pylori, an organism that has impacted more than half of the world’s population and continues to pose great risk to human health because of its association with gastric cancer and MALT lymphoma. Genetic heterogeneity of the bacterium within a host population as shown in this study should be taken into account when studying the epidemiology

and pathogenesis of H. pylori since there is clearly variation in incidence and severity of the disease in different populations. Methods Source of gastric PND-1186 mouse biopsies and culture of H. pylori isolates Gastric biopsies were collected as part of a large-scale gastric cancer study conducted in symptomatic patients find more undergoing gastroenterological examination at the Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. All biopsies were obtained with the informed consent of the patients and this study was approved by the Human Ethics Committees of the University of New South Wales and the University of Malaya. Based on endoscopic and histological examinations, patients were diagnosed as having

gastric cancer or functional dyspepsia. All except seven samples were from patients with functional dyspepsia as shown in Table 2. H. pylori was cultured by inoculating biopsies on Campylobacter selective agar (CSA) containing 4% blood base agar No. 2 MLN2238 cost (Oxoid), defibrinated horse blood (Oxoid), and one vial of Skirrow’s supplement (Oxoid) containing 2.5 mg Trimethoprim, 5.0 mg Vancomycin, and 1250 IU polymyxin B. Primary cultures were incubated at 37°C with 10% CO2 in a CO2 incubator (Plymouth, USA) for up to 10 days, observing daily for growth. For isolation of pure cultures a single colony was picked and subcultured onto CSA for four days. Identification of H. pylori was based on microscopic morphology and biochemical testing (urease, oxidase and catalase). One isolate from

each biopsy was selected for this study and 78 isolates were obtained from patients of different ethnic background, including 27 Chinese, 35 Indian and 16 Malay (Table very 2). We used all Malay biopsy samples available. Despite the fact that this study spanned a period of four years the number of Malay subjects from whom H. pylori could be cultured was low which reflects the relative low prevalence in this population. Isolates from this study are available to researchers upon request to HM. Chromosomal DNA purification One plateful of bacterial culture was collected and suspended into 215 μl of Tris (50 mM), 15 μl of EDTA (0.5 M) and incubated for 10 min. Two μl of proteinase K (10 mg/ml) and 20 μl of SDS (10%) were added followed by incubation at 50°C for a minimum of 2 h or until clear. One μl of RNase (10 mg/ml) was added and incubated at 65°C for an additional 20 min. the mixture was then transferred into a 1.