The pathogenicity of the spores of Clostridium botulinum

1. The injection of mice with botulinum spores, freed from all traces of superficial toxin, can cause death but only if a very large number is given. This number was found in the case of a highly toxic strain to be of the order of 20 million spores given intramuscularly. This dose was fatal in the absence of spore germination. 2. In human botulism it is concluded that the spores of Clostridium botulinum persent in spoiled foodstuffs are not of importance compared with the toxin produced by the initial growth of the contaminating organisms. 3. Toxin could be demonstrated in the cytoplasm of botulinum spores when these were disintegreted by mechanical means. This is of theoretical interest as the toxin within the spores is more heat-stable than the extracellular form. 4. A local anaerobic myositis could be produced in mice by the intramuscular injection of spores plus 2·5% CaCl2. The number of viable spores in the LD50 was of the order of 50,000. 5. Calcium chloride solution in the commonly used strength of 2·5% was shown regularly to cause a drop in the number of botulinum spores in a given suspersion of some 40% and a parallel loss of viability of about 60%.