Clostridium botulinum is a spore-forming, gram-positive, anaerobic rod. A number of different potent neurotoxins (from A-G) are produced by different strains. The name is derived from the Latin for sausage, botulus, due to its association with food poisoning from bad sausages. Botulinum toxin A is the most widely studied; it is the easiest to obtain from culture and was the first to be commercially prepared as Botox (Allergan). The toxin, consisting of two subunits (light and heavy chains are connected by a disulphide bridge), selectively inhibits acetylcholine release at the neuromuscular junctions in a dose-dependent manner.