Prevalence of Helicobacter pylori pathogenicity-associated cagA and vacA genotypes among Pakistani dyspeptic patients

The cytotoxin-associated gene A ( cagA ), and the vacuolating cytotoxin gene A ( vacA ) products are considered the most important pathogenic determinants of Helicobacter pylori , a gram-negative bacterium causing gastrointestinal disorders such as duodenal ulcers, gastritis and mucosa-associated lymphoid tissue disease. A higher prevalence of H. pylori has been reported in various regions in the Pakistani population; however, no data are available about the virulence-associated genetic determinants. The objective of this study was to determine the prevalence of virulence-associated genes, cagA, vacA and particularly vacA allelic variants among dyspeptic patients from Pakistan. Gastric biopsy samples were obtained from 78 adult patients presenting dyspepsia symptoms. DNA was isolated and analyzed for the presence of H. pylori and its genotypes by PCR. Genus-specific PCR involving 16S rRNA gene revealed that 66 of the 78 patients were positive for H. pylori , an overall prevalence of 84.6% for this particular study. The most common vacA genotype was s1b/m2 (54.5%) followed by s1a/m1 (19.7%). cagA was positive in 24.2% of the cases and strongly associated with s1a/m1, vacA . The prevalence of virulent cagA , and vacA allelic form s1a/m1 was lower than that reported from neighboring countries.     

No correlation of babA2 with vacA and cagA genotypes of Helicobacter pylori and grading of gastritis from peptic ulcer disease patients in Brazil

BACKGROUND: The babA2 gene, which encodes a blood-group antigen-binding adhesin that mediates attachment of Helicobacter pylori to human Lewis(b) antigens on gastric epithelial cells, has been associated with a higher risk of peptic ulcer and gastric cancer. The purpose of this study was to ascertain the frequency of babA2 genotype in H. pylori strains of patients with peptic ulcer and to correlate with other virulence factors. MATERIALS AND METHODS: vacA, cagA, and babA2 genotypes of H. pylori were determined by using polymerase chain reaction (PCR). DNA was extracted from positive urease test gastric samples of 150 patients with peptic ulcer. Antrum and corpus biopsies were taken for histologic examination according to the updated Sydney system classification. RESULTS: babA2 genotype was present in 104 (69.3%) and cagA in 113 (75.3%) gastric samples. No significant correlation was observed between babA2 and vacAs1 genotype or between babA2 and cagA status. The correlation of vacAs1 genotype with positive cagA was statistically significant ( p < .001). The babA2-positive strain was more frequently found from the gastric samples of men, than of women (p = .01). Strains harboring cagA, vacAs1, and babA2 genotypes had no association to the grading of gastritis, presence of glandular atrophy, or intestinal metaplasia. The simultaneous presence of cagA, vacAs1, and babA2 was found in 32.6% of the H. pylori strains. CONCLUSIONS: babA2 genotype is frequently found in H. pylori strains from peptic ulcer disease in Brazil, although it has no significant correlation to the worsening of the gastritis and to other virulence markers such as vacAs1 and cagA.     

Determination of Helicobacter pylori cagA, vacA genotypes with real-time PCR melting curve analysis.

OBJECTIVES: genotypes of Helicobacter pylori are the focus of interest because they play a prominent role in mucosal injury. The purpose of this study was to determine cagA and vacA genotypes of H. pylori using real-time polymerase chain reaction (PCR) method with a double strain DNA binding SYBR Green I.dye, and to compare this with those of two immunohistochemical methods. METHODS: forty-three paraffin-embedded biopsy tissue samples were examined by histology, epidermal growth factor receptor (EGFR), proliferating cell nuclear antigen (PCNA) immunohistochemistry and melting curve analysis of real-time PCR. RESULTS: the presence of cagA gene was associated with a significantly higher frequency of gastritis (P=0.003) than that of vacA gene with intestinal metaplasia (P=0.045). Significant difference was found between the presence of cagA gene and EGFR expression in intestinal metaplasia cases in comparison with cagA negative samples (P=0.0418). Statistically significant difference was detected between increased cell proliferation and the presence of gastritis. CONCLUSIONS: this method seems to be suitable for H. pylori genotype determination. Sensitivity, speed and simplicity are key areas in the development of PCR assays for H. pylori. Results supported the notion that infection with cagA positive H. pylori strain causes more augmentated cell proliferation in the stomach mucosa.     

