Racial differences in Helicobacter pylori seroprevalence in Singapore: correlation with differences in peptic ulcer frequency

Overview of Helicobacter pylori Infection in Indonesia: What Distinguishes It from Countries with High Gastric Cancer Incidence?

Helicobacterpylori infects more than half the human population. However, the prevalence in Indonesia is low, as is the prevalence of gastric cancer. Hence, it could be instructive to compare these prevalence rates and their determining factors with those of countries that have high gastric cancer incidence. Ethnicity and genetic characteristics of H. pylori are important determinants of the H. pylori infection rate in Indonesia. The infection rate is higher in Bataknese, Papuans and Buginese than in Javanese, the predominant ethnic group. Ethnicity is also an important determinant of the genetic characteristics of H. pylori. Analysis of CagA in the EPIYA segment showed that the predominant genotypes in Papuans, Bataknese and Buginese are ABB-, ABD- and ABC-type CagA, respectively. Meanwhile, in the countries with high gastric cancer incidence, almost all strains had East Asian type CagA. An antibiotic susceptibility evaluation showed that the standard triple therapy can still be used with caution in several cities. There is a very high rate of resistance to second-line regimens such as levofloxacin and metronidazole. Recent studies have shown that furazolidone, rifabutin and sitafloxacin are potential alternative treatments for antibiotic-resistant H. pylori infection in Indonesia. Rather than focusing on early detection and eradication as in countries with high gastric cancer prevalence, countries with low gastric cancer prevalence should focus on screening the several groups that have a high risk of gastric cancer. (Gut Liver 2021;15:-665)

Helicobacter pylori in the Indonesian Malay's descendants might be imported from other ethnicities

BACKGROUND

Even though the incidence of H. pylori infection among Malays in the Malay Peninsula is low, we observed a high H. pylori prevalence in Sumatra, which is the main residence of Indonesian Malays. H. pylori prevalence among Indonesian Malay descendants was investigated.

RESULTS

Using a combination of five tests, 232 recruited participants were tested for H- pylori and participants were considered positive if at least one test positive. The results showed that the overall H. pylori prevalence was 17.2%. Participants were then categorized into Malay (Aceh, Malay, and Minang), Java (Javanese and Sundanese), Nias, and Bataknese groups. The prevalence of H. pylori was very low among the Malay group (2.8%) and no H. pylori was observed among the Aceh. Similarly, no H. pylori was observed among the Java group. However, the prevalence of H. pylori was high among the Bataknese (52.2%) and moderate among the Nias (6.1%). Multilocus sequence typing showed that H. pylori in Indonesian Malays classified as hpEastAsia with a subpopulation of hspMaori, suggesting that the isolated H. pylori were not a specific Malays H. pylori.

CONCLUSIONS

Even though the ethnic groups live together as a community, we observed an extremely low H. pylori infection rate among Indonesian Malay descendants with no specific Indonesian Malay H. pylori. The results suggest that H. pylori was not originally among these groups and H. pylori was imported from other ethnic groups.

Global Prevalence of Helicobacter pylori Infection: Systematic Review and Meta-Analysis

BACKGROUND & AIMS

The epidemiology of Helicobacter pylori infection has changed with improvements in sanitation and methods of eradication. We performed a systematic review and meta-analysis to evaluate changes in the global prevalence of H pylori infection.

METHODS

We performed a systematic search of the MEDLINE and EMBASE databases for studies of the prevalence of H pylori infection published from January 1, 1970 through January 1, 2016. We analyzed data based on United Nations geoscheme regions and individual countries. We used a random effects model to calculate pooled prevalence estimates with 95% confidence intervals (CIs), weighted by study size. We extrapolated 2015 prevalence estimates to obtain the estimated number of individuals with H pylori infection.

RESULTS

Among 14,006 reports screened, we identified 263 full-text articles on the prevalence of H pylori infection; 184 were included in the final analysis, comprising data from 62 countries. Africa had the highest pooled prevalence of H pylori infection (70.1%; 95% CI, 62.6-77.7), whereas Oceania had the lowest prevalence (24.4%; 95% CI, 18.5-30.4). Among individual countries, the prevalence of H pylori infection varied from as low as 18.9% in Switzerland (95% CI, 13.1-24.7) to 87.7% in Nigeria (95% CI, 83.1-92.2). Based on regional prevalence estimates, there were approximately 4.4 billion individuals with H pylori infection worldwide in 2015.

