It's a gram negative spiral shaped pathogenic bacterium which inhabits the human gastric mucosa. The bacterium is present in approximately half of the worlds population, but it causes symptomatic disease in only 10-15% of those infected where it invades the gastric epithelial lining.

India is the prototypical developing country as far as Helicobacter pylori is concerned and more than 20 million Indians are estimated to suffer from peptic ulcer disease.

The prevalence of h pylori in the Indian subcontinent can be as high as 80% or more in rural areas. The most commonly recognised manifestation of H.pylori infection in India is peptic ulcer disease, particularly duodenal ulcer disease, which outnumbers gastric ulcers between 8:1 and 30:1. The population of Indians are approximately 1.2 billion. If the H. Pylori prevalence was 60%, more than 726 million individuals would be infected with h pylori. The estimated prevalence of duodenal ulcers is 3% and means that atleast 18 million people could need h pylori therapy.

H. pylori infection most often presents as a predominantly antral gastritis with normal or increased acid production. Local gastrin production may be increased, but hypergastrinemia (increased serum gastrin) is uncommon. When inflammation remains limited to the antrum, increased acid production results in greater risk of duodenal peptic ulcer. In other patients gastritis may progress to involve the gastric body and fundus. This multifocal atrophic gastritis is associated with patchy mucosal atrophy, reduced parietal cell mass and acid secretion, intestinal metaplasia, and increased risk of gastric adenocarcinoma. Thus, there is an inverse relationship between duodenal ulcer and gastric adenocarcinoma that correlates with the pattern of gastritis.H. pylori organisms have adapted to the ecologic niche provided by gastric mucus. Its virulence is linked to certain factors like flagella, urease, adhesins, toxins.

The current gold standard to diagnose h.pylori infection invasively is two positive tests, which in India could be a combination of rapid urease test and examination of endoscopic biopsies by histology. The urea breath test is based on the generation of ammonia by the bacterial urease. The advantage of endoscopy is that symptomatic patients can be evaluated for mucosal disease. Endoscopy also allows one to take biopsy specimens that can be examined by histology, rapid urease tearing, brush cytology, or even culture. The other non invasive tests for active infection are urea breath test, stool antigen tests, and serology.

Across India, 1,342,561,902 people were surveyed. The percentage of people who have the ‘O’ blood group are 29.28%. The percentage of people who have the ‘A’ blood group are 28.42%. The percentage of people who have the ‘B’ blood group are 39.93%. Lastly, the remaining 9.42% of the population have AB blood group.

Most of the research done on risk factors for H. pylori infection have focused on environmental and lifestyle factors (e.g. smoking and diet). However, recently as well as according this study, there's Increasing evidence for the role of genetic factors in susceptibility to H. pylori infection. One genetically determined trait with known polymorphic expression between individuals and populations that has attracted interest as potential risk factors for H. pylori infection is ABO blood group. This premise was developed from previous studies showing a higher frequency of blood group O amongst patients with duodenal ulcer. Since duodenal ulcer disease is associated with antral H. pylori infection in 90–100% of cases, blood group O might also be a risk factor for acquiring H. pylori infection. ABO blood groups have also been investigated as risk factors for H. pylori associated gastric cancer, however there are conflicting studies due to multiple confounding effects. Since the discovery of the ABO blood group, there has been an ongoing interest in the potential role of blood groups in infectious disease. Blood group antigens are receptors for toxins, parasites, and bacteria, where they can facilitate colonisation or invasion or evade host clearance mechanisms. Previous studies demonstrated that blood-group antigen-binding adhesion (BabA) mediate adherence of H. pylori to human Lewis b (α-1,3/4-difucosylated) blood-group antigens on gastric epithelial cells.

During the last few decades, evidence for the role of ABO groups as potential risk factors for H. pylori infection has emerged from animal model studies and epidemiological data. H. pylori infection was found in some studies to be positively associated with O blood group, whilst others found no correlations.

Meta-analysis is a well-established method that pools data from smaller inconclusive studies to provide greater statistical power. Therefore, the current systematic review and meta-analysis of the relevant epidemiological literature aims to quantify the association between ABO blood group and H. pylori infection status.

The study design was a case control design adopted by the department of Gastroenterology (endoscopy) at a central hospital- Saveetha Medical College and Hospital.

A total of 120 patients who reported to the endoscopic division of Gastroenterology department of Saveetha Medical college and Hospital between January, 2019 – March 2019 were selected for the prospective study . A test group of 32 individuals belonging to the A blood group, another group of 26 individuals belonging to the B blood group, another test group of 9 individuals belonging to the AB blood group and lastly, a test group of 53 individuals belonging to the O blood group who came with the symptoms of dyspepsia or other symptoms deferrable to the proximal alimentary canal, from our outpatient gastroenterology- endoscopic department who were referred for serological diagnosis of H. Pylori infection.

The study was performed according to the local ethical committee of medical sciences. We excluded patients with history of taking eradication therapy of Helicobacter pylori positive infections within 6 months, patients with acute infection and gastro intestinal bleeding or patients with history of proton pump inhibitor or antibiotics intake within 2 weeks before the endoscopic procedure as these factors may result in false negative results for helicobacter pylori testing.

The data for both groups included the demographics (age, gender), IP number, Blood group, symptoms on admission, provisional diagnosis, endoscopical and histological finding.

All patients underwent the endoscopic procedure with standard technique (using Olympus GF260, 9.6 mm diameter scope) to assess for HPPI test. Patient were lying in the left lateral position with a mouth piece placed and their throat sprayed with adequate xylocaine. Two antral biopsies were taken from antrum and lower body for each patient, as per the routine practice of the endoscopy unit, and submitted for histologic evaluation. No complication related to endoscopy was reported in any subject. The specimens were stained by hematoxylin and eosin stain or methylene blue. The laboratory investigator was blinded to the sample status to avoid bias.

ABO blood groups were determined for seropositive and seronegative patients, using standardized hemagglutination methods.

Statistical Analysis was conducted using SPSS software. Descriptive analysis was conducted for the continuous and categorical variables. The different variables such as age, sex, height, weight, BMI, Helicobacter pylori positivity and negativity were first independently calculated and represented in the form of frequencies and percentages. Chi square tests were conducted to explore the relationship of continuous and categorical variables with the dependent variable. A p value of <0.05 was considered significant.

Chi square tests were conducted between the various variable like age, sex, blood group with respect to H. Pylori incidence.

Age*H pylori

Sex*H.pylori

Blood group* H. Pylori

A P value of < 0.004 was obtained, proving the presence of a significant association between the O blood group and Helicobacter pylori incidence.