Prevalence of Helicobacter pylori infection and atrophic gastritis in patients with dyspeptic symptoms in Myanmar

Prevalence of Gastric Precursor Lesions in Countries With Differential Gastric Cancer Burden: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

The prevalence of precursor lesions for gastric cancer (GC) and the differential burden between countries of varying GC risk is not well-understood. We conducted a systematic review and meta-analysis to estimate the global prevalence of precursor lesions.

METHODS

We estimated the prevalence of atrophic gastritis (AG), gastric intestinal metaplasia (IM), and dysplasia in regions with low, medium, and high GC incidence. Because IM is an advanced manifestation of AG, we assessed the prevalence of less advanced precursors, regardless of the presence of more advanced lesions. Prevalence was sub-stratified by Helicobacter pylori infection, symptomatology, and period (<2000, 2000-2010, and >2010).

RESULTS

Among the 582 articles that underwent full-text review, 166 studies met inclusion criteria. The global prevalence estimates of AG, IM, and dysplasia were 25.4%, 16.2%, and 2.0%, respectively, on the basis of 126 studies that reported the prevalence of less advanced precursors, regardless of the presence of more advanced lesions. The prevalence of all precursor lesions was higher in high and medium compared with low GC incidence countries (P < .01). Prevalence of AG and IM was significantly higher among H pylori-infected individuals (P < .01) but not statistically different between symptomatic and asymptomatic individuals (P > .17). All precursors demonstrated a secular decrease in prevalence over time.

CONCLUSIONS

Gastric precursor lesions have differences in prevalence in regions with differential GC incidence and are associated with H pylori infection. Because of the substantial prevalence of precursor lesions in both symptomatic and asymptomatic individuals, symptomatic evaluation may not be sufficient to identify individuals at risk. These estimates provide important insights for tailoring GC prevention strategies.

Correlation analysis of gastric mucosal lesions with Helicobacter pylori infection and its virulence genotype in Guiyang, Guizhou province, China

Background

Helicobacter Pylori (H. pylori) infection is the most important factor affecting clinical outcome in patients with gastric mucosal lesions. This study aimed to investigate H. pylori infection in patients with gastric mucosal lesions and their virulence genotype in Guiyang, China.

Methods

Pathological examinations of 1,364 biopsies from patients with upper gastrointestinal symptoms and H. pylori infection were analyzed according to different pathological types. The bacterial genome DNA was extracted from H. pylori strains isolated from gastric biopsies, and the cagA, vacA, and iceA virulence genes were detected and typed to analyze the correlation of their genotypes between different pathological lesions.

Results

The positive rate of H. pylori infection was approximately 19.9% (272/1,364), as determined by histopathological examination (HPE). It was more frequently detected in men than in women. A total of 85 H. pylori isolates were obtained from 280 clinical samples (positive rate 30.4%, 85/280). Of these 85 strains, cagA, vacA, and iceA genes were identified in 85.9%, 100%, and 83.5% of samples, respectively. Approximately 74.1% of strains were cagA East Asian type (cagA-ABD), and 11.8% of were cagA Western strains (cagA-AB, cagA-ABC), only present in patients with chronic non-atrophic gastritis. Gastric intraepithelial neoplasia and gastric cancer harbored both Asian strains. A total of 7 combinations of vacA genotypes were noted, among which s1c/m1b (30.6%) and s1c/m2 (41.2%) were the dominant genotypes. The predominant iceA genotype was iceA1 (64.7%).

Conclusions

We observed that the positive rate of H. pylori infection was related to the pathological type of patients' gastric mucosal lesions. Isolated H. pylori strains showed a unique genotype, mainly East Asian type cagA (ABD), vacA s1c/m2 genotype, and iceA1. These results provide an important reference for further studies of H. pylori in Guizhou province, China.

