Helicobacter pylori vacA and cagA genotypes in patients from northeastern Brazil with upper gastrointestinal diseases

Helicobacter pylori causes chronic gastric inflammation and significantly increases the risk of duodenal and gastric ulcer disease and distal gastric carcinoma. In this study, we evaluated the Helicobacter pylori vacA and cagA genotypes in patients from a Brazilian region where there is a high prevalence of gastric cancer. Polymerase chain reaction (PCR) was used to investigate vacA mosaicism and cagA status in the gastric mucosa of 134 H. pylori-positive patients, including 76 with gastritis: 28 with peptic ulcer disease and 30 with gastric cancer. The s1m1 variant was the predominant vacA genotype observed, whereas the s1 allele was more frequently observed in patients with more severe diseases associated with H. pylori infection [p = 0.03, odds ratio (OR) = 5.72, 95% confidence interval (CI) = 1.15-38.60]. Furthermore, all of the s1 alleles were s1b. Mixed vacA m1/m2 strains were found more frequently in patients with gastric cancer and a cagA-positive status was significantly associated with gastric cancer (p = 0.016, OR = 10.36, 95% CI = 1.35-217.31). Patients with gastric cancer (21/21, 100%, p = 0.006) or peptic ulcers (20/21, 95%, p = 0.02) were more frequently colonised by more virulent H. pylori strains compared to gastritis patients (41/61, 67.2%). In conclusion, in the northeastern of Brazil, which is one of the regions with the highest prevalence of gastric cancer in the country, infection with the most virulent H. pylori strains, carrying the cagA gene and s1m1 vacA alleles, predominates and is correlated with more severe H. pylori-associated diseases.     

幽门螺杆菌毒力基因型与胃癌的相关性研究

目的:研究中国东部地区幽门螺杆菌(H.pylori)cagA、vacA和iceA1毒力基因型的分布状况及其与胃癌的相关性。方法:从52例病人胃黏膜活检组织(31例慢性浅表性胃炎,21例胃癌)中分离培养H.pylori,用PCR方法扩增分离菌株的cagA、iceA1、vacAs,i,m区毒力基因片段,统计并分析上述毒力因素与胃癌发生的相关性。结果:在52例菌株中,cagA、vacAs1/i1/m1、vacAs1/i1/m2和iceA1的阳性率分别是92.3%(48/52),48.1%(25/52),48.1%(25/52),90.4%(47/52);所有的胃癌分离株中均为cagA(+)vacAs1/i1(+)型,vacAm1、vacAm2和iceA1在胃癌组中的阳性率分别是47.6%(10/21),52.4%(11/21),95.2%(20/21),与胃炎组相比,上述基因型的阳性率差异均无显著统计学意义(P>0.05)。结论:cagA、vacAs1/i1/m1、vacAs1/i1/m2和iceA1是中国东部地区H.pylori的优势基因型;cagA、vacAs1、vacAi1和iceA1毒力基因型的存在与胃癌的发生无相关性。     

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, vacA, babA2 and iceA genes in H. pylori strains isolated from Colombian patients with functional dyspepsia

The clinical outcome of Helicobacter pylori infection has been particularly associated with virulence genotypes. These genotypes are useful as molecular markers in the identification of patients that are infected and at high risk for developing more severe gastric pathologies. Our main objective was to determine the prevalence of virulence genotypes cagA, vacA, iceA and babA2 of H. pylori, in patients with functional dyspepsia who are infected with the bacteria. H. pylori genotypes babA2 and cagA as well as vacA and iceA allelic variants were identified by PCR in 122 isolates resulting from 79 patients with functional dyspepsia. A high prevalence of genes cagA+ (71%), vacAs1am1 (34%), babA2 (57%) and iceA1 (87%) was found. The most frequent combined genotype found were cagA+/vacAs1am1/babA2+/iceA1 and cagA-/vacAs1am1/babA2+/iceA1, regardless of any family history of gastric cancer or MALT lymphoma. The very virulent genotype cagA+/vacAs1am1/babA2+/iceA1 prevailed in the studied patients with functional dyspepsia. Our results provide information about the prevalence of four of the more important virulent factors and constitute new evidence on the prevalence of the most virulent H. pylori genotype in patients with functional dyspepsia.     