CONCLUSIONS

In a systematic review and meta-analysis to assess the prevalence of H pylori infection worldwide, we observed large amounts of variation among regions-more than half the world's population is infected. These data can be used in development of customized strategies for the global eradication.

Helicobacter pylori among patients with symptoms of gastroduodenal ulcer disease in rural Uganda

Introduction

To meet key millennium development goals, the rural population needs to be reached for health assessment and service delivery. Gastroduodenal ulcer disease is a common ailment affecting the health of people in Uganda. A cross-sectional study was conducted at Bwera Hospital in Kasese district of western Uganda, to establish the prevalence and predisposing factors of Helicobacter pylori among gastroduodenal ulcer disease patients.

Methods

A sample of 174 patients with symptoms of gastroduodenal ulcer disease was purposively obtained. Using two laboratory test methods, the prevalence of H. pylori among these patients was determined. A structured questionnaire was administered to participants to establish their demographic background and selected aspects of their lifestyle. Finally, the results obtained by enzyme-linked immunosorbent assay (ELISA) and immunochromatographic rapid test (IRT) were compared.

Results

We established the prevalence of H. pylori as 29.9% (52/174) by ELISA and 37.4% (65/174) by IRT. Cigarette smoking, poor sanitation, and lack of formal education were the significant predisposing factors with p-values <0.05. The two tests gave identical results in 87.9% of the patients.

Discussion

The prevalence of H. pylori by IRT and ELISA test methods was similar to what has been reported elsewhere in developed countries; but was lower than previously reported in developing countries including Uganda. The previous studies in Uganda were carried out in the urban population and on young children; and some used antibody-detection methods only, therefore leading to different prevalence as a result of difference in study population and methods.

Chronic adult primary immune thrombocytopenia (ITP) in the Asia-Pacific region

Patients with primary immune thrombocytopenia (ITP) from the Asia-Pacific region often exhibit characteristics distinct from those of patients from the West. Moreover, as the region itself is heterogeneous, the ITP landscape among individual Asia-Pacific countries can be diverse. The recently released international consensus report on ITP places new emphasis on ITP, but does not address the unique ITP landscape in the Asia-Pacific region, which is home to 60% of the world's population. In an attempt to characterize how the ITP landscape differs between the West and the Asia-Pacific region, an expert panel with representatives from Northeast Asia, Southeast Asia, and Australia was convened. Important differences were identified between the guidance provided in the international consensus report and experience in the Asia-Pacific region, namely diagnostic practices, incidence and approach to ITP secondary to H. pylori infection, systemic lupus erythematosus-related ITP, the use of bone marrow examination, initial treatment strategies, and the role of splenectomy, rituximab, and thrombopoietin receptor agonists.

Epidemiology of Helicobacter pylori among multiracial community in Northern Peninsular, Malaysia: effect of age across race and gender

OBJECTIVE

To study the epidemiology of Helicobacter pylori (H. pylori) infection according to age group.

METHODS

H. pylori infection data among 1 965 consecutive patients referred to the Endoscopy Unit collected at Sungai Petani Hospital for oesophagogastro-duodenoscopy (OGD). The patients were divided into 9 age groups (10-19, 20-29, 30-39, 40-49, 50-59, 60-69, 70-79, 80-89 and 90-99 years). In addition these groups were further divided into three minor group namely young adults (10-39), older adults (40-69) and geriatric groups (70-99).

RESULTS

Overall prevalence of infection of H. pylori was analyzed and found that the prevalence increase with age (P<0.05). When the patients divided by ethnic and gender group with age, prevalence rate among young adults and older adults significantly higher (P<0.05) compared to geriatric groups across all races and gender (P<0.05). Furthermore, significantly higher number of males were infected compared to female (P<0.05) but such trend was only observed among older adult groups. In addition, there is a significant differences in H. pylori infection prevalence rates among ethnic groups (highest in Indians adults, followed Chinese and low in Malays, P<0.05).

CONCLUSIONS

The overall prevalence of H. pylori did increase with age group across ethnicity and gender, in Northern Peninsular Malaysia.