Association between cagA and vacA genotypes and pathogenesis in a Helicobacter pylori infected population from South-eastern Sweden

ABSTRACT: BACKGROUND: Chronic gastritis, peptic ulcer disease, and gastric cancer have been shown to be related toinfection with Helicobacter pylori (H. pylori). Two major virulence factors of H. pylori,CagA and VacA, have been associated with these sequelae of the infection. In this study, totalDNA was isolated from gastric biopsy specimens to assess the cagA and vacA genotypes. RESULTS: Variations in H. pylori cagA EPIYA motifs and the mosaic structure of vacA s/m/i/dayregions were analysed in 155 H. pylori-positive gastric biopsies from 71 individuals usingPCR and sequencing. Analysis of a possible association between cagA and vacA genotypesand gastroduodenal pathogenesis was made by logistic regression analysis. We found that H. pylori strains with variation in the number of cagA EPIYA motif variants present in the samebiopsy correlated with peptic ulcer, while occurrence of two or more EPIYA-C motifs wasassociated with atrophy in the gastric mucosa. No statistically significant relation betweenvacA genotypes and gastroduodenal pathogenesis was observed. CONCLUSIONS: The results of this study indicate that cagA genotypes may be important determinants in thedevelopment of gastroduodenal sequelae of H. pylori infection. In contrast to other studies,vacA genotypes were not related to disease progression or outcome. In order to fullyunderstand the relations between cagA, vacA and gastroduodenal pathogenesis, themechanisms by which CagA and VacA act and interact need to be further investigated.     

Prevalence of cagA and vacA genes in isolates from patients with Helicobacter pylori-associated gastroduodenal diseases in Recife, Pernambuco, Brazil

Geographical differences in the prevalence of Helicobacter pylori genes and their association with disease severity have been identified. This study analyzes the prevalences of the cagA gene and alleles of the vacA gene in H. pylori-associated gastroduodenal diseases in isolates from Recife, PE, Brazil. Gastric biopsy of 61 H. pylori-positive patients were submitted to DNA extraction and gene amplification by polymerase chain reaction. Among the 61 patients, 21 suffered from duodenal ulcer (DU) and 40 from gastritis (GT). The prevalence of H. pylori strains harbouring the cagA gene was higher in the DU group (90.5%) than in the GT group (60%) (p=0.02). The vacA gene was amplified in 56 out of 61 biopsies, of which 43 (76.8%) contained bacteria carrying the s1 allele and 13 (23.2%) the s2. However, the prevalence of the vacA s1 genotyping was the same in either DU or GT group. The majority of the s1-typed strains, 39 (90.7%) out of 43, were subtype s1b. In resume there was a strong association between the H. pylori cagA+ gene and DU. However, there were no differences between the DU and GT groups in relation to the vacA s1 and s2 alleles distribution, albeit the subtype s1b was predominant.     