Next-Generation Sequencing-Based Study of Helicobacter pylori Isolates from Myanmar and Their Susceptibility to Antibiotics

Evaluation of Helicobacter pylori resistance to antibiotics is crucial for treatment strategy in Myanmar. Moreover, the genetic mechanisms involved remain unknown. We aimed to investigate the prevalence of H. pylori infection, antibiotic resistance, and genetic mechanisms in Myanmar. One hundred fifty patients from two cities, Mawlamyine (n = 99) and Yangon (n = 51), were recruited. The prevalence of H. pylori infection was 43.3% (65/150). The successfully cultured H. pylori isolates (n = 65) were tested for antibiotic susceptibility to metronidazole, levofloxacin, clarithromycin, amoxicillin, and tetracycline by Etest, and the resistance rates were 80%, 33.8%, 7.7%, 4.6%, and 0%, respectively. In the multidrug resistance pattern, the metronidazole–levofloxacin resistance was highest for double-drug resistance (16/19; 84.2%), and all triple-drug resistance (3/3) was clarithromycin–metronidazole–levofloxacin resistance. Twenty-three strains were subjected to next-generation sequencing to study their genetic mechanisms. Interestingly, none of the strains resistant to clarithromycin had well-known mutations in 23S rRNA (e.g., A2142G, A2142C, and A2143G). New type mutation genotypes such as pbp1-A (e.g., V45I, S/R414R), 23S rRNA (e.g., T248C), gyrA (e.g., D210N, K230Q), gyrB (e.g., A584V, N679H), rdxA (e.g., V175I, S91P), and frxA (e.g., L33M) were also detected. In conclusion, the prevalence of H. pylori infection and its antibiotic resistance to metronidazole was high in Myanmar. The H. pylori eradication regimen with classical triple therapy, including amoxicillin and clarithromycin, can be used as the first-line therapy in Myanmar. In addition, next-generation sequencing is a powerful high-throughput method for identifying mutations within antibiotic resistance genes and monitoring the spread of H. pylori antibiotic-resistant strains.

Serum Helicobacter pylori antibody reactivity in seven Asian countries using an automated latex aggregation turbidity assay

BACKGROUND AND AIM

To determine the application range of diagnostic kits utilizing anti-Helicobacter pylori antibody, we tested a newly developed latex aggregation turbidity assay (latex) and a conventional enzyme-linked immunosorbent assay (E-plate), both containing Japanese H. pylori protein lysates as antigens, using sera from seven Asian countries.

METHODS

Serum samples (1797) were obtained, and standard H. pylori infection status and atrophy status were determined by culture and histology (immunohistochemistry) using gastric biopsy samples from the same individuals. The two tests (enzyme-linked immunosorbent assay and latex) were applied, and receiver operating characteristics analysis was performed.

RESULTS

Area under the curve (AUC) from the receiver operating characteristic of E-plate and latex curves were almost the same and the highest in Vietnam. The latex AUC was slightly lower than the E-plate AUC in other countries, and the difference became statistically significant in Myanmar and then Bangladesh as the lowest. To consider past infection cases, atrophy was additionally evaluated. Most of the AUCs decreased using this atrophy-evaluated status; however, the difference between the two kits was not significant in each country, but the latex AUC was better using all samples. Practical cut-off values were 3.0 U/mL in the E-test and 3.5 U/mL in the latex test, to avoid missing gastric cancer patients to the greatest extent possible.

CONCLUSIONS

The kits were applicable in all countries, but new kits using regional H. pylori strains are recommended for Myanmar and Bangladesh. Use of a cut-off value lower than the best cut-off value is essential for screening gastric cancer patients.

