Clostridium botulinum is a group of bacteria best known as the main source of botulinum neurotoxin, the cause of botulism in humans. There are several types of botulism. Foodborne botulism is caused by consumption of pre-formed toxin, whereas infant/intestinal (adult) botulism and wound botulism are infections involving toxin formation in situ.
The symptoms of botulism are primarily neurological and frequently begin with blurred vision, continuing to a descending bilateral flaccid paralysis, and in severe cases a flaccid paralysis of the respiratory or cardiac muscles. In many countries, equine antitoxin is administered to adults suffering from botulism, although in severe cases full recovery may take months or even years. The fatality rate is approximately 5 to 10% of cases. The economic and medical costs associated with foodborne botulism are extremely high.
Clostridium botulinum is defined solely on the basis of an ability to form botulinum neurotoxin, rather than on phylogenetic relationships. This approach is taken in order to emphasize the importance of neurotoxin formation. As a consequence, however, C. botulinum is a heterogeneous "species" that actually comprises four phylogenetically and physiologically distinct clades, known as C. botulinum Groups I to IV, with the distinction among the groups strong enough to merit treatment as four different species.Proteolytic C. botulinum (C. botulinum Group I) and non-proteolytic C. botulinum (C. botulinum Group II) are responsible for most cases of foodborne botulism.
(Peck et al. 2011 and references therein)
Based on research begun in the 1980s, botulinum toxin has been found useful in an expanding list of medical applications that require the blocking of involuntary muscle contractions, including eyelid twitching and other neurological problems. In the late 1980s, it was found that injection of botulinum toxin had cosmetic dermatological applications (wrinkle reduction) as well. Botulinum toxin entered the cultural mainstream in the United States in the formulation known as Botox®, establishing a new and highly profitable market for a product once known only as the cause of death for unfortunate individuals consuming improperly prepared sausages.(Kopera 2011)
More information on botulism is available from the U.S.Centers for Disease Control and Prevention.
Clinical Applications of Clostridium botulinum
Botulinum toxin is produced by anaerobic Clostridium botulinum bacteria and causes a paralysis called botulism. It was known as a deadly form of food poisoning but while this toxin is one of the deadliest on the planet, it also has a variety of clinical indications.In the 1950’s doctors discovered that injecting overactive muscles with small doses of toxin resulted in reduced muscle activity by blocking the release of acetylcholine at the neuromuscular junction3 and thus weakening the affected muscle for 4-6 months. It has since developed into a therapeutic tool. Since its discovery as a muscle inhibitor a variety of uses have been found for botulinum toxin ranging from cosmetic and medicinal aids to biological weapons.The most popular and recognizable use is a cosmetic injectable form (Botox or Dysport) that reduces wrinkles and signs of aging in the face. Local injection of botulinum toxin is also used to treat excessive sweating, cervical and laryngeal dystonia, excessive blinking and crossed eyes, Tardive dystonia, as well as other disorders of the central nervous system which result in lack of muscle control such as Parkinson’s, stroke and multiple sclerosis2. Botulinum toxin is the most common treatment for symptoms of movement disorders2 such as spasmodic torticollis, tics, tremors and dysphonia.Botulinum Toxin A has been effective in treating migraines and headaches and has been shown to improve gait patterns in patients with cerebral palsy who suffer from foot deformities4. Botulinum toxin has a multitude of medical uses but it must used carefully and with control to avoid permanent paralysis or poisoning.
Botulinum toxin has some unfavorable indications as well. Due to its high toxicity and potency, botulinum toxin has great potential for use as a biological weapon1. Great care need be taken when handling or using Botulinum toxin. A single gram of crystalline toxin, evenly dispersed, can kill over 1 million people1. Also due to its deadly toxicity, botulinum toxin can be used as a powerful poison if misused or ingested. As mentioned above, the toxin can cause a deadly form of food poisoning because it is found in soil and thennwhen transmitted in food sources. . Marine animals have even been shown to ingest C. botulinum from shellfish, resulting in contamination of the intestinal tract5 that is then spread to humans through onshore butchering and poor food preparation precautions.