幽门螺杆菌vacA和cagA基因全长分子系统发育分析

文章从GenBank中下载所有含有vacA和cagA基因的H.pylori菌株的VacA和CagA全长氨基酸序列,利用ClastalX 2.0和MEGA 5.05软件构建VacA和CagA分子系统发育树,探讨两基因之间的分子系统发育关系和不同聚类群的临床感染结果与基因型特征。结果显示,VacA和CagA具有高度相似的分子系统发育树,并且所有H.pylori菌株在系统发育树中具有相同的分布特点,分别聚类为东亚株群1、2和西方株群3个聚类群。其中东亚株群1患萎缩性胃炎比例较高,vacA基因型以s1c/m1b和s1a/m1b为主,cagA基因型以EPIYA-ABD为主;东亚株群2患十二指肠溃疡的比例较高,vacA基因型以s1c/m2和s1a/m2为主,cagA基因型以EPIYA-AB’C为主;西方株群患十二指肠溃疡和胃炎的比例相当,萎缩性胃炎比例较低,vacA基因型以s1a/m1a和s1b/m1a为主,cagA基因型以EPIYA-AB/B’CC为主。这些结果说明,vacA和cagA基因可能具有共进化的遗传关系;东亚株群1、2和西方株群分别具有不同的vacA和cagA基因亚型,这可能与其临床感染结果密切相关,因此,在进行H.pylori相关性疾病分析时,有必要结合vacA和cagA基因型的亚型做深入分析。     

cagA gene and vacA alleles in Spanish Helicobacter pylori clinical isolates from patients of different ages

The prevalence of the cagA gene and vacA alleles in 124 Spanish Helicobacter pylori clinical isolates from patients of different ages ranging from 3 to 78 years was studied (21 patients < or = 10 years, 30 patients 11-20 years, 17 patients 21-40 years, 31 patients 41-60 years and 25 patients 61-80 years). The cagA gene and vacA s1 or vacA s2 alleles were identified by PCR from the strain. 66.9% of the isolates were cagA+ and 33.1% cagA-. vacA s1 was detected in 48.4% of the isolates and vacA s2 in 51.6%. 44.4% of patients were cagA+/vacA s1, 22.5% were cagA+/vacA s2, 4% were cagA-/vacA s1 and 29% were cagA-/vacA s2. The percentage of cagA+ isolates and the vacA s1 alleles in the different groups were as follows: 23.8% and 28.6% in 0-10 years, 40% and 30% in 11-20 years, 88.2% and 70.6% in 21-40 years, 90.3% and 70.9% in 41-60 years and 92% and 44% in the 61-78 years group. 93% (54/58) of isolates found in ulcer patients and 90.9% (10/11) of isolates from gastritis patients older than 20 years were cagA+. In patients younger than 20 years ulcer disease was rare with 60% of isolates being cagA+ (3/5) compared with 31.6% cagA+ isolates (12/38) in patients suffering from gastritis in the younger group. The prevalence of the cagA gene and vacA s1 allele increased with age, being more frequent in older patients than in younger.     

Clinical relevance of the cagA,vacA and iceA genotypes of Helicobacter pylori in Brazilian clinical isolates

Infection with Helicobacter pylori strains harboring determinants of pathogenicity may lead to a strong inflammatory response in gastric mucosa. In this work, we examined the frequency of the cagA, vacA and iceA genotypes in H. pylori strains isolated from Brazilian patients and correlated these with the clinical manifestations. H. pylori was isolated from 165 patients [30 with non-ulcer dyspepsia cases (NUD); 93 peptic ulcer disease (PUD): 31 gastric ulcers (GU) and 62 duodenal ulcer disease (DU); 18 with erosive gastritis (EG); and 24 gastroesophageal reflux disease (GERD)]. Allelic variants of cagA, vacA and iceA were identified using the polymerase chain reaction. More than one H. pylori strain was detected in 28 cases (17%), and these were excluded from the statistical analysis. We were unable to confirm an association between iceA status and clinical outcome. There was a strong association between the genotype cagA-positive vacA s1 and PUD. However, logistic regression analysis showed that vacA s1 was the only predictive factor for PUD (OR=4.19; 95% CI 1.95-8.98). The presence of the less virulent strain vacA s2 was related to GERD (OR=8.59; 95% CI 2.85-25.91). Our results support the hypothesis that virulent strains may protect against the development of GERD.     

