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

Prevalence of cagA, cagM, vacA and oipA genes in isolates of Helicobacter pylori obtained from hospital patients in Northeast Brazil

Helicobacter pylori is a major cause of gastrointestinal disorders such as chronic gastritis, peptic ulcers, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric cancer. It is estimated that around half of the world's population is infected with this pathogen, with underdeveloped countries reporting the highest frequencies. The genes cagA, cagM, vacA, and oipA are some of the most important virulence factors of H. pylori; however, there are no recent studies from Recife-PE demonstrating their frequency, and their relationship with severe gastric modifications. This work aims to use qualitative PCR to detect the virulence genes cagA, cagM, vacA, and oipA in H. pylori isolates obtained from patients in a public hospital in Recife (PE). We collected samples from the stomach's body and antrum of 147 patients, from which 71 (48%) tested positive for H. pylori. Among positive samples, the most frequently infected gender was female (44/71, 62%), and the most frequently infected age group was those above the age of 46 (31/71, 44%). Histological examination of H. pylori-positive samples revealed alterations other than chronic gastritis, including metaplasia and atrophy. The frequency of cagA, cagM, and oipA genes were identified in 84%, 56%, and 69% of the samples tested, respectively, as well as the vacA-s1m1 allelic combination (77%). However, there was no statistically significant variation in the occurrence of these genes, therefore they cannot be considered unique markers of severity in our setting. New research with larger samples and investigations of other genetic markers can aid uncover local risk factors and lead to a better understanding of H. pylori's pathogenesis.

Relationship between Helicobacter pylori virulence genes and gastroduodenal disease

OBJECTIVE

This study aimed to identify Helicobacter pylori virulence factors and examine their associations with clinical outcomes in Thai patients. Moreover, the association between these genotypes and gastric mucosa morphological patterns was investigated.

METHODS

This retrospective study enrolled patients who underwent esophagogastroduodenoscopy at Suranaree University of Technology Hospital. The presence of the cagA and vacA genes was investigated by real-time polymerase chain reaction.

RESULTS

The H. pylori-specific genes ureA and 16S rRNA were detected in all 698 gastric biopsy specimens. In total, 567 (81.23%) patients with H. pylori infection were positive for the cagA gene, 443 (63.46%) were positive for the vacA gene, and 370 (53.0%) were positive for both. The cagA genotype was significantly more common in patients with chronic gastritis and peptic ulcers (78.99% and 79.41%, respectively) than the vacA gene (51.48% and 55.88%, respectively) and combined genotypes (32.34% and 47.05%, respectively). Moreover, the cagA genotype was significantly more common in patients with type 4 or 5 gastric mucosa patterns (69.49% and 76.31%, respectively).

CONCLUSIONS

The cagA genotype is the main cause of serious inflammation of the gastric mucosa. The cagA gene is possibly an important factor explaining gastroduodenal disease outcomes in Thai patients with H. pylori infection.

Virulence determinants and genotypes of <i>Helicobacter pylori</i> clinical isolates

Background. H. pylori is the principal causative agent of gastroduodenal disorders in humans. The development and severity of lesions in infected individuals depend on the virulence of H. pylori strains. Aims: Detection of virulence determinants and comparative analysis of H. pylori genotypes in patients with chronic gastritis (CG) and duodenal ulcer (DU). Materials and methods. The 53 H. pylori strains were isolated in St. Petersburg from patients with CG (n = 34) and DU (n = 19). The genetic determinants of virulence cagA, iceA, vacA and H. pylori genotypes in patients with CG and UC were determined using the standard PCR method. Results. The cagA gene was found in 64.1% of H. pylori strains. The proportions of cagA+ isolates from patients with CG and DU was 55.8% (15/34) and 78.9% (15/19), respectively (p 0.05). The iceA1 allele of H. pylori was detected in 47.4% of patients with DU, the iceA2 in 47.1% of patients with CG (p 0.05). The vacAs1 allele was significantly dominant in patients with DU 94.7% versus 70.6% in CG (p 0.05). No significant difference in vacA m1 and m2 alleles was found in H. pylori from different groups of patients (p 0.05). All cagA+ strains were carriers of the vacA s1 allele. The vast majority of strains (10 out of 11) of the cagA/vacAs2 genotype were isolated from patients with CG. Conclusion. The significant association between vacAs1, vacAs2 allelic variants, as well as vacA s1/m2, vacA s2/m2 genotypes of the pathogen and severity of clinical manifestations of H. pylori infection has been established in our study. The vacAs1 and vacA s1/m2 genotypes of the pathogen are associated with duodenal ulcer.