Comparison of clinical symptoms after Helicobacter pylori eradication in functional dyspepsia patients based on endoscopic view of antral gastropathy

Functional dyspepsia is a common gastric disease that can be associated with Helicobacter pylori infection. The aim of this study is to evaluate antral endoscopy of individuals who presented with functional dyspepsia, H. pylori infection status and the effects of eradication therapy on the symptoms. Following the diagnosis of dyspepsia as per Rome III criteria, 260 individuals who were eligible for the study underwent upper gastrointestinal endoscopy and were divided into four groups of 65 according to the endoscopic view, grades I, II, III and IV (negative). Stool antigen test was also performed for all patients to identify H. pylori infection. The early signs of dyspepsia were assessed by a standard questionnaire. In all groups, omeprazole, amoxicillin, clarithromycin and metronidazole were used for eradication treatment, and 1 month after the treatment, a faecal antigen test was repeated to evaluate the eradication of H. pylori. There was no statistically significant difference between the groups in terms of clinical symptoms before treatment. The highest response to eradication treatment was seen in individuals with antral gastropathy grade III (66.2%) and the lowest response was in patients without antral gastropathy Grade IV (32.3%). This difference was statistically significant. There was no statistically significant relationship between the participants in terms of family history, age, gender and response to treatment. Eradicating H. pylori reduces the symptoms of dyspepsia. The response of eradication therapy was greatest among the patients with grade III antral gastropathy.

Serum pepsinogens as a gastric cancer and gastritis biomarker in South and Southeast Asian populations

Serum pepsinogens have been widely acknowledged as gastric mucosal biomarkers; however, a multicountry report on the benefits of pepsinogens as biomarkers has not yet been published. We analyzed 1,206 sera and gastric mucosal samples collected from Bangladesh, Bhutan, Indonesia, Myanmar, Nepal and Thailand then assessed the association between gastric mucosal changes and Helicobacter pylori infection. The new cutoff values for serum pepsinogen values were evaluated using a receiver operating characteristic analysis. The participants with H. pylori infection had significantly lower pepsinogen I and higher pepsinogen II values, but a lower pepsinogen I/II ratio than participants without the infection (all P < .001). The pepsinogen I and pepsinogen I/II values were significantly higher and lower, respectively, in individuals with atrophic gastritis than in those without (both P < .001). Among uninfected individuals, only the pepsinogen I/II ratio was significantly lower in atrophic individuals. Pepsinogen I/II ratio also were significantly different between disease among H. pylori-positive and H. pylori-negative individuals, suggesting the pepsinogen I/II ratio is a robust biomarker for determining both chronic and atrophic gastritis. The cutoffs for detecting chronic and atrophic gastritis for the pepsinogen I/II ratio were 4.65 and 4.95, respectively. In conclusion, pepsinogen levels are useful biomarker for both chronic gastritis and atrophic gastritis, but they should be used with caution. Population-based validation is necessary to determine the best cutoff values. Among all pepsinogen values, the pepsinogen I/II ratio was the most reliable gastric mucosal-change biomarker.

Sequential Helicobacter pylori eradication therapy in Myanmar; a randomized clinical trial of efficacy and tolerability

BACKGROUND AND AIM

There is little published research to examine the best approach to the management of Helicobacter pylori in Myanmar. This study aimed to determine the relative efficacy and tolerability of sequential eradication therapy compared to Myanmar's current recommendation of a concomitant four drug regimen.

METHODS

Patients were screened for H. pylori using monoclonal Stool Antigen Testing (SAT). Those testing positive were randomized 1:1 to receive receive Myanmar's first-line regimen of 14 days of concomitant rabeprazole, clarithromycin, amoxycillin and tinidazole (140 pills, cost US$23) or 10 days of sequential rabeprazole, clarithromycin, amoxycillin and tinidazole (60 pills, cost US$10). Adherence and adverse effects were recorded, and the efficacy of the regimens assessed with repeat SAT.

RESULTS

Of the 1011 patients screened for H. pylori infection, 313 (31%) tested positive. There was no statistical difference in the cure rates of the two regimens in either intention-to-treat: 128/157 (82%; 95% confidence interval (CI): 75-87%) receiving sequential therapy versus 123/156 (79%; 95% CI: 72-85%) receiving concomitant therapy (P = 0.55) or per-protocol analysis: 125/131 (95%; 95% CI: 90-98) receiving sequential therapy versus 121/130 (93%; 95% CI: 87-96) receiving concomitant therapy (P = 0.42). Side effects of therapy were reported in 54/157 (47%) patients taking sequential therapy compared with 62/156 (53%) taking concomitant therapy, but this difference did not reach statistical significance (P = 0.33).

