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BACILLIUS ANTHRACIS

Bacterium Bacillus Anthracis is a Gram-positive rod-shaped measuring about 1x6 micrometers and is the cause of anthrax.

Bacillius anthracis is the first bacterium shown to cause disease. This is shown by Robert Koch in 1877. The name derives from the Greek anthracis anthrax (ἄνθραξ), meaning coal, referring to the blackening of the skin on the victim.

These bacteria commonly found in soil in the form of spores, and can live for decades in this form. If entering a kind of herbivores, these bacteria will begin to proliferate in the animal and eventually kill him, and then continue to proliferate in the carcass of the animal. When the nutrients absorbed by the animal have been exhausted, they turned back to the spore form.

Bacillus anthracis has the genes and traits that resemble Bacillus cereus, a bacterium commonly found in soil worldwide, and also resembles Bacillus thuringiensis, pantogen to the larvae of Lepidoptera.Living in a land of vast quantities of bacteria belonging to the genus Bacillus. The genus consists of aerobic, Gram-positive, spore-forming rod. All members have certain characteristics, including the ability to exist in two different forms. When the conditions for good growth, with abundant nutrients and water available, they are rod-shaped organisms that grow and divide. When conditions are unfavorable, each forming a highly resistant dormant spores that can survive in extreme environmental conditions.


spores were dehydrated cells with thick walls and additional layers are formed inside the cell membrane. It can remain dormant for many years, but if he comes to a favorable environment, it begins to grow again. Sometimes called endospores, as originally developed in the form of rod-shaped. Features such as the location of the trunk, the size and form endospores, and whether or not cause the wall to bulge out of the trunk is the nature and characteristics of certain species of Bacillus. Depending on the species, endospores are round, oval, or sometimes cylindrical. They are highly refractile and contain dipicolinic acid. section electron micrographs show that they have a thin coat of spores outside, a thick spore cortex, and the membrane surrounding the spore content of spores. Spore heat resistance, drying and many disinfectants (including 95% ethanol).


Most of the Bacillus species that grow on dead organic matter and decomposing, and not harmful to humans and animals. One species, however, Bacillus anthracis, is a dangerous pathogen that causes anthrax disease. It is a zoonosis, meaning it affects domestic and wild animals, and humans secondary.
The ability of Bacillus anthracis spores can make the organism difficult to control. Spores can exist in soil for decades. They can float a soft breeze, dormant until they find a place that has a temperature, nutrients, and other conditions to allow for growth. When they discover their new host (animal or human) they transform into rod-like shape and begin to multiply rapidly. While they are in the form of their spores can survive boiling, freezing, or even suspension in alcohol. It takes special measures to kill them, such as steam under pressure, or chemicals known as sporicides. The ability to survive in extreme conditions for long periods of time is one of the reasons Bacillus anthracis have been used by a major terrorist.

For a microbiologist, grew Bacillus anthracis in the laboratory and causing it to form spores is an easy task. However, putting the culture containing millions of spores of Bacillus anthracis into a form that makes an effective weapon is not easy.

Disease  
Bacillus anthracis is usually a disease of herbivores (plant-eating mammals), although it can affect other animals as well. Among domesticated animals, cattle, sheep, and goats have been victimized most often. In most industrialized countries, livestock are routinely vaccinated, and cases of anthrax are rare. In developing countries, however, where animals are not regularly practiced vaccination, anthrax in animals is a problem. This is especially true in the tropics and sub-tropics. In the United States, anthrax cases among animals has been generally confined to the western plains. 

Endospores can survive in soil for many years. Animals consuming the spores along with the grass as they graze. Once the spores enter the animal, they germinate, transforming into a resistant form of growing and dividing vegetative form. The lysis sporangium, the spores germinate, and the bacilli multiply rapidly. Anthrax is a very serious disease in animals, culminating in a fatal septicemia. Animal carcasses should be burned where it was. Carcasses should not be opened, because doing this will cause the vegetative form, which can be destroyed relatively easily, to form into resistant spores that can persist for years. Virulent Bacillus anthracis vegetative cells form acid capsule poly-D-glutamate after they enter their host. This capsule has a negative charge which inhibits the macrophage from engulfing and destroying vegetative cells, inhibits the host immune response. So the capsule allows virulent anthrax bacilli to grow virtually unimpeded in the infected host.2 

Infection in humans has traditionally been far less frequent than infection in animals. Anthrax occurs in people who come in contact with animals or animal products. This is often an occupational disease, affects veterinarians, people who raise livestock, and people who prepare the products of wool, hides, and animal hair. Inhalation form of anthrax used to be known as woolsorters disease, because it affects people who work with wool. Products from countries where anthrax is common in animals is still a problem. Goat hair and skin containing animal crafts from the Middle East has been a recurring source of infection.3 ordinary citizens in the United States are most likely to face anthrax from imported products that have not been treated sufficiently to destroy spores. 


