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KEY TO THE MORE COMMON SPORE PRODUCING LACTOSE FERMENTING 



ANAEROBES. 



I. Gelatin liquefied (generally pathogenic). 



A. Coagulated serum, liquefied (non-pathogenic) 



1. Cl. aerofetidum 



B. Coagulated serum not liquefied (pathogenic) 



1. Non motile 2. Cl. welchii 



2. Motile 



a. Sucrose fermented salicin not attacked 



3. Cl. chauvoei 



b. Sucrose not attacked, salicin fermented 



4. Cl. oedematis 



II. Gelatin not liquefied (non pathogenic) 



A. Non motile or very faintly motile 5. CL tertium 



B. Motile 



1. Salicin not fermented 6. Cl. butyricum 



2. Salicin fermented 



a. Glycerol and inulin fermented 7. CL multifermentans 



b. Glycerol and inulin not fermented. 



8. CL sphenoides 



Creel made a very interesting and, from the standpoint of the pre- 

 sumptive test, an important observation in his study of drinking waters on 

 railroad trains. He found two types of anaerobes which he designates 

 "Group A and B" respectively. "Group A" comprises very long Gram- 

 negative bacili (6-9 microns long and about 0.5 microns in width) whose 

 spores are very much larger than the diameter of the cell. It is particularly 

 significant to note that this group grows very rapidly producing consider- 

 able gas in lactose broth, under anaerobic conditions, but that no gas is 

 evolved in the lactose bile medium. Creel's anaerobes of "Group B" were 

 found to be non-motile, capsulated, resembling in general CL welchii. This 

 group will not produce gas in lactose broth unless the medium has been 

 freshly boiled or steamed in the Arnold until all air is expelled but in or- 

 dinary lactose bile, on the other hand, gas is formed very readily. 



These observations may explain the controversy as to the relative value 

 of lactose broth and bile as a presumptive test for the colon group. In 

 dealing with waters -containing anaerobes of "Group A" lactose bile will 

 prove more reliable whereas if "Group B" is the predominating anaerobe 

 then lactose broth will be found to give a higher proportion of confirmed 

 presumptive tests. 



Isolation of Anaerobes. Several methods have been suggested and 

 employed for the isolation of anaerobic spore forming lactose fermenters 

 from water. That originally described by Kline is as follows: 



Milk is inoculated with the water under examination and heated for 

 10 minutes at 80 C. to destroy vegetative cells. The tube is then cooled, 

 made anaerobic, and incubated at the body temperature. In about 24 

 to 36 hours, a characteristic, so-called "sporogenes" reaction will be ob- 



