Barik A. Salih

Analysis of Helicobacter pylori Genotypes and Correlation with Clinical Outcome in Turkey

ABSTRACT The predominant Helicobacter pylori strains circulating among geographic locations differ in regard to genomic structure. The association of the cagA-positive, vacA s1 genotypes with peptic ulcer disease (PUD) and gastric cancer was reported in Western countries but not in East Asian countries. Strains from Western countries predominantly possessed cagA type 2a, vacA s1a or s1b/m1a, or vacA m2a genotypes, whereas strains from East Asia possessed cagA type 1a, vacA s1c/m1b, or vacA m2b genotypes. Whether the Turkish strains possessed such genotypes was investigated and correlated with the disease outcome. Seventy-three patients from Turkey were enrolled. H. pylori was detected in 65 (89%) patients (22 with gastritis, 33 with PUD, and 10 with gastric cancer) by any of the following tests: Campylobacter-like organism test, culture, or PCR. Among the H. pylori-positive patients, presence of the cagA gene (78%) was significantly associated with PUD (P < 0.00001), gastric cancer (P < 0.001), and vacA s1a genotypes (P < 0.0001). Multiple vacA genotypes were more prevalent in PUD and gastric cancer patients than in patients with gastritis. Restriction fragment length polymorphism analysis of the cagA gene revealed three different patterns with no significant association with clinical outcome. Turkish strains examined predominantly possessed cagA type 2a, vacA s1a/m1a, or vacA m2a genotypes, which were typical genotypes in strains from Western countries. This fact might be one of the reasons for the low prevalence of severe gastroduodenal diseases in Turkey compared to the East Asian countries.

Helicobacter pylori Infection in Developing Countries: The Burden for How Long?

Approximately 50% (over 3 billion) of the world populations are known to be infected with Helicobacter pylori, mainly in the developing countries. Among those, hundreds of millions of people develop peptic ulceration during their lifetime and still tens of millions might progress to gastric cancer. Possible modes of H. pylori transmission generally described are through direct contact between family members and also through contaminated water and food. Because the high prevalence of infection occurs mainly in developing countries and because the test-and-treat strategy puts a huge economic burden on many of these countries, it is time to take an immediate action toward this bacterial infection and adopt a strategy to prevent it. To address this issue, an updated prevalence of infection, modes of transmission, economics of infection and preventative measures to block the infection process have been discussed.

A Follow-up Study on the Effect of Helicobacter pylori Eradication on the Severity of Gastric Histology

Helicobacter pylori genetic diversity and geographic distribution affect the severity of gastric histology; while eradication heals gastritis, the improvement of atrophy and intestinal metaplasia (IM) is still controversial. We investigated whether H. pylori infection and genotypes (cagA–vacA) influence the histological changes and whether eradication resolves these changes. Twenty-one patients (11 duodenal ulcer, 2 gastric ulcer, 8 gastritis) received treatment. Biopsies for CLO, PCR, histology, and culture were collected before and at 1 and 12 months after treatment, and serum samples at 0, 1, 2, 6, and 12 months. H. pylori eradication was achieved in 71% of the patients. Histological scores for H. pylori densities were significantly higher in the antrum and incisura angularis. Scores for mononuclear cell and neutrophil infiltration were significantly higher in regions with a high H. pylori density and improved progressively after eradication. Eight patients with atrophy including five with IM showed no significant changes 12 months after eradication. The cagA gene, detected in 13 (62%), the vacA-s1a gene, in 20 (95%), and the vacA-m1 gene, in 12 (57%) of 21 patients were significantly associated with duodenal ulcer. A gradual decline in antibody titer reached an average of 67% 12 months after eradication. H. pylori infection and the associated genotypes (cagA of Western type) affect the severity of the gastric histology (mild forms of atrophy and IM) and the disease outcome. Eradication of H. pyloriresulted in healing of gastritis, but with no significant improvement in atrophy or IM.

Helicobacter pylori anti-CagA antibodies: prevalence in symptomatic and asymptomatic subjects in Turkey.

