The History Of Listeria Biology Essay

The History Of Listeria Biology Essay Salmonellosis, Shigellosis, Yersinosis and many other infectious diseases were named after the one who discovered them unlike Listeriosis. Once the causative agent was discovered by Murray, Webb and Swann, generic names such as bacterium monocytogenes was used and finally Listeria (Pirie) to honor Dr. Lister, the discoverer of antisepsis. Hence, in the past the disease was known as Listeriosis until, Listeria came into the general usage. Listeria was first known to be the causative agent of epidemic and sporadic cases in 50 species of animals, now the disease has been appearing on an increasing rate in the population of mankind. In 1926, Murray, Webb identified Listeria Monocytogenes and the bacterium was named by Swann. The bacterium was then renamed by Pirie in 1927 and was given its current name, Listeria Monocytogenes. In 1891, doctors in France and Germany discovered a gram positive bacterium in samples of tissues of patients who suffered and died from a disease similar to Listeriosis. In 1929, Nyfeldt described the first confirmed report of Listeriosis in humans caused by Listeria Monocytogenes. Listeria was first known to be the cause of epidemic and sporadic cases in 50 species of animals. Characterization of Listeria Monocytogenes. Listeria Monocytogenes is a small highly motile gram positive rod. It is a non spore-forming cocco-bacillus, facultative anaerobe which is catalase positive. These ubiquitous saprophytes are widespread in nature that is they can be found in soil and water. Vegetables can get contaminated if the soil, manure or the water used is contaminated. The bacterium can also be carried away by both wild and domestic animals that may apparently appear healthy. The bacterium is an opportunistic pathogen. It is capable of surviving and multiplying outside animal hosts and in quite simple nutrient medium. (Chapman and Hall, 1996.). It grows under refrigeration conditions from 1 °C up to 44 °C. However, its growth rate decreases below 1C and it is easily destroyed by heat. Normally pasteurization and cooking kill Listeria, but in certain ready-to-eat food, it can be found. This is due to contamination which occurs prior to packaging. Serology: Listeria Monocytogenes can be further characterized based on the presence of specific heat stable somatic (0) and heat-labile flagella (H) antigens. Based on the O and H antigens, strains of Listeria Monocytogenes, isolated from pathological sources are subdivided into serotypes: 1/2a,1/2 b, 1/2c, 3a,3b,3c,4a,4ab,4b,4c,4d,4e,4f,5 and 6. Serotypes 1/2a, 1/2b and 4b are responsible for greater than 95% of all human infections (Frances Pouch Downee, Keith Ito, 2001). Factors affecting growth and survival of Listeria Monocytogenes. Listeria Monocytogenes is a psychotropic bacterium that is it has the ability to resist the cold temperature of refrigeration. However, Listeria Monocytogenes is also thermo tolerant when subjected to temperatures above the optimum. The broad pH range for growth for Listeria Monocytogenes allows it to survive. pH 7.0 7.5 is the optimum pH for the growth of Listeria Monocytogenes (Dean, 1990). The bacteria can resist a high concentration of salt that is an environment with a low water potential. It has been shown that the organism can tolerate environments of 25.6 % Nacl for at least 132 days at 22 °C and 5 days at 37 °C (Adams; 2001; Lovette, 1989). Moreover the presence of other microorganisms in the same medium (on the same contaminated food) can cause a decrease in the population of Listeria Monoctyogenes. Listeriosis: Also known as the Circling Disease or Silage sickness, Listeriosis is a sporadic bacterial infection caused by Listeria Monocytogenes. It is a worldwide disease and a serious food borne disease for humans. The term Listeriosis encompasses a wide variety of disease symptoms that are similar on animals and humans. Persons of advanced age, pregnant women, new born and adults with infected immune systems are normally prone to attract this disease. A normal person without those criteria mentioned above can also be affected. He can be infected by consuming contaminated food. Babies may get infected at birth itself if their mother had consumed contaminated food during pregnancy. According to the world health organization (WHO), outbreaks of Listeriosis have been reported from many countries, including Australia, S Switzerland, France and the United states. Two recent outbreaks of Listeria Monocytogenes in France in 2000 and in the USA in 199 caused by contaminated pork tongue and hot dogs. CASES IN MAURITIUS MISSING!!!!!!!!!! Health risk of listeria: Hayes (1992) considered Listeria Monocytogenes as a low grade pathogen since there is no clinical manifestation in healthy individuals upon ingestion of low numbers of viable cells. According to the center for food security and public health 1-10 % of the population is thought to carry Listeria Monocytogenes