Prevalence, risk factors, and virulence genes of Helicobacter pylori among dyspeptic patients in two different gastric cancer risk regions of Thailand.

Phawinee Subsomwong,Thawee Ratanachu-Ek,Tomohisa Uchida,Ratha-Korn Vilaichone,Varocha Mahachai,Muhammad Miftahussurur,Yoshio Yamaoka

doi:10.1371/journal.pone.0187113

Abstract

Gastric cancer risk is varied among different regions of Thailand. We examined the characteristics of Helicobacter pylori infection in two regions of Thailand. The H. pylori status of 273 dyspeptic patients (136 from the South and 137 from the North; a low and high incidence of gastric cancer region, respectively) was evaluated, and virulence genotypes (cagA, vacA, hrgA and jhp0562-positive/β-(1,3)galT) were determined. The overall H. pylori infection rate was 34.1% (93/273). The prevalence was higher in the North than in the South (50.4% vs. 17.6%, P <0.001) and was significantly higher among individuals with the following characteristics: low income, birthplace in the Northeast or North regions, agricultural employment, or consumption of alcohol or unboiling water. Among these socio-demographic determinants, region was an independent risk factor for H. pylori infection (odds ratio = 6.37). Patients including both H. pylori infected and uninfected cases who lived in the North had significantly more severe histological scores than those in the South. In contrast, among H. pylori-positive cases, patients in the South had significantly more severe histological scores than those in the North. Of the 74 strains cultured, 56.8% carried Western-type cagA, with a higher proportion in the South than in the North (76.2% vs. 49.1%, P = 0.05). In disagreement with the current consensus, patients infected with the Western-type cagA strains had more severe inflammation scores in the antrum than those infected with the East Asian-type cagA strains (P = 0.027). Moreover, Western-type cagA strains induced more severe histological scores in patients from the South than those of either genotype from the North. Other virulence genes had no influence on histological scores. The incidence of gastric cancer in Thailand was different among regions and corresponded to differences in the prevalence of H. pylori infection. More careful follow-up for patients in the South will be required, even if they are infected with H. pylori carrying Western-type cagA.

Highlights

For more than a century, it was believed that the presence of bacteria in the human stomach came from digested food contaminants, until the identification of a gram-negative bacteria, Helicobacter pylori, which is a causative agent of various severe gastroduodenal diseases, including gastric cancer [1]
We determined that the patient was H. pylori-positive if culture and/or histology confirmed by IHC had positive results; the final prevalence was determined to be 34.1%
As there was no difference in the prevalence between the two cities in the North, Chiang Kong and Chiang Saen (50.5% vs. 50.0%, P = 0.95), we combined both cities in the subsequent analyses

Summary

Introduction

For more than a century, it was believed that the presence of bacteria in the human stomach came from digested food contaminants, until the identification of a gram-negative bacteria, Helicobacter pylori, which is a causative agent of various severe gastroduodenal diseases, including gastric cancer [1]. The risk of developing gastric cancer is reduced following H. pylori eradication, and eradication should be performed before there is irreversible damage done to the patient [2]. Several environmental factors are associated with an increased risk of H. pylori infection, and these factors are found among those living in developing countries and in lower socioeconomic groups in the developed world, probably due to poor hygiene standards and crowded households [3]. H. pylori infection rates decreased in those born after 1950, simultaneously with a rapid change in sanitary conditions and in the standard of living. These changes include the development of a clean public water systems in Japan following World War II [5]. In addition to bacterial and host factors, there is a positive correlation between gastric cancer risk and smoking habits [6] and alcohol consumption [7], in addition to the fermented food [8], salt [9], and nitrates [10, 11]

Methods

Results

Discussion

Conclusion