BACKGROUND Several reports have shown the prevalence of anti-CagA antibodies to be associated with the development of peptic ulcer diseases, while others have indicated that there is no such association. AIM To examine the prevalence of antibodies to CagA and other Helicobacter pylori antigens in symptomatic and asymptomatic subjects in Turkey. subjects and METHODS Sixty-six symptomatic subjects, 16 to 74 years of age, were examined for H pylori by biopsy-based tests and ELISA. One hundred nineteen asymptomatic subjects, 20 to 65 years of age, were also tested serologically for the presence of H pylori. Samples from both groups that were found to be positive for H pylori by ELISA were then tested by immunoblotting. RESULTS Fifty-four (82%) symptomatic subjects and 76 (64%) asymptomatic subjects were found to be H pylori-positive by ELISA. Samples from 30 symptomatic subjects who were found to be H pylori-positive by ELISA were analyzed by immunoblotting. Antibodies to CagA (116 kDa) antigen were detected in immunoblots of 11 of 14 (79%) with chronic gastritis, 12 of 13 (92%) with duodenal ulcer and three of three (100%) with gastric cancer. Antigens of the following molecular weights were also detected in these 30 subjects: 89 kDa (VacA) in 21 (70%), 37 kDa in 21 (70%), 35 kDa in 19 (63%), 30 kDa in 27 (90%) and 19.5 kDa in 19 (63%). Immunoblots of 40 ELISA-positive asymptomatic subjects showed that 33 (83%) had antibodies to CagA antigen, 26 (65%) to VacA antigen, 30 (75%) to a 37 kDa antigen, 30 (75%) to a 35 kDa antigen, 39 (98%) to a 30 kDa antigen and 36 (90%) to a 19.5 kDa antigen. CONCLUSIONS Antibodies to CagA antigen were prevalent in both groups, regardless of the presence of gastroduodenal disease.

Antimicrobial resistance of Helicobacter pylori strains to five antibiotics, including levofloxacin, in Northwestern Turkey

INTRODUCTION Antibiotic resistance is the main factor that affects the efficacy of current therapeutic regimens against Helicobacter pylori. This study aimed to determine the rates of resistance to efficacy clarithromycin, amoxicillin, tetracycline, levofloxacin and metronidazole among H. pylori strains isolated from Turkish patients with dyspepsia. METHODS H. pylori was cultured from corpus and antrum biopsies that were collected from patients with dyspeptic symptoms, and the antimicrobial susceptibility of H. pylori was determined using the E-test (clarithromycin, amoxicillin, tetracycline, metronidazole and levofloxacin) according to the EUCAST breakpoints. Point mutations in the 23S rRNA gene of clarithromycin-resistant strains were investigated using real-time PCR. RESULTS A total of 98 H. pylori strains were isolated, all of which were susceptible to amoxicillin and tetracycline. Of these strains, 36.7% (36/98) were resistant to clarithromycin, 35.5% (34/98) were resistant to metronidazole, and 29.5% (29/98) were resistant to levofloxacin. Multiple resistance was detected in 19.3% of the isolates. The A2143G and A2144G point mutations in the 23S rRNA-encoding gene were found in all 36 (100%) of the clarithromycin-resistant strains. Additionally, the levofloxacin MIC values increased to 32 mg/L in our H. pylori strains. Finally, among the clarithromycin-resistant strains, 27.2% were resistant to levofloxacin, and 45.4% were resistant to metronidazole. CONCLUSIONS We conclude that treatment failure after clarithromycin- or levofloxacin-based triple therapy is not surprising and that metronidazole is not a reliable agent for the eradication of H. pylori infection in Turkey.

Comparison of the lateral flow immunoassays (LFIA) for the diagnosis of Helicobacter pylori infection.

Helicobacter pylori infection is the most common human infection where approximately 50% of the world populations are infected. The diagnosis of such infection is mainly done by endoscopy where gastric biopsies are examined for the presence of H. pylori. Such invasive approach is costly, time consuming and generally requires more than one test to confirm the infection. Serology on the other hand is a non-invasive approach that can detect H. pylori exposure. The lateral flow immunoassays (LFIA) support the serological approach and have the advantage of being fast, economic and require no additional equipment or experience. In this review the principles, components of the LFIA, sensitivities and specificities of the commercially available H. pylori test strips were compared and discussed.

A study on the effect of Helicobacter pylori infection on p53 expression in gastric cancer and gastritis tissues

INTRODUCTION Helicobacter pylori cause damage to gastric epithelial cells and alterations in the p53 gene that lead to cancer development. This study aimed to determine the correlation of p53 expression with H. pylori using immunohistochemistry, RFLP-PCR, and histopathology. METHODOLOGY Gastric biopsy samples from gastric cancer (GC) (n = 54) and gastritis (n = 31) patients were examined for histopathological changes and expression of p53 protein by immunohistochemistry. RESULTS Immunohistochemical analysis of p53 protein expression in H. pylori-positive GC sections showed an average of 44.3% positive cells in tumors and 6.9% in normal tissues, as compared to 16.4% and 4.4% in H. pylori-negative sections. P53 expression showed significant association with H. pylori (P = 0.005), invasion depth (P = 0.029) and inflammation reaction (P = 0.008). In gastritis sections, no difference in the average p53 staining in H. pylori-positive or -negative sections was seen. PCR-RFLP results also showed no difference in genotype frequencies of p53 in H. pylori-positive or -negative gastritis sections. Histopathology study of H. pylori-positive GC sections showed that 97.2% were the intestinal type and 2.8% the diffuse type, while in H. pylori-negative sections 35.2% were the intestinal type and 64.8% the diffuse type. Biopsy sections from H. pylori-positive gastritis patients revealed more severe inflammation than those of H. pylori-negative patients. CONCLUSION Our results show that H. pylori infection affects p53 expression in GC. The average p53 expression was significantly higher in tumor than in normal tissues. In gastritis sections p53 expression was significantly associated with H. pylori.