CONCLUSIONS

In this high-burden, resource-poor setting, less expensive sequential therapy was as effective and as well tolerated as the currently recommended concomitant four drug regimen for eradication of H. pylori.

Prediction of Chronic Atrophic Gastritis and Gastric Neoplasms by Serum Pepsinogen Assay: A Systematic Review and Meta-Analysis of Diagnostic Test Accuracy

Serum pepsinogen assay (sPGA), which reveals serum pepsinogen (PG) I concentration and the PG I/PG II ratio, is a non-invasive test for predicting chronic atrophic gastritis (CAG) and gastric neoplasms. Although various cut-off values have been suggested, PG I ≤70 ng/mL and a PG I/PG II ratio of ≤3 have been proposed. However, previous meta-analyses reported insufficient systematic reviews and only pooled outcomes, which cannot determine the diagnostic validity of sPGA with a cut-off value of PG I ≤70 ng/mL and/or PG I/PG II ratio ≤3. We searched the core databases (MEDLINE, Cochrane Library, and Embase) from their inception to April 2018. Fourteen and 43 studies were identified and analyzed for the diagnostic performance in CAG and gastric neoplasms, respectively. Values for sensitivity, specificity, diagnostic odds ratio, and area under the curve with a cut-off value of PG I ≤70 ng/mL and PG I/PG II ratio ≤3 to diagnose CAG were 0.59, 0.89, 12, and 0.81, respectively and for diagnosis of gastric cancer (GC) these values were 0.59, 0.73, 4, and 0.7, respectively. Methodological quality and ethnicity of enrolled studies were found to be the reason for the heterogeneity in CAG diagnosis. Considering the high specificity, non-invasiveness, and easily interpretable characteristics, sPGA has potential for screening of CAG or GC.

Enhanced infectivity of strains of Helicobacter pylori isolated from children compared with parental strains

PURPOSE

Intra-familial infection, mother-to-child infection, is considered to be one of the main routes of transmission for Helicobacter pylori, in developed countries such as Japan. A major role for intra-familial spread in the pathogenicity of H. pylori is now beyond controversy, although the major route of transmission remains poorly understood. We performed this study to clarify the factors determining intra-familial transmission.

METHODOLOGY

We used several H. pylori strains isolated from family members to compare infectivity. H. pylori K21 and K22 strains were isolated from the father and mother, and the K25 strain was isolated from the third child of the family. Mongolian gerbils were inoculated with H. pylori strains and the infectivity of three strains was compared in each experiment. In addition, the whole genome sequence, adhesion to gastric epithelial cells and the growth of static condition or continuous flow culture among three strains of H. pylori were analysed.Results/Key findings. Most of the colonies were determined as the same molecular type K25 in all of the four grouped animals and H. pylori K25 was observed as the dominant strain. The stronger adhesion capacity of the K25 strain was observed in comparison with the other two strains through in vitro analysis. By assessing the genomic profiles of H. pylori isolates from three strains, identified TnPZ regions were detected only in the K25 strain.

CONCLUSION

The infectivity of H. pylori isolates intra-familial infection and animal infection were prescribed by the adhesion capacity and molecular type of each strain.