Success of 14-day triple and quadruple therapy for the control of Helicobacter pylori infections in Kohat district

Introduction:

Helicobacter pylori is an important medical pathogen present in more than half of the world’s population. Various treatment regimen are in use for the eradication of H. pylori, but due to the emergence of antibiotic resistance, its management is a big issue for clinicians.

Methods:

In this study all suspected cases that had visited District Headquarters Hospital Kohat were considered for screening of H. pylori infections. Preliminary information about their age, gender, general health conditions, occupation, etc. was taken for consideration. After recording initial signs and symptoms, samples were considered for H. pylori detection using stool antigen test and endoscopy. Fourteen-day proton pump inhibitor base triple and quadruple therapy were administered to each patient.

Results:

In total (n = 178), there were high numbers of positivity in patients aged below 30 years (82; 46.06%), most of whom belonged to rural areas.

Conclusion:

This study concludes that there were high numbers of positive patients aged below 30 years, and according to this study MEL (Metronidazole + Esomeprazole + Levofloxacin) is the most effective treatment regimen for the eradication of H. pylori.

Prevalence of Helicobacter pylori vacA, cagA, cagE, oipA, iceA, babA2 and babB genotypes in Iranian dyspeptic patients

There is diversity in clinical outcome of Helicobacter pylori infection in different regions. Microbial, host and environmental factors seem to be reason of such variation. Considering microbial factors, we studied H. pylori genotypes and their association with clinical feature of the infection. Overall 160 H. pylori-positive patients were enrolled in this study. Clinical information and biopsy were collected from each patient. The presence of the major virulence genes were determined by PCR. Regardless to clinical outcomes, vacA, cagA, cagE, oipA, iceA1, babA2 and babB genes was positive in 100%, 69%, 51%, 55%, 26%,78% and 28% of 160 strains respectively. The s1m2 was more common vacA allels and s1a and m1a were predominant s and m regions. In patient with gastric cancer (GC), the oipA was less frequent while the iceA1 was the most common. The babA2 was common in all patient groups. The babB was significantly observed in strains isolated from patients with GC. There were significant association among cagA status with presence of vacAs1, vacAm2, cagE, oipA, iceA1 and babA2. Presence of the babB and oipA was connected with higher and lower risk for GC respectively. There was no association between the cagA, vacA, cagE or iceA status and clinical outcome in patients in Iran. We showed that presence of the babB and iceA1 were significantly connected with higher risk for gastric cancer development in Iranian dyspeptic patients while H. pylori isolates with positive oipA had little threat for leading patients to cancer.

Role of Plasticity Region Genes and cagE gene of cagPAI of Helicobacter pylori in Development of Gastrointestinal (GI) Diseases

Backround::

Helicobacter pylori is a Gram-negative, micro aerophilic bacterium in the human stomach that is associated with the development of gastrointestinal ailments such as peptic ulcer (PU) and gastric cancer (GC). In the present study, plasticity region genes (jhp0940, jhp0945 and jhp0947) and and cagE gene of cag PAI were assessed independently and in combination for their ability to predict clinical consequences.

Materials and Methods::

A total of 211 strains which were isolated from patients with different gastrointestinal diseases (114 with non-atrophic gastritis, 59 with PU, and 38 with GC) were genotyped by PCR and sequencing. Data were collected and analyzed using SPSS software version 19. Logistic regression models were applied to determine relationships between the plasticity region genes and cagE of H.pylori and clinical status.

Results::

The cagE gene (71.1%) had the highest frequency and jhp0945 (13.7%) was the least abundant among the genes examined. The jhp0940 gene was significantly associated with GC (P = 0.0007), but not PU. On multiple logistic regression analysis, adjusted for both age and sex, the jhp0940 genotype was significantly associated with GC (odds ratio, OR = 2.8, 95%CI = 1.1–7.0; P = 0.027). The jhp0940+/ jhp0945+/jhp0947+ genotype was also linked to an increased risk of GC (OR = 50.4, 95%CI = 5.1–500.0; P = 0.0008) while no genotype correlation was found with PU in Iran (P > 0.05).

Conclusions::

Given the high frequency of cagE, this gene could be a suitable marker for the presence of cag PAI in Iranian strains. The jhp0940 genotype could also be a strong predictor of GC in Iran.

