SpecificsThere are three forms of human botulism: Infant botulism, food borne botulism and wound botulism (Arnon 1997). Due to the limits presented by this assignment, I will concentrate on food borne botulism, otherwise known as classical botulism.General DescriptionClostridium botulinum is a gram- positive, spore forming, rod shaped bacterium which is derived from the soil, but grows in many meats and vegetables (Minton 1989). C. botulinum is known to grow best in the absence of air (Encarta 2000). Therefore, the growth of C. botulinum and the cause of the disease, classical botulism, is usually the result of improperly canned foods (Campell et al.). The bacterium produces an extremely potent neurotoxin which has devastating effects on the human body. The effects of botulism ranges from flaccid paralysis to death(Arnon 1997). The potency of the botulinum toxin is astonishing. The botulinum toxin is approximately 800 million times more potent than cyanide, 400 million times more potent than arsenic and 300 million times more potent than rattlesnake venom (Arnon 1997). It is thus easy to see why C. botulinum attracts so much attention from the medical and scientific community. Requirements for Laboratory GrowthClostridia botulinum can be readily grown in laboratories. The C. botulinum grows best in an anaerobic environment (Minton 1989). The presence of oxygen will kill the vegetative cells, however the spores formed by C. botulinum can withstand long periods of time exposed to oxygen (Minton 1989). The organisms grow best in a neutral environment but have been found in low acidic vegetables (>pH 4.5) (Arnon 1997). Due to the obvious potency of C. botulinum, an experimental vaccine has been developed to safeguard lab workers against C. botulinum. Immunity towards botulism is not possible though because the amount need to induce an immune response would be toxic (Arnon 1997).
PathogenicityA dilute solution of purified botulinum toxin is colorless, odorless and tasteless (Arnon 1997). As stated earlier, the bacteria are grown in improperly canned foods and are extremely deadly. It has been estimated that one gram of botulism is sufficient to kill one million people (Campell et al.). The toxin, when entered into the human body, is carried by the bloodstream to peripheral cholinergic synapses where it binds irreversibly, blocking acetylcholine release at the neuromuscular junction, thereby preventing muscle contraction (flaccid paralysis) (Science Net, March 21, 2000, electronic communication). From the neuromuscular junction, the toxin is then internalized into the motoneuron cell. The main cause of death from botulism is usually suffocation due to paralysis of airway and respiratory musculature (Arnon 1997).Clinical ManagementThe misdiagnosis of botulism is accredited with its rarity (Arnon 1997). Classical botulism usually starts with signs of vomiting and diarrhea. Once flaccid paralysis becomes apparent, usually constipation occurs (Arnon 1997). Symptoms appear usually after 18 to 36 hours (Encarta, March 21, 2000, electronic communication). Depending on the amount of toxin consumed, the illness can begin in as little as 2 hours or as long as 8 days (Arnon 1997). C. botulinum can be detected in serum, wound material or feces. Adhering to safe methods of home canning best prevents botulism. Boiling for 30 minutes can kill the spores, but the toxins can be killed using moist heat at 80 degrees for the same amount of time (Encarta, March 21, 2000, electronic communication). There are botulism antitoxins available and passive immunization with an antibody is also another possible treatment for botulism.(Science Net, March 21, 2000, electronic communication) However, both treatments lose their effectiveness with time. A late diagnosis of botulism is almost always, deadly (Arnon 1997).