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.     

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.     

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.     

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.     

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.     

Comparative Analysis of Different Typing Methods for Helicobacter pylori Clinical Isolates

The goal of the present work was to compare different techniques of molecular typing using as an example clinical isolates of Helicobacter pylori obtained from patients in different regions of Russia. DNA-macroarray genome scanning using individual genes was employed to set up our basic classification of isolates that did or did not contain pathogenicity islands. In parallel, DNA of the same isolates was used in the conventional random amplified polymorphic DNA (RAPD) PCR analysis, and the isolates were also genotyped (cagA, vacA, iceA, and babA status) and their proteomic maps were obtained by means of unidimensional SDS polyacrylamide gel electrophoresis (1D-SDS-PAGE) coupled with identification using peptide mass fingerprinting by MALDI-TOF mass spectrometry. A statistically significant correlation (coefficient of correlation r = 0.25, p = 0.005) was observed between the results of genome scanning and 1D-SDS-PAGE. No correlation was found between RAPD-PCR typing and genome scanning.     

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。     

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.     

A simple multiplex PCR assay for diagnosing virulent Helicobacter pylori infection in human gastric biopsy specimens from subjects with gastric carcinoma and other gastro-duodenal diseases

AIM: To evaluate and develop a multiplex polymerase chain reaction (PCR) assay for diagnosing and specific identification of virulent Helicobacter pylori strains and their main virulence genes cagA, cagE, cagT, vacA and hrgA. METHODS AND RESULTS: Genomic DNA from 82 gastric tissues was screened. A master pool of all the ingredients of multiplex reaction was prepared for amplification. Amplicons were sequenced to confirm the amplification of each target genes. Multiplex PCR assay was able to detect all the five target genes in 81.7% and deletions in one or more loci among 18.3%. Genotype cagT +ve/hrgA +ve/cagA +ve/cagE +ve/vacAs1 +ve was more predominant in this study population (67.07%). hrgA, cagT, cagE and cagA genes were present in 100%, 92.7%, 85.4% and 81.7% of the subjects, respectively. The vacAs1 subtype had higher prevalence frequency in patients with overt gastrointestinal disease (78.57%) than with GERD (gastro-esophageal reflux disease) and NUD (non-ulcer dispepsia) (50%). CONCLUSIONS: The multiplex PCR assay developed herein was able to genotype H. pylori isolates based on the main virulence genes. SIGNIFICANCE AND IMPACT OF THE STUDY: The ability to identify H. pylori and the majority of their virulence gene markers by multiplex PCR assay represents a considerable advancement over other PCR-based methods for genotyping H. pylori from large population, and can be explored to gain insights at the genotypic variability exhibited by this pathogen.     

Investigation of the biological relevance of Helicobacter pylori cagE locus diversity,presence of CagA tyrosine phosphorylation motifs and vacuolating cytotoxin genotype on IL-8 induction in gastric epithelial cells

Isolates of Helicobacter pylori from dyspeptic patients in England and South Africa were tested for ability to induce interleukin-8 (IL-8) in gastric cells. All isolates were cagA-positive, which was used as a marker for the presence of the cag pathogenicity island. The aims were to determine if activities were related to diversity within cagE (HP0544), a locus encoding a key component in the Type IV secretion system, and if disease severity might be linked to a combination of strain features. We found that isolates were heterogeneous in ability to induce IL-8 activity with the 23 positive isolates (59%) showing activities ranging from 260 to 3200 pg ml(-1). The cagE locus was detected in most isolates and RFLP analysis of a 1.52-kb internal fragment showed interstrain diversity with 12 combined (MboI/NlaIII) types. Most cagE genotypes were not associated with IL-8 induction, however two genotypes were found only in IL-8-inducing strains and one genotype was associated with lack of IL-8 induction. IL-8 activity was not associated with either the number or composition of cagA tyrosine phosphorylation motifs and vacA m-type. Although we found a weak association between cagE type and the ability to induce IL-8, our results imply that gastric cell factors or bacterial factors other than vacA, cagA and cagE are involved in the induction of IL-8 and the development of severe gastric disease.     

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.     

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.     

