CHAPTER XXXIII 

 BACILLUS AEROGENES CAPSULATUS 



B. PERFRINGENS, B. EMPHYSEMATIS VAGINAE, B. PHLEGMONIS EMPHYSEMA- 



OR B. WELCHH 



Bacillatus aerogenes capsulatus occurs in air, dust, soil and water; it is 

 frequently, if not constantly, an inhabitant of the intestinal canal of man and 

 animals. 



Extensive studies would seem to indicate that this organism is frequently 

 present in the gall-bladder, liver and blood of apparently healthy normal dogs 

 and in the liver or blood of some apparently healthy people. It is not uncom- 

 mon to find the bacillus aerogenes capsulatus in blood cultures, and cultures 

 from diseased joints in cases of rheumatism and arthritis deformans, even when 

 it is demonstrable that bacillus aerogenes capsulatus is not the cause of the 

 arthritis. 



This organism is frequently found in water polluted with sewage. 



Morphology. B. aerogenes capsulatus is a large bacillus, 3 to 8 ^ long, has 

 ends which are square or slightly rounded, is non-motile and is arranged singly 

 and in chains. Organisms removed from tissue, especially blood, usually show 

 a distinct capsule; in culture the capsule may disappear. 



Staining. It stains with all the common stains and is Gram positive. 



Growth. Bacillus aerogenes capsulatus is an obligate anaerobe and grows 

 best at 37C. 



Bouillon incubated at 37C. shows marked cloudiness in 12 to 24 hours; 

 later an abundant whitish flocculent sediment forms. 



Agar. Within 1 8 to 24 hours round, grayish colonies develop. They vary 

 in size from 2 millimeters to i centimeter in diameter, are flat and have irregular 

 margins. 



Stab cultures in agar show gas formation. 



Gelatin. Growth on this medium is the same as on agar. Gelatine is 

 slowly liquefied in the majority of cases; occasionally liquefaction does not 

 occur. 



Milk is rapidly acidulated and coagulated. 



Potato. Slight growth without any characteristic appearance occurs on 

 potato. 



Glucose, lactose and saccharose are fermented; gas is produced from 

 roteids. 



Bacillus aerogenes capsulatus forms spores. 



Toxin. There is little, if any, toxin production. 



Resistance. Bacillus aerogenes capsulatus is somewhat more resistant to 

 chemical and thermal germicides than the typhoid bacillus. Spores are highly 

 resistant to chemicals and require boiling for i hour to kill. 



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