Traditional bacterial genetics

Detoxification. The process by which bacterial toxins are converted to harmless toxoids. Formaldehyde is used to detoxify the toxins of Corynebacterium diphtheriae, Clostridium botu-linum and Cl. tetani. The detoxification may be performed either on the whole culture in the fermenter or on the purified toxin after fractionation. Traditionally the former approach has been adopted, as it is much safer for the operator. However, the latter gives a purer product. The pertussis toxin used in acellular vaccines may be detoxified with formaldehyde, glutaraldehyde, or both, hydrogen peroxide or tetranitromethane. In the case of genetically detoxified pertussis toxin, a treatment with a low concentration of formaldehyde is still performed to stabilize the protein. 

There is a long tradition and vast literature which uses the term resistant to refer to bacteria that have been shown, in susceptibility tests, to be less susceptible than other members of the group or species to which they belong. It is important to note that resistance, as defined here, is a measure of an in vitro bacterial phenotype. It is a formal error to consider that it has a necessary relationship to the clinical outcome of any proposed therapy. Defined in this way resistance is a very useful term for those whose primary interest is in bacterial phenotypes and the molecular and genetic mechanisms that underlie them. It is, however, less useful and can, in fact, be misleading, for those whose primary interest is in predicting the possible outcomes of a proposed antibiotic therapy. 

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