Analysis of virulence diversity of 73 Helicobacter pylori strains isolated in Guizhou province, China

The present study aimed to investigate the virulence diversity of Helicobacter pylori (H. pylori) in major ethnic groups residing in Guizhou province, China, and its association with clinical outcomes. Gastric mucosal biopsies were collected from the pylorus of patients with gastrointestinal disorders. H. pylori was identified by colonial morphology, Gram staining, a urease test and H. pylori‑specific 16S rRNA gene fragment PCR amplification. DNA was extracted from pure culture and used for virulence gene analysis. The cytotoxin associated gene A (cagA), vacuolating cytotoxin A (vacA) and induced by contact with epithelium gene A (iceA) genes were analyzed by polymerase chain reaction analysis. The cagA gene was further analyzed through sequencing of the C‑terminal region containing EPIYA motifs, and phylogenetic analysis of the cagA C‑terminal variable region was performed using MEGA 6.0 software. In the present study, 73 H. pylori strains were isolated from clinical samples. cagA genotypes were detected in all strains, namely cagA‑AB, ‑ABC, ‑ABD and ‑BD genotypes were found in five (6.85%), three (4.11%), 63 (86.30%) and two (2.74%) isolates, respectively. Phylogenetic analysis showed that there was a clustering association between the cagA‑AB and cagA‑ABC genotypes, and between the cagA‑ABD and cagA‑BD genotypes. In terms of the frequency of the four EPIYA or EPIYA‑like motifs, the most predominant was EPIYA (92.92%), followed by EPIYT (3.77%), ESIYA (2.83%) and ESIYT (0.47%). The predominant vacA genotype was s1c/m2 (65.75%), and the predominant iceA genotype was iceA1 (79.45%). There were no associations between the H. pylori cagA, vacA or iceA genotypes and clinical outcomes. No significant difference was found in the distribution of these genotypes according to the age, ethnicity or location of residence of patients. In conclusion, H. pylori isolated from patients in Guizhou region, China, showed a unique genotype, which was mainly East Asia‑type cagA (ABD), vacA s1c/m2 genotype or iceA1‑postiive. These results provide important information on the distribution of H. pylori virulence genotypes in Guizhou province, China.

Molecular Epidemiology of Helicobacter pylori Infection in a Minor Ethnic Group of Vietnam: A Multiethnic, Population-Based Study

The Helicobacter pylori-induced burden of gastric cancer varies based on geographical regions and ethnic grouping. Vietnam is a multiethnic country with the highest incidence of gastric cancer in Southeast Asia, but previous studies focused only on the Kinh ethnic group. A population-based cross-sectional study was conducted using 494 volunteers (18-78 years old), from 13 ethnic groups in Daklak and Lao Cai provinces, Vietnam. H. pylori status was determined by multiple tests (rapid urease test, culture, histology, and serology). cagA and vacA genotypes were determined by PCR-based sequencing. The overall H. pylori infection rate was 38.1%. Multivariate analysis showed that variations in geographical region, age, and ethnicity were independent factors associated with the risk of H. pylori acquisition. Therefore, multicenter, multiethnic, population based study is essential to assess the H. pylori prevalence and its burden in the general population. Only the E De ethnicity carried strains with Western-type CagA (82%) and exhibited significantly lower gastric mucosal inflammation compared to other ethnic groups. However, the histological scores of Western-type CagA and East-Asian-type CagA within the E De group showed no significant differences. Thus, in addition to bacterial virulence factors, host factors are likely to be important determinants for gastric mucosal inflammation and contribute to the Asian enigma.

Characterizing Helicobacter pylori cagA in Myanmar

BACKGROUND/AIMS

Differences in the Helicobacter pylori infection rate are not sufficient to clarify the dissimilarity of gastric cancer incidence between Myanmar and its neighboring countries. To better understand this trend, the H. pylori virulence gene cagA was characterized in Myanmar.

METHODS

Glutamate-proline-isoleucine-tyrosine-alanine (EPIYA) patterns and CagA multimerization (CM) motifs of cagA genotypes were examined by performing polymerase chain reactions and DNA sequencing.

RESULTS

Of 69 tested H. pylori strains, cagA-positive patients had significantly more severe histological scores in their antrum than cagA-negative patients. Sequence analysis revealed that 94.1% of strains had Western-type cagA containing an EPIYA motif (92.6%) or EPIYT motif (6.4%). The intestinal metaplasia scores in the antral of patients infected with the ABC and ABCC types of cagA were significantly higher than those of patients with AB-type cagA. Interestingly, in patients infected with H. pylori, 46.3% of strains with three EPIYA motifs contained two identical Western-typical CM motifs, and these patients showed significantly higher antrum inflammation scores than patients infected with two identical nontypical-CM motif strains (p=0.02).

