Clostridium+tetani

Clostridium tetani: Tetanus media type="youtube" key="trWerFo5xdw?fs=1" height="385" width="480" align="center"


 * __ Scientific Classification __**


 * ** Kingdom ** || Bacteria ||
 * ** Phylum ** || Firmicutes ||
 * ** Class ** || Clostridia ||
 * ** Order ** || Clostridiales ||
 * ** Family ** || Clostridiaceae ||
 * ** Genus ** || Clostridium ||
 * ** Species ** || tetani ||

The **Firmicutes** (Latin: //firmus//, strong, and //cutis//, skin, referring to the cell wall) are a phylum of bacteria, most of which have Gram-positive cell wall structure. A few however, such as Megasphaera, Pectinatus, Selenomonas, and Zymophilus, have a porous pseudo-outer-membrane that causes them to stain Gram-negative. Scientists once classified the Firmicutes to include all Gram-positive bacteria, but have recently defined them to be of a core group of related forms called the low-G+C group, in contrast to the Actinobacteria. They have round cells, called cocci (singular coccus), or rod-shaped forms. Many //Firmicutes// produce endospores, which are resistant to desiccation and can survive extreme conditions. They are found in various environments, and the group includes some notable pathogens. Those in one family, the heliobacteria, produce energy through photosynthesis. Firmicutes play an important role in beer, wine, and cider spoilage.
 * __ Description of Phylum: Firmicutes __**

**__ Introduction to species __** Tetanus was well known to ancient people, who recognized the relationship between wounds and fatal muscle spasms. In 1884, Arthur Nicolaier isolated the strychnine-like toxin of tetanus from free-living, anaerobic soil bacteria. The etiology of the disease was further elucidated in 1884 by Antonio Carle and Giorgio Rattone, who demonstrated the transmissibility of tetanus for the first time. They produced tetanus in rabbits by injecting their sciatic nerve with pus from a fatal human tetanus case in that same year. In 1889, //C. tetani// was isolated from a human victim, by Kitasato Shibasaburō, who later showed that the organism could produce disease when injected into animals, and that the toxin could be neutralized by specific antibodies. In 1897, Edmond Nocard showed that tetanus antitoxin induced passive immunity in humans, and could be used for prophylaxis and treatment. Tetanus toxoid vaccine was developed by P. Descombey in 1924, and was widely used to prevent tetanus induced by battle wounds during World War II.

= This picture is an unrooted phylogram detailing the phylogeny of the //Clostridium// genus relative to other bacterial genera. //Clostridium// has been highlighted by a white border for ease of location. = =    = =   = // C. tetani // is a rod-shaped, anaerobic bacterium. Like other //Clostridium// species, it is Gram-positive, and its appearance on a gram stain resembles tennis rackets or drumsticks. During vegetative growth, the organism cannot survive in the presence of oxygen, is heat-sensitive and exhibits flagellar motility. As the bacterium matures, it develops a terminal spore, which gives the organism its characteristic appearance. //C. tetani// is found as spores in soil or as parasites in the gastrointestinal tract of animals. The spores are extremely hardy as they are resistant to heat and most antiseptics. They are distributed widely in manure-treated soils and can also be found on human skin and in contaminated heroin.
 * __ Unique Morphological Features __**

**__ Unique Anatomical/Physiological Features __** // Clostridium tetani // is an anaerobic pathogenic bacterium that is primarily found in soil and animal intestinal tracts. As characteristic of all bacteria, //C. tetani// bacteria are single-celled and do not contain any membrane-bound organelles, such as a nucleus. This bacterium is Gram-positive, meaning it lacks an outer lipopolysaccharide membrane and possesses only a thick peptidoglycan cellular wall. However, established vegetative bacterium occasionally stain Gram-negative, indicating a development of a thin lipopolysaccharide membrane. This bacterium is characteristically rod-shaped and flagellated in its vegetative state, and drumstick shaped in its spore form. There are currently eleven identified strains of //C. tetani//, and all eleven strains are known to produce an identical neurotoxin known as tetanospasmin. This potent toxin is the cause of the central nervous condition known as tetanus, which is commonly fatal unless treated.