Helicobacter pylori induces apoptosis of rat gastric parietal cells

Gastric Helicobacter pylori infection may lead to multifocal atrophic corpus gastritis associated with loss of epithelial cells as well as glandular structures. The current work investigated H. pylori effects on cell death of isolated, nontransformed rat parietal cells (PC). Highly enriched rat PC (>97%) were isolated from gastric mucosa and cultured in serum-free medium over 24 h. The cells were cocultured over 8 h with cytotoxin-associated immunodominant protein (cagA)(+)/vacuolating toxin (vacA)(+) or with cagA(-)/vacA(-) H. pylori laboratory strains and also with H. pylori mutants deleted in several genes of the cag pathogenicity island. Staphylococcus aureus or Campylobacter jejuni were used as controls. Apoptosis was determined by terminal deoxynucleotidyl transferase dUTP nick-end labeling staining and electron microscopy. Interleukin (IL)-8 and cytokine-induced neutrophil chemoattractant (CINC)-1 secretion was measured by ELISA. Activation of nuclear factor-kappaB (NF-kappaB) was studied in nuclear extracts of PC by electrophoretic mobility shift assay. Apoptosis of PC was induced in a concentration- and time-dependent manner by cagA(+)/vacA(+) H. pylori strains but not by cagA(-)/vacA(-) negative strains or by the cagE knockout mutant. S. aureus and C. jejuni had no effect. PC showed no IL-8 or CINC-1 secretion on exposure to cagA(+)/vacA(+) H. pylori. cagA(+)/vacA(+) strains induced activation of NF-kappaB complexes in nuclear extracts of PC, which were composed of p65 and p50 subunits. No significant stimulation of NF-kappaB activation was detected by incubation of PC with the cagE knockout mutant. Preincubation of PC with antisense but not missense oligodeoxynucleotides against the p65 subunit significantly reduced DNA binding to the kappaB recognition sequence. The p65 oligonucleotides as well as the proteasome inhibitor N-CBZ-isoleucin-glutamin-(o-t-butyl-)-alanin-leucin and the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine completely prevented PC apoptosis induced by cagA(+)/vacA(+) strains. In summary, cagE presence appears to be essential for H. pylori-induced apoptosis of gastric parietal cells, and this effect is dependent on the activation of NF-kappaB and production of nitric oxide.     

CagA and VacA: Virulence Factors of Helicobacter pylori in Thai patients with Gastroduodenal Diseases

Background. The aim of this study was to assess the seroprevalence of cytotoxin-associated gene A ( cag A) and vacuolating cytotoxin gene A ( vac A) of Helicobacter pylori in selected Thai populations with specific gastroduodenal diseases.
Materials and Methods. The immunoblot assay was used to detect serum antibodies against CagA and VacA obtained from the following patients: 87 cases of nonulcer dyspepsia (NUD), 61 cases of duodenal ulcer (DU), 49 cases of gastric ulcer (GU), and 10 cases of gastric cancer (GC).
Results. Serum antibodies to CagA were detected in 75.4% of all patients (70.1% of NUD, 78.7% of DU, 77.6% of GU, and 90% of GC). Although the prevalence of CagA seropositivity in GC patients was higher than in the other three groups, the difference was not statistically significant ( p > .05).
Conclusions. The high seroprevalence of the CagA-positive H. pylori strain in patients with peptic ulcer, GC, and NUD indicates that this strain is common in Thai patients with gastroduodenal diseases. Furthermore, phenotypic classification of H. pylori into type 1 (CagA-positive, VacA-positive) and type 2 (CagA-negative, VacA-negative) is not a useful marker for screening patients with severe forms of gastroduodenal diseases.     

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.     

Correlation of the Helicobacter pylori adherence factor BabA with duodenal ulcer disease in four European countries

Helicobacter pylori strains harboring the vacAs1, cagA and babA2 have been associated with ulcer disease (UD). We compared the prevalence of these different genotypes and adhesive properties in H. pylori infected patients with UD in four European countries. Genomic DNA was isolated from 314 H. pylori strains: Germany (GER; n=92), Sweden (SWE, n=74), Portugal (POR, n=91) and Finland (FIN, n=57). The frequencies of babA2 genotype varied from 35% to 60%. Triple-positive strains (vacAs1+, cagA+ and babA2+) were significantly associated with UD in GER and POR and were closely correlated with UD in FIN, but not in SWE. Classification as triple-positive strains had a higher specificity for detection of UD in GER, POR and FIN than type1 or cagA+ strains. In vitro adhesion assays revealed that Swedish strains showed high adhesion properties and were thus correlated with the diagnosis of UD, although PCR detected the babA2 gene at lower frequencies and failed to show a correlation with UD. This finding appears to reflect allelic variations of the babA2 gene in SWE, although adhesive properties of the strains are retained.     

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。     

Genotypic,phenotypic, and clinical characteristics of isolates of<Emphasis Type="Italic">Helicobacter pylori</Emphasis> from San Luis,Argentina

The vacA and cagA genotypes of Helicobacter pylori exhibited distinct geographic distribution and correlation with severity of disease. In the above genotypes (obtained from 150 H. pylori-positive patients--139 with gastritis, 10 with ulcer and 1 patient with gastric cancer) combinations vacA s1/m1 and s2/m2 were detected using PCR in 75 and 25% of isolates, respectively, in patients with chronic gastritis. The of s1/m1 and s2/m2 combinations were also detected from ulcers (60 and 40%, respectively). The cagA was detected in 30% of isolates. Concentrated culture supernatants of 7 (64%) out of 11 H. pylori strains induced vacuolization in Vero cells in titers ranging from 1:5 to 1:40. The vacA s1 genotype was significantly associated with, but not predictive of the presence of vacuolating cytotoxin activity and the cagA gene.     

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.     

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.