asymptomatically in the intestines (May, 2005). Vomiting, Nausea, Cramps, Diarrhea, severe headache, constipation ad persistent fever are the symptoms that may occur suddenly. Meningitis encephalitis is the infection of the brain and its surrounding tissue. Septicemia is the poisoning of blood caused by listeria. The overall mortality rate in the group of susceptible people mention in sectionà ¢Ã¢â€š ¬Ã‚ ¦. Are 20 -30%. Listeria Monocytogenes can be identified in tissues using ELISA, PCR and other molecular techniques. It is treated with antibiotics depending on the form of the disease. Mode of invasion and spread of Listeria in host cells: Listeria Monocytogenes is acquires by ingestion. The bacterium must find and adhere to the intestinal mucosa or the intestinal crypt cells, which are the only undifferentiated mucosal cells. Once the bacterium is phagocytosed, it becomes enclosed in a phagolysosome, a sub cellular organelle. Normally the low pH and the contents of the phagosomes are toxic to microorganism, however, environment of low pH causes Listeria Monocytogenes to produce hemolysin, Listeriolysin O (LLO).LLO lyses the cell membrane of the phagolysosome and this causes release of the Listeria into the cytoplasm. According to F.S Southwick and D.L Purich all pathogenic strains of Listeria produce Listeriolysin-O which is important for their escape and pathogenesis. Once in the cytoplasm, the bacteria multiply and proliferate and the bacteria become surrounded by an electron-dense material. The bacteria are then known to be polarized at one end. The electron-dense material give the bacterium an elongated protrusions form and filopods which are in turns ingested by adjacent cells and the cycle begins anew. Spreading from cell to cell without directly being in contact with the extracellular environment is how Listeria Monocytogenes invade the cells of its hosts. Isolation of Listeria Monocytogenes: Since there has been increasing interest in the presence or absence of Listeria Monocytogenes in foods, as a result of some substantial outbreaks of food borne listeriosis in North America and Europe, there has been a vital need to develop methods to isolate it in various type of food. Several methods such as ELISA, PCR and genetic hybridization technologies (Entis and Lerner, 1991, RMR Labs, 2000, certification, Report, 2000; Klein and Juneja, 2001) have been developed. Department of agriculture (USDA) and the Food and Drug Administration (FDA), are the two US agencies that made use of different protocol for analysis of Listeria Monocytogenes. The techniques for isolation of Listeria Monocytogenes involve two- stage enrichment, the pre-enrichment followed by enrichment and plating for isolation. The enrichment procedures helps to keep the level of contaminating microorganisms to a reasonable numbers and allow multiplication of Listeria Monocytogenes to levels that are enough for detection of the organism. Half Fraser Broth and the University of Vermont broth (UVM) are examples of broths for the pre-enrichment procedures. They allow revival of injured Listeria cells. The Fraser broth is used with a selective Fraser broth supplement in enriching for the enrichment steps after the pre-enrichment and for detecting Listeria. Both the Fraser and Half Fraser Broth contain sodium phosphate and potassium phosphate which are buffering agents. The presence of ferric ions acts as an indicator since the bacteria produces 6, 7- dihydroxycoumarin that reacts with the ferric ions thus resulting in the blackening of the medium. Lithium chloride, nalidixic acid and acriflavine give the broth a higher concentration of salt and inhibit growth of enterococci. However, it is only after 48 hours that there is blackening of the broth. For plating, PALCAM, Oxford and Modified Oxford (MOX) are used as selective agars for isolation of Listeria Monocytogenes. Lithium chloride, polymyxin B sulphate and acriflavine HCl, present in the PALCAM medium Base and ceftazidine found in the PALCAM supplement ensure the selectivity of the medium. These elements suppress other bacteria present in food except Listeria. For differentiation, the PALCAM medium provides esculin and mannitol. Hydrolysis of esculin by Listeria causes production of 6, 7, dihydroxycoumarin, which reacts with the ferric ions that are present in the PLACAM medium to form blacken halos. USDA method: The USDA method involve a two- stage enrichment procedure with a 24-48 hours primary enrichment with UVM medium followed by a second enrichment phase with Fraser broth. Black colonies on the MOX plates show the presence of Listeria Monocytogenes. FDA method: This method involves 48 hour enrichment at 30 °C in buffered Listeria Enrichment Broth (BLEB). Pre enrichment procedure is optional which is done 4 hours at 30 °C prior to the addition of the selective supplements. After 24 hours to 48 hours the culture is streaked onto Oxford, PALCAM, Lithium chloride-phenyl ethanol moxalactant (LPM). After 24-48 hours at 30 °C, black-halo colonies prove the presence of Listeria. ISO method: The ISO method and the USDA method are alike with only the difference of using Half Fraser Broth for enrichment in the ISO method. The enrichment is done using Fraser Broth. On PALCAM or Oxford agar, the Listeria colonies are gray green with the black halo and black respectively.