Distinct cagA EPIYA motifs are associated with ethnic diversity in Malaysia and Singapore

BACKGROUND

In vitro studies have shown that the biologic activity of CagA is influenced by the number and class of EPIYA motifs present in its variable region as these motifs correspond to the CagA phosphorylation sites. It has been hypothesized that strains possessing specific combinations of these motifs may be responsible for gastric cancer development. This study investigated the prevalence of cagA and the EPIYA motifs with regard to number, class, and patterns in strains from the three major ethnic groups within the Malaysian and Singaporean populations in relation to disease development.

MATERIALS AND METHODS

Helicobacter pylori isolates from 49 Chinese, 43 Indian, and 14 Malay patients with functional dyspepsia (FD) and 21 gastric cancer (GC) cases were analyzed using polymerase chain reaction for the presence of cagA and the number, type, and pattern of EPIYA motifs. Additionally, the EPIYA motifs of 47 isolates were sequenced.

RESULTS

All 126 isolates possessed cagA, with the majority encoding EPIYA-A (97.6%) and all encoding EPIYA-B. However, while the cagA of 93.0% of Indian FD isolates encoded EPIYA-C as the third motif, 91.8% of Chinese FD isolates and 81.7% of Chinese GC isolates encoded EPIYA-D (p < .001). Of Malay FD isolates, 61.5% and 38.5% possessed EPIYA-C and EPIYA-D, respectively. The majority of isolates possessed three EPIYA motifs; however, Indian isolates were significantly more likely to have four or more (p < .05).

CONCLUSION

Although, H. pylori strains with distinct cagA-types are circulating within the primary ethnic groups resident in Malaysia and Singapore, these genotypes appear unassociated with the development of GC in the ethnic Chinese population. The phenomenon of distinct strains circulating within different ethnic groups, in combination with host and certain environmental factors, may help to explain the rates of GC development in Malaysia.

The response of Asian patients with functional dyspepsia to eradication of Helicobacter pylori infection

OBJECTIVES/BACKGROUND

The role of Helicobacter pylori infection in functional dyspepsia (FD) remains controversial. Several randomized controlled trials involving populations in the West, observed no statistically significant advantage over placebo. However, none of these studies involved Asian populations which have high infection rates.

METHODS

A double blind, randomized, placebo-controlled trial of H. pylori eradication for FD was conducted in our Singapore-based Asian population. Forty-one patients received active treatment consisting of a 1-week course of omeprazole 20 mg once daily, clarithromycin 250 mg twice daily and tinidazole 500 mg twice daily whereas another 41 patients received matching placebo tablets. A dyspepsia score was derived by grading 5 dyspeptic symptoms on a Likert scale. Symptom assessment and urea breath test were repeated at 6 weeks, 6 and 12 months from the start of treatment. The primary end point was symptom resolution, defined as a dyspepsia score of 0 or 1 at the end of 12 months follow-up.

RESULTS

On intention-to-treat analyses, symptom resolution was observed in 24% of patients on active treatment and 7% on placebo; the difference in proportion of patients with symptom resolution was statistically significant (P=0.02, 95% confidence interval: 1.1-17.7). H. pylori eradication rates perprotocol and intention-to-treat were 80.0 and 68.3%, on active treatment and 5.6 and 4.9% on placebo (both P values<0.0001). Among patients with H. pylori eradicated on active treatment the symptom resolution rate was 39% (10 of 26), whereas it was 3% (one of 35) among patients in the placebo group who had persistent H. pylori infection. In multivariate analysis, posttreatment H. pylori status was the only predictor of symptom resolution. The majority of patients, 91.5%, had ulcer-like dyspepsia; heartburn and acid regurgitation were uncommon, and no increase was observed after treatment.

CONCLUSION

In contrast to Western populations, our results suggest that patients with FD in Asia would benefit from treatment for H. pylori infection with as much as a 13-fold increased chance of symptom resolution following its eradication.

Cost effectiveness analysis of population-based serology screening and 13C-Urea breath test for Helicobacter pylori to prevent gastric cancer: A markov model

AIM: To compare the costs and effectiveness of no screening and no eradication therapy, the population-based Helicobacter pylori (H pylori) serology screening with eradication therapy and ¹³C-Urea breath test (UBT) with eradication therapy.