兰州地区幽门螺杆菌分离株主要毒力基因的研究

本文首次报道了兰州地区胃病患者幽门螺杆菌分离株主要毒力基因ｕｒｅＡ ｖａｃＡ 和ｃａｇＡ的 ＰＣＲ 检测情况。共获 ４１ 株Ｈｐ 分离株,分别来自于慢性胃炎病人（３２ 株）、胃－十二指肠溃疡病人（７株）和胃癌病人（２ 株）。检测结果表明,４１ 株Ｈｐ 分离株的ｕｒｅＡ,ｖａｃＡ 及ｃａｇＡ 的阳性率分别为１００％ ,１００％ 和９７．６％ ;含有ｕｒｅＡ,ｖａｃＡ 和ｃａｇＡ 基因的Ｈｐ 与人类胃部疾患密切相关,而ｃａｇＡ 基因的存在可能与更加严重的胃部疾病有关。Ｈｐ 毒力基因的检测结果与其它地区Ｈｐ 分离株的检测结果相似。作者建议,对ｕｒｅＡ 基因的ＰＣＲ 检测可以作为鉴定Ｈｐ 的一个指标。     

Conservation and microdiversity of the phospholipase A (pldA) gene of Helicobacter pylori infecting dyspeptics from different countries

Phospholipase activity is important in bacterial pathogenicity and could contribute to the pathogenic role of Helicobacter pylori by degradation of the gastric mucus, and in maintaining long-term colonisation. Our aim was to determine the degree of variation in the phospholipase A gene (pldA) of H. pylori from different geographic locations, and to investigate links between pldA genotype and clinical disease severity, as well as with variation in cagA status and vacA genotypes. PCR-restriction fragment length polymorphism (RFLP) analysis with MboI and HaeIII was used to study 124 isolates from 10 countries that included the two genome-sequenced strains (26695 and J99), as well as Tx30a and NCTC 11637 (type strain). The 925-bp pldA fragment was amplified with a frequency of 90%. The presence of pldA was confirmed in the other strains using an alternative forward primer. Isolates were distinguished by PCR-RFLP analysis with 10 MboI and four HaeIII restriction patterns that combined to give 25 distinct pldA RFLP types. The pldA M2H2 strain genotype was most common (20%) in the UK but similar strains came from several other countries. Microdiversity was evident in pldA sequences of strains representing different RFLP types, and five M2H2 strains each had a distinct pldA sequence type. Intragenic variation was independent of gastric disease severity as well as strain cagA status and vacA genotype, with the exception of eight geographically diverse strains all with the pldA M4H3/cagA+/vacA s1m1 genotype predominantly from peptic ulcer patients. The study indicated a spectrum of genotypic variants and was supportive of a pldA function in H. pylori colonisation and persistence rather than in chronicity of infection.     

Helicobacter pylori and Gastroesophageal Reflux Disease: A Case–Control Study

Background:  Gastric colonization with Helicobacter pylori is a proposed protective factor against gastroesophageal reflux disease (GERD), but little population-based data exist and other data conflict.
Methods:  We conducted a case–control study within the membership of a large integrated health-care system that compared GERD-free subjects with two groups: subjects with a physician-assigned GERD diagnosis and randomly selected members with self-described weekly GERD symptoms. Subjects completed interviews, GERD questionnaires, and antibody testing for H. pylori and its cagA protein.
Results:  Serologic data were available for 301 physician-assigned GERD patients, 81 general membership subjects with GERD symptoms, and 175 general membership subjects without GERD symptoms. Physician-assigned GERD patients were less likely to have H. pylori antibodies than GERD-free member controls (odds ratio (OR) = 0.27, 95% confidence interval (CI) 0.15–0.47); there was also an inverse association between H. pylori and GERD symptom severity (OR = 0.18, 95% CI 0.08–0.41; severe or very severe symptoms) and GERD frequency (OR = 0.18, 95% CI 0.09–0.38; for symptoms at least weekly). The association was stronger among persons with erosive GERD and was similar between H. pylori -positive subjects with and without cagA. There was no association among persons who were cagA positive, but H. pylori negative. Similar findings were found in analyses of the general membership with self-described GERD symptoms.
Conclusions:  H. pylori antibody status was inversely associated with a GERD diagnosis and GERD symptoms compared with a general membership population.     