Ecology and Wildlife Risk Evaluation Analysis Essay

This analysis of case studies from Los Alamos National Laboratory, and the case study to predict the effects of pesticides on aquatic systems and the waterfowl that uses them. Comparing the two processes of these case studies, along with analysis of the assessments. Describing the case study on the effects of pesticides in aquatic ecosystem, the risk assessment correlated to observed field studies and evaluate the importance of this type of correlation in general for all risk assessment efforts. Breaking down the ecological and social values in the assessments. Try to establish a value for the components in each case and how the risk assessment was determined. The process of defining ecological value in Los Alamos National Laboratory (LANL) from section 19. 5 took an approach to take a structured process to break down the value of the different species that are located at LANL. This was done to ensure that all relevant valued resources was used to come up with the endpoints, and provide the proper documentation to form a structured that was based on the resources. This process known as the general assessment endpoints (GAE) helped eliminate data that was not needed and helped provide the means of having data that was needed to follow through with the assessment, along with the values for each potential ecosystem that is based on potential exposure to the environmental stressors. The comparison of the two assessments take a different approach as the endpoints are staggering in the LANL case as the amount of species possess many possibilities to establish the relevant value of the endpoints that are needed to complete the assessment. By utilizing just the values that the stakeholders suggested in case study Los Alamos National Laboratory, the assessors focused on the immediate values on certain species the all as a hole eliminated the possibility of the lesser values in the case study. The aquatic workgroups began their efforts by discussing the basic problem addressed in a pesticide risk assessment and then began defining the sources of uncertainty for assessing effects and exposure. This technique of probabilistic assessment has helped in the reanalysis of the case study of pesticides on aquatic systems. Allowing assessors to look closer at the issues at hand relating to the organisms. The case from chapter 22 is based on a case study on how pesticides affect the impact on ecology. This assessment took a term of probabilistic assessment, and broke down the probability of evaluating the potential of direct effects on the duck population. The time frame that the pesticides are used to reduce grasshopper population is around the same time that the ducks are breeding, rear young and lay eggs. This is the concern for the use of pesticides in these pothole regions across America and Canada. This case study provides a reanalysis of the wildlife in the pothole regions. The use of probabilistic methods is entered into the process to characterize variability’s and the uncertainties of the effects on aquatic macro invertebrates from the pesticides that are released to control agricultural pest control. The assessment shows in the data that the results of the analysis are a way to relate the uncertainties of mortality in the ecosystem. Along with the damage that is done with the food source for the ducks. The pesticides case study applied a different risk assessment framework and hypothesizes to improve the final analysis process to cover all the grounds and bring attention the uncertainties of the damage that is being inflicted onto the water fowl and ducklings that are in the region during the time of treatments. The exposure levels are at a high during the treatment process. Thus setting up a risk assessment frame work allows the assessor to take the uncertainties to another level to determine the effects on the contamination faze of the treatment time frame. A conceptual framework was developed that incorporated characteristics of chemicals, agricultural landscapes, and aquatic ecosystems that interact to influence exposure. From this framework, the workgroups designed a tiered system for the risk assessment process in which the assessment progresses from a deterministic assessment to probabilistic assessments of increasing complexity. Each tier includes several experimental and analytical options that reduce uncertainty and provide more complete descriptions of the aquatic environment (Environmental Proection Agency, 2012). The risk assessment was to use the field data to include the uncertainties that eliminates any