CONCLUSIONS

In Myanmarese strains, Western-type cagA was predominant. The presence of CM motifs and the proportion of multiple EPIYA-C segments might partially explain the intermediate gastric cancer risk found in Myanmar.

Helicobacter pylori bab characterization in clinical isolates from Bhutan, Myanmar, Nepal and Bangladesh

BACKGROUND

Helicobacter pylori BabA is an important outer membrane protein that involves in the attachment to the gastric mucosa and enhances the virulence property of the bacterium. This study was aimed to characterize the bab genotypes, to evaluate its association with cagA, vacA and clinical diseases as well as degree of gastric inflammation.

METHODS

H. pylori isolates from four countries were subjected for the characterization of bab. The locus specific forward and bab specific reverse primers were used to get the specific products by PCR, which could distinguish the three locus (A, B and C). The histological activities were evaluated according to the Updated Sydney system.

RESULT

In patients from high risk countries (Bhutan and Myanmar) relatively higher frequencies of strains with babA-positivity (91.8% and 90.7%, respectively), babA at locus A (98% and 91.2%, respectively) and with single babA (96.8% and 91.2%, respectively) were found. Strains with two loci occupied were the most prevalent in Bhutan (84.6%), Myanmar (74.7%), Nepal (58.3%) and Bangladesh (56.9%). The genotype babA at locus A/babB at locus B/bab-negative at locus C (babA/babB/-) was the most common genotype isolated from Bhutan (82.7%), Myanmar (58.7%), Nepal (32%) and Bangladesh (31.4%) among all genotypes assessed. This genotype was also associated with the peptic ulcer disease (P = 0.013) when compared to gastritis. babA-positive characteristics and the genotype babA/babB/- exhibited the enhanced histological activities.

CONCLUSIONS

The higher prevalence of virulence associated babA-positive characteristics and enhanced histological activities in Bhutan than in Myanmar, Nepal and Bangladesh might partly explain why the peoples in Bhutan are at higher risk for developing severe gastric complications.

Gastric mucosal status in populations with a low prevalence of Helicobacter pylori in Indonesia

In Indonesia, endoscopy services are limited and studies about gastric mucosal status by using pepsinogens (PGs) are rare. We measured PG levels, and calculated the best cutoff and predictive values for discriminating gastric mucosal status among ethnic groups in Indonesia. We collected gastric biopsy specimens and sera from 233 patients with dyspepsia living in three Indonesian islands. When ≥5.5 U/mL was used as the best cutoff value of Helicobacter pylori antibody titer, 8.6% (20 of 233) were positive for H. pylori infection. PG I and II levels were higher among smokers, and PG I was higher in alcohol drinkers than in their counterparts. PG II level was significantly higher, whereas PG I/II ratios were lower in H. pylori-positive than in H. pylori-negative patients. PG I/II ratios showed a significant inverse correlation with the inflammation and atrophy scores of the antrum. The best cutoff values of PG I/II were 4.05 and 3.55 for discriminating chronic and atrophic gastritis, respectively. PG I, PG II, and PG I/II ratios were significantly lower in subjects from Bangli than in those from Makassar and Surabaya, and concordant with the ABC group distribution; however, group D (H. pylori negative/PG positive) was the lowest in subjects from Bangli. In conclusion, validation of indirect methods is necessary before their application. We confirmed that serum PG level is a useful biomarker determining chronic gastritis, but a modest sensitivity for atrophic gastritis in Indonesia. The ABC method should be used with caution in areas with a low prevalence of H. pylori.

Prevalence of Helicobacter pylori infection in newly arrived refugees attending the Migrant Health Service, South Australia

BACKGROUND

To determine the prevalence of Helicobacter pylori infection in the refugee population attending the Migrant Health Service, South Australia, identify demographic factors associated with infection and compare prevalence of infection in refugees with that of the nonrefugee population in Australia.