HELICOBACTER PYLORI INFECTION IN PATIENTS WITH DIFFERENT GASTROINTESTINAL DISEASES FROM NORTHERN BRAZIL

BACKGROUND

The mechanisms whereby Helicobacter pylori produces different pathological manifestations in the stomach and duodenum are not fully understood. Considering the geographic diversity in the prevalence of virulence factors of this microorganism and their association with the development of different diseases, the search for pathogenicity markers such as CagA and VacA alleles by molecular techniques has intensified.

OBJECTIVES

To investigate the presence of H. pylori infection and the frequency of different genotypes of this bacterium in patients with gastrointestinal diseases from Northern Brazil, and to establish their association with the histopathological findings.

METHODS

In a prospective study, samples were collected from 554 patients with different gastrointestinal diseases (gastritis, duodenal ulcer, gastric ulcer, and gastric cancer) seen at a referral hospital attending the entire State of Pará, located in the metropolitan region of Belém. Data such as gender and age obtained with an epidemiological questionnaire were analyzed. The presence of H. pylori and the bacterial genotype were investigated by PCR. Gastric biopsies were assessed histologically.

RESULTS

The prevalence of H. pylori infection was 91%. Infection was more frequent among patients with gastric ulcer and gastric cancer. In these groups, there was a predominance of men and older patients when compared to the other two groups studied. The predominant bacterial genotype was s1m1cagA+, which was more frequent among patients with gastric ulcer, duodenal ulcer and gastric cancer. A significant association was observed between s1m1cagA+ strains and a higher degree of inflammation, neutrophil activity and development of intestinal metaplasia.

CONCLUSION

The present study demonstrates a high incidence of H. pylori infection in the patients analyzed, especially among those with gastric ulcer and gastric cancer. Virulent s1m1cagA+ strains predominated and were associated with more severe lesions.

Relationship between ureB Sequence Diversity, Urease Activity and Genotypic Variations of Different Helicobacter pylori Strains in Patients with Gastric Disorders

Association of the severity of Helicobacter pylori induced diseases with virulence entity of the colonized strains was proven in some studies. Urease has been demonstrated as a potent virulence factor for H. pylori. The main aim of this study was investigation of the relationships of ureB sequence diversity, urease activity and virulence genotypes of different H. pylori strains with histopathological changes of gastric tissue in infected patients suffering from different gastric disorders. Analysis of the virulence genotypes in the isolated strains indicated significant associations between the presence of severe active gastritis and cagA+ (P = 0.039) or cagA/iceA1 genotypes (P = 0.026), and intestinal metaplasia and vacA m1 (P = 0.008) or vacA s1/m2 (P = 0.001) genotypes. Our results showed a 2.4-fold increased risk of peptic ulcer (95% CI: 0.483-11.93), compared with gastritis, in the infected patients who had dupA positive strains; however this association was not statistically significant. The results of urease activity showed a significant mean difference between the isolated strains from patients with PUD and NUD (P = 0.034). This activity was relatively higher among patients with intestinal metaplasia. Also a significant associa-tion was found between the lack of cagA and increased urease activity among the isolated strains (P = 0.036). While the greatest sequencevariation of ureB was detected in a strain from a patient with intestinal metaplasia, the sole determined amino acid change in UreB sequence (Ala201Thr, 30%), showed no influence on urease activity. In conclusion, the supposed role of H. pylori urease to form peptic ulcer and advancing of intestinal metaplasia was postulated in this study. Higher urease activity in the colonizing H. pylori strains that present specific virulence factors was indicated as a risk factor for promotion of histopathological changes of gastric tissue that advance gastric malignancy.

Helicobacter pylori CagA and VacA genotypes and gastric phenotype: a meta-analysis

BACKGROUND

CagA+ and vacuolizing cytotoxin (VacA)-specific strains of Helicobacter pylori have been associated with different risks for developing gastric lesions. We aim to summarize a possible association between these genotypes and the risk for developing different gastric phenotypes.

MATERIALS AND METHODS

A MEDLINE database (PubMed) search was performed and a meta-analysis conducted.

RESULTS

Forty-four studies were retrieved, all with either a case-control (n=13) or cross-sectional (n=31) design, including 17 374 patients. CagA positivity was associated with an increased risk for gastric cancer [odds ratio (OR) 2.09 (95% confidence interval (CI), 1.48-2.94)] compared with that in individuals without gastric lesions [OR 2.44 (95% CI 1.27-4.70)] and in those with previously identified gastritis. In addition, there was an increased risk for peptic ulcer disease [OR 1.69 (95% CI 1.12-2.55)]. Individuals harboring the H. pylori strains VacA s1 (vs. s2), m1 (vs. m2), s1m1 (vs. s1m2), and s1m1 (vs. s2m2) had an increased risk for development of cancer [OR of 5.32 (95% CI 2.76-10.26), 2.50 (95% CI 1.67-3.750), 2.58 (95% CI 1.24-5.38), and 4.36 (95% CI 2.08-9.10), respectively]. s1m1 strains (vs. s2m2) were also associated with peptic ulcer disease [OR 2.04 (1.01-4.13)].