more future concerns with affecting the species during this process, along with the reduction of the mortality rate among the ducklings. The breakdown of the uncertainties was used for predicting the magnitude and probabilities of adverse effects to non target aquatic and terrestrial species resulting from the introduction of pesticides into their environment the probabilistic analysis used in the assessment provides quantification towards the uncertainties in the risk estimate. The risk assessment of the complex exposure to the pesticides provides methods to estimate the probability and impacts resulting from exposure, in this approach. In al it sheds light on the case study that certain elements and processes need to be changed in all phases of general risk assessment. The ecological and social values of concern in the first case study Los Alamos National Laboratory is the different array of possibilities that are presented in the amount of species that are involved, establishing a structured assessment to eliminate the less valued resources. The process is used to establish the most valued resources to help in setting management goals and endpoints to complete the assessment. The ecological and social values of concern in the case study on pesticide contamination are that there are so many aspects on how to eliminate the less informative data to complete the case study. The social value is to combine the stakeholders concerns and incorporate assessment managers and assessors input to implement valued endpoints to reach a conclusion and game plan to eliminate the risk that are on hand. The social values of these cases, points to preserving the regions that are treated, eliminating the harm to all organisms in the ecosystem that is contaminated by the pesticides. The social values are that these regions house many species and food sources, this assessment breaks down the damage that is being done and the damages that are effecting the ducks in the region. The ponds are watersheds that protect the habitats of many organism, thus having a healthy environment is needed to produce a healthy ecosystem. The ecological view is to preserve the regions from harm, allowing the pesticides to be used in a manner that the organisms are not affected by them. The value of the ecological components in the Los Alamos National Laboratory case study would be the principle values the functional integrity, biodiversity, and the energy dynamics and nutrient contents. By doing so the strongest of the species are chosen to be valued endpoints, so positive results come from the assessment. The trade off would be instilling sensitive species that could be extinct with the decision to use as a value endpoint when they are too sensitive to give a positive result. The value of the ecological components in the effects of pesticides on aquatic systems is that the uncertainties of the valued resources are eliminated and evaluated to have the best valued endpoint to work with in the case study. The tradeoffs relating to the wildlife and development is that the species if not grasshoppers that are at risk then it is the ducks that are present during treatment process. The contamination will alter either one of these species value in the ecosystem. The risk assessment in these cases is determined by compiling the concerns of all parties involved and eliminating the less valued uncertainties, to have valued data to come up with goals to meet all of the concerns. Risk assessment is a process where scientific information is used to address potential environmental risks associated with pesticide use. Good regulatory decisions depend on documented scientific research, an understanding of the strengths and weaknesses of the specific risk assessment, and sound professional judgment in drawing conclusions from compiled data. Risk assessments should clearly identify pertinent facts and any assumptions deemed necessary to accurately evaluate the pesticide (Environmental Proection Agency, 2012). The probabilistic analysis process can be improved in the chapter 22 case study by more research of the effects on the organisms involved, along with going in another direction on controlling the grasshopper’s presence in these pothole regions. Doing a process of elimination of what harms of being caused by the toxin. The analysis can be altered to focus on the main risk factors and once those issues are addressed then one can run another assessment and conclusion as you eliminate even more sensitive data from the finale analyst. The conclusion to the analysis of the case study helps break the process of implementing different type of risk assessments for different issues on hand. The need to eliminate the more sensitive values and collection of data is the key to performing an assessment to help the environment. Finding the valued endpoints and compelling enough data to eliminate the more sensitive resources, to come up with a positive and accurate decision in the long run.