MATERIALS AND METHODS

Cross-sectional study conducted between October 2010 and August 2013. Monoclonal stool antigen testing for H. pylori infection is performed as part of a comprehensive health assessment for newly arrived refugees. The sample population included 922 adults and children. Outcome measures were (i) prevalence of H. pylori infection (ii) association between demographic factors such as sex, ethnicity and age, and H. pylori infection.

RESULTS

H. pylori infection was detected in 198 (21.5%) participants (95% CI 18.9%-24.3%). The odds of infection were lower in females OR 0.71 (95% CI 0.51-0.98) compared to males. Compared to Middle Eastern participants, the odds of infection were 1.75 (95% CI 1.17-2.62) times higher in African and 1.90 (95% CI 1.10-3.26) times higher in Burmese participants. Infection was not associated with age.

DISCUSSION AND CONCLUSION

H. pylori infection is common among newly arrived refugees. The long latency of infection to development of complications and the availability of testing and relatively effective eradication regimens all add weight to a decision to screen in this population.

Serum VEGF Levels in Helicobacter pylori Infection and Correlation with Helicobacter pylori cagA and vacA Genes

BACKGROUND:

Helicobacter pylori vacA and cagA genes are associated with higher virulence. Vascular Endothelial Growth Factor (VEGF) is one important marker for neo-angiogenesis.

AIM:

The purpose of this study was to investigate the relationship between VEGF serum levels with cagA and vacA genes in H. pylori infection.

METHODS:

A cross-sectional study was done on eighty patients that consecutive admitted to endoscopy unit. The diagnosis of H. pylori infection was based on rapid urease test. Serum samples were obtained to determine circulating VEGF level. Polymerase chain reaction was done to examine H. pylori vacA and cagA genes. Data analysis were carried-out using SPSS version 22.

RESULTS:

A total of 80 patients were examined. There were 45 (56.3%) patients infected with Helicobacter pylori. There were 33 (73.3%) patients with H. pylori cagA positive. Serum VEGF levels in patients with the H. pylori positive were significantly higher compared to the patients that have no H. pylori. Serum levels of VEGF were significantly higher in cagA positive than negative.

CONCLUSION:

Serum VEGF level is correlated with H. pylori infection and its virulence status. The more virulence of H. pylori, cagA gene, the higher serum VEGF levels were found.

Newly arrived refugee children with Helicobacter pylori are thinner than their non-infected counterparts

The hypothesis of this study was that those refugee children with Helicobacter pylori are thinner than their non-infected counterparts. This cross-sectional study investigated the height and weight of newly arrived refugee children up to age 19 years, who were screened for H. pylori using a stool antigen test at the Migrant Health Service in Adelaide between August 2010 and October 2013. Of 460 children, 21% were infected with H. pylori. After adjusting for vitamin B12 and iron levels, ethnicity, age and sex, the odds of being thin in the 10- to 19-year-old age group was 4.28-fold higher (95% CI 1.48–12.4) if they were H. pylori positive compared with those who were H. pylori negative. The difference between the two groups is statistically significant (P=0.01). Screening and treatment for H. pylori in the general population in developed countries is not recommended unless there are symptoms such as dyspepsia or risk of peptic ulcer, duodenal ulcer or gastric cancer. Given the findings of this study, a recommendation could be made that newly arrived refugee children who are thin should be tested for H. pylori. Thinness in children may influence their cognitive ability, school performance, physical endurance and hence their ability to successfully settle into their new country.