幽门螺杆菌毒力基因cagA、vacA和iceA与胃十二指肠疾病的关系

目的了解长春地区就医人群中幽门螺杆菌(Helicobacterpylori,H.pylori)毒力基因分布,分析本地区H.pylori主要毒力基因型与胃十二指肠疾病关系。方法将胃黏膜标本培养分离H.pylori并运用聚合酶链式反应(polymerase chain reaction,PCR)对H.pylori的三种毒力基因cagA、vacA(s1a、s1b、s1c、s2、m1a、m1b、m2、i1和i2)、iceA(iceA1和iceA2)及其亚型进行检测,分析H.pylori的毒力基因型与疾病之间的关系。结果分离H.pylori 60株,标本依据病理诊断结果分为4组:消化性溃疡组(peptic ulcer disease,PUD)25株、非溃疡性消化不良组(non-ulcer dyspepsia,NUD)9株、糜烂性胃炎组(gastritis erode,GE)15株和胃癌组(gastric cancer,GC)11株。cagA基因的阳性率为90.0%,与阴性相比在疾病中的分布差异有统计学意义(x~2=8.4440,P=0.0270)。vacA基因的s1和s2亚型的阳性率分别为86.7%和13.3%。在s1阳性菌株中,s1c等位基因检出率最高为33.3%,其次s1a检出率为23.3%,而s1b在NUD和GC中检出率为0.0%。vacA基因m区m1检出率为43.3%(m1a和m1b检出率均为21.7%)和m2检出率为56.7%。vacA基因i区等位基因i1和i2的检出率分别为78.3%和21.7%,i1明显高于i2,可能是胃肠道疾病的主要毒力因子,但与疾病的类型无明显相关性。iceA1和iceA2的阳性率分别为80.0%和16.7%,iceA1/iceA2混合型的阳性率为3.3%。三种毒力基因混合型以cagA~+/vacAs1m1i1/iceA1的菌株最多,占总数的31.7%,其次为cagA~+/vacAs1m2i1/iceA1,占总数的28.3%。结论本地区H.pylori毒力因子cagA、vacA和iceA都与胃十二肠疾病的发生密切相关,但与疾病的类型无关。H.pylori毒力基因混合型cagA+/vacAs1m1i1/iceA1和cagA~+/vacAs1m2i1/iceA1是胃十二肠疾病疾病中最主要的优势基因型,其分布也与疾病的类型无密切相关性。     

Non-invasive genotyping of Helicobacter pylori cagA, vacA, and hopQ from asymptomatic children

Background: Helicobacter pylori infection is usually acquired in childhood, but little is known about its natural history in asymptomatic children, primarily due to the paucity of non‐invasive diagnostic methods. H. pylori strains harboring cagA and specific alleles of hopQ and vacA are associated with increased risk for gastric cancer. Many studies of H. pylori virulence markers in children have the bias that symptomatic subjects are selected for endoscopy, and these children may harbor the most virulent strains. Our aim is to genotype cagA, hopQ, and vacA alleles in stool DNA samples of healthy Colombian children residing in an area with high incidence of gastric cancer, to avoid selection bias resulting from endoscopy. Methods: H. pylori status of 86 asymptomatic children was assessed by ¹³C‐urea breath test (UBT) and PCR. H. pylori 16S rRNA, cagA, hopQ, and vacA genes were amplified from stool DNA samples and sequenced. Results: UBT was positive in 69 (80.2%) of 86 children; in stool DNA analysis, 78.3% were positive by 16S rRNA PCR. cagA, vacA, and hopQ were detected in 66.1%, 84.6%, and 72.3% of stool DNA samples from 16S rRNA‐positive children. Of the children’s DNA samples, which revealed vacA and hopQ alleles, 91.7% showed vacA s1 and 73.7% showed type I hopQ. Type I hopQ alleles were associated with cagA positivity and vacA s1 genotypes (p < 0.0001). Conclusions: Using stool DNA samples, virulence markers of H. pylori were successfully genotyped in a high percentage of the asymptomatic infected children, revealing a high prevalence of genotypes associated with virulence. Type I hopQ alleles were associated with the presence of cagA and the vacA s1 genotype.     