METHODS: A Markov model simulation was carried out in all 237 900 Chinese males with age between 35 and 44 from the perspective of the public healthcare provider in Singapore. The main outcome measures were the costs, number of gastric cancer cases prevented, life years saved, and quality-adjusted life years (QALYs) gained from screening age to death. The uncertainty surrounding the cost-effectiveness ratio was addressed by one-way sensitivity analyses.

RESULTS: Compared to no screening, the incremental cost-effectiveness ratio (ICER) was $16 166 per life year saved or $13 571 per QALY gained for the serology screening, and $38 792 per life year saved and $32 525 per QALY gained for the UBT. The ICER was $477 079 per life year saved or $390 337 per QALY gained for the UBT compared to the serology screening. The cost-effectiveness of serology screening over the UBT was robust to most parameters in the model.

CONCLUSION: The population-based serology screening for H pylori was more cost-effective than the UBT in prevention of gastric cancer in Singapore Chinese males.

Cost-effectiveness analysis of Helicobacter pylori screening in prevention of gastric cancer in Chinese

OBJECTIVES

The aim of this study was to evaluate the costs and effectiveness associated with no screening, Helicobacter pylori serology screening, and the 13C-urea breath test (UBT) for gastric cancer in the Chinese population.

METHODS

A Markov model simulation was carried out in Singaporean Chinese at 40 years of age (n = 478,500) from the perspective of public healthcare providers. The main outcome measures were costs, number of gastric cancer cases prevented, life-years saved, quality-adjusted life-years (QALYs) gained from the screening age to death, and incremental cost-effectiveness ratios (ICERs), which were compared among the three strategies. The uncertainty surrounding ICERs was addressed by scenario analyses and probabilistic sensitivity analysis using Monte Carlo simulation.

RESULTS

The ICER of serology screening versus no screening was $25,881 per QALY gained (95 percent confidence interval (95 percent CI), $5,700 to $120,000). The ICER of UBT versus no screening was $53,602 per QALY gained (95 percent CI, $16,000 to $230,000). ICER of UBT versus serology screening was $470,000 per QALY gained, for which almost all random samples of the ICERs distributed above $50,000 per QALY.

CONCLUSIONS

It cannot be confidently concluded that either H pylori screening was a cost-effective strategy compared with no screening in all Chinese at the age of 40 years. Nevertheless, serology screening has demonstrated much more potential to be a cost-effective strategy, especially in the population with higher gastric cancer prevalence.

Clinical outcome of patients with Helicobacter pylori infection: the bug, the host, or the environment?

It is well established that only a minority of patients with Helicobacter pylori infection develop severe inflammation leading to peptic ulcer or gastric cancer. Recent evidence suggests that the virulence factors of the organism do not seem crucial in the progression of inflammation towards a more severe disease. It seems probable that other host derived and environmental factors are more significant in determining clinical outcome but additional studies are needed to clarify the underlying mechanisms involved in the pathogenesis of infection.

Gastroesophageal reflux disease in Asian countries: disorder of nature or nurture?

Gastroesophageal reflux disease (GERD) is less prevalent in Asia than in the West, but there is now evidence to suggest that its frequency is rapidly rising in Asia. The different prevalence rates reported in various Asian studies may represent different points in the 'rising' phase of GERD. The cause for the lower but increasing prevalence of GERD in Asia is not known, but genetics and to some extent environmental factors, may have initially protected Asians against GERD. However, with the recent globalization of economies, the associated lifestyle changes in many developing Asian countries may have tipped the balance in favor of the development of GERD.

Validation of four Helicobacter pylori rapid blood tests in a multi-ethnic Asian population

AIM: To validate the accuracy of four rapid blood tests in the diagnosis of Helicobacter pylori.

METHODS: Consecutive dyspeptic patients scheduled for endoscopy at the National University Hospital, Singapore, were interviewed and had blood drawn for serology. The first 109 patients were tested with BM-test (BM), Pyloriset Screen (PS) and QuickVue (QV), and the next 99 subjects were tested with PS and Unigold (UG). Endoscopies were performed blinded to rapid blood test results and biopsies were taken for culture and rapid urease test. Urea breath tests were performed after endoscopies. The rapid blood test results were compared with four reference tests (rapid urease test, culture, serology, and breath test).

