An overview of vaccines for human use is presented in Vaccines for Human Use—General Considerations 〈1235〉, which includes a glossary of terms. Bacterial vaccines can be derived from whole cells, either killed or attenuated in their ability to cause disease, or from some component(s) of the intact cell that is important for virulence or damage to the host (see Table 1 for examples). In some cases, the antigen may be recombinant and produced in a non-pathogenic organism. Another subset of bacterial vaccines, derived from toxins, is the toxoids. Bacterial vaccine products can be mixtures of components from different species, from different strains or different serotypes of the same species, or from different components from cells of the same species.