CONCLUSION

Our results indicate that individuals infected with CagA+ H. pylori strains and those infected with VacA s1 and m1 strains have an increased risk for gastric cancer. Cohort studies are welcome to integrate this information in the management of at-risk individuals such as those with precancerous cancer conditions and/or a family history of gastric cancer.

ROLE OF HELICOBACTER PYLORI INFECTION AND LIFESTYLE HABITS IN THE DEVELOPMENT OF GASTRODUODENAL DISEASES IN A POPULATION FROM THE BRAZILIAN AMAZON

Context Although more than half of the world's population is colonized with Helicobacter pylori, it remains unknown why this organism is able to produce severe disease in some hosts and be innocuous in others. The clinical outcome of infection is determined by several factors, including differences in the host response to bacterial stimulation, specific virulence factors of the organism and environmental influences, or a combination of these factors. Objectives This study compared the prevalence of H. pylori infection and risk factors (infection with CagA+ strains, excessive alcohol consumption, smoking, and inadequate eating habits) between patients with different gastrointestinal disorders and associated these risk factors with the histopathological findings. Methods In a prospective study, samples were collected from 442 patients and a standardized questionnaire regarding lifestyle habits (excessive alcohol consumption, smoking, and eating habits) was applied. The presence of H. pylori and of the cagA gene was investigated by polymerase chain reaction (PCR). Gastric biopsies were obtained for histological assessment. Results The frequency of alcohol consumption, smoking, inadequate diet and infection with CagA+ H. pylori was higher among patients with peptic ulcer and adenocarcinoma when compared to those with gastritis. Gastric inflammation was more pronounced in patients infected with CagA+ strains. Conclusion We conclude that infection with CagA+ H. pylori strains, excessive alcohol consumption, smoking and inadequate eating habits increase the risk of developing peptic ulcer and gastric carcinoma.

Prevalence of genotypes in Helicobacter pyloriisolates from patients in eastern Turkey and the association of these genotypes with clinical outcome

There is not much information available regarding the prevalence of the genotypes of Helicobacter pylori isolates in Turkey, particularly in eastern Turkey. The aims of this study were to detect the prevalence of different genotypes of H. pylori in Turkish patients with gastrointestinal complaints and to determine the relationship of these genotypes with clinical outcome and sex. One hundred forty H. pylori isolates were examined for the presence of its genotypes by the PCR. We found that the prevalence of vacAs1,vacAs2, cagA, cagE, iceA1, iceA2 and babA2 genes were 88.6%, 11.4%, 71.4%, 35.7%, 41.4%, 58.6%, and 62.1%, respectively. The most predominant vacA subtype was s1a (81.4%). The most vacA allelic combination detected were vacAs1m1 (65.2%) and s1m2 (53.9%) in patients with peptic ulcer and gastritis, respectively. The only vacAs1 isolate was significantly associated with gastritis and peptic ulcer (p<0.05). The vacAs1a, ml, slml and babA2 genes were significantly associated with peptic ulcer (p<0.05), whereas m2 gene was significantly associated with only gastritis (p<0.05). The difference between sex and genotypes was statistically significant among the cagA,vacAs1, iceA2 and babA2 genes. This study reported for the first time the prevalence of H. pylori genotypes in patients with gastrointestinal complaints in eastern Turkey. Further studies are needed to understand epidemiological importance of the genotypes of H. pylori isolates in this region and the association between the virulence genes and clinical outcome in different regions.

Prevalence of genotypes in Helicobacter pyloriisolates from patients in eastern Turkey and the association of these genotypes with clinical outcome

