570 ANAEROBIC ORGANISMS IN GANGRENE 



It is a normal inhabitant of the alimentary canal of man and many of the lower 

 animals and it possibly plays a part in the aetiology of certain forms of diarrhoea 

 (Tissier, Metchnikoif). It is also present in bodies undergoing decomposition. 



1. Experimental inoculation. 



Guinea-pigs are the animals most susceptible to experimental inoculation. 

 Death follows sub-cutaneous inoculation in 24-48 hours with lesions similar 

 to those of malignant oedema : at the site of inoculation the skin is stripped 

 up by a gas-containing abscess : the internal organs are crowded with micro- 

 organisms. 



Rabbits are not so susceptible. Sub-cutaneous inoculation is followed by 

 the formation of a large gas-containing abscess which generally resolves : 

 if death occur it does not usually take place until about a week after the 

 inoculation. Inoculation into the veins even is not always fatal. 



2. Morphology. 



The Bacillus perfringens is a large, straight, non-motile bacillus of variable 

 length and a little larger than the anthrax bacillus. The ends are square 



cut or slightly rounded. In the tissues the 

 bacilli are as a rule shorter than in cultures, are 

 often surrounded by a very distinct capsule, and 

 are occasionally (e.g. in the peritoneal exudate) 

 arranged in somewhat long chains. In cultures 

 on liquid media the bacilli are generally long 

 and slender : in old cultures involution forms 

 occur deformed bacilli with rounded ends and 

 staining irregularly. 



Spore formation does not occur in sugar-con- 

 taining media but in media containing no sugar 

 and especially on cooked white of egg in normal 

 FIG. 267. Bacillus perfringens. saline solution an oval spore is formed towards 

 CarLiSn1n gl Tfooo th ^^ one end whi cn stains with difficulty (Musca- 



tello). 



Staining reactions. The Bacillus perfringens stains easily with the basic 

 aniline dyes and is gram-positive. 



3. Cultural characteristics. 



The Bacillus perfringens is a strictly anaerobic organism and grows best 

 on media containing glucose. At 37 C. and even at ordinary temperatures 

 it grows very rapidly. It decomposes powerfully sugars and proteins giving 

 off a considerable quantity of gas which has an odour of butyric acid. It 

 produces no indol. According to Achalme it reduces nitrates to nitrites. 



The vitality of the bacillus is rather low and it should be frequently sub- 

 cultivated. 



Rosenthal claims to have been able to adapt the Bacillus perfringens to aerobic 

 conditions. Rosenthal distinguishes two varieties of the bacillus, the common 

 variety which grows with a fetid odour, and a variety which does not give rise to 

 this disagreeable smell and is less active in attacking culture media : the latter 

 variety is said to correspond to Achalme' s rheumatism bacillus. 



Broth. The medium soon becomes cloudy and later the growth precipitates 

 in the form of whitish flakes leaving the broth clear. 



Gelatin. In gelatin containing no sugar, some strains distinctly liquefy 

 the medium while with others liquefaction only takes place slowly and to a 

 slight degree. 