In humans there are three possible forms of anthrax disease. Historically, the most common form of skin anthrax have been, where organisms entering through breaks in the skin. Cutaneous form begins as a papule at the site entry that develops over several days and then ulcerates vesicles. Edema, sometimes large, round lesions, which later developed the typical black eschar. Patients may experience fever, malaise and headache.4 A small skin infection becomes systemic, and can be fatal. 


A more serious form is inhalation anthrax. Here breathing victim in the organism and develop severe respiratory disease. systemic infection caused by inhalation of Bacillus anthracis has a mortality rate approaching 100%. early symptoms are vague and resemble the flu, go to hypotension, shock and bacteremia and toxemia large. Severe symptoms are believed to result bacillis exotoxins. The initial treatment of antibiotics is an absolute necessity and should begin during the incubation period if someone has exposed.5 After the acute symptoms have appeared, antibiotics can kill the organism, but will not destroy the powerful toxins that have been formed, and generally died within 2-3 days of respiratory failure and septic shock. 


The third form, intestinal anthrax, contracted from consumption of contaminated meat. In industrialized countries this is not usually a risk, though rare exceptions have been described. In August 2000, the Minnesota Health Department was informed that the Bacillus anthracis have been isolated from the drive on a farm in Roseau County. The infected drive is one of five dead cattle found in pastures. On the basis of identification of bacteria by phage typing isolates cultured from tissue and blood samples by the North Dakota State University Veterinary Diagnostic Laboratory, anthrax was confirmed. A report of this incident illustrates the management and public health response to human exposure to meat contaminated with anthrax. 


In countries where hunger is a serious problem, the consumption of contaminated meat is more of a risk than in the U.S. oropharyngeal anthrax begins with a severe sore throat or ulcers in the oropharyngeal cavity, accompanied by neck swelling and fever. Gastrointestinal anthrax begins with anorexia, nausea, vomiting and abdominal pain. There may be bleeding diarrhea.7 intestinal anthrax can become systemic and result in death.
Anthrax can be treated with antibiotics, but it is important that treatment is started early. If it is known that a person has been exposed, treatment should begin immediately, even before symptoms appear. In inhalation anthrax, the most serious form of disease, early symptoms of common flu-like respiratory symptoms. If treatment is delayed until the specific symptoms appear, death rates are very high. Ciprofloxacin and doxycycline are the drugs of choice. Penicillin can also be used. Because it is important to completely eradicate the organism, the treatment of anthrax should continue for an extended period, usually sixty days.
Because of current public health issue, The New England Journal of Medicine has published three articles on the Web at www.nejm.org, several weeks before their appearance in print in the November issue of March 29, 2001,. 


"Cutaneous anthrax infection" (published November 6) by KJ Roche, MW Chang and H. Lazarus describes the case of a baby seven months old boy who was hospitalized with a two-day history of left arm swelling and weeping lesions in the left elbow. It was first diagnosed as spider bites. He was treated with ampicillin-sulbaktam and clindamycin. He has been in office the mother in a television network three days before entering. After exposure to anthrax were reported in another television network, two punch biopsy of the lesion performed. Polymerase chain reaction and immunostaining for Bacillus anthracis is positive.
"Recognition and management update anthraxan" (published November 6) by MN Swarz review the characteristics of the organism and the diagnosis and treatment of disease. 


"The index case of fatal inhalational anthrax due to bioterrorism in the United States" (published 8 November) by LM Blush, BH Abrams, A. Beall, and CC Johnson explains in detail the first case of inhalation anthrax occurred in the United States since 1978. The patient worked as photo editor for a major tabloid newspaper in Florida, where he spent most of the day reviewing photographs submitted by mail or over the Internet. Colleagues reported that patients had closely examined a suspicious letter containing powder around eight days before the onset of disease. Bacillus anthracis cultured from blood and from cerebrospinal fluid. 