There is not much information available regarding the prevalence of the genotypes of Helicobacter pylori isolates in Turkey, particularly in eastern Turkey. The aims of this study were to detect the prevalence of different genotypes of H. pylori in Turkish patients with gastrointestinal complaints and to determine the relationship of these genotypes with clinical outcome and sex. One hundred forty H. pylori isolates were examined for the presence of its genotypes by the PCR. We found that the prevalence of vacAs1,vacAs2, cagA, cagE, iceA1, iceA2 and babA2 genes were 88.6%, 11.4%, 71.4%, 35.7%, 41.4%, 58.6%, and 62.1%, respectively. The most predominant vacA subtype was s1a (81.4%). The most vacA allelic combination detected were vacAs1m1 (65.2%) and s1m2 (53.9%) in patients with peptic ulcer and gastritis, respectively. The only vacAs1 isolate was significantly associated with gastritis and peptic ulcer (p<0.05). The vacAs1a, ml, slml and babA2 genes were significantly associated with peptic ulcer (p<0.05), whereas m2 gene was significantly associated with only gastritis (p<0.05). The difference between sex and genotypes was statistically significant among the cagA,vacAs1, iceA2 and babA2 genes. This study reported for the first time the prevalence of H. pylori genotypes in patients with gastrointestinal complaints in eastern Turkey. Further studies are needed to understand epidemiological importance of the genotypes of H. pylori isolates in this region and the association between the virulence genes and clinical outcome in different regions.

Helicobacter pylori iceA, clinical outcomes, and correlation with cagA: a meta-analysis

Background

Although the iceA (induced by contact with epithelium) allelic types of Helicobacter pylori have been reported to be associated with peptic ulcer, the importance of iceA on clinical outcomes based on subsequent studies is controversial. The aim of this study was to estimate the magnitude of the risk for clinical outcomes associated with iceA.

Methods

A literature search was performed using the PubMed and EMBASE databases for articles published through April 2011. Published case-control studies examining the relationship between iceA and clinical outcomes (gastritis, peptic ulcer, including gastric ulcer and duodenal ulcer, and gastric cancer) were included.

Results

Fifty studies with a total of 5,357 patients were identified in the search. Infection with iceA1-positive H. pylori increased the overall risk for peptic ulcer by 1.26-fold (95% confidence interval [CI], 1.09–1.45). However, the test for heterogeneity was significant among these studies. Sensitivity analysis showed that the presence of iceA1 was significantly associated with peptic ulcer (odds ratio [OR] = 1.25, 95% CI = 1.08–1.44). The presence of iceA2 was inversely associated with peptic ulcer (OR = 0.76, 95% CI = 0.65–0.89). The presence of iceA was not associated with gastric cancer. Most studies examined the cagA status; however, only 15 studies examined the correlation and only 2 showed a positive correlation between the presence of cagA and iceA1.

Conclusion

Our meta-analysis confirmed the importance of the presence of iceA for peptic ulcer, although the significance was marginal.

Characterization of virulence genes cagA and vacA in Helicobacter Pylori and their prevalence in gastrointestinal disorders

Prevalence of H. pylori infection was determined using cultures of gastric biopsy samples of patients attended at the academic hospital of the Federal University of Paraná, Curitiba, Paraná, Brazil. Molecular methods were used to characterize the cagA and vacA genes from bacterial isolates associated with different diseases presented by patients. Out of a total of 81, forty-two gastric biopsy samples tested were positive for H. pylori, with a prevalence of 51.9%. No significant difference was found with regard to the gender (p=0.793) and age (p=0.183) of the patients. Genotype s1m1 vacA gene was found in 67% of the cases of peptic ulcer investigated (p=1.0), despite the limited number of patients with this disease (n=3). A correlation between the presence of less virulent strains (s2m2) and reflux esophagitis was found in the majority of the cases (45%), but without statistical significance. An association between the prevalence of cagA gene, found in 92% of isolates, and peptic ulcer was not observed (p=1.0), suggesting that this gene cannot be considered a specific marker of severity in our environment. The results reinforce the importance of conducting regional studies and the need to characterize H. pylori virulence genes associated with different diseases.

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.

Molecular Basis of pathogenicity in Helicobacter pylori clinical isolates

This study identified pathogenicity genes in 40 Helicobacter pylori clinical isolates. The cagA, vacA, and iceA genes were detected in 65%, 97.5%, and 97.5% of the isolates, respectively. The cagA, iceA1, and vacAs1a/m1 genes were related to erosive gastritis, whereas the vacAs2/m2 and iceA2 genes were associated with enanthematous gastritis.

Gastric adenocarcinoma and Helicobacter pylori: correlation with p53 mutation and p27 immunoexpression

INTRODUCTION

Helicobacter pylori infection is an established risk factor for gastric cancer development, but the exact underlying mechanism still remains obscure. The inactivation of tumor suppressor genes such as p53 and p27(KIP1) is a hypothesized mechanism, although there is no consensus regarding the influence of H. pylori cagA(+) in the development of these genetic alterations.

