THE ANAEROBIC BACILLI 751 



The proteolytic group includes: 



B. sporogcnes 

 B. histolyticus 

 B. putrificus 



This classification, like most others, is not a rigid one. It merely 

 means that members of the saccharolytic group have a much greater 

 avidity for carbohydrates than have members of the proteolytic 

 group. 



It may be possible to demonstrate proteolytic activity of the 

 organisms included in the saccharolytic group on special media from 

 which all carbohydrate has been removed, but on the ordinary 

 culture media the difference between the two groups is striking. 



Members of the proteolytic group can be distinguished from 

 the saccharolytic group by the fact that they liquefy coagulated 

 horse serum. Organisms of the saccharolytic group fail to liquefy 

 this medium even after prolonged incubation. In milk the saccharo- 

 lytic bacilli produce acid and varying amounts of gas. The pro- 

 teolytic bacilli digest milk with the production of alkali. 



The organisms of the proteolytic group are not in themselves 

 pathogenic, but complicate wounds by their intense proteolytic 

 action. They are saprophytes, they have no power of invading the 

 tissues and if present without members of the saccharolytic group 

 usually do not interfere with the healing of the wound. 



Whether the organisms of the saccharolytic group are sapro- 

 phytes or not, is an open question. De Kruif 5 concludes that B. 

 Welchii cannot be classified as a pure saprophyte, because a twice 

 washed bacillary emulsion in doses of 0.1 c.c. to 1 c.c. will kill 

 a guinea pig. But in this case even the most careful intramuscular 

 injection will kill some of the tissue at the point of inoculation, 

 and with even a very small amount of dead tissue, B. Welchii can 

 produce a toxin which has tremendous aggressive action and has 

 the property of killing the tissue with which it comes in contact. 

 This makes possible the further invasion of B. Welchii. 



B. Welchii. B. Welchii is the organism most frequently found 

 in gas gangrene. It was present in about 72 to 80 per cent of the 

 cases of gas gangrene studied during the war, and has been con- 

 sistently associated with civilian cases of gas gangrene. It is gener- 

 ally considered the most important etiological factor in this disease. 



* De Kruif, Jour, Infec. Dis., 21, 1917, No. 6. 



