Helicobacter pylori genotypes and expression of gastritis in erosive gastro-oesophageal reflux disease

BACKGROUND: Epidemiological studies suggest a negative association between Helicobacter pylori and gastro-oesophageal reflux disease (GORD). Moreover, cagA-positive strains are reported to protect from complications of GORD. The aim of this study was to determine virulence factors (cagA, vacA and iceA) of H. pylori strains and the pattern of gastritis in patients with GORD in comparison with patients with duodenal ulcer (DU) or functional dyspepsia (FD). METHODS: H. pylori strains isolated from gastric biopsies of 105 consecutive patients with mild to moderate erosive GORD (n = 35, LA grade A-B), and from sex- and age-matched patients with DU (n = 35) or FD (n = 35 without reflux symptoms) were investigated. CagA, vacA, and iceA genotypes were determined by PCR analysis of the isolates. Gastritis was classified in accordance with the updated Sydney classification. RESULTS: The prevalence of all three H. pylori virulence factors was higher in patients with GORD (cagA+ 80%, vacA s1 77%, iceA1 71%) and DU (cagA+ 83%, vacA s1 80%, iceA1 74%) than in patients with FD (cagA+ 40%, vacA s1 49%, iceA1 46%). Gastritis activity in the antrum and corpus did not differ between the three groups. However, lymphocytic infiltration of the gastric antral mucosa was more pronounced in DU patients than in those with GORD or FD. CONCLUSIONS: H. pylori strains obtained from patients with mild to moderate erosive GORD show a virulence pattern similar to that found in DU patients. The presence of these virulence factors does not appear to protect against erosive lesions in the oesophagus.     

Helicobacter pylori vacA, iceA, and cagA status and pattern of gastritis in patients with malignant and benign gastroduodenal disease

OBJECTIVE: Both bacterial virulence factors and the pattern of Helicobacter pylori (H. pylori) gastritis may contribute to the development of clinically relevant gastroduodenal disease. The aim of our study was to investigate the frequency of H. pylori vacA alleles, iceA, and cagA, and the pattern of gastritis in patients with gastric cancer (GC), gastric lymphoma (MALT), duodenal ulcer (DU), and functional dyspepsia (FD). METHODS: H. pylori was cultured from 141 patients (34 GC, 26 MALT, 49 DU, 32 FD). Allelic variants of vacA and iceA, and cagA were identified by polymerase chain reaction. Antrum and corpus biopsies were obtained for assessment of gastritis according to the updated Sydney System. RESULTS: The vacA sl,ml genotype was more frequently detected in H. pylori from GC patients (70.6%) than from MALT, DU, and FD patients (p < 0.05). The frequency of iceA1 and cagA did not differ among the groups. The proportion of patients with severe gastritis in the corpus was significantly higher in patients with GC and MALT compared with patients with DU (p < 0.001). CONCLUSIONS: In a German patient population, only the vacA s1,m1 genotype of H. pylori is associated with GC, and therefore may be useful to identify infected patients being at an increased risk for GC.     

H pylori iceA alleles are disease-specific virulence factors

AIM: To characterize and compare genotype profiles of H pylori strains isolated from patients with chronic gastritis and duodenal ulcer in western part of Turkey. METHODS: A total of 46 patients [30 chronic gastritis (CG) and 16 duodenal ulcer (DU)] who had undergone endoscopy because of dyspeptic complaints were studied. The antral biopsy specimens were evaluated for the presence of H pylori by rapid urease test and culture, and the genotype profiles were determined by real-time PCR. RESULTS: The cagA gene was observed in 43 (93.5%) isolates. The vacA s1m2 genotype was the predominant subtype, found in 63.3% and 68.7% of isolates in patients with CG and DU, respectively. Twenty (66.6%) isolates from patients with CG were iceA2 positive while the iceA1 was predominant in those with DU (68.8%). In terms of the association of the iceA alleles to other genes, both alleles were significantly associated with the cagA vacA s1m2 genotype. CONCLUSION: The prevalent circulating genotypes in CG and DU were cagA vacA s1m2 iceA2 and cagA vacA s1m2 iceA1 genotype, respectively. It was found that cagA vacA s1m2 genotype seems to be common virulence factors in both CG and DU while iceA alleles show specificity for gastroduodenal pathologies in this study.     