The diversity of vacA and cagA genes of Helicobacter pylori in East Asia

It has been reported that Helicobacter pylori infection with the type I strain, which expresses the VacA and CagA antigens, is associated with duodenal ulcer. We examined the diversity of vacA and cagA genes in 143 isolates obtained from patients with duodenal ulcer or chronic gastritis in East Asia (two different areas of Japan, Fukui and Okinawa, and also in Hangzhou, China) by polymerase chain reaction (PCR) and sequence analysis. Diversities of cagA and vacA genes were detected in East Asia. The prevalence of cagA-positive H. pylori was significantly different between Fukui and Okinawa (P=0.0032). The prevalence of Western type CagA was significantly higher in Okinawa than in Fukui (P<0.0001). However, there was no significant association between the genotype of cagA and clinical outcome. In Japan, the predominant vacA genotype was s1c/m1b. In contrast, in Hangzhou, the predominant vacA genotype was s1c/m2, and they were all East Asian CagA-positive. These findings suggest that a distinct distribution of the vacA and cagA genotypes is present in East Asia, regardless of clinical outcome.     

Prevalence of Helicobacter pylori vacA, cagA, cagE, iceA, babA2 genotypes and correlation with clinical outcome in Turkish patients with dyspepsia

BACKGROUND: Distinct virulence factors of Helicobacter pylori have been associated with clinical outcome of the infection; however, considerable variations have been reported from different geographic regions and data on genotypes of Turkish H. pylori isolates are sparse. AIM: To determine the prevalence of specific genotypes of H. pylori in Turkish patients with dyspepsia. MATERIALS AND METHODS: Ninety-three H. pylori-positive patients [30 with non-ulcer dyspepsia (NUD), 30 with duodenal ulcer (DU), and 33 with gastric cancer (GC)] who were admitted to our endoscopy unit due to dyspepsia were enrolled in the study. H. pylori infection was confirmed in all patients by histology and rapid urease test (RUT). The presence of vacA alleles, cagA, cagE, iceA, and babA2 genotypes were determined by polymerase chain reaction (PCR). Chi-squared test and Fisher's exact test were used for statistical comparisons and multivariate regression analysis was performed to find out independent predictors of different clinical outcomes. RESULTS: Turkish strains examined predominantly possessed the vacA s1,m2 (48.4%) and s1,m1 (40.7%) genotypes. The vacA s1a genotype was detected in 66.7, 96.4, and 87.9% of isolates from patients with NUD, DU, and GC, respectively, and its presence was significantly associated with that of DU (p = .004), GC (p = .043), and cagA gene (p = .021). None of the cases was found to harbor the s1c genotype. The frequencies of the cagA and cagE genes among studied isolates were 73.6 and 59.3%, respectively. The cagA gene was significantly associated with the presence of DU (p = .004) and GC (p = .003), and the cagE gene, too, was significantly associated with the presence of DU (p = .002) and GC (p = .000). All H. pylori isolates possessed the iceA gene. In all, 68 isolates (74.7%) were positive for iceA1 and 23 (25.3%) for iceA2. The frequency of icea1 gene was significantly higher in cases with GC (85%) than in cases with NUD (60%) (p = .026). The frequency of babA2 gene was 23.3, 46.4, and 87.9% in isolates of patients with NUD, DU, and GC, respectively. When compared to cases with NUD (p = .000) and DU (p = .000), the presence of babA2 gene was significantly higher in cases with GC. Multivariate regression analysis disclosed cagE (p = .006) and vacA s1a (p = .027) genotypes to be independent predictors of DU and babA2 (p = .000) and cagE (p = .013) genotypes to be independent predictors of GC. CONCLUSIONS: H. pylori vacA s1a, cagA, cagE genotypes have significant relations with the presence of DU and GC, and iceA1, babA2 with GC in Turkish patients with dyspepsia, whereas cagE and vacA s1a genotypes are independent predictors of DU, and babA2 and cagE genotypes are independent predictors of GC.     