Diagnostic Methods of Helicobacter pylori Infection for Epidemiological Studies: Critical Importance of Indirect Test Validation

Among the methods developed to detect H. pylori infection, determining the gold standard remains debatable, especially for epidemiological studies. Due to the decreasing sensitivity of direct diagnostic tests (histopathology and/or immunohistochemistry [IHC], rapid urease test [RUT], and culture), several indirect tests, including antibody-based tests (serology and urine test), urea breath test (UBT), and stool antigen test (SAT) have been developed to diagnose H. pylori infection. Among the indirect tests, UBT and SAT became the best methods to determine active infection. While antibody-based tests, especially serology, are widely available and relatively sensitive, their specificity is low. Guidelines indicated that no single test can be considered as the gold standard for the diagnosis of H. pylori infection and that one should consider the method's advantages and disadvantages. Based on four epidemiological studies, culture and RUT present a sensitivity of 74.2–90.8% and 83.3–86.9% and a specificity of 97.7–98.8% and 95.1–97.2%, respectively, when using IHC as a gold standard. The sensitivity of serology is quite high, but that of the urine test was lower compared with that of the other methods. Thus, indirect test validation is important although some commercial kits propose universal cut-off values.

Helicobacter pylori Infection in Thailand: A Nationwide Study of the CagA Phenotype

Background

The risk to develop gastric cancer in Thailand is relatively low among Asian countries. In addition, the age-standardized incidence rate (ASR) of gastric cancer in Thailand varies with geographical distribution; the ASR in the North region is 3.5 times higher than that in the South region. We hypothesized that the prevalence of H. pylori infection and diversity of CagA phenotype contributes to the variety of gastric cancer risk in various regions of Thailand.

Methods

We conducted a nationwide survey within Thailand. We determined H. pylori infection prevalence by detecting H. pylori, using histochemical and immunohistochemical methods. The anti-CagA antibody and anti-East-Asian type CagA antibody (α-EAS Ab), which showed high accuracy in several East Asian countries, were used to determine CagA phenotype.

Results

Among 1,546 patients from four regions, including 17 provinces, the overall prevalence of H. pylori infection was 45.9% (710/1,546). Mirroring the prevalence of H. pylori infection, histological scores were the lowest in the South region. Of the 710 H. pylori-positive patients, 93.2% (662) were immunoreactive with the anti-CagA antibody. CagA-negative strain prevalence in the South region was significantly higher than that in other regions (17.9%; 5/28; p < 0.05). Overall, only 77 patients (11.6%) were immunoreactive with the α-EAS Ab. There were no differences in the α-EAS Ab immunoreactive rate across geographical regions.

Conclusions

This is the first study using immunohistochemistry to confirm H. pylori infections across different regions in Thailand. The prevalence of East-Asian type CagA H. pylori in Thailand was low. The low incidence of gastric cancer in Thailand may be attributed to the low prevalence of precancerous lesions. The low incidence of gastric cancer in the South region might be associated with the lower prevalence of H. pylori infection, precancerous lesions, and CagA-positive H. pylori strains, compared with that in the other regions.

The Prevalence of Helicobacter pylori Virulence Factors in Bhutan, Vietnam, and Myanmar Is Related to Gastric Cancer Incidence

Gastric cancer is a significant health problem in Asia. Although the prevalence of Helicobacter pylori infection is similar in Bhutan, Vietnam, and Myanmar, the incidence of gastric cancer is highest in Bhutan, followed by Vietnam and Myanmar. We hypothesized that H. pylori virulence factors contribute to the differences. The status of cagA, vacA, jhp0562, and β-(1,3)galT(jhp0563) was examined in 371 H. pylori-infected patients from Bhutan, Vietnam, and Myanmar. Each virulence factor could not explain the difference of the incidence of gastric cancer. However, the prevalence of quadruple-positive for cagA, vacA s1, vacA m1, and jhp0562-positive/β-(1,3)galT-negative was significantly higher in Bhutan than in Vietnam and Myanmar and correlated with gastric cancer incidence. Moreover, gastritis-staging scores measured by histology of gastric mucosa were significantly higher in quadruple-positive strains. We suggest that the cagA, vacA s1, vacA m1, and jhp0562-positive/β-(1,3)galT-negative genotype may play a role in the development of gastric cancer.