الفهرس 
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Abstract
H. pylori is present in around 50 % of the population. H. pylori infection produces persistent inflammation, which significantly raises the risk of duodenal, gastric ulcer, and stomach cancer.
Many of the virulence characteristics of H. pylori allow the bacteria to stick to gastric epithelial cells, and damage affected tissues. One of these virulence factors is vacA, a pore-forming toxin that results in the formation of vesicles in the cells of the gastric epithelium. It has a wide range of polymorphic rearrangements, the s1 or s2 kind is encoded in the s-region and the m-region encodes the m1 or m2 type.
The aim of this study was the molecular characterization of vacuolating cytotoxin A (VacA) gene in Helicobacter pylori among patients with gastric diseases.
This cross-sectional study included 50 H. pylori infected patients with positive urease test. 100 specimens were obtained from (stool (N= 50) and gastric tissues (N= 50)) over a period of three months (from July to September 2022). Rapid antigen test (RAT) was performed on stool specimens while PCR was used for detection of ureC gene in stool and tissue specimens. Also,62 specimens (31 stool & 31 tissue which were mutually positive for ureC gene by PCR) were further tested for the presence of some virulence genes for subgroup typing. We tested three main regions including 1) S region, 2) M region and 3) IceA region.
The majority of patients 62% were females and 38% were males with mean ± SD of age was (41±15) years. Regarding the clinical symptoms, abdominal pain was the most common symptom in 70%, followed by dyspepsia in 20% patients. The most common presenting endoscopic findings was erosive gastritis in 51.6% followed by gastritis in 41.9%.
S region was detected in 100% tissue samples and 77.4% stool samples, M region was detected in 67.7% in tissue samples and only 3.2% in stool samples, while iceA region was detected in 67.7% in tissue samples and 16.1% in stool samples. There was a statistically significant difference (P value=0.011) in PCR results for S region as well as a highly statistical difference for both M and iceA regions between tissue and stool specimens (P value<0.001).
The most common pattern of S region was s1/s2 in 70.96% of tissue samples and s2 in 67.74% stool samples, there was a highly statistically significant difference (P value<0.001) between patterns of s region in both tissue and stool specimens. Also, for M region the most common was m1/m2 in 45.16% of tissue samples and m2 in 3.22% of stool samples and lastly for iceA region, iceA1 was present in 35.48% of tissue samples and iceA2 in 12.9% of stool samples. The most common genetic combination was s1/s2, m1/m2 and iceA1 in 19.35% tissue samples and s2 in 58.06% stool samples.