Canonical Correlation Analysis of Factors Involved in the Occurrence of Peptic Ulcers

The impact of risk factors on the development of peptic ulcers has been shown to vary among different populations. We sought to establish a correlation between these factors and their involvement in the occurrence of peptic ulcers for which a canonical correlation analysis was applied. We included 7,014 patient records (48.6% women, 18.4% duodenal ulcer [DU], 4.6% gastric ulcer [GU]) of those underwent upper gastroendoscopy for the last 5 years. The variables measured are endoscopic findings (DU, GU, antral gastritis, erosive gastritis, pangastritis, pyloric deformity, bulbar deformity, bleeding, atrophy, Barret esophagus and gastric polyp) and risk factors (age, gender, Helicobacter pylori infection, smoking, alcohol, and nonsteroidal anti-inflammatory drugs [NSAIDs] and aspirin intake). We found that DU had significant positive correlation with bulbar deformity (P=2.6×10–23), pyloric deformity (P=2.6×10–23), gender (P=2.6×10–23), H. pylori (P=1.4×10–15), bleeding (P=6.9×10–15), smoking (P=1.4×10–7), aspirin use (P=1.1×10–4), alcohol intake (P=7.7×10–4), and NSAIDs (P=.01). GU had a significantly positive correlation with pyloric deformity (P=1,6×10–15), age (P=2.6×10–14), bleeding (P=3.7×10–8), gender (P=1.3×10–7), aspirin use (P=1.1×10–6), bulbar deformity (P=7.4×10–4), alcohol intake (P=.03), smoking (P=.04), and Barret esophagus (P=.03). The level of significance was much higher in some variables with DU than with GU and the correlations with GU in spite of being highly significant the majority, were small in magnitude. In conclusion, Turkish patients with the following endoscopic findings bulbar deformity and pyloric deformity are high-risk patients for peptic ulcers with the risk of the occurrence of DU being higher than that of GU. Factors such as H. pylori, smoking, alcohol use, and NSAIDs use (listed in a decreasing manner) are risk factors that have significant impact on the occurrence of DU; aspirin has a significant impact on both DU and GU.

Evaluation of immobilized metal affinity chromatography kits for the purification of histidine-tagged recombinant CagA protein.

Immobilized metal affinity chromatography (IMAC) technique is used for fast and reliable purification of histidine(His)-tagged recombinant proteins. The technique provides purification under native and denaturing conditions. The aim of this study is to evaluate three commercially available IMAC kits (Thermo Scientific, GE Healthcare and Qiagen) for the purification of a 6xHis-tagged recombinant CagA (cytotoxin-associated gene A) protein from IPTG-induced Escherichia coli BL21(DE3) culture. The kits were tested according to the manufacturer instructions and the protein was purified with only GE Healthcare and Qiagen kits under denaturing conditions. 1% (w/v) SDS was used as denaturing agent in PBS instead of extraction reagent of Thermo Scientific kit to lyse bacterial cells from 100ml culture. The 6xHis-tagged recombinant protein was purified by the three kits equally.

Global Research on Helicobacter pylori

To the Editor: The isolation of Helicobacter pylori from the human stomach by the Nobel laureates Marshall and Warren in 1983 paved the way for the current understanding of the important role of this bacterium in peptic ulcer disease and gastric cancer. H. pylori infection is now recognized as one of the most common bacterial infections in humans, with approximately half of the world’s populations currently infected (prevalence rates of 25% in developed countries and >90% in developing countries) [1]. During the years following the first isolation of this bacterium, interest in H. pylori research has expanded tremendously. A PubMed bibliographic database search conducted for the last 23 years revealed over 15,000 publications, and the number continues to increase. The distribution of the scientific contributions to H. pylori research among the continents and some of the leading countries is shown in Table 1. The European countries had the major contribution, with 7051 (46.7%) publications cited, the United Kingdom (18.5%) being on top of the list, followed by Italy, Germany, the Netherlands, and Sweden. Asia contributed a total of 3987 (26.4%) publications, with Japan (50.2%) leading the Asian countries, followed by China, Taiwan, Hong Kong, and Turkey. North America was responsible for 2971 (19.7%) publications, with the United States (85.6%) the leading country in the world regarding number of publications. South America had 434 (2.9%) publications, of which Brazil (37.1%) contributed the high