GOALS

To verify the relationship among H. pylori infection, p53 mutations and p27(Kip1) Protein (p27) expression in gastric adenocarcinomas (GA) seventy-four tissues were assayed by PCR for H. pylori and cagA presence. Mutational analysis of p53 gene was performed by single-strand conformation polymorphism (SSCP). Seventy tissues were analyzed by an immunohistochemical method for p27 expression.

RESULTS

From the samples examined, 95% (70/74) were H. pylori positive, 63% cagA(+). Altered p53 electrophoretic mobility was found in 72% of cases and significantly more frequent in the presence of cagA. Considerable reduction in p27 expression (19%) was found with a tendency for association between cagA(+) and p27(-), although the results were not statistically significant. Concomitant alterations of both suppressor genes were detected in 60% of cases. In the cases cagA(+), 66.7% of them had these concomitant alterations.

CONCLUSIONS

The data suggest that H. pylori cagA(+) contributes to p53 alteration and indicate that concomitant gene inactivation, with reduced p27 expression, may be a mechanism in which H. pylori can promote the development and progression of gastric cancer.

Analysis of drug resistance and virulence-factor genotype of Irish Helicobacter pylori strains: is there any relationship between resistance to metronidazole and cagA status?

BACKGROUND

Helicobacter pylori infection is eradicated with antimicrobial agents and drug-resistant strains make successful treatment difficult. Geographical variations in virulence-factor genotype also exist.

AIM

To evaluate prevalence of drug resistance and virulence-factor genotype in Irish H. pylori strains and to investigate if there is any relationship between drug resistance and genotype.

METHODS

Helicobacter pylori strains isolated from 103 patients were examined. Antimicrobial susceptibilities were tested by Etest. The virulence-factor genotypes were determined using PCR. Frequencies of spontaneous metronidazole-resistance were measured in vitro.

RESULTS

Metronidazole resistance was present in 37.9% of strains examined. 16.5% of strains were clarithromycin-resistant and resistance to both agents observed was found in 12.6% of strains. 68% of strains were cagA(+). The dominant vacA type was s1/m2, followed by s1/m1 and s2/m2. The metronidazole resistance rate in cagA(-) group was significantly higher than in cagA(+) (P = 0.0089). Spontaneous resistance to metronidazole in cagA(-) occurred in higher frequency when compared with cagA(+).

CONCLUSIONS

cagA(+) and vacAs1/m2 type was the dominant genotype in Irish H. pylori strains. Significant rates of metronidazole resistance were observed in cagA(-) group. cagA(-) strains tend to acquire metronidazole resistance in vitro. Absence of cagA might be a risk factor in development of metronidazole resistance.

High prevalence of virulent Helicobacter pylori strains in symptomatic Bulgarian patients

The aim of the study was to evaluate the prevalence of main virulence genes in Helicobacter pylori strains from 116 patients with peptic ulcers (41 cases) and nonulcer diseases (75) by polymerase chain reaction (PCR) with pure cultures and to compare the results with those by multiplex PCR in 39 H. pylori-positive gastric biopsies in another center in Sofia, Bulgaria. Strain susceptibility to amoxicillin, metronidazole, and clarithromycin was determined by agar dilution method. By PCR with pure cultures, coinfections with multiple H. pylori strains were found in 8 (6.9%) patients who were excluded from the statistical analysis. Prevalence of toxigenic type vacA s1 was higher (91.7%) than that usually reported in Europe. cagA-positive genotype was detected in most (81.5%) strains, and almost all of them harbored vacA s1 genotype. Strains with cagA+/vacA s1a genotype were more common (80.6%) than the other genotypes (19.4%, P = 0.0001). The ulcer patients had more often virulent strains than the other patients (92.3% versus 75.4% for cagA+, 100.0% versus 87.0% for vacA s1, 100% versus 84.0% for vacA s1a, and 92.3% versus 73.9% for cagA+/vacA s1a, respectively). The prevalence of H. pylori virulence-associated genes was not associated with patients' sex and age or with the antibacterial resistance of strains. The most common H. pylori genotype was cagA+/vacA s1a. Similar prevalence of cagA-positive (82.1%), vacA s1 (97.4%), and cagA+/vacA s1 strains (79.5%) was found by multiplex PCR in gastric biopsies in the 2nd center. In conclusion, H. pylori strains with virulent genotypes are widespread in symptomatic Bulgarian patients.