__ Toxicity __
// C. tetani // usually enters a host through a wound to the skin and then it replicates. Once an infection is established, //C. tetani// produces two exotoxins, tetanolysin and tetanospasmin. Eleven strains of //C. tetani// have been identified, which differ primarily in flagellar antigens and in their ability to produce tetanospasmin. The genes that produce toxin are encoded on a plasmid which is present in all toxigenic strains, and all strains that are capable of producing toxin produce identical toxins. Tetanolysin serves no known benefit to //C. tetani//. Tetanospasmin is a neurotoxin that causes the clinical manifestations of tetanus. Tetanus toxin is generated in living bacteria, and is released when the bacteria lyse, such as during spore germination or during vegetative growth. A minimal amount of spore germination and vegetative cell growth are required for toxin production. // Clostridium tetani // produces spores that are found abundantly in soil and the feces of both animals and humans. It is an anaerobic organism, thriving on injured or dead wound tissue. Even though wounds are often contaminated with soil and the bacterium is present, the disease does not always develop in a great majority of cases**. The condition of the wound must contain the proper environment for the spores to germinate, the bacteria to proliferate, and the toxins to be produced. ** // C. tetani // is found as spores in soil or as parasites in the gastrointestinal tract of animals. Tetanus still frequently crops up among drug abusers. Without treatment, the disease is always fatal. To show how fast the toxin travels once it enters the bloodstream, a Japanese scientist, Shibasaburo Kitasato, injected the bacteria into the tail tip of a mouse and then chopped it off an hour later, but it was too late to stop the action.
 * __ Adaptive Habitat Features __**
 * __ Range on Earth __**
 * Clostridium tetani can infect almost any human, and therefore it’s range on Earth o anywhere (or wherever there are people/”infectable” animals). However, it is predominant in poor African countries with no available protection/treatment options. **


 * __ Interesting facts __**

// C. tetani // produces a potent biological toxin, tetanospasmin, and is the causative agent of tetanus, a disease characterized by painful muscular spasms that can lead to respiratory failure and, in up to 40% of cases, death. On the basis of weight, tetanospasmin is one of the most potent toxins known. The estimated minimum human lethal dose is 2.5 nanograms per kilogram of body weight, or 175 nanograms in a 70 kg (154 lb) human. The only toxins more lethal to humans are botulinum toxin, produced by close relative //Clostridium botulinum// and the exotoxin produced by //Corynebacterium diphtheriae//, the causative agent of diphtheria. Signs and symptoms of disease usually occur four to ten days after injury, but it can be delayed by several months. As the spores multiply in the wounds, they produce the exotoxin tetanospasmin, which is the actual cause of the disease. Therefore, the disease cannot be considered contagious. The toxin travels through the blood and nerves to the brain and spinal cord, interfering with messages sent out to the muscles. The muscles then go into spasms because they are not receiving their normal messages. As the facial muscles start to disfigure, the characteristic "grin" it causes (risus sardonicus) and the locking of the jaw are first telltale signs. It is the difficulty in opening the mouth that will clue in medical personnel as to with what they are dealing. As the disease progresses, spasms in other muscles occur. They can be brief, but are often frequent enough to cause great pain and exhaustion. In some cases, the spasms are so powerful, they cause bones to break. Respiratory complications are common, and death rates are high, especially in young children and the elderly. In nonfatal cases, recovery takes several weeks. A frequently encountered form of tetanus is one involving the umbilical cords of babies born in underdeveloped countries. Often the cords are cut with nonsterile instruments, sharp rocks or stones, and the area packed with dirt, according to tribal custom. More than ½ million babies die each year in Asia and Africa because their unbilical cords have been treated in this manner. Tetanus was recognized by Hippocrates in the 5th century BCE and most probably in ancient Egypt as well since dung was the favored cure of the day.


 * __ References __**
 *  Ryan, K. J., Ray, C. G., & Sherris, J. C. (2010). //Sherris medical microbiology// (5th ed.). New York: McGraw Hill Medical.
 *  Madigan, M. T., & Brock, T. D. (2009). //Brock biology of microorganisms// (12th ed.). San Francisco, CA: Pearson/Benjamin Cummings.
 *  Unrein, B. (n.d.). Clostridium tetani. //BioWeb Home//. Retrieved November 14, 2010, from http://bioweb.uwlax.edu/bio203/s2008/unrein_bren/