The importance of vacA, cagA, and iceA genotypes of Helicobacter pylori infection in peptic ulcer disease and gastroesophageal reflux disease

OBJECTIVE: To study the relationship between the presence of H. pylori virulence factors and clinical outcome in H. pylori infected patients. METHODS: DNA was isolated from an antral biopsy sample and vacA, cagA, and iceA genotype were determined by PCR and a reverse hybridization technique in 183 patients with culture-proven H. pylori infection: 51 with peptic ulcer disease (PUD), 62 with gastroesophageal reflux disease (GERD), and 70 with a normal endoscopy (gastritis only; GO). RESULTS: Forty-four samples (24%) showed more than one allelic variant in the vacA s- or in-region and/or both iceA1 and iceA2 genotypes, indicating multiple strain infection. These were excluded from statistical analysis. vacA s1 and cagA were significantly more common in PUD than in GERD and GO. Logistic regression analysis showed that GERD patients were more often infected with strains lacking both cagA and iceA than GO patients (OR = 0.36; CI = 0.15-0.89). Trend analysis showed that GERD patients were most often infected with less virulent strains (p < 0.002). CONCLUSION: Multiple strain infection is common. H. pylori strains possessing the vacA s1 genotype and/or cagA are associated with PUD. GERD patients, infected with H. pylori, mostly carry less virulent strains possessing neither cagA nor iceA1. Our findings support the hypothesis that virulent strains protect against the development of GERD.     

Prevalence of Helicobacter pylori vacA, cagA and iceA genotypes in South African patients with upper gastrointestinal diseases

Clinical response to Helicobacter pylori infection may be determined by specific virulence-associated genotypes which varies geographically. The aim of this study was to investigate the diversity of putative virulence markers of H. pylori; cagA, vacA and iceA in the Eastern Cape Province of South Africa. One hundred H. pylori strains obtained from dyspeptic patients were used. Gastric biopsies were obtained from 254 dyspeptic patients. H. pylori was cultured and strains were studied. Bacterial genotypes cagA, vacA (s and m subtypes) and iceA were analysed by PCR using specific primers. CagA was identified in 90% of the strains investigated. Fifty-eight of the 100 strains had the vacA signal sequence genotype s1 and 26 had subtype s2. Combined vacA s1/s2 was detected in 16 of the strains. VacA middle region analysis showed that 8 (8%) strains were m1 while 50 were m2. Combined vacA m1/m2 was detected in 36 of the strains. s1m2 (20%) and s2m2 (20%) genotypes were the most common allelic combinations of the vacA gene among the strains. Multiple vacA genotypes were detected in this study. Twenty-six percent of the strains identified had both iceA1 and iceA2. All our strains tested positive for the ureC (glmM) gene. This study reveals a high prevalence of vacA, cagA and iceA2.     

Helicobacter pylori Genotypes Are Associated with Clinical Outcome in Portuguese Patients and Show a High Prevalence of Infections with Multiple Strains

Background: Clinical outcome of Helicobacter pylori infection is associated with virulence-associated bacterial genotypes. This study assessed the relationships between vacA, cagA and iceA genotypes and gastric diseases in Portuguese patients. Methods: A total of 319 patients were endoscoped and gastric biopsy specimens were studied by PCR and reverse hybridization (LiPA^TM). Results:vacA genotypes s1/ m1, s1/m2 and s2/m2 were observed in 53%, 14.5% and 32.5% of the cases, respectively. The majority (93.4%) of the s1 cases were s1b and 6.6% were s1a. Multiple vacA genotypes were found in 37.3% of the cases. Gastric ulcer and gastric carcinoma were associated with the presence of vacA s1 (P = 0.008 and P &lt; 0.001, respectively) and vacA m1 genotypes (P = 0.007 and P &lt; 0.001, respectively). Duodenal ulcers were associated with vacA s1 (P &lt; 0.001) but not with the vacA m genotype (P = 0.221). cagA was present in 71.2% of the cases and was associated with duodenal ulcer (P &lt; 0.001), gastric ulcer (P = 0.009) and gastric carcinoma (P &lt; 0.001). iceA1 was found in 27.3% and iceA2 in 32.3% of the cases. In 36.7% of the isolates both iceA alleles were found, and 3.8% were negative for iceA. The iceA genotype was not associated with clinical outcome. Conclusions:vacA s1 and cagA + H. pylori strains are associated with duodenal ulcer, gastric ulcer or gastric carcinoma. vacA m1 is associated with gastric ulcer or carcinoma but not with duodenal ulcer. Infection with multiple H. pylori strains is remarkably high in Portugal and is more frequent in duodenal ulcer patients.     

