Molecular epidemiology and outcome of Helicobacter pylori infection in Thailand: a cultural cross roads

ABSTRACT Background. Thailand is at the cultural cross roads between East and South Asia. It has been suggested that this is also the region where the predominant Helicobacter pylori (H. pylori) genotype changes from East Asian to South Asian. Methods. We compared the molecular epidemiology and outcome of H. pylori infections among different ethnic groups in Thailand (Thai, Thai-Chinese and Chinese). H. pylori isolates were genotyped by polymerase chain reaction based on cagA, cag right end junction and vacA genotypes. Results. Ninety-eight isolates from 38 ethnic Thai, 20 ethnic Chinese and 40 Thai-Chinese were categorized into East Asian (45%), South/Central Asian (26%), Western (1%) or mixed type (29%). The East Asian genotype was the most common among Chinese (85%) and Thai-Chinese (55%) (p <.01 compared to ethnic Thai). The ethnicity of the mother among mixed Thai-Chinese marriages predicted the genotype of the child's H. pylori (e.g. when the mother was Chinese, 84% had East Asian type vs. 29% when the mother was Thai) (p <.001). Gastric cancer was common among ethnic Chinese with East Asian genotype (e.g. all Chinese with gastric cancer or peptic ulcer disease had East Asian genotype, whereas only 40% of Chinese with gastritis had this genotype). Conclusions. Immigration, intermarriage and the variety of H. pylori genotypes in Thailand suggest that Thailand is an ideal site for epidemiological studies attempting to relate H. pylori genotypes and host factors to outcome. Our data also support the hypothesis that the primary caretaker of the children is most likely the source of the infection.     

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.     

Pilot studies to identify the optimum duration of concomitant Helicobacter pylori eradication therapy in Thailand

Background and Aim: Eradication rate for Helicobacter pylori infection with standard triple therapy has globally declined including in Thailand, and new regimens are required that provide reliable high eradication rates. The study was designed to determine whether concomitant therapy administered for either 5 or 10 days would produce a ≥ 95% (grade A) treatment success in H. pylori infected Thai subjects with nonulcer dyspepsia. Methods: Two prospective, but separate, pilot single‐center studies were carried out during September 2009–December 2010 at Thammasat University Hospital, Thailand. H. pylori infected subjects were randomized into the two pilot studies; either 5‐day or 10‐day concomitant therapy. Thai concomitant therapy consisted of rabeprazole (20 mg) twice daily, amoxicillin 1 g twice daily, metronidazole 400 mg three times a day, and clarithromycin MR 1 g once daily. H. pylori status was assessed by ¹³C‐urea breath test 4 weeks after completion of the treatment. Successful treatment was defined as achieving a grade A result (≥95%) and failure by <90% cured. Results: A total of 110 subjects were randomized (55 to the 5‐day treatment trial and 55 to the 10‐day regimen). Baseline subject demographic and clinical characteristics were similar in both studies. All subjects completed their assigned therapies. The 10‐day concomitant treatment trial was successful in 53 of the 55 subjects (96.4%; 95% CI 87.4–99.5%). The 5‐day concomitant pilot was judged to be a failure as only 49 of 55 subjects (89.1%; 95% CI = 77.7–95.8%) were cured. The frequency of adverse events was low and similar in the two studies. Conclusion: The 10‐day concomitant regimen provided excellent treatment success (eradication rate >95%) and was well tolerated. Ten‐day concomitant therapy is likely to become useful first‐line H. pylori eradication in Thailand.     

Systematic review and meta-analysis: Helicobacter pylori eradication therapy after simple closure of perforated duodenal ulcer

Background: The most common complications of peptic ulcer are bleeding and perforation. In many regions, definitive acid reduction surgery has given way to simple closure and Helicobacter pylori eradication. Aim: To perform a systematic review and meta‐analysis to ask whether this change in practice is in fact justified. Materials and Methods: A search on the Cochrane Controlled Trials Register, Medline, and Embase was made for controlled trials of duodenal ulcer perforation patients using simple closure method plus postoperative H. pylori eradication therapy versus simple closure plus antisecretory non‐eradication therapy. The long‐term results for prevention of ulcer recurrence were compared. Results: The pooled incidence of 1‐year ulcer recurrence in H. pylori eradication group was 5.2% [95% confidence interval (CI) of 0.7 and 9.7], which is significantly lower than that of the control group (35.2%) with 95% CI of 0.25 and 0.45. The pooled relative risk was 0.15 with 95% CI of 0.06 and 0.37. Conclusions: Helicobacter pylori eradication after simple closure of duodenal ulcer perforation gives better result than the operation plus antisecretory non‐eradication therapy for prevention of ulcer recurrence. All duodenal ulcer perforation patients should be tested for H. pylori infection, and eradication therapy is required in all infected patients.     

Characterization and Antibacterial Activity Against Helicobacter pylori of Lactic Acid Bacteria Isolated from Thai Fermented Rice Noodle

Probiotics and Antimicrobial Proteins - A total of 32 lactic acid bacteria (LAB) were isolated from Khanom-jeen, a Thai traditional fermented rice noodle. They belonged to the genus Leuconostoc...