Research  

It has been known for years that part of the organism that causes symptoms of anthrax toxins, poisons are very strong. Much current research involves examining the anthrax toxin in great detail, making small changes in structure, and see how these changes affect its properties. Researchers are trying to understand each step in how the toxin may have an effect. If this procedure is fully understood, so researchers can look for specific steps in which they can block the action of the toxin. A recent article in Critical Reviews in Microbiology (vol. 27, no 3,. Page 167-200) by R. Bhainagar and S. Batra review of anthrax toxin.
Low levels of anthrax toxin causes the release of cytokines such as tumor necrosis factor alpha. Dehydroepiandrosterone and melatonin has been found to inhibit cytokine production increased anthrax lethal toxin and may have a role in therapy.
It has been found that anthrax toxin is actually comprised of three proteins. protective antigen (PA) binds to the receptor cells and mediates the entry of two other components to the cytoplasm. Edema factor (EF), named for its ability to produce edema, is a calcium / calmodulin-dependent adenylate cyclase. Lethal factor (LF), the dominant virulence factor associated with toxic, proteolytically inactivates mitogen-activated protein kinase kinase (MAP kinase kinase), which is important in intracellular signal transduction.
Three separate proteins that make up anthrax toxin acts PA, EF and LF in binary combinations to produce two distinct reactions in experimental animals: edema (PA + EF) and death (PA + LF).
There has been much interest in the PA, because it is important for both activities of EF and LF. It has been found that a 63-kDa fragment of proteolytically activated PA bind LF / EF and translocates them into the mammalian cell cytosol. PA domain II has been implicated in membrane insertion and channel formation.
One study found that the PA has been greatly reduced toxicity of mutant in combination with LF, as well as the decrease in membrane insertion and translocation of LF into cytosol.11 In another study, mutations block the ability of PA to mediate pore formation and translocation in cells but had no effect on receptor binding activation, proteolytic, or ability to oligomerize and bind the toxin enzymes.12 other studies identify PA mutants that co-assemble with wild-type protein and block its ability to translocate the enzyme in the membrane. These mutants strongly inhibits the action of toxins in cell culture and in animal models of toxicity, suggesting they could be useful in the treatment of anthrax. 


PA and LF act together to produce death in animals is often referred to as a deadly poison. It has been shown that lethal toxin suppresses the production of proinflammatory cytokines in macrophages by inhibiting transcription of cytokine messenger RNA, even at very low levels of deadly poison. Thus, one way to cause the disease anthrax lethal toxin is to suppress the inflammatory response.
Another action is to pellet toxin lethal macrophages, which is one important mechanism of the body's defense against attacking organisms. Lethal factor of the zinc-binding proteins with metalloproteinase activity. MAP kinase kinase Mek1 and Mek2 are proteins that interact with macrophages. Lethal factor and cut Mek1 MKK3.15 Mek2 and additional factors associated 


Pretreatment of cultured peritoneal macrophages with intracellular calcium release inhibitors protect against the cytotoxicity of anthrax lethal toxin. Calcium release from intracellular stores may be an important step for the spread of deadly toxins that damage cells induced in macrophages, imparting a potential way to prevent the toxicity of anthrax lethal toxin.16
Two recent papers in Nature (vol. 414, November 8, 2001) is interesting. The first, by A. D. Pannifer, et al. (P. 229-233), is "The crystal structure of anthrax lethal factor". It identifies the LF as a highly specific proteinase that cuts MAP kinase kinase (MAPKK), and details of the complex with the N terminal MAPKK2. 


Another paper, by K.A. Bradley, et al. (P. 225-229) is the "Identification of cellular receptors for anthrax toxin." PA binds to cellular receptors, and the cloning of this receptor, are described.
Researchers have found that EF is an adenylate cyclase activated by calmodulin at resting state calcium concentrations in infected cells.17 EF has been purified and studied to determine the residues required for binding PA.18 anthrax 


Another very interesting field is the development of rapid diagnostic tests for anthrax. Since it is very important to start treatment early, it is very important to know whether a person with common symptoms have been anthrax or less serious diseases where an entirely different treatments are shown. 