Prevalence of Helicobacter pylori in Georgian patients with dyspepsia

BACKGROUND: Georgia has showed a high prevalence of peptic ulcer disease (PUD), but the prevalence of Helicobacter pylori in this country is practically unknown. The purpose of this study was to determine the prevalence of H. pylori and specific genotypes in different populations in Georgia. MATERIALS AND METHODS: We studied 62 patients from several hospitals in Tbilisi, Georgia. More than 55% of patients had PUD. We determined H. pylori presence as well as specific genotypes cagA and vacA by polymerase chain reaction. In addition, we studied serum samples from 94 healthy persons to determine H. pylori and CagA prevalence by ELISA. RESULTS: We found a high prevalence of H. pylori and CagA in the healthy population (70.2 and 57.4%, respectively) and a high prevalence of CagA among the H. pylori-positive persons (71.2%). Prevalence increased with age as reported in other countries (p = .05). Among symptomatic persons, we found nearly the same high prevalence of H. pylori (64.5%) as in the asymptomatic population. Furthermore, in symptomatic H. pylori patients, we found 65.0 and 67.5% prevalence of cagA and vacA, respectively. For 33 patients with PUD, 24 patients (72.7%) were H. pylori positive and 66.7% of them were cagA positive. In contrast, among the patients with non-ulcer dyspepsia (NUD), 16 (55.2%) were H. pylori positive and 62.5% of them were colonized with cagA-positive strains. H. pylori and cagA prevalence were not significantly different between PUD and patients with NUD. CONCLUSIONS: We confirmed that among individuals in Georgia, the prevalence of H. pylori is high and cagA-positive strains were equally present among H. pylori-positive patients with PUD and NUD and asymptomatic persons.     

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.     

Helicobacter pylori genotyping and sequencing using paraffin-embedded biopsies from residents of colombian areas with contrasting gastric cancer risks

Background:   cagA -positive and vacA s1 and m1 genotypes of Helicobacter pylori are associated with an elevated risk of gastric cancer (GC). We determined these genotypes using paraffin-embedded gastric biopsy specimens harvested from infected individuals and compared genotype distributions in two Colombian populations residing in geographic regions with a high and low incidence of GC.
Methods:   DNA from paraffin-embedded gastric biopsies from 107 adults was amplified using primers specific for cagA , for the cag 'empty site', for the s and m alleles of vacA , and for H. pylori 16S rRNA.
Results:   H. pylori infection was detected by molecular assays in 97 (90.7%) biopsies. Complete genotyping of cagA and vacA was achieved in 94 (96.9%) cases. The presence of cagA was detected in 78 of 97 cases (80.4%); when considered separately, cagA and vacA s regions were not significantly associated with a particular geographic area. The vacA m1 allele and s1m1 genotypes were more common in the area of high risk for GC ( p =  .037 and p  = .044, respectively), while the vacA m2 allele and s2m2 genotypes were more prevalent in the low-risk area. The prevalence of the combination of cagA -positive, vacA s1m1 genotypes was 84.3% and 60.5% for high and low risk areas, respectively ( p =  .011).
Conclusions:  H. pylori cagA and vacA genotyping from paraffin-embedded gastric biopsies permitted reliable typability and discrimination. The more virulent cagA- positive s1m1 strains, as well as vacA m1 genotype, were more prevalent in high risk than in low risk areas, which may contribute to the difference in GC risk between those two regions.     

A model of Helicobacter pylori persistence in a case of gastric cancer

The aim of this work was to analyze several clones of Helicobacter pylori isolated from a patient with gastric cancer, to evaluate i) genetic variability ii) virulence factors profile and iii) antimicrobial susceptibility against the drugs commonly used in the H. pylori therapy. A total of 32 H. pylori clones isolated from a biopsy sample coming from a patient with gastric cancer previously treated for H. pylori infection, were analyzed for: the genetic variability by amplified fragment polymorphism analysis; the vacA, cagA virulence status by PCR; the antimicrobial susceptibility by minimum inhibitory concentrations with the agar dilution method towards amoxicillin, clarithromycin, levofloxacin and tinidazole. The patient showed a mixed infection with the presence of at least 3 different strains. The clones isolated possessed the vacA, cagA virulence factors with a different allelic combination (vacA s1/i1/m1; s1/i1i2/m1; s2/i2/m2; s2/i1i2/m2) together with repeated cagA EPIYA motif pattern P1P2P3P3P3. Moreover, a pattern of multi-drug resistance was disclosed in the different clones. The presence of multiple H. pylori strains colonizing the same patient, with the main virulence factors displaying a different allelic combination and a different multi-drug resistance among isolates, point out the role of genetic variability generating, in time, more virulent and adapted strains.     