The association of vacA genotype and Helicobacter pylori-related disease in Latin American and African populations

In the populations of Western countries, particular genotypes of the vacuolating cytotoxin gene, vacA (vacA s, signal region variants; vacA m, middle region variants) of Helicobacter pylori are believed to be risk factors for the development of peptic ulcers and gastric cancer. However, it was unclear whether these vacA gene variants are associated with the development of gastrointestinal diseases in developing nations. The relationship between vacA genotypes and H. pylori-related disease development in Latin American and African populations was investigated using meta-analysis of 2612 patients from Latin America (2285 strains) and 520 patients from Africa (434 strains). The frequencies of vacA s and m genotypes differed between strains from Latin America (77.2% for s1 and 68.1% for m1) and Africa (83.9% for s1 and 56.7% for m1). Latin American strains with s1 and m1 genotypes increased the risk of gastric cancer (OR 4.17, 95% CI 2.49-6.98 for s1, and 3.59, 2.27-5.68 for m1) and peptic ulcers (e.g. 1.73, 1.37-2.20 for s1). African strains with the s1 or m1 genotypes also increased the risk of peptic ulcers (8.69, 1.16-64.75 for s1) and gastric cancer (10.18, 2.36-43.84 for m1). The cagA-positive genotype frequently coincided with s1 and m1 genotypes in both populations. Overall, the vacA s and m genotypes were related to gastric cancer and peptic ulcer development and might be useful markers of risk factors for gastrointestinal disease, especially in Latin America. Further studies will be required to evaluate the effects of vacA genotypes in African populations because of the small sample number currently available.

Prevalence of Helicobacter pylori vacA, cagA, cagE, iceA and babA2 genotypes in Thai dyspeptic patients

OBJECTIVES

To investigate the prevalence of the vacA, cagA, cagE, iceA, and babA2 genotypes in Helicobacter pylori strains isolated from Thai dyspeptic patients, and to determine whether any correlation exists between these genotypes and clinical manifestations.

METHODS

Helicobacter pylori was examined in 112 patients (62 with non-ulcer dyspepsia (gastritis), 34 with peptic ulcer disease, and 16 with gastric cancer (GCA)), detected by culture or direct detection from gastric biopsies. Allelic variants of the vacA, cagA, cagE, iceA, and babA2 genotypes were identified by using the polymerase chain reaction.

RESULTS

The positive rates for the vacAs1, vacAs2, cagA, cagE, iceA1, iceA2, and babA2 genes in H. pylori of dyspeptic patients were 100%, 0%, 98.2%, 88.4%, 45.5%, 33.1%, and 92%, respectively. The allelic variant vacAs1m1 was more prevalent (58%) than vacAs1m2 (42%). The cagA and cagE genes were commonly found together (87.5%). The most predominant genotypes were vacAs1m1, cagA, cagE, iceA1, and babA2. The various genes alone or in combination had no statistically significant association with the clinical outcomes (p>0.05).

CONCLUSION

Neither single gene nor combination of vacA, cagA, cagE, iceA, and babA2 genes was significantly helpful in predicting the clinical outcome of H. pylori infection in Thai patients. The high prevalence of these genes in H. pylori isolated from Thai patient groups suggests that H. pylori strains are geographically dependent.

J. Análise das impressões digitais de DNA e de fatores de virulência de linhagens de Helicobacter pylori

RACIONAL: Helicobacter pylori é hoje aceito como o principal agente etiológico de gastrite em seres humanos e fator de risco para úlcera péptica e câncer gástrico. A evolução da infecção está relacionada a diversos fatores, inclusive bacterianos, como presença do gene cagA e o genótipo vacA s1m1, associados ao desenvolvimento de úlcera e adenocarcinoma gástrico. A técnica de RAPD ("random amplified polimorphic") tem sido amplamente utilizada para obtenção de impressões digitais de DNA para examinar a similaridade entre linhagens. OBJETIVOS: Avaliar a presença de cagA e alelos do vacA em amostras de H. pylori e associar os achados com a doença apresentada e também investigar possível clonicidade entre os fatores de virulência e as doenças com a impressão digital de DNA gerada pelo RAPD-PCR. MÉTODOS: Foram incluídas 112 amostras provenientes de pacientes com diferentes laudos endoscópicos: gastrite (n = 41), esofagite de refluxo (n = 14), úlcera gástrica (n = 19) e úlcera duodenal (n = 38). A análise dos fatores de virulência da bactéria foi feita por PCR e as impressões digitais de DNA foram estabelecidas pelo método de RAPD-PCR. RESULTADOS: Os resultados obtidos indicam que houve uma associação significativa entre úlcera duodenal e o mosaico vacA s1m1. Analisando-se os padrões de bandas geradas pelo RAPD-PCR, sete diferentes dendogramas foram construídos e não foi possível detectar associação significativa entre os agrupamentos, sugerindo que as amostras não possuem perfil clonal. CONCLUSÃO: Os resultados reforçam a importância do gene vacA como um marcador de virulência do H. pylori. O RAPD da impressão digital de DNA realizado foi incapaz de associar o padrão de bandas com as enfermidades e os genótipos de vacA e cagA.

