الفهرس 
Chapter (1): History & Epidemiology of H. pyloriOnly 14 pages are availabe for public view
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Abstract
Helicobacter pylori infection is a major cause of chronic active gastritis, peptic ulcer disease and gastric carcinoma. It is well known that H. pylori virulence genes along with host genetic factors lead to different clinical outcomes in different geographical locations. The global allocation and high level of frequency with the consequence of related pathologies make the eradication of H. pylori is a very useful advance to test and treat. In addition, the determination of the genotype of H. pylori isolates helps us to comprehend the correlation between assumed virulence genes and clinical disease outcome.
The objectives of this study were to determine the prevalence of H. pylori infections in patients complaining of gastric disorders, to determine the best phenotypic method for detection of H. pylori, to determine the antimicrobial susceptibility patterns among the isolated strains, to compare between phenotypic and genotypic detection methods and to evaluate the frequency of different virulence genotypes (vacA, cagA and iceA) with their clinical outcomes in gastric patients from Menoufia University Hospitals.
The study was carried out by collecting six gastric biopsy endoscopic specimens from each participant complaining of gastrointestinal disorders. All participants admitted to Internal Medicine Endoscopy Unit, Faculty of medicine, Menoufia University during the period from March 2016 to August 2017. Demonstration of H. pylori in gastric biopsy specimens was done using polymerase chain reaction, microaerophillic culturing, histopathological examination by H&E and Giemsa stains and rapid urease (CLO) test. Antimicrobial susceptibility testing against amoxacillin, tetracycline, ciprofloxacin, metronidazole & clarithromycin was done for all H. pylori isolates by disk diffusion method. Some
virulence genes (cytotoxin-associated gene (cagA), vaculating cytotoxin (vacA) alleles and induced by contact with gastric epithelium (iceA)) were determined using multiplex PCR.
A total of 92 participants were included in this study (54 males and 38 females). The mean age of the participants was 47.2 ± 16.6 years old. Participants were classified into three endoscopic groups; the first normal mucosa group 21.7%, the second gastritis group 41.3% and the third ulcer group 37.1%. About 47.7% of gastritis group & 64.7% of ulcer group were older than 55 years old while (50%) of normal group were younger than 35 years old. Male patients (57.1%) were more than females (42.9%). Most patients were from rural areas (65.7%) mainly of low socioeconomic status (55.7%) especially with gastritis and ulcer endoscopic groups.
Helicobacter pylori genome (UreA) detection by conventional PCR was used as the confirmatory diagnostic tool, about 70 isolates out of 92 (76.1%) participants were positive by PCR. Histo-pathological examination by both H&E and Giemsa stain detected H. pylori in 68/92 cases (73.9%). Campylobacter like organisms (CLO) rapid urease test detected H.pylori urease activity in 64/92 cases (69.6%). On the other hand microaerophillic culturing on selective and non-selective media detected H. pylori growth in only 32/92 cases (34.8%). Considering PCR as the gold standard diagnostic test, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of histopathological method for H. pylori detection were 97%, 100%, 100%, 92% and 98% respectively, for CLO test were 91%, 91%, 97%,77% and 91% respectively , while for culturing were 46%, 100%, 100%, 37% and 59% respectively. In comparison to the gold standard diagnostic method (PCR) results, histopathological method was the best followed by CLO
test while the culture under micro-aerophilic conditions was the least dependable diagnostic tool.
About100%, 68.8%, 81.3%, 68.8% and 12.5% of H. pylori isolates were resistant to metronidazole, amoxicillin, tetracycline, clarithromycin and ciprofloxacin respectively and about 94% of the resistant isolates were included in ulcer and gastritis groups. The risk factors for symptomatic H.pylori infections were old age, smoking, low socioeconomic status, bad hygienic practice and bad dietary habits.
As regard the presence of different H. pylori genotypes, cagA gene was identified in 58/70 isolates (82.9%), iceA in 38/70 (54.3%) and as regard vacA alleles; vacAs1, vacAs2 and vacAm were identified in 22/70 (31.4%), 10/70 (14.3%) and 32/70 (45.7%) respectively. The most prevalent H.pylori genotypes were CagA, cagA+iceA and cagA+vacAs1m1+IceA by 18/70(25.7%), 16/70(22.9%) and16/70(22.9%) respectively. About 73.3% and 100% of patients in gastritis and ulcer groups respectively owned cagA gene. Also IceA1 gene was significantly detected in 60% and 64.3% of gastritis and ulcer groups respectively. However, as regard vacA alleles, no significant statistical difference was detected among various endoscopic groups.