Free Biology Essay Example: Anthrax and Disinfectants
Essay 1. Anthrax
Anthrax is a lethal disease which could affect most of the animals including humans. The major cause of anthrax is the bacterium Bacillus anthracis. It is a large gram-positive bacterium which is non-motile and could form spores (Rao et al, 2010). The bacterium lives in the soil in a spore from which could provide them protection and survive for more than decades. While in the spore from, they produces the toxins that could infect animals and humans into three major factors. The three major factors that could provide the virulence of the Bacillus anthracis which are lethal toxin, edema toxin and capsular antigen (Gardner, 2001). The individual proteins have no physiological effects to humans and animals but it has serious effects when it comes in pairs. These proteins are produced when the bacterium in spore form are trying to enter the cell and replicate. The lethal toxin are responsible for the necrosis of tissues and the edema factor is responsible for the elevation of intracellular cAMP. Lastly, the protective toxin or the capsular antigen mediates the two other proteins for cell entry (Rao et al, 2010).
There are four major locations where the anthrax infection could occur which are gastro intestines, skin, respiratory organs and blood. Gastrointestinal infection have fatality rates of over 25 – 60% and its major symptoms are blood vomiting and sever diarrhea. The gastrointestinal infection usually occurs when animals eat grass with the bacterium spore or when animals eat the anthrax infected meat (Gardner, 2001). The skin infection appears like boils with black center. The skin anthrax infection usually forms when the bacterium spore enters the cuts of skin. The respiratory infection usually occurs like a flu or severe pneumonia. The bacterium spores enters the respiratory system as a result of inhalation. The blood infection is the result of the other three infections. These locations probably allow infection to occur since the bacterium is in spore formation which survives even at most severe conditions and it could not be deactivated easily by the immune system of the body (Rao et al, 2010).
In the discovery of the anthrax, vaccines have been the main scientific method for its prevention. Over the past decade, site clean-up and decontamination has been the major method. One of the most advanced biocide which cleanups anthrax contaminated sites is the chlorine dioxide. It has been implemented to use in the decontamination of major buildings and establishment all over United States. For curing the disease, antibiotics have been the major scientific method for the past decade. Raxibacumab is commercially produce in 2009 for the emergency treatment of anthrax inhalation. This drug reduce the growth of the bacterium spores (Rao et al, 2010). The cure for anthrax has been difficult for the scientists since the bacterium could not be easily killed. Prevention is their major concern for the past decade. The dead bodies of the people and animals confirmed to be contaminated with anthrax are isolated to avoid further spread (Gardner, 2001).
The anthrax spores can be used for biological weapon. In fact, it has been used during the World Wars. The main characteristic that could make it a biological weapon is that the anthrax spores could be cultivated easily with only a few numbers of special equipment. The anthrax could also be observed anywhere but the producers of the weapon preferably used spores from the dead bodies confirmed to be contaminated with anthrax. The anthrax spores could also be easily used as a biological weapon since there are main points of entry that could infect the target people such as inhalation, digestion and skin infection (Gardner, 2001).
Essay 2. Disinfectants and the Kirby-Bauer Method
Disinfectants are agents that are applied to non-living objects to destroy or kill microorganism on the object. There are three major mechanism in which the disinfectants work to destroy the microorganism (Russel, 1999). The first mechanism is the cross-linking/coagulation/clumping process of disinfecting microorganisms. The most common disinfectants in this process are alcohol and phenols. In this mechanism, the agent or substance penetrate and disrupt the cell wall which kills the microorganism. The agent could also cause the microorganisms as well as other cells to clump and lose their functions. Alcohols and phenols are best when diluted with water so that proteins are easily denatured (Russel, 1999).
The second mechanism of disinfectants is the function and structure disruption of microorganisms. The most common substances that functions in this mechanism are the ammonium compounds. In this mechanism, disrupts the proteins of the cell or the microorganisms by denaturation. When the structure is disrupted, some of the vital substances are leaked out. It also affects the metabolic processes in the cell which disrupts its major functions (Russel, 1999).
The third mechanism of the disinfectants is the oxidation process. The most common substances that functions in this mechanism are the Peroxygen compounds and chlorine. In this mechanism, the agents oxidize the proteins, carbohydrates and lipid parts of the cell or the microorganism. The oxidation destroys the parts of the microorganism and eventually killing it. Oxidation of the agents usually targets the cells protective parts which could also disrupts the substance transport of the microorganism (Russel, 1999).
The different groups and form of microbes have different resistance to disinfectants. The most susceptible microbes to chemical disinfectants are the gram-positive bacteria. This is a group of bacteria that stains violet when used in gram staining method. One of the main reason for its susceptibility to disinfectants is its lack of outer membrane. Gram positive bacteria have not much protective layer that could provide resistance to chemical agents. These group of bacteria is also susceptible to disinfectants since the outermost layer of the microbe could be easily targeted by oxidation and denaturation. On the other hand, the most resistant microbe to disinfectant agents are the bacterial spores. It is a structure that is produced by a bacteria which could protect it from severe conditions. The spore formation is a survival mechanism of the bacteria. The disinfectant agents or substances could not penetrate the interior of the bacterial cell since it is protected a spore formation (Bonev, 2008).
The Kirby-Bauer method could be used to test if the antibiotic affects the bacterial growth and development. The zone of inhibition is the visible area in which the bacteria have not grown properly. The size of the zone of inhibition is affected by the effectiveness of the antibiotic in reducing or stopping the growth of the bacteria. The antibiotic which is strong in stopping the bacterial growth could result to larger zone of inhibition. There are other factors that could affect the zone of inhibition such as pH, agar depth, antibiotic diffusion and presence of other metals. In order to test if the antibiotic agent is bactericidal or bacteriostatic, a sample from the zone of inhibition is inoculated. If the bacteria grow in the broth, then the antibiotic is bacteriostatic which means it only stops the growth of the bacteria. If the bacteria does not grow, then the antibiotic is bactericidal which means it kills the bacteria (Bonev, 2008).
Bonev, E. (2008) Principles of assessing bacterial susceptibility to antibiotics using the agar diffusion method. Journal of Antimicrobial Chemotherapy 61(6), 1295-1301
Gardner, R. (2001). Anthrax (Bacillus anthracis). Journal of Toxicology, 39(1), 85-100
Rao, S., Mohan, K., & Atreya, C. (2010). Detection technologies for Bacillus anthracis: Prospects and challenges. Journal of Microbiological Methods, 82(1), 1-10.
Russel, A. (1999). Bacterial resistance to disinfectants: present knowledge and future problems. The Journal of Hospital Infection, 43(1), 57-68
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