Association of peptic ulcer with increased expression of Lewis antigens but not cagA, iceA, and vacA in Helicobacter pylori isolates in an Asian population

BACKGROUND: Studies in Western populations suggest that cagA, iceA, and vacA gene status in Helicobacter pylori isolates is associated with increased virulence and peptic ulcer disease. AIM: To investigate the relationship between peptic ulcer and expression of Lewis (Le) antigens as well as cagA, iceA, and vacA in H pylori isolates in Singapore. METHODS: Expression of Le antigens in H pylori isolates obtained from patients with dyspepsia was measured by enzyme linked immunosorbent assay. The cagA, iceA, and vacA status was determined by polymerase chain reaction. RESULTS: Of 108 H pylori isolates, 103 (95.4%) expressed Le(x) and/or Le(y), while Le(a) and Le(b) were expressed in 23 (21.3%) and 47 (43.5%) isolates, respectively. Expression of two or more Le antigens (Le(x), Le(y), Le(a), or Le(b)) was significantly higher in H pylori isolated from ulcer patients than in non-ulcer patients (89.6% v 73.2%, p=0.035). There were no significant differences in the prevalence of cagA or iceA1 in H pylori isolates from peptic ulcer and non-ulcer patients (86.6% v 90.2% for cagA; 70.1% v 68.3% for iceA1), and no association of peptic ulcer with any specific vacA genotype. CONCLUSIONS: The present study indicates that peptic ulcer disease is associated with increased expression of Lewis antigens but not cagA, iceA, or vacA genotype in H pylori isolates in our population. This suggests that cagA, iceA, and vacA are not universal virulence markers, and that host-pathogen interactions are important in determining clinical outcome.     

The Relationship Between Virulence Factors of Helicobacter pylori and Severity of Gastritis in Infected Patients

The outcome of Helicobacter pylori infection has been related to specific virulence-associated bacterial genotypes. The best known genotypic virulence factors of H. pylori are cytotoxin-associated gene A (cagA) and vacuolating cytotoxin gene A (vacA). The objective of this study was to assess the relationship between H. pylori cagA and vacA status and histopathological findings. Esophagogastrodoedonoscopy was performed in 80 dyspeptic patients. Antrum and corpus biopsies were obtained for isolation of H. pylori and for histopathological assessment. The polymerase chain reaction was used to detect cagA and vacA genes of H. pylori using specific primers. Biopsy samples were stained with hematoxylin and eosin, and histopathological findings were graded using the “updated Sydney system”. H. pylori from 57 of the 80 patients was incubated. Of the 57 patients, 44 were cagA positive. In the corpus biopsy specimens there was a significant relationship between the density of H. pylori colonization (P = 0.02) and chronic inflammation (P = 0.02) and cagA-positive genotypes. In the antrum specimens there was a significant relationship between cagA positivity and neutrophil activity (P = 0.003) and glandular atrophy (P = 0.002), but not with H. pylori density, chronic inflammation, and intestinal metaplasia. The odds ratio of cagA-positive vs. cagA-negative strains for the presence of glandular atrophy, irrespective of grading and of gastric localization, was 4.62 (95% CI, 1.18–18.08, P = 0.041). No significant relationships were observed between vacA s1 and s2 genotypes and histopathological parameters. Corpus neutrophil infiltration was found to be more severe in the m1 group than in the m2 group (P = 0.004). Other histopathological features showed no difference between m1 and m2 genotypes. In conclusion H. pylori strains showing cagA positivity are associated with more severe gastritis in some histological features but virulence factors of H. pylori do not appear to determine the overall pattern of gastritis.     

Prevalence of Helicobacter pylori virulence genotypes among children in Eastern Turkey

