Bacterial toxins are by-products produced by pathogenic microbes that have taken up residence in the body. The bacterium can enter a host through various means, such as consumption of contaminated food or water. Bacteria can also be introduced through mucous membranes, either by direct contact with the source or as a consequence of inhalation of airborne bacteria. The type of bacterial toxins released depends on the species of invading bacteria.
The cell structure of the bacteria also influences the types of bacterial toxins that are produced. While all bacteria have individual cells, there is a difference between their outer membranes that results in two classifications of bacteria: Gram-positive or Gram-negative. This distinction is visible when subjected to a "Gram stain", which is an injection of a purple dye and a subsequent wash with alcohol. Cells that retain the color of the dye are Gram positive; those that are not Gram-negative.
There are several types of bacterial toxins that can infect the human body at different sites. For example, enterotoxins are toxic proteins generated in the intestines. Neurotoxins specifically target nerve cells. In addition, certain enzymes can be produced that can affect metabolic functioning. However, there are two main groups of bacterial toxins that the above generally fall into in terms of mechanism: exotoxins and endotoxins.
Both Gram-positive and Gram-negative bacteria produce exotoxins, some of which are quite poisonous. For example, tetanus is caused by a bacterial toxin produced by Clostridium tetani which acts as a neurotoxin. In general, the severity of symptoms and the rate of recovery depend on how the infection occurs. However, it has been established that only a small amount of the pure toxin will prove fatal. Fortunately, this bacterium, as well as other exotoxins, can be adapted to produce preventative vaccines.
Endotoxins are released by gram-negative bacteria. At first, they are not as aggressively toxic as exotoxins due to the fact that they remain largely contained in the cell walls of the bacteria. However, as these cells complete their life cycle and die, the circulating volume of this toxin increases. Also, they cannot be used to make vaccines.
Normally, the body tries to eliminate bacterial toxins before they can cause harm. The immune system is the first line of defense, but can be overwhelmed by the rate of bacterial replication. In fact, inflammation is an indication that bacterial overgrowth is occurring. In this case, the immune system will do the next best thing: get the bacteria out of the way. Usually, fat cells are the selected storage sites, which can lead to the formation of cysts and tumors.
Without intervention, bacterial toxins can eventually build up to the point where they move out of fat cells and into other body tissues. This process can take years to develop, but the end result is often a degenerative disease. In fact, many age-related conditions and metabolic disorders are associated with long-term accumulation of these toxins, including heart disease, cancer, arthritis, and diabetes.