RESULTS: The study population composed of 208 patients (mean age 43.1 years; range 18-73 years; 119 males; 174 Chinese). The number of evaluable patients for BM, QV, UG and PS were 102, 102, 95, and 197, respectively. The sensitivity and specificity, respectively were: PS 80.2%, 95.8%; UG 55.9%, 100%; QV 43.3%, 100%; BM 67.2%, 97.1%.

CONCLUSION: The rapid blood test kits showed high specificity and positive predictive value (97-100%), while sensitivity and negative predictive value ranged widely (43%-80% and 47%-73%, respectively). Among test kits, PS showed the best sensitivity (80%), best negative predictive value (73%) and best negative likelihood ratio (0.207). PS had a specificity of 96%, positive predictive value of 97% and positive likelihood ratio of 19.1.

Increasing trend of reflux esophagitis and decreasing trend of Helicobacter pylori infection in patients from a multiethnic Asian country

OBJECTIVES

This study aimed to determine time trends in the frequency of endoscopic esophagitis, and Helicobacter pylori (H. pylori) infection in a large Singaporean teaching hospital over a 10-yr period.

METHODS

We studied a consecutive series of 16,375 patients who had been newly referred for diagnostic esophagogastroduodenoscopy from 1992 to 2001. All endoscopic findings were prospectively recorded. From 1995, an antral biopsy was taken from 6,185 unselected patients for an in-house biopsy urease test. Endoscopic esophagitis was defined as the presence of erosions and/or ulceration. The relationship between erosive esophagitis and various relevant factors was analyzed.

RESULTS

The overall prevalence of endoscopic esophagitis was 6.9% (95% CI, 6.5-7.3). It was 7.3% (95% CI, 6.2-8.4) in patients with a positive urease test, and 9.0% (95% CI, 8.1-9.9) in those in whom the urease test was negative (p < 0.001). From 1992 to 2001, the frequency of endoscopic esophagitis increased (p < 0.001 for trend) while that of positive urease test decreased from 1995 to 2001 (p < 0.001 for trend). The increase in the prevalence of endoscopic esophagitis (RR 1.99, 95% CI 1.18-3.36, p= 0.0098), and its inverse relationship with positive urease test results (RR 0.991, 95% CI 0.983-0.999, p= 0.049) remained significant even after adjusting for age, gender, ethnic distribution, and hiatal hernia.

CONCLUSIONS

The frequency of endoscopic esophagitis increased in Singapore from 1992 to 2001. This increase within a short period of time suggests that environmental factors, of which the decreasing rate of H. pylori infection may be one, are important in the pathogenesis of gastroesophageal reflux disease.

Effect of biopsies on sensitivity and specificity of ultra-rapid urease test for detection of Helicobacter pylori infection: A prospective evaluation

AIM: To prospectively assess the sensitivity, specificity and time to positivity of theUltra-rapid urease test (URUT) for Helicobacter pylori (H pylori ), and compare the results of one with those of two biopsies.

METHODS: Five antral biopsies were taken in consecutive patients undergoing upper endoscopy: one and two biopsies for URUT, and one each for H pylori culture and histology. URUT was read at 1, 5, 10, 20 and 30 min, 1, 2, 3 and 24 h after biopsy insertion into the reagent. A positive histology and/or culture was used as positive reference ”gold standards”.

RESULTS: URUT was more sensitive for detecting H pylori with two biopsies rather than one, at all time points up to 120 min. The sensitivity improved from 3.6% to 82.1% for one biopsy and 10.7% to 85.7% for two biopsies from 1 to 120 min. The sensitivity reached 96.4% at 24 h for both, but the specificity reduced from 100% to 96% and 92% for one and two biopsies, respectively.

CONCLUSION: Development of a positive URUT result is hastened by doubling the number of gastric biopsies. We recommend taking two instead of one biopsy to achieve an earlier positive URUT result so that H pylori eradication therapy can be initiated before patient is discharged from the endoscopy suite.