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.     

Distinctiveness of genotypes of Helicobacter pylori in Calcutta, India

The genotypes of 78 strains of Helicobacter pylori from Calcutta, India (55 from ulcer patients and 23 from more-benign infections), were studied, with a focus on putative virulence genes and neutral DNA markers that were likely to be phylogenetically informative. PCR tests indicated that 80 to 90% of Calcutta strains carried the cag pathogenicity island (PAI) and potentially toxigenic vacAs1 alleles of the vacuolating cytotoxin gene (vacA), independent of disease status. This was higher than in the West (where cag PAI(+) vacAs1 genotypes are disease associated) but lower than in east Asia. The iceA2 gene was weakly disease associated in Calcutta, whereas in the West the alternative but unrelated iceA1 gene at the same locus is weakly disease associated. DNA sequence motifs of vacAm1 (middle region) alleles formed a cluster that was distinct from those of east Asia and the West, whereas the cagA sequences of Calcutta and Western strains were closely related. An internal deletion found in 20% of Calcutta iceA1 genes was not seen in any of approximately 200 strains studied from other geographic regions and thus seemed to be unique to this H. pylori population. Two mobile DNAs that were rare in east Asian strains were also common in Calcutta. About 90% of Calcutta strains were metronidazole resistant. These findings support the idea that H. pylori gene pools differ regionally and emphasize the potential importance of studies of Indian and other non-Western H. pylori populations in developing a global understanding of this gastric pathogen and associated disease.     

Clinical and pathological importance of vacA allele heterogeneity and cagA status in peptic ulcer disease in patients from North Brazil

We have examined the prevalence of gene cagA and vacA alleles in 129 patients, 69 with gastritis and 60 with peptic ulcer diseases from North Brazil and their relation with histopathological data. vacA and cagA genotype were determined by polymerase chain reaction. Hematoxylin-eosin staining was used for histological diagnosis. 96.6% of the patients were colonized by Helicobacter pylori strains harboring single vacA genotype (nont-mixed infection). Among them, 11.8% had subtype s1a, 67.8% had subtype s1b, and 17% subtype s2. In regard to the middle region analysis, m1 alleles were found in 75.4% and m2 in 21.2% of patients. The cagA gene was detected in 78% patients infected with H. pylori and was associated with the s1-m1 vacA genotype. The H. pylori strains, vacA s1b m1/cagA-positive, were associated with increased risk of peptic ulcer disease and higher amounts of lymphocytic and neutrophilic infiltrates and the presence of intestinal metaplasia. These findings show that cagA and vacA genotyping may have clinical relevance in Brazil.     

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.     

Characteristics of Helicobacter pylori-induced gastritis and the effect of H. pylori eradication in patients with chronic idiopathic thrombocytopenic purpura

BACKGROUND: The association between Helicobacter pylori infection and idiopathic thrombocytopenic purpura (ITP) has been reported widely. We investigated the prevalence of H. pylori infection, its virulence profile and the effectiveness of its eradication in patients with ITP. MATERIALS AND METHODS: Twenty patients with ITP, 20 with peptic ulcer (10 gastric ulcer (GU), 10 duodenal ulcer (DU)) and 20 with NUD were studied. The virulence profile of the strains was assessed by genotyping for cagA, vacA, iceA, and hpyIIIR/hrgA and by assaying for IL-8 and DNA fragmentation after incubation with AGS cells. Infected patients and two uninfected ITP patients received triple therapy and platelets were counted before and 1 month, 6 months, 1 year, and 2 years after eradication therapy. RESULTS: H. pylori infection was found in 17 ITP (85%), 20 ulcer (100%) and 13 NUD (65%) patients. Biopsies and strains were collected from five ITP, 20 ulcer and 13 NUD patients. The ITP patients had a pangastritis or corpus-predominant gastritis pattern. All H. pylori isolates, from ITP, ulcer and NUD patients, were cagA(+) and vacA s1/m1, and did not differ in levels of IL-8 induction or DNA fragmentation. Fifteen ITP (88%) and 17 ulcer (85%) patients had successful eradication of H. pylori. Ten of these 15 (67%) H. pylori-eradicated ITP patients had platelet recovery. There was no significant change in platelet count in the two ITP patients in whom eradication failed or in the two originally H. pylori-uninfected ITP patients, or in the treated ulcer patients. Age at onset of ITP was the main determinant of platelet recovery: 100% of patients diagnosed after the age of 60 recovered compared with only 22% of those diagnosed before 50. CONCLUSIONS: H. pylori-infected ITP patients have a corpus-predominant pattern of gastritis but the virulence profile of their strains does not differ from that of ulcer or NUD patients. Eradication of H. pylori infection is a good therapeutic option for some patients with chronic ITP, especially for those who develop ITP in older age.     

