please answer all my questions (microbiology) 1. Helobacter pylori is responsibl
ID: 179608 • Letter: P
Question
please answer all my questions (microbiology)
1. Helobacter pylori is responsible for most peptic ulcer diseases. describe its pathogenicity and why the discovery of this organism was so important in the treatment of ulcers.
2.Interaction between host and microbe doesn't always lead to disease. what factors contribute to the development of disease, and what factor is most important?
3. streptococcus pyogenes produces streptokinase. How can this add to the pathogenicity of the bacterium, but be used therapeutically in others?
4. explain why endotoxin release is so difficult to treat.
5.Explain why a good diagnosis of giardia is so important.
Explanation / Answer
1. H. pylori exhibits a narrow host and target organ range, but infection is usually lifelong. This suggests strong adaptation to its natural habitat, the mucus layer overlying the gastric epithelial cells. In the human host, H. pylori is thought to be exposed to oxidative stress produced by the active immune response. To combat such forms of oxidative stress, H. pylori expresses several key components of bacterial oxidative stress resistance; these include the superoxide stress defense mediated via the iron-cofactored superoxide dismutase. H. pylori produces large amounts of urease, and it has been estimated that up to 10% of the total protein content of H. pylori consists of urease. Due to this it can survive in the strong acicdic conditions of human gastrointestinal tract.
t has been known for more than a century that bacteria are present in the human stomach. Initially, they were thought to be contaminants from digested food rather than true gastric colonizers. However, later on it was discovered by Barry Marshall and Robin Warren that this bacteria can colonize the human stomach, thereby inducing inflammation of the gastric mucosa. It was also observed that gastric colonization with H. pylori can lead to variety of upper gastrointestinal disorders, such as chronic gastritis, peptic ulcer disease, gastric mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric cancer.
2. Host-pathogen interaction will not contribute to the disease, when defence mechanism of the host is strong.Gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric environment. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA help in this colonization of the gastric mucosa.
3. This could be due to release of endotoxins which are released by the antibiotics
4. Endotoxins are considered to be most important in the pathogenesis of gram negative bacteria. Once in the circulation, endotoxin promotes release of Tumor necrosis factor alpha (TNF-alpha), IL-1, IL-6 and other related cytikines which lead to a inflammatory response and finalle results in the damage of the enothelium which could not be treated easily.
5.Apart from intestinal effects due to Giardia, there could be certain long term effects of Giardia like arhritis, allergies and muscular complications. It is also related to mortality in children. So, a good diagnosis of the disease is important. It is usually done by examining the stool samples repeteadly.
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