CHAPTER 36 



CLOSTRIDIUM 



THE SPORE-BEARING ANAEROBES 



Definition.— Clostridmm. 



Anaerobic or microaerophilic rods, producing endospores, wliich are usually 

 wider than the vegetative organisms in which they arise — so-called Clostridium 

 forms. Generally Gram-positive. Often decompose protein media and often 

 ferment carbohydrates. Many species form exotoxins, and many are pathogenic. 



Type species is Clostridium butyricum Prazmowski. 



Before the war of 1914-18, the study of the spore-bearing anaerobes had been 

 undertaken fitfully and by imperfect methods ; much attention had been paid to 

 their pathogenicity, but little to their general biological characters. One and the 

 same organism had received many different names, and many organisms with the 

 same name undoubtedly belonged to different species. The only two organisms 

 about which no doubt existed were the two that formed a highly potent toxin, 

 recognizable by the specific effects they produced on injection into animals — namely 

 CI. tetani and CI. hotulinum. It was not till the exigencies of war rendered an 

 intensive study of the anaerobes necessary, and till the introduction of Mcintosh 

 and Fildes' jar made it feasible to obtain pure cultures with relative ease, that 

 the obscurity surrounding this group was dispersed. 



Most of the older workers had failed to realize the difficulty inherent in obtaining 

 pure cultures of the anaerobic bacilli. The new technique, especially by enabling 

 plate cultures to be made, revealed at once the impurity of many of the classical 

 strains, and provided a means for the preparation of single-colony cultures. For 

 the first time a distinctive account was provided of the main species, which made 

 possible their identification, and which disposed of many spurious characters that 

 had been attributed to them. Incidentally fresh species were discovered. (For 

 references on the production of anaerobiosis see Liborius 1886, Frankland 1889, 

 Smith 1890, Tarozzi 1905, Smith et al. 1905-06, Laidlaw 1915, Mcintosh and Fildes 

 1916, Report 1917, Holker 1918-19, Rockwell 1924, Varney 1926, Wilson 1928, 

 Hall 1929a, Dickens 1934, McClung et al. 1935). 



Habitat. — The anaerobes are widely distributed in nature, but their main 

 habitat is undoubtedly the soil. Some of them appear to be common inhabitants 

 of the intestinal canal of man and animals. CI. welchii, for example, is uniformly 

 present in human faeces ; Gl. tetani has been found in about 10-40 per cent, of faecal 

 specimens of domestic animals ; CI. sporogenes is frequently, and CI. kistolyticum 

 occasionally present. It has been held by some that the intestinal canal is the 

 main habitat of certain of the anaerobes, particularly CI. tetani, and that their 

 presence in the soil can be explained by faecal contamination. The fact that this 



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