Micro Organisms

Question : Discuss about the Nursing Micro Organismms ? Answer : Introduction Infection is the incursion of host body by micro-organisms, which then multiply inside hosts body tissues. Then the hosts body consequently responds towards the microbial toxins, which might result in illness. These infectious diseases are caused by the interaction of host, microbial agent, and environment. The transmission of infection occurs when the microbes go from the host or its reservoir through the portal of exit, using a suitable mode of transmission. Infectious agents then enter into the host body by a fitting portal of entry to cause infection to a vulnerable host. The order in which infectious disease is caused is often called as the chain of infection. For an infection to take place, it is crucial that all these links of the infection chain must be present in the sequential order. A healthcare worker must understand all the features of these infectious links so as to prevent the spreading of infection. The links are: Etiological agents These are micro-organisms which have the capable of causing infectious disease. Most of the infectious agents include bacteria, virus, fungi etc. Greater the virulence and pathogenicity of microorganisms, greater is their chain of causing an infection. Generally, the sources of infection can be divided into two categories: Endogenous/self-infection - This type of infection takes place when the micro-organisms which are often considered harmless at a particular site, cause infection when it reaches another site. For example, when Escherichia coli reach the urinary tract from the gastrointestinal tract, it causes a urinary tract infection (Ronald, 2003, pp. 71-82). Exogenous/cross-infection - This type of infection takes place when the micro-organisms reach the site of infection from another source. For example consumption of food contaminated with Salmonella species (Goldrick, 2003, pp. 105-6). Reservoirs It is the site where micro-organisms can effectively thrive. These reservoirs may include human beings, animals, and even the environment. These may or may not be the source of the microbial agent from which they are transmitted to host body. Various types of infectious diseases use the human body as their reservoirs. Commonly transmitted diseases that are transferred from one person to another without any intermediate are mumps, measles, venereal diseases, streptococcal infection, and respiratory infections. Some infectious agents are also present in animals. Generally, the infectious diseases are transmitted from animals to human beings under normal environmental conditions (zoonosis). For example, anthrax, brucellosis, plague, rabies etc. (Taylor, Latham Mark, 2001, pp. 983-9). Sometimes, the diseases from one animal to another are transferred via humans, acting as incidental hosts. Infectious microbes also use environmental vessels like soil, water, and plants as reservoirs. Exa mples include Legionella pneumophila (Greub Raoult, 2003, pp. 619-21), Histoplasma capsulatum (Kauffman, 2007, pp. 115-32) etc. It is the route by which the microbial pathogens move out of the reservoir. These are usually the locations where the microbes are localized. For instance, organisms causing flu may exit the host via the respiratory tract, schistosomes via urine, cholera via fecal route. Some microbes (rubella, syphilis) can pass from mother to children (Ebert, 2013, pp. 623-43), while other agents exit via needles or mosquito bites. Means of Transmission It refers to ways in which the microbes are transmitted. Infectious microbes may get transmitted in different ways. Usually, these types of transmission modes are classified as: Direct (via direct contact or droplets) - It occurs via direct contact via skin or via droplet scattering from sneeze or a cough from the infected host or the source containing infectious agents. Examples include venereal disease, intestinal disease from hookworm; meningococcal and pertussis infection. Indirect (via air, vehicle or mechanical or biological vectors) - It refers to transmission of infectious agent by air, living or non-living objects (Pica Bouvier, 2012, pp. 90-5). Examples include measles (via air), hepatitis A virus and botulinum toxin by Clostridium botulinum (via vehicles) and Shigella species and Yersinia pestis (flies as the vector). Portal of Entry It refers to the point/opening that allows the infectious microbes to enter the susceptible host. It includes different openings in the body, mucosal membranes, fresh wound on the skin or intubation in the body. These entry points must give entrance to the tissues in which the infectious pathogens can thrive. Sometimes, these microbes exploit the same point for entering and exiting the host body (influenza virus), while other pathogens use the different point of entry into and exit from the host (microbes causing gastroenteritis). Other examples include the mucous membrane for syphilis, skin for hookworm, and blood for the human immune-deficiency virus, hepatitis B. Susceptible Host It is the final component in the chain of infection. A susceptible host is a person who cannot defend itself against an invading micro-organism, its multiplication, and the resultant infection. The host is vulnerable to the infection due to lack of immunity or resisting ability to suppress the invasion by the pathogenic microbes. The vulnerability of host depends on their constitutional or genetic make-up. The host's genetic constitution may either enhance or reduce their susceptibility towards infectious disease. For instance, people who are carriers of sickle cell traits are found to be immune towards a particular type of malaria infection (Serjeant, 2010, pp. 425-9). The speci?c immunity provided by the defensive antibodies which are specifically directed against particular antigens. These antibodies may be developed by the susceptible hosts body in response to a vaccine, infection or toxins which have already been inactivated but still retains their capacity to activate the produ ction of antibodies or may be transferred from mother to their unborn child via placental transfer or via administration of immunoglobulins or antitoxin. The non-specific parts of the immunity system that protect the host body against infectious disease include the mucosal membrane, skin tissue, ciliary processes present in the respiratory passage, cough response, gastric acid etc. Various factors that may enhance the susceptibility of a host towards infectious disease by disturbing the host defense system include alcoholism, malnutrition and diseases or treatment that weakens the non-specific immune response of the host. Conclusion The purpose of studying the various components of the infection cascade is to find better ways of controlling infectious diseases. The knowledge of the means of transmission of infectious microbes along with their portals of exit and entry provides us with a strong basis for developing appropriate control measures which are frequently directed against the most susceptible components in the chain of infection. References Ebert, D. (2013). The epidemiology and evolution of symbionts with mixed-mode transmission. Annual Review of Ecology, Evolution, and Systematics, 44, 623-643. Goldrick, B. A. (2003). Foodborne Diseases: More efforts needed to meet the Healthy People 2010 objectives. AJN The American Journal of Nursing, 103(3), 105-106. Greub, G., Raoult, D. (2003). Morphology of Legionella pneumophila according to their location within Hartmanella vermiformis. Research in Microbiology, 154(9), 619-621. Kauffman, C. A. (2007). Histoplasmosis: a clinical and laboratory update. Clinical Microbiology Reviews, 20(1), 115-132. Pica, N., Bouvier, N. M. (2012). Environmental factors affecting the transmission of respiratory viruses. Current Opinion in Virology, 2(1), 90-95. Ronald, A. (2003). The etiology of urinary tract infection: traditional and emerging pathogens. Disease-a-Month, 49(2), 71-82. Serjeant, G. R. (2010). One hundred years of sickle cell disease. British Journal of Haematology, 151(5), 425-429. Taylor, L. H., Latham, S. M., Mark, E. J. (2001). Risk factors for human disease emergence. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 356(1411), 983-989.