Immune responses to differentiated forms of Helicobacter pylori in children with epigastric pain

Helicobacter pylori infection affects human populations of all ages. This gastric bacterium exists in spiral form and the reported viable but nonculturable coccoid form. The present study aims to examine the probable role of the coccoid form in H. pylori infection by comparing the seroprevalences of the spiral and the coccoid forms in children with epigastric pain. Four hundred eighty-nine children (mean age, 8.5 years) with epigastric pain formed the basis of this study. Five hundred ninety-nine schoolchildren of comparable ages and with no record of dyspepsia served as controls. The seroprevalence of antigens prepared from both morphological forms was examined by enzyme-linked immunosorbent assay. The results showed that 65 (13.3%) and 273 (55.8%) of 489 symptomatic children were seropositive for antigens of the H. pylori spiral and coccoid forms, respectively. In contrast, only 7.0% of the control group had elevated levels of immunoglobulin G antibodies against the spiral form, while 26.5% were positive for antibodies against the coccoid form. There were no significant differences between genders or among ethnic groups. The study showed a rise in seroprevalence corresponding with age: 7.1% for those < or =5 years to 21.4% for those > or =11 years. The seroprevalence of antigens of the H. pylori spiral and coccoid forms in children with epigastric pain was twofold higher than that in the control subjects. Interestingly, there was a fourfold increase in seropositivity for coccoid-form antigen compared to that for the spiral-form antigen among the symptomatic pediatric patients as well as the control group, indicating a possible infective role of the coccoid form of H. pylori in the pediatric patients with epigastric pain.

Study of p53 immunostaining in the gastric epithelium of cagA-positive and cagA-negative Helicobacter pylori gastritis

BACKGROUND

p53 mutations are an early event in the multistep progression of gastric carcinoma. These mutations are often present in dysplastic and intestinal metaplastic gastric epithelium. However, the presence of immunohistochemically detectable p53 protein and p53 mutations in nondysplastic/nonmetaplastic gastric mucosa is more controversial. Recent reports have suggested that immunohistochemically detectable p53 protein may be present in the gastric epithelium of Helicobacter pylori gastritis. Furthermore, because cagA-positive H. pylori is associated with greater mucosal injury but decreased apoptosis, it would be interesting to determine if this phenotype is associated with greater immunostaining of p53, as the wild-type p53 gene helps to initiate apoptosis.

METHODS

One hundred thirty-five patients with H. pylori-associated gastritis were immunohistochemically stained for p53 and quantified for the extent and intensity of the staining using a semiquantitative method (0, nil staining; 6, extensive and strong staining). The cagA status of the organism was determined by Western blot.

RESULTS

Thirty-one patients (23%) showed strong p53 staining (> or = 4 of 6) in inflamed but otherwise normal gastric epithelium. In the 123 cagA-positive H. pylori gastritis patients, the average p53 staining score was 2.5 of 6. This is significantly higher than the corresponding score of 1.7 of 6 observed in the 12 patients with cagA-negative H. pylori gastritis (P = 0.04).

CONCLUSIONS

Our results indicate that p53 protein is immunohistochemically detectable even before gastric metaplastic/dysplastic change occurs. The results also suggest that cagA-positive H. pylori might be associated with greater p53 immunohistochemical staining. This would indicate that p53 immunohistochemical staining does not reliably differentiate between gastric dysplasia and reactive inflammatory atypia. If the p53 protein detected is a consequence of mutation, this would help to explain why cagA-positive H. pylori gastritis is associated with decreased apoptosis.

H. pylori and gastric cancer: the Asian enigma

The actual distribution of Helicobacter pylori infection and its related diseases in various Asian countries is controversial. Only limited information is available regarding this issue. We discuss the etiological role of H. pylori in gastric cancer through the Asian experience. Seroprevalence of H. pylori infection in asymptomatic subjects and the annual incidence rate of gastric cancer per 100,000 in various Asian countries are summarized from literature reviews and World Health Organization statistics, respectively. There is a large intercountry variation in incidence of gastric cancer and H. pylori seroprevalence among Asian countries. There is a strong link between H. pylori infection and gastric cancer in many countries, such as Japan. By contrast, the prevalence of H. pylori infection is high in some countries, including India and Bangladesh, but low gastric cancer rates have been reported. These disparate observations represent the Asian enigma. Factors that may influence the etiology of gastric cancer include the genetic diversity of the infecting H. pylori strains and differences in the host genetic background in various ethnic groups, including gastric acid secretion and genetic polymorphisms in proinflammatory cytokines. These factors, in addition to environmental factors, such as personal hygiene and dietary habits, reflect the multifactorial etiology of gastric cancer.