AIM:To identify the virulence genotypes of Helicobacter pylori(H.pylori)if present in children in Eastern Turkey and if those genotypes are mostly associated with severe clinical presentations.METHODS:A total of 49 H.pylori positive Turkish children(42 with antral nodularity and 7 with peptic ulcer)who underwent upper gastrointestinal endoscopy with abdominal symptoms during the period from March 2011 to September 2012 were enrolled in this study.Antral nodularity was diagnosed endoscopically by two of the authors.We determined for the presence of cagA,vacA,cagE,iceA and babA2 genotypes of H.pylori isolates in DNA obtained directly from frozen gastric biopsy samples by polymerase chain reaction test using specific primers.RESULTS:Of the 49 H.pylori isolates studied,61.2%,91.8%,22.4%,28.6%,57.1%and 40.8%were positive for the cagA,vacA s1,cagE,iceA1,iceA2 and babA2 genes,respectively.We showed that the most common vacA subtype was s1a(79.6%).However,the s2 gene was found less frequently with an isolation rate of 8.2%of the H.pylori isolates.The genotypes iceA2 and vacA s1m2 were the most frequently found types in children with antral nodularity.In addition,the genotypes iceA1,babA2 and vacA s1m1 were found in similar ratios in all the H.pylori isolates obtained from children with peptic ulcer.The genotypes vacA s2m1and s1c were not observed in any of isolates studied.CONCLUSION:This study showed that vacA s1m2,cagA and iceA2 were the most common genotypes,and no association between antral nodularity and genotypes was observed.     

Helicobacter pylori genotypes are associated with clinical outcome in Portuguese patients and show a high prevalence of infections with multiple strains

BACKGROUND: Clinical outcome of Helicobacter pylori infection is associated with virulence-associated bacterial genotypes. This study assessed the relationships between vacA, cagA and iceA genotypes and gastric diseases in Portuguese patients. METHODS: A total of 319 patients were endoscoped and gastric biopsy specimens were studied by PCR and reverse hybridization (LiPA). RESULTS: vacA genotypes s1/m1, s1/m2 and s2/m2 were observed in 53%, 14.5% and 32.5% of the cases, respectively. The majority (93.4%) of the s1 cases were s1b and 6.6% were s1a. Multiple vacA genotypes were found in 37.3% of the cases. Gastric ulcer and gastric carcinoma were associated with the presence of vacA s1 (P = 0.008 and P < 0.001, respectively) and vacA m1 genotypes (P = 0.007 and P < 0.001, respectively). Duodenal ulcers were associated with vacA s1 (P < 0.001) but not with the vacA m genotype (P = 0.221). cagA was present in 71.2% of the cases and was associated with duodenal ulcer (P < 0.001), gastric ulcer (P = 0.009) and gastric carcinoma (P < 0.001). iceA1 was found in 27.3% and iceA2 in 32.3% of the cases. In 36.7% of the isolates both iceA alleles were found, and 3.8% were negative for iceA. The iceA genotype was not associated with clinical outcome. CONCLUSIONS: vacA s1 and cagA+ H. pylori strains are associated with duodenal ulcer, gastric ulcer or gastric carcinoma. vacA m1 is associated with gastric ulcer or carcinoma but not with duodenal ulcer. Infection with multiple H. pylori strains is remarkably high in Portugal and is more frequent in duodenal ulcer patients.     

上海地区幽门螺杆菌菌株iceA、babA2基因型与临床的关系

目的检测上海地区幽门螺杆菌(Hp)感染患者中Hp菌株iceA、babA2的分布特征，探讨与Hp临床感染结局相关的菌株基因型。方法141株Hp菌株分离自43例慢性胃炎(CG)、47例十二指肠球部溃疡(DU)、30例胃溃疡(GU)和21例非贲门部胃癌患者的胃镜活检标本。采用PCR方法检测Hp菌株的iceA、babA2、cagA和vacA基因型。结果141株Hp菌株中，iceA1、iceA2和babA2的总检出率分别为74．5％(105／141)、15．6％(22／141)和63．8％(90／141)，其中2例(1．4％)为iceA1、iceA2均阳性，16例(11．3％)为iceA1、iceA2均阴性。DU组的babA2检出率显著高于GU组(74．5％比50．0％。P=0．028)，DU组的cagA^ ／babA2^ 检出率亦显著高于GU组(70．2％比46．7％，P=0．039)。其余疾病组之间的babA2检出率差异无显著性。未发现不同临床疾病与iceA基因型的相关性。结论上海地区Hp感染者的菌株基因型主要是iceA1^ ／babA2^ ，babA2在DU和GU的发病机制中起不同作用。未发现iceA亚型与Hp临床感染结局有相关性。     

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.     

