins. Specific agglutinins are present in the serum of immunized 

 animals. 



Pathogenesis. Bacillus prodigiosus is a saprophyte, in old cultures it is 

 occasionally slightly pathogenic. This organism is of interest to physicians 

 because it is frequently present in dirty foods and may alter them in a deleterious 

 manner; also it is used in preparing Coley's fluid, an agent used in the treatment 

 of certain cases of sarcoma. 



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