A polymerase chain reaction (PCR) amplification on a microarray of gel-immobilized oligonucleotides have been used to detect bacterial toxins, including anthrax toxin genes.19 other authors have examined the molecular characterization of Bacillus anthracis using multiplex PCR, enterobacterial repetitive consensus between genes-PCR (ERIC-PCR ), and random amplification of polymorphic DNA (RAPD) .20 rpoB gene has also been used as a specific chromosomal marker for real-time PCR detection of Bacillus anthracis. Variable region 1 of the rpoB gene was sequenced from 36 strains of Bacillus, including 16 strains of Bacillus anthracis and 20 other related bacilli. The four nucleotides specific for Bacillus anthracis were identified. The same test for 144 strains of Bacillus anthracis from different geographical locations and not cross-react with 175 strains of other related bacilli, with the exception of one strain.21 molecular methods, which examine the nature of the organism, could potentially be developed into a rapid diagnostic method, provide an answer within minutes or hours, not days. 


For epidemiological work, as has been done with the recent terrorist incidents, it is important to determine whether anthrax bacilli isolated from different sources are the same or different strains. One method to distinguish strains of Bacillus anthracis used long-term repetitive element polymorphism-PCR. The authors examine five different genetic groups of diverse geographical origin. All the strains produced fingerprints of seven to eight bands, referred to as the band's framework, while the 1-3 bands diagnostic to distinguish between strains of Bacillus anthracis. Fingerprints of Bacillus anthracis shows very little in common with those related species such as Bacillus cereus, Bacillus thuringiensis, and Bacillus mycoides.22 


Immunoassays can also be useful in detecting Bacillus anthracis. A platform-based sensors to detect the fluorescent immunoaffinity bacterial spores have been developed. There is interest in the production field portable sensors for use by non-specialists. Immunoaffinity column can catch the spores. This was followed by elution, washing and fluorescent detection of spores. Spores are commonly detected through dipicolinic acid extraction followed by chelation with TB to produce fluorescent complex.23 

Vaccine 
There is a human vaccine for anthrax, but has been recommended only for people who work to make them face the risk of anthrax. In recent years, due to the threat of bioterrorism, anthrax vaccine given to U.S. military personnel. It is not recommended for use by the general civilian population. There is much controversy over safety and effectiveness of current vaccines.

Many people who receive the vaccine at this time may experience mild flu-like illness and pain at the injection site, but systemic reactions are rare. A recent study among military personnel estimate that 30% of recipients experience mild local reactions. One of the recipients has been delayed and potentially life-threatening serious adverse reaction.24 There is great interest in developing a new anthrax vaccine that will contain only the antigen (s) required for protection, and not part of the cell that can cause a reaction to the vaccine.


Advisory Committee on Immunization Practices has issued recommendations on the use of aluminum hydroxide absorbed cell-free anthrax vaccine (anthrax vaccine adsorbed) in the States States.25 This vaccine has been studied in a rabbit model. At 6 and 10 weeks, anti-protective antigen immunoglobulin G and quantitative ELISA antibody test toxin-antidote used to measure levels of antibodies against protective antigen. Rabbits were challenged at 10 weeks with a lethal dose of inhaled anthrax spores. All the rabbits that received pure and 1:4 dilution of vaccine survived. levels of antibodies to protective antigen in the second week of 6 and 10 were significant predictors of survival.26 Passive transfer of lymphocytes and sera from mice immunized using two different formulations of PA have been used to study the mechanisms of protection against infection with Bacillus anthracis. These results also indicate that antibody responses may be important in protection against anthrax.27


In another study, guinea-pigs immunized with PA and then challenged with a lethal dose of anthrax spores. A direct relationship between life and neutralizing antibody titers was found. Passive transfer of hyperimmune sera showed a similar relationship between the titer of neutralizing antibodies and protection. Such consistency is not found for antibody titers measured by ELISA.28


Although most studies concentrate on the purification of PA for use as a vaccine, a study in mice immunized with plasmid encoding a protein lethal factor provides protection against lethal challenge with anthrax toxin.
For the average citizen today, protection for anyone exposed to anthrax is through treatment with doxycycline, ciprofloxacin, or penicillin. Vaccines are still in limited supply and is available for those who work can bring them in contact with anthrax, including military personnel in locations where they will face it.




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