Accuracy of a monoclonal antibody-based stool antigen test in the diagnosis of Helicobacter pylori infection

Background: Recent availability of tests for Helicobacter pylori antigens in stool samples has provided potentially useful tools for epidemiological studies and clinical settings. The aim of this study was to evaluate a monoclonal antibody-based H. pylori antigen stool test in the primary diagnosis of H. pylori infection, and to study the test performance after patients were treated with lanzoprazole, and after eradication therapy. Methods: The study included 122 dyspeptic patients. At gastroscopy, biopsy specimens were obtained for culture and histology. Stool antigen and [[Formula: See Text]C]-urea breath tests were performed concurrently. Positive culture alone or a positive [[Formula: See Text]C]-urea breath test in combination with positive histology defined the reference standard. Forty-three Hp +ve patients were treated with lanzoprazole for 2 to 4 weeks, and stool antigen tests were performed on days 1 and 7 post-treatment. After eradication therapy, 32 patients were re-examined for H. pylori infection. Results: Prevalence of H. pylori was 44.3%. Sensitivity and specificity for the stool antigen test in the primary diagnosis of H. pylori infection were 98% and 94%, with positive and negative likelihood ratios of 16.7 and 0.02, respectively. All patients had positive stool tests immediately after lanzoprazole treatment, whereas 2 patients had negative stool tests after 7 days. Triple therapy rendered all patients stool test negative. Conclusions: The monoclonal antibody-based stool antigen test is an accurate tool in the primary diagnosis of H. pylori infection and after eradication therapy. Lanzoprazole treatment does not influence the clinical performance of the test.     

Clinical Relevance of CagA-specific Antibodies Related to CagA Status of Heliobacter pylori Isolates Using Immunofluorescence Test and PCR

Background: The cagA (cytotoxin-associated gene A) protein is found in about 50% of Helicobacter pylori strains; its clinical relevance in gastroduodenal disease is uncertain. Patients and Methods: The frequency of IgG antibodies to cagA was studied by using a commercial Western blot assay in sera of 189 patients with endoscopically and histologically confirmed gastroduodenal disease. In addition, 38 H. pylori strains isolated from biopsies were analyzed by immunofluorescence test (IFT) and PCR for detection of cagA protein and cagA gene sequences, respectively. Results: 54.3–60.0% of all patients with gastrointestinal diseases (chronic gastritis, gastric or duodenal ulcer and chronic duodenitis) and 28.6% with a normal mucosa were found to be positive for anti-cagA IgG antibodies. There was no significant difference in anti-cagA IgG seroprevalence between the different clinical entities. CagA-positive (cagA⁺) H. pylori strains were detected in 44.7% and 50% of the 38 isolates by PCR and IFT, respectively. 22 of 23 patients infected with cagA⁺ strains had anti-cagA antibodies. Using PCR as a gold standard, the sensitivity and specificity of the cagA IgG Western blot were 100.0% and 35.0%, respectively; the sensitivity and specificity of the cagA IFT were 76.5% and 71.4%, respectively. The incidence of the cagA⁺ H. pylori strains detected either by PCR or IFT was significantly higher (p < 0.05 and p < 0.01, respectively) in patients with chronic duodenitis, gastric or duodenal ulcer compared to patients with chronic gastritis (66.7%, 80% and 30.4%, respectively). Conclusion: In this study the cagA-specific serological status in H. pylori infections as diagnosed by IgG Western blot was of no predictive value for severity of disease. In contrast, the cagA status of H. pylori isolates, diagnosed by IFT or PCR, was a predictive marker for severe disease and, therefore, also of clinical relevance in the assessment of the virulence of the infecting strain. Received: July 21, 2000 · Revision accepted: March 2, 2001     

Indistinguishable cellular changes in gastric mucosa between Helicobacter pylori infected asymptomatic tribal and duodenal ulcer patients

