الفهرس 
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Abstract
H. pylori is a Gram-negative microaerophilic spiral bacterium previously known as Campylobacter pylori. It has a significant attention since its isolation and characterization in 1983. It colonizes the gastrointestinal mucosa of its host in spite of a strong persistent humoral and cellular immune response to H. pylori at the local and systemic level, the organism persists for the lifetime in its host.H. pylori, a gram negative urease producing bacterium has been associated with many benign forms of gastritis, peptic ulcer disease and malignancies as gastric adenocarcinoma and gastric mucosa-associated lymphoid tissue (MALT) lymphoma. H. pylori-induced gastrodudenal disease depends on the inflame - matory response of the host and on the production of specific virulence factors, such as urease, which is responsible for ammonia generation; the vacuolating cytotoxin VacA; the cytotoxin-associated gene A product CagA; and the type IV secretion system encoded by the cag pathogenicity island. Several methods are currently available to detect the presence of H. pylori; each has its own advantages, disadvantages, and limitations. A classic way to categorize the methods is according to whether or not an endoscopy is necessary. Biopsy-based tests include histological evaluation, culture, polymerase chain reaction (PCR), and the rapid urease test (RUT), all of which are performed on tissue obtained during endoscopy. Alternatively, the urea breath test (UBT), serology test, and stool antigen test (SAT) can be performed as non-invasive procedures. This study aimed to evaluate and compare the diagnostic accuracy of one invasive method (RUT) and one noninvasive method (serologic detection of anti H.pylori IgG antibodies by ELISA test) for the diagnosis of H. pylori infection in dyspeptic patients with reference to histopathology as the gold standard. The prevalence of H. pylori CagA gene in patients with gastrointestinal disorders and its relation to the clinical presentations was also studied. Sixty-seven patients with dyspeptic symptoms were enrolled in this study in the period from October 2014 to December 2015. For the detection of H. pylori infection, three endoscopic gastric biopsies were obtained from each patient for RUT, histopathological examination and PCR respectively. Blood samples were taken for the anti H. pylori IgG antibody ELISA test. Among sixty-seven patients undergoing upper gastro endoscopy, 33 were males and 34 were females. Their ages ranged from 19-84 years with a mean age 45.27 ± 15.11 years. The common endoscopic change in the studied patients was duodenal ulcer in 40 patients (59.7%) followed by gastro oesphygeal reflux disease (GERD) in 21 patients (31.3%), then gastritis in 20 patients (29.9%) and portal hypertensive gastropathy (PHG) in 18 patients (26.9%). The prevalence of H. pylori infection by histopathological examination was 68.7%. Regarding the histopathological identification of H. pylori as a gold standard, H. pylori IgG ELISA test had 93.48% sensitivity, 85.71% specificity, 93.5% positive predictive value (PPV), 85.7% negative predictive value (NPV) and 91.04% accuracy while RUT had 86.96% sensitivity, 47.62% specificity, 78.4% PPV, 62.5% NPV and 74.6% accuracy. H pylori infection was positive in 14 (70.00%) of gastritis patients, 33 (82.50%) of duodenal ulcer patients, 15 (71.42%) of GERD patients and 8 (44.44%) of PHG patients. The prevalence of H. pylori CagA gene in infected patients was 47.8% CagA was detected in 16 (48.5%) patients with duodenal ulcer, 8(57.1%) patients with gastritis, 9 (36.4%) patients with GERD and 4(50%) patients with PHG respectively with no significant statistical difference as regard the prevalence of CagA in the studied patient groups. Intestinal metaplasia was detected in six patients (13.0%). Active inflammation (neutrophil infiltration) identified in 24 cases (52.2%). The intensity of this activity was variable, with Grade 1 activity detected in 16 cases (34.8%), Grade 2 activity in 7 cases (15.2%), and Grade 3 activity in one case (2,2%). Conclusions H. pylori is a common pathogen associated with many gastric diseases mainly with duodenal ulcer. H. pylori infection is independent of ”Age and sex” of patients in our study. H. pylori infection is strongly associated with duodenal ulcer and PHG than other gastric pathologies. There is a statistically significant relationship between H. pylori infection and Active inflammation. It is accepted that CagA is an important virulence factor of H. pylori, but we found that the existence of CagA was not different among the disease groups of studied patients. ELISA testing to detect anti H. pylori IgG antibodies is non invasive, easy to perform and can be expedient as a screening test and thus serve as an alternative to endoscopy. There is significant association between neutrophil activity and Infection with CagA positive strains of H. pylori. Recommendations: 1- Great care is to be taken not to underestimate the prevalence of H. pylori infection in case of negative results of IgG serology in clinical practice, thus histopathology is indicated for purpose of excluding infection in such circumstances. 2- More Studies are required to detect the prevalence of H. pylori virulence factors other than CagA in Egyptian population and to detect its possible association with clinical outcome. 3-Extended large scale studies are required to find the prevalence of H. pylori infection in Egyptian population and to assessed those at high risk of developing sever gastric pathologies.