High Diversity of vacA and cagA Helicobacter pylori Genotypes in Patients with and without Gastric Cancer

Background

Helicobacter pylori is associated with chronic gastritis, peptic ulcers, and gastric cancer. The aim of this study was to assess the topographical distribution of H. pylori in the stomach as well as the vacA and cagA genotypes in patients with and without gastric cancer.

Methodology/Principal Findings

Three gastric biopsies, from predetermined regions, were evaluated in 16 patients with gastric cancer and 14 patients with dyspeptic symptoms. From cancer patients, additional biopsy specimens were obtained from tumor centers and margins; among these samples, the presence of H. pylori vacA and cagA genotypes was evaluated. Positive H. pylori was 38% and 26% in biopsies obtained from the gastric cancer and non-cancer groups, respectively (p = 0.008), and 36% in tumor sites. In cancer patients, we found a preferential distribution of H. pylori in the fundus and corpus, whereas, in the non-cancer group, the distribution was uniform (p = 0.003). A majority of the biopsies were simultaneously cagA gene-positive and -negative. The fundus and corpus demonstrated a higher positivity rate for the cagA gene in the non-cancer group (p = 0.036). A mixture of cagA gene sizes was also significantly more frequent in this group (p = 0.003). Ninety-two percent of all the subjects showed more than one vacA gene genotype; s1b and m1 vacA genotypes were predominantly found in the gastric cancer group. The highest vacA-genotype signal-sequence diversity was found in the corpus and 5 cm from tumor margins.

Conclusion/Significance

High H. pylori colonization diversity, along with the cagA gene, was found predominantly in the fundus and corpus of patients with gastric cancer. The genotype diversity observed across systematic whole-organ and tumor sampling was remarkable. We find that there is insufficient evidence to support the association of one isolate with a specific disease, due to the multistrain nature of H. pylori infection shown in this work.     

Prevalence of Helicobacter pylori genotypes (vacA, cagA, cagE and virB11) in gastric cancer in Brazilian's patients: an association with histopathological parameters

Purpose: To investigate the frequency and the association of vacA alleles, cagA, cagE and virB11 genes of Helicobacter pylori from patients with gastric cancer, considering the clinic histopathological parameters. Methods: One hundred and one gastric adenocarcinoma tissues were assessed by PCR to detect H. pylori and vacA alleles, cagA, cagE and virB11. Results: The distribution of cases according to the presence of the genes studied showed that the group containing vacA s1m1, cagA, cagE and virB11 H. pylori genes was significantly more frequent, followed by the group with at least one marker on the right side and left of the island. They were also present in the early stages and were the most frequent in nearly all histopathological grades. Conclusions: This study verified that vacAs1m1 and cag-PAI genes, cagA, cagE and virB11 are important H. pylori markers for gastric cancer development. Also, this study corroborates the importance of cagE and cagA together as cag-PAI marker.     

Comparison of genotyping of Helicobacter pylori cagA and vacA virulence genes from gastric biopsies and stool specimens

Background. We compared results of genotyping of Helicobacter pylori cagA and vacA virulence genes in DNA from gastric biopsies, both paraffin‐embedded and frozen, and from stool samples, in order to evaluate the comparative sensitivity of the stool assay. Methods. Genomic DNA from paraffin‐embedded biopsies, unfixed frozen biopsies, and stool samples of the same 20 patients was amplified for the cagA gene, an empty site (which provides a positive signal for cagA negative strains) and for the s and m alleles of the vacA gene. Composite genotypes were determined by combining data from analysis of all three materials. Results. Analysis of none of the materials taken singly showed all of the genotypes revealed by all three materials taken together, probably because of sampling error. Analysis of paraffin biopsies revealed 83.5%, that of frozen biopsies revealed 74.7% and that of stools revealed 75.9% of the genotypes. There was no significant difference in the percentage of the H. pylori genotypes identified from the three materials. Analysis of combinations of frozen biopsies and stools revealed 89.9% of the composite genotypes, and that of paraffin biopsies and stools revealed 96.2% of the composite genotypes. Evidence of multiple genotypes was found in 10 of 20 (50%) of the cases. Conclusions. Any one of the investigated biological materials can be used for detection of cagA and vacA genes, but no single assay provided a complete genotype. The use of a combination of two materials may generate a more accurate representation of H. pylori genotypes in each individual.     

