Helicobacter pylori
H.pylori is a spiral shaped gram-negative bacterium found in the mucus lining of the stomach and duodenum. It is motile due to the presence of a sheathed flagella which, together with its spiral morphology, aids in the colonization of the gastric and duodenal mucus (Eaton, Morgan, Krakowka, 1992). It has a cell wall containing lipopolysaccharides (LPSs) which is typical of other gram-negative bacteria. Aside from maintaining physical integrity and function of the cell envelope, the LPSs also afford immunomodulating and immunostimulating properties due to their lipid component known as lipid A. The biological activity of lipid A is though to play an essential role in the pathogenecity of H.Pylori
Enzymes produced by H.pylori
H.pylori produces the enzyme urease which enables it to survive the highly acidic environment within the gastrum and duodenum. Urease catalyzes the conversion of urea into ammonia and carbamate which in turn increases the local pH thereby protecting H.pylori from gastric acid within the mucosa (Mobley 2001). H.pylori also possess mucinase activity which is thought to aide in the dissolution of the mucosal barrier allowing H.pylori to survive and colonize the thick mucus layer of the upper gastrointestinal tract (ORourke Bode 2001).
Prevalence of H.pylori infection
H.pylori infection is a very common infection especially among patients with peptic ulcer disease. In approximately 9 out of 10 cases, peptic ulcers are likely caused by H.pylori infection. Both males and females are affected. Although it is a ubiquitous infection, it is more prevalent in developing countries than in developed countries. This is attributed to the high prevalence of infection in children under 10 years old in developing countries. This is also associated with the low socioeconomic status which increases the risk of H.pylori infection particularly during childhood.due to the poor availability of safe drinking water and the high rate of transmission caused by crowded households with several siblings (Mitchell 2001).
Pathogenesis of H.pylori infection
The pathogenesis of H.pylori is primarily attributed to its ability to persist in the host where it can cause damage to mucosal tissues. After ingestion, it is able to penetrate the viscid mucosal layer where it causes chronic inflammation. Glandular atrophy follows either due to direct mucosal injury caused by H.pylori or due to the prolonged inflammatory response to H.pylori infection. The loss of mucosal and grandular tissue then leads to ulceration (Dixon 2001).
Gastrointestinal disorders associated with H.pylori infectionChronic gastritis is the common denominator associated with disorders caused by H.pylori infection. These disorders include ulceration, gastric carcinoma and lymphoma. The histologic feature of chronic gastritis encompass chronic inflammation, gastric atrophy and instestinal metaplasia. Intestinal metaplasia refers to the change from gastric epithelium to intestinal epithelium caused by abnormal growth stimulation after repeated mucosal injury (Dixon 2001).
Diagnosis of H.pylori infection
Previously, the presence of disorders associated with H.pylori infection such as histologic gastritis, peptic ulcer and gastric carcinoma is the first indication suggestive of the infection. However, newer serologic tests such as elevated serum gastrin and pepsinogen levels suggest H.pylori infection (Graham Qureshi, 2001).
Lifestyle modification for patients with peptic ulcers
Patients with peptic ulcer should observe lifestyle changes such as stress reduction, avoidance of excessive alcohol consumption and high fiber diet. The rationale for these changes is to limit gastric acid production and promote ulcer healing.
Enzymes produced by H.pylori
H.pylori produces the enzyme urease which enables it to survive the highly acidic environment within the gastrum and duodenum. Urease catalyzes the conversion of urea into ammonia and carbamate which in turn increases the local pH thereby protecting H.pylori from gastric acid within the mucosa (Mobley 2001). H.pylori also possess mucinase activity which is thought to aide in the dissolution of the mucosal barrier allowing H.pylori to survive and colonize the thick mucus layer of the upper gastrointestinal tract (ORourke Bode 2001).
Prevalence of H.pylori infection
H.pylori infection is a very common infection especially among patients with peptic ulcer disease. In approximately 9 out of 10 cases, peptic ulcers are likely caused by H.pylori infection. Both males and females are affected. Although it is a ubiquitous infection, it is more prevalent in developing countries than in developed countries. This is attributed to the high prevalence of infection in children under 10 years old in developing countries. This is also associated with the low socioeconomic status which increases the risk of H.pylori infection particularly during childhood.due to the poor availability of safe drinking water and the high rate of transmission caused by crowded households with several siblings (Mitchell 2001).
Pathogenesis of H.pylori infection
The pathogenesis of H.pylori is primarily attributed to its ability to persist in the host where it can cause damage to mucosal tissues. After ingestion, it is able to penetrate the viscid mucosal layer where it causes chronic inflammation. Glandular atrophy follows either due to direct mucosal injury caused by H.pylori or due to the prolonged inflammatory response to H.pylori infection. The loss of mucosal and grandular tissue then leads to ulceration (Dixon 2001).
Gastrointestinal disorders associated with H.pylori infectionChronic gastritis is the common denominator associated with disorders caused by H.pylori infection. These disorders include ulceration, gastric carcinoma and lymphoma. The histologic feature of chronic gastritis encompass chronic inflammation, gastric atrophy and instestinal metaplasia. Intestinal metaplasia refers to the change from gastric epithelium to intestinal epithelium caused by abnormal growth stimulation after repeated mucosal injury (Dixon 2001).
Diagnosis of H.pylori infection
Previously, the presence of disorders associated with H.pylori infection such as histologic gastritis, peptic ulcer and gastric carcinoma is the first indication suggestive of the infection. However, newer serologic tests such as elevated serum gastrin and pepsinogen levels suggest H.pylori infection (Graham Qureshi, 2001).
Lifestyle modification for patients with peptic ulcers
Patients with peptic ulcer should observe lifestyle changes such as stress reduction, avoidance of excessive alcohol consumption and high fiber diet. The rationale for these changes is to limit gastric acid production and promote ulcer healing.
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