The racial cohort phenomenon: seroepidemiology of Helicobacter pylori infection in a multiracial South-East Asian country

BACKGROUND

Malaysia is a multiracial country where three major Asian races live together: Malay, Chinese and Indian. In addition, there are a number of native or indigenous races, particularly in East Malaysia. Differences in prevalence of gastric diseases between races have been noted, particularly with respect to peptic ulcer disease and gastric cancer. The aim of this study is to determine the prevalence rates and risk factors for Helicobacter pylori infection among various races in Malaysia.

METHODS

A large-scale prospective seroepidemiological study in West and East Malaysia using the HEL-p II commercial enzyme-linked immunosorbent assay kit (AMRAD, Melbourne, Australia) to detect H. pylori antibodies. Populations surveyed in West Malaysia were a rural community from Kuala Pilah, and blood donors from Kuala Lumpur and Kota Baru. Subjects studied in East Malaysia were volunteer blood donors from Kota Kinabalu, and blood donors and healthy volunteers from Sibu. Statistical analyses using multiple logistic regression analysis were carried out to identify independent risk factors for H. pylori infection

RESULTS

A total of 2,381 subjects were evaluated. H. pylori prevalence varied from different areas of study and ranged from a low of 26.4% in blood donors from Kota Baru to a high of 55.0% in Kota Kinabalu. The most striking differences, however, were noted in the prevalence rates among different racial groups. Prevalence rates among the Malays ranged from 11.9 to 29.2%, while the Chinese ranged from 26.7 to 57.5%, and those of Indians in two studies were 49.4 and 52.3%. In every location, Malays had a significantly lower prevalence compared with the other races. The highest prevalence rates were recorded among the indigenous races in Kota Kinabalu, East Malaysia. There was no difference between males and females in the studies. An increasing trend with age was noted in the majority of studies; however, no increase in prevalence rates was noted among the Malays.

CONCLUSIONS

The pattern of infection in a multiracial population in Malaysia points to a 'racial cohort' phenomenon. The infection appears to be confined to a racial group, with the Malays having consistently low prevalence rates. This observation may provide clues to the mode of transmission of infection.

Further evidence for an exceptionally low prevalence of Helicobacter pylori infection among peptic ulcer patients in north-eastern peninsular Malaysia

The Helicobacter pylori infection rate was determined in 124 consecutive patients with duodenal ulcers (DU), gastric ulcers (GU), duodenal erosions or gastric erosions diagnosed by endoscopy at a single institution in north-eastern peninsular Malaysia in 1996-97. Biopsies of the gastric antrum and body were subjected to the urease test, Gram staining of impression smears, culture and histopathological examination. Serology was undertaken on all patients using a locally validated commercial kit. Infection was defined as a positive result in at least one test. The infection rates were 20% (10/50), 21.2% (7/33), 16.7% (1/6) and 17.1% (6/35) in DU, GU, duodenal erosion and gastric erosion patients, respectively. The infection rate among Malays [7.0%, (6/86)] was lower than in non-Malays [47.4% (18/38)] (P < 0.001). There was a higher infection rate among males, who constituted 62.1% (77/124) of the sample. Seventy-eight patients (62.9%) were receiving non-steroidal anti-inflammatory drugs (NSAIDs) and 33 patients (26.6%) were neither receiving NSAIDs nor were infected with H. pylori. The H. pylori infection rate among peptic ulcer patients in this predominantly Malay rural population appears to be the lowest reported in the world thus far. Empirical H. pylori eradication therapy in peptic ulcer patients is clearly not indicated in this community. The possible reasons for the low prevalence of H. pylori infection are discussed.

Helicobacter pylori genotyping from positive CLOtests in patients with duodenal ulcer

Even though the seroprevalence of H. pylori may be high in the normal population, a minority develops peptic ulcer. Colonization of the gastric mucosa by more pathogenic vacA strains of H. pylori seems to be associated with enhanced gastric inflammation and duodenal ulcer. H. pylori genotyping from positive CLOtests was developed to determine the vacA genotypes and cagA status in 40 duodenal ulcer patients and for routine use. The pathogenic s1b/ m1/ cagA genotype was the most frequently occurring strain (17/42.5%); only two (5%) patients presented the s2/ m2 genotype, the less virulent strain. Multiple strains were also detected in 17 (42.5%) patients. Multiple strains of H. pylori colonizing the human stomach have been underestimated, because genotyping has been performed from cultures of H. pylori. We concluded that genotyping of H. pylori from a positive CLOtest had the advantages of reducing the number of biopsies taken during endoscopy, eliminating the step of culturing H. pylori, and assuring the presence of H. pylori in the specimen being processed.

