Bacterial and Cyanobacterial (Blue-Green Algae)

Abstract

This chapter deals with the toxic effects of botulinum toxins, enterotoxemias (Clostridium perfringens infections), and blue-green algae (cyanobacterial toxins). Bacteria generate toxins which may be exotoxins (generated and actively secreted) or endotoxins (remain part of the bacteria). An endotoxin is part of the bacterial outer membrane, and it is not released until the bacterium is killed by the immune system. Blue-green algae produce toxins from cyanobacteria. There are >30 species of cyanobacteria that can be associated with toxic water blooms responsible for most cases of toxicity in animals. Classical mode of action of botulinum toxins is to presynaptically bind to high-affinity recognition sites on the cholinergic nerve terminals, decrease the release of acetylcholine, and produce presynaptic neuromuscular blockade. Enterotoxemia is induced by toxins produced by Clostridium perfringens. There are several strains of C. perfringens (Type B, Type C, and Type D) that may lead to toxemias. Toxins produced from blue-green algae are specifically toxic to the liver; microcystins cause severe hepatomegaly macroscopically and progressive centrolobular hepatocyte rounding, dissociation, and necrosis; and breakdown of the sinusoidal endothelium and intrahepatic hemorrhage ultimately result in death in animals.