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Studies on spore resistance and toxigenic characteristics of Clostridium botulinum, type E Munro, Elma Joan

Abstract

A brief historical review of Type E botulism is presented. Emphasis is placed on the role of fish in the epidemiology. Experimental details are given of tests carried out on the spore resistance of these Type E strains in comparison with the other types of CI. botulinum. The data obtained indicate that they are more thermolabile than any of the other types, especially A or B. In addition, evidence is presented which shows that the Type E strains seem to be divisible into two groups on the basis of their spore stability. The importance of this thermolability is stressed in regard to isolations of the seemingly rare Type E from suspected foodstuffs or in routine surveys. Details are given also of experiments conducted on the Type E toxins. The effect of dextrose, certain peptones, and colony type on toxin production is discussed. Some experiments on the storage properties of the toxins are presented. Active immunization experiments on mice indicate that Type E toxoids are poor antigens. In only two groups did the mice exhibit demonstrable immunity. Even in these groups the level of immunity was exceedingly variable. By contrast, a Type A toxoid proved a good antigen, protecting mice to a uniformly high degree against the homologous toxin. Efforts to increase the antigenicity of Type E toxoids are discussed. In vitro cross-neutralization tests with four Type E toxins and their antitoxins are described. On the basis of these in vivo and in vitro tests, it is concluded that Type E toxins are not homogeneous: a conclusion supported by the evidence that some Type E toxins contain a chicken-lethal factor, while others do not. This evidence is discussed in relation to the problem of human immunization.

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