My Beautiful Place

I think we all have a beautiful place in our mind. I have a wonderful place that made me happy when I was a little girl. But sometimes I think that I am the only person who likes this place and I'm asking myself if this place will be as beautiful as I thought when I will go back to visit it again. Perhaps I made it beautiful in my mind. Located on Ireland’s dramatic coastline that has been carved out by the huge Atlantic waves, lonely lakes and lofty mountains that separate communities.Follow the coast round into the north and you’ll discover the famous stones of the Giant’s Causeway – a magical combination of myths, legends and mystical coastal scenery. My family grew up in Ireland as I wish i had, sadly I went to visit when I was still learning my ABCs. I can’t remember much, but the one place that I’d never forgotten was the Giants causeway. It’s on the battered shore and smells like a public toilet, but the astonishing beauty just takes your breath away.The crashing tides try grab your toes while standing on the edge, and the jelly bean coloured grass waved under that miserable sun. All is left now is crumbled rocks and magical crevices. The myth is that two enemy giants, Benandonner, who lived in Scotland, and Finn MacCool in Ireland. the two giants would shout across the sea to each other challenging a fight of strength. Finn MacCool decided to build a rocky path across the too, but exhausted by the work, he fell asleep on the causeway and was found by his giant wife Oonagh. Suddenly she saw Benandonner approaching, who was a huge giant.Knowing that Finn would be no match for the huge giant, she placed a coat on top of Finn Benandonner demanded to know where Finn was. Oonagh replied, â€Å"Be quiet or you will wake my child. † Seeing this, Benandonner had second thoughts. If that was the size of their child, how big would Finn be? He ran back to Scotland, smashing the causeway in his trail. This plac e is far, far-away in time and space, part of my childhood It means a lot to me because it is beautiful and natural, is a clean and quiet place in a world of noise and dirty air.

Gender Issues in Corrections - 1439 Words

FIRST DRAFT INTRO: The issue of Corrections today focuses on female offenders and is a part of the American Correctional Associations long-standing effort to improve programming and services for women and girls in the criminal justice system. Until recently, women and girls were called the forgotten offenders because they were frequently overlooked in correctional research, policy development, program design and organizational management. Female and male correctional officers also face a wide range of issues as well. They are exposed to the correctional environment issues with males working in all women prisons and females working inside male prisons. Sexual harassment lawsuits, rape charges, abuse reports, etc. This topic is important†¦show more content†¦Simon and Simon found that female C.O.s write approximately the same number of misconduct reports as male C.O.s, for the same types of violations. Jurik and Halemba found one significant difference between male and female officer perceptions of the job. The men wanted more discretion. The women wanted more structure. Both male and female C.O.s tended to believe that the majority of their work-related problems were caused by superiors, although women were more likely to express negative attitudes toward male coworkers and view them as the cause of many of their problems. Fry and Glasner (1987) found that female officers were more negative in their evaluation of inmate services. However, male officer hostility to the hiring of female C.O.s has been a consistent problem in corrections and women are still a numeric minority in most mens prisons. Their appearance, demeanor, behavior, performance, and mistakes receive a disproportionate amount of attention (Zimmer). 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