How Bacterial Pathogens Damage Host Cells A. Toxins 1. Exotoxins - Proteins, mostly enzymes, that catalyze certain biochemical reactions that destroy part of the cell or inhibit certain metabolic functions. Most lethal substances known. Diseases are caused by very minute amounts. Causes paralysis in which muscle tone is lacking.
Result is uncontrollable muscle contraction.
Also produces another type associated with toxic shock syndrome. Exert effect when bacteria die and substances are liberated. Small, circular, double-stranded DNA molecules that are not connected to the main bacterial chromosome. These molecules are responsible for resistance of some organisms to antibiotics, toxins, capsules, and fimbriae - all factors in pathogenicity. Are beginning to preferentially survive.