Review: Helicobacter pylori and non‐malignant upper gastrointestinal diseases

This review covers recent publications investigating the relationship between Helicobacter pylori infection and gastroesophageal reflux disease, Barrett's esophagus, eosinophilic esophagitis, peptic ulcer disease (PUD), H pylori gastritis, and functional dyspepsia. In the area of gastroesophageal reflux disease, new data suggest that reflux may have a role in the transmission of H pylori infection. In addition to several observational studies, data on alterations in esophageal physiology in patients with H pylori infection are presented. Further evidence for the inverse relationship between H pylori infection and Barrett's esophagus is available in the form of a meta‐analysis from the North American Barrett's and Esophageal Carcinoma Consortium. The relationship between H pylori infection and eosinophilic esophagitis remains uncertain. Although new data do not indicate a significantly lower prevalence of H pylori among patients with eosinophilic esophagitis, a meta‐analysis showed a 37% reduced risk of eosinophilic esophagitis among H pylori‐infected patients. Novel data are presented on the genetic variability of bacterial virulence factors and their relationship with PUD. We also report data on plasma biomarkers, which may detect progression to gastric cancer in H pylori‐associated PUD. A new meta‐analysis was published, which assessed the risk of PUD in low‐dose aspirin users with H pylori infection. Finally, we report on the ongoing attempts to stratify patients with gastritis using endoscopic methods when compared to standard biopsy examination.     

Distribution of vacA genotypes in Helicobacter pylori strains isolated from Brazilian adult patients with gastritis,duodenal ulcer or gastric carcinoma

This PCR-based analysis is the first molecular epidemiological study in Brazil testing Helicobacter pylori cagA and vacA distribution in adults with gastric complaints, that includes a large number of carcinoma patients. Multiple-strain infection was identified in 11/13.4% patients. vacA s1-m1 and cagA(+) genotypes were the most common in patients with a non-mixed infection. All vacA s1 strains were s1b, so subtyping s1 strains was not useful. vacA s1b-m1 and cagA(+) strains were associated with higher prevalence of peptic ulcer and gastric carcinoma than vacA s2-m2 and cagA(-) ones. In conclusion, cagA and vacA genotyping may have clinical relevance in Brazil.     

Diversity of Helicobacter pylori cagA and vacA genes in Costa Rica: its relationship with atrophic gastritis and gastric cancer

BACKGROUND: Associations between Helicobacter pylori gene diversity and gastric cancer have not been reported on in Costa Rica, despite its being one of the countries with the highest gastric cancer incidence and mortality rates in the world. The aim of this study was to determine the prevalence of H. pylori cagA and vacA genes and investigate whether it could be correlated with atrophic gastritis (AG) and gastric cancer (GC) in Costa Rica. MATERIALS AND METHODS: Genomic DNAs from isolates of 104 patients classified into two groups: non-atrophic gastritis group (n = 68) and atrophic gastritis group (n = 36), were subjected to PCR-based genotyping of cagA and vacA genes and their correlation with clinical outcome was investigated. Total DNA extractions from gastric tissues of 25 H. pylori-infected gastric cancer patients were utilized for comparative purposes. RESULTS: The presence of cagA (75.3%), vacA s1b (75.3%), and vacA m1 (74.2%) was detected, and colonization by strains with different vacA genotypes in the same stomach was found in 9.7% of the patients. Age- and sex-adjusted vacA s1b and vacA m1 were associated with GC while only vacA m1 was significantly associated with AG. A tendency for association between cagA and vacA s1b, and AG was reported. CONCLUSIONS: The prevalence status of the cagA and vacA (s1/m1) genes in Costa Rica seems to fall between that found in European/North American and East Asian countries, and both cagA and vacA seem to have clinical relevance in this country.