Association between Helicobacter pylori genotypes and gastric disorders in relation to the cag pathogenicity island

Helicobacter pylori is a bacterium associated with upper gastrointestinal diseases in humans. However, only a small proportion of infected people become sick. Although several studies have tried to establish an association between known virulence markers and clinical outcomes, in many cases the results have been conflicting. The aim of this study was to investigate the importance of virulence markers to predict clinical outcome in Brazil. Mixed infections by genetically unrelated strains detected by vacA genotyping were found in 18% of the patients. The cagA and cagE genes and the vacAs1 genotype were associated with the development of peptic ulcer disease (PUD). The cagAvacAs1m1 genotype was associated with PUD and duodenal ulcer (DU). Conversely, jhp947 was not associated with DU or PUD, indicating that this gene is not a universal virulence marker. These results also show that a high proportion of the patients were simultaneously infected by cag-positive and cag-negative H. pylori types. This finding suggests the existence of a dynamic equilibrium between the loss and gain of the cag pathogenicity island, probably depending on the physiologic conditions of the patient's stomach. To the best of our knowledge, this is the first study that has documented this finding in Brazil.

Prevalence of Helicobacter pylori cagA, iceA and babA2 alleles in Brazilian patients with upper gastrointestinal diseases

Helicobacter pylori is an important human pathogen associated with gastrointestinal diseases such as gastritis, gastric and duodenal ulcer (peptic ulcer disease, PUD), and gastric cancer. A number of pathogenic factors have been described for this bacterium, and some of them have been proposed as markers for the prediction of the clinical outcome. However, with the exception of the cag and vacA status, there is no universal consensus regarding the importance of the other virulence factors. Therefore, the aim of this study was to investigate the status of H. pylori strains regarding the babA and iceA alleles, as well as the cagA genotype, to reveal any association between these genotypes and clinical outcomes in Brazilian patients. The great majority (92.6%) of the strains were typed as iceA1, while 40.4% were found to possess the babA2 allele. The cagA gene was detected in 73.4% of the strains. The iceA2 and cagA genotypes were associated with PUD, while iceA1 was negatively correlated with PUD. However, considering the high percentage of strains typed as iceA1, these associations must be treated with caution. No clinical entity was associated with the babA2 allele. These results suggest that iceA1 is not a good marker for the diseases associated with H. pylori infection in Brazil. Further studies are needed in order to elucidate the relevance of the babA status, because other studies performed in Brazil have associated the babA2 allele with clinical outcomes. These results also indicate the existence of regional differences in the H. pylori genotypes and their association with clinical outcomes.

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.

Helicobacter pylori virulence factors in duodenal ulceration: A primary cause or a secondary infection causing chronicity

Reports from countries with a high prevalence of Helicobacter pylori (H pylori) infection do not show a proportionately high prevalence of duodenal ulceration, suggesting the possibility that H pylori cannot be a primary cause of duodenal ulceration. It has been mooted that this discrepancy might be explained by variations in the prevalence of virulence factors in different populations. The aim of this paper is to determine whether the published literature gives support to this possibility. The relevant literature was reviewed and analyzed separately for countries with a high and low prevalence of H pylori infection and virulence factors. Although virulent strains of H pylori were significantly more often present in patients with duodenal ulcer than without the disease in countries with a low prevalence of H pylori infection in the population, there was no difference in the prevalence of virulence factors between duodenal ulcer, non - ulcer dyspepsia or normal subjects in many countries, where the prevalence of both H pylori infection and of virulence factors was high. In these countries, the presence of virulence factors was not predictive the clinical outcome. To explain the association between virulence factors and duodenal ulcer in countries where H pylori prevalence is low, only two papers were found that give little support to the usual model proposed, namely that organisms with the virulence factors are more likely than those without them to initiate a duodenal ulcer. We offer an alternative hypothesis that suggests virulence factors are more likely to interfere with the healing of a previously produced ulcer. The presence of virulence factors only correlates with the prevalence of duodenal ulcer in countries where the prevalence of H pylori is low. There is very little evidence that virulence factors initiate duodenal ulceration, but they may be related to failure of the ulcer to heal.