HIV protease inhibitors attenuate adherence of Candida albicans to epithelial cells in vitro

The cagA gene is a key marker for the Helicobacter pylori cag pathogenicity island (PAI), which may vary in composition in different strains with insertion sequence mediated interruptions and deletions of genes. While presence of cagA has been associated with increased risk for peptic ulcer disease and gastric cancer, the precise link with virulence is controversial. We investigated H. pylori from dyspeptics in one location in England (mid-Essex) with reference to the prevalence and distribution by age cohort of different cag PAI forms to determine if presence of the insertion element IS605 had a modifying effect on the severity of associated disease. H. pylori isolated from gastric biopsies over a 4-year period were screened by specific PCR assays for the presence of cagA, cagD, cagE and virD4 genes in the cag PAI, and for the presence of IS605 in the PAI and elsewhere in the genome. Most (68%) of the 166 isolates of H. pylori contained a PAI based on detection of cagA whereas 29% had no detectable PAI using multiple loci. The cagA+ genotype frequencies were similar in the peptic ulcer and non-ulcer dyspepsia-gastritis groups (79% vs. 74%) whereas frequencies in the NUD-oesophagitis and normal mucosa groups were lower (58%) but not significantly different (P>0.41). Genomic IS605 inserts were present at an overall frequency of 32% and were widely distributed with respect to patient age and disease severity. The combined cagA+/IS- strain genotype was common but not significantly associated with PUD compared to endoscopically normal mucosa (P> or =0.807). We concluded that presence of the IS605 element, whether in cagA+ or cagA- strains of H. pylori, did not systematically modify the severity of associated disease in the study population.     

淮南地区幽门螺杆菌感染个体菌株基因多态性与感染结局的影响

目的:探讨淮南地区幽门螺杆菌感染个体菌株基因多态性及其与感染结局的影响。方法:选取125例幽门螺杆菌(H.pylori,HP)感染的慢性胃炎、消化性溃疡患者,常规获取胃窦、胃体部粘膜,进行HP分离、培养,提取HP基因组DNA,采用随机扩增多态性DNA(RAPD)指纹分析法检测菌株基因多态性;125例患者均给予质子泵抑制、H2受体拮抗剂、铋剂为基础的三联或四联疗法治疗,治疗后4~6周进行14C-尿素呼气试验评估Hp根除情况;获取HP根除失败患者的胃窦、胃体黏膜进行HP分离、培养、鉴定,并采用RAPD指纹分析法检测菌株来源,评估HP基因多态性对治疗结局的影响。结果:cagA、iceA1、iceA2、vacAs1、vacAm1、babA2阳性率分别为92.80%、36.00%、93.60%、93.60%、29.50%、53.50%,cagA、iceA2、vacAs阳性率均高于其他基因类型阳性率(P0.05或P0.01),其他基因类型阳性率比较差异无统计学意义(P0.05)。经治疗后HP根除率为86.4%(107/125),14.4%(18/125)根除失败;18例根除失败患者中,15例患者治疗前后的菌株具有相同的指纹图谱,证实为原菌株复发,其中cagA、iceA1、iceA2、vacAs1、vacAm1、babA2阳性率分别为93.33%、13.33%、86.67%、93.33%、6.67%、20.00%,cagA、iceA2、vacAs阳性率均高于其他基因类型阳性率(P0.05或P0.01)。结论:cagA+、vacAs+、iceA2+为淮南地区HP感染的优势基因型,该基因型易导致HP根除失败;未发现babA2与HP感染结局存在相关性。     

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.     

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.