Recent developments in the epidemiology of Helicobacter pylori

Prevalence determinations have been performed around the world, and regardless of how exotic a location, H. pylori is found in a substantial proportion of the population. H. pylori remains among the most universal of infections. Understanding of some features of infection has changed. Infection can be gained and lost at rates higher than previously realized. Oral-oral and oral-fecal transmission account for most, if not nearly all, cases of infection. H. pylori infection has declined rapidly in developed countries, which probably has contributed to declines in duodenal ulcer disease and gastric cancer. The full health implications of the potential elimination of infection are unknown.

Peptic ulcer and gastritis in uraemia, with particular reference to the effect of Helicobacter pylori infection

AIMS

To determine: (i) the prevalence of histological gastritis and peptic ulcer; and (ii) the clinical features of peptic ulcer, in patients with end-stage renal failure.

METHODS

Upper endoscopy was performed by a single observer in 268 patients with end-stage renal failure over a 6-year period. Gastric histology and Helicobacter pylori status were studied in 40 consecutive subjects in whom there were no contraindications for gastric biopsy and who had not used antibacterial drugs in the preceding 4 weeks. As there are only limited data for healthy volunteers in Singapore, 33 age-, sex- and race-matched patients with functional dyspepsia from an earlier drug trial and 18 healthy volunteers who were not age-matched were used as controls. The clinical features of 43 consecutive uraemic patients with peptic ulcer were compared with those of 118 consecutive non-uraemic peptic ulcer patients seen by the same author.

RESULTS

Among uraemic patients, histological gastritis was less common, compared with healthy volunteers and functional dyspepsia patients. Helicobacter pylori infection as assessed by histology was also less common among uraemic patients compared with functional dyspepsia patients, but the difference was not statistically significant on serological assessment. Uraemic patients with ulcer had an equal sex ratio, in contrast to a male preponderance among peptic ulcer patients with normal renal function. Uraemic patients with ulcer were more likely to be pain-free, to present with haemorrhage, to have multiple ulcers and postbulbar duodenal ulcers, but were less likely to have H. pylori infection. Among uraemic subjects, the prevalence of H. pylori infection was similar whether or not peptic ulcer was present.

CONCLUSIONS

The prevalence of histological gastritis was lower in uraemic patients when compared with patients with functional dyspepsia and healthy volunteers. Peptic ulcers in uraemic subjects have different clinical characteristics from peptic ulcer in non-uraemic subjects.

Reflux esophagitis patients in Singapore have motor and acid exposure abnormalities similar to patients in the Western hemisphere

OBJECTIVE

Endoscopic esophagitis is less common in the East than in the West. The reason for this is unknown. This study examines prospectively the relationship between endoscopic esophagitis and lower esophageal sphincter pressure, distal esophageal contractility, esophageal peristaltic performance, esophageal acid exposure, gastric acid output, and Helicobacter pylori (H. pylori) status in a consecutive series of Asian patients.

METHODS

Esophageal manometry and ambulatory pH monitoring were carried out in 48 patients with endoscopic esophagitis and 208 patients with symptoms suspicious of gastroesophageal reflux disease but without esophagitis. Gastric acid output and H. pylori serology were determined in 22 of the esophagitis group and 36 of the nonesophagitis group.

RESULTS

Compared to the nonesophagitis patients, esophagitis patients had a higher prevalence of hypotensive lower esophageal sphincter (49% vs 24%, p < 0.001), impaired esophageal contractility (45% vs 22%, p < 0.005), poor peristaltic performance (23% vs 12%, p < 0.05), and pathological acid reflux (48% vs 27%, p < 0.005). However, there was no difference in the two groups with respect to gastric acid output and H. pylori positivity.

CONCLUSIONS

Lower esophageal sphincter competence, esophageal peristaltic contractility, and esophageal acid exposure were important factors in the pathogenesis of reflux esophagitis--results identical to Western studies. Gastric acid output per se and H. pylori infection might not be responsible for susceptibility to esophagitis.