AIM： To investigate the changing pattern of different histological parameters occurring in the stomach tissue of Helicobacter pylori （H pylori） infected tribal populations and duodenal ulcer patients among ethnic Bengalis and correlation of the genotypes of H pylori with different histological parameters. METHODS： One hundred and twelve adult individuals were enrolled into this study between 2002 and 2004. Among them, 72 had clinical features of duodenal ulcer （DU） from ethnic Bengali population and 40 were asymptomatic ethnic tribals. Endoscopic gastric biopsy samples were processed for histology, genotyping and rapid urease test. Histologically, haematoxylin and eosin staining was applied to assess the pathomorphological changes and a modified Giemsa staining was used for better detection of Hpylori. For intestinal metaplasia, special stainings, i.e. Alcian blue periodic acid-Schiff and high iron diamine-Alcian blue staining, were performed. PCR was performed on bacterial DNA to characterize the presence or absence of virulence-associated genes, like cagA, and distribution of different alleles of vacA and iceA. RESULTS： Intraglandular neutrophil infiltration, a hallmark of activity of gastritis, was present in 34 （94%） of tribals （TRs） and 42 （84%） of DU individuals infected with H pylori. Lymphoid follicles and aggregates, which are important landmarks in H pylori infection, were positive amongst 15 （41%） of TRs and 20 （40%） of DU subjects. Atrophic changes were observed in 60% and 27.7%, respectively, among DU cases and tribals （P 〉 0.003）. Metaplastic changes were detected in low numbers in both groups. Moderate to severe density distribution of Hpylori in the gastric mucosa was 63% among TRs, whereas it was 62% in DU subjects. There were no significant differences in the distribution of virulence-associated genes like cagA, vacA and iceA of H pylori strains carried by these two populations. CONCLUSION： Our study showed almost similar distribution of inflammatory cells among asymptomatic tribals and DU Bengali patients. Interestingly, the tribal population are free from any clinical symptoms despite evidence of active histologic gastritis and infection with Hpylori strains carrying similar virulence markers as of strains isolated from patients with DU. There was an increased cellular response, especially in terms of neutrophil infiltration, but much lower risk of developing atrophy and metaplastic changes among the tribal population.     

Analysis of genetic variability, antimicrobial susceptibility and virulence markers in Helicobacter pylori identified in Central Italy

OBJECTIVE: To assess the relationship between the presence of mixed infection of Helicobacter pylori and both antimicrobial susceptibility and virulence markers. MATERIAL AND METHODS: Thirty-six patients with H. pylori infection were included in the study. Three colonies were selected from each positive biopsy sample collected from each host for a total of 108 H. pylori strains. The genetic variability was evaluated through the amplified fragment length polymorphism (AFLP) analysis; the antibiotic susceptibility to amoxicillin, clarithromycin, moxifloxacin, rifabutin and tinidazole was determined using the minimum inhibitory concentrations (MICs) with the agar dilution method. Moreover, the vacA, cagA, iceA and babA2 statuse were detected by polymerase chain reaction (PCR). RESULTS: There was a strong connection between mixed H. pylori infection and antimicrobial resistance. In particular, H. pylori strains with genetic variability, in the same host, expressed more resistance to clarithromycin, moxifloxacin and tinidazole than that expressed in strains with a unique genetic host pattern. VacA s1m1/s1m2 genotypes were found in 70% of strains isolated in mixed infection, whereas the same allelic combinations were found in 42% of strains, isolated in single infection. The cagA(+) status prevailed both in patients with mixed (97%) and in those with single infection (85%) without significant differences. The iceA1 status was more commonly found in patients with mixed infection, whereas the babA2 status was significantly prevalent in single H. pylori infection. CONCLUSIONS: Mixed H. pylori infection harbouring in one patient is significantly related to strains that are more resistant to antibiotics and with a more virulent genotype (vacA s1m1/s1m2, cagA, iceA1) than strains responsible for single infection.     

幽门螺杆菌不同基因型和基因亚型与甲硝唑耐药性的研究

目的研究Helicobacter pylori菌株本身的毒力差异是否与H.pylori菌株对甲硝唑的敏感性有关。方法 用E-test方法检测109株H.pylori菌株对甲硝唑的敏感性;PCR检测H.pylori菌株不同的vacA基因亚型、cagA、iceA和babA2基因型。结果 云南地区甲硝唑耐药率为67.89％;vacA、cagA、iceAl、babA2基因的各种基因亚型和基因型在H.pylori菌株甲硝唑耐药率上无显著性差异。结论 H.pylori菌株本身的毒力差异与H.pylori菌株对甲硝唑的敏感性无关。     

Helicobacter pylori cagA, vacA and iceA genotypes in northern Thai patients with gastric disease

Helicobacterpylori, a common infectious bacterium, has been linked to chronic gastritis, peptic ulcer and gastric cancer. Gastric biopsy specimens were obtained from 58 northern Thai patients with gastritis, 28 with gastric ulcer, 45 with duodenal ulcer and 4 with gastric cancer. cagA, vacA s1 and iceA gene was found in 88, 98, and 89% of the specimens, respectively. For vacA, the frequency of subtype s1a, s1c and combined sla and s1c was 40, 16, and 41%, respectively. The frequency of subtype s1a/m1 and s1a/s1c/m1 was 27 and 20%, respectively. Fifty-three patients (39%) were infected with multiple vacA genotypes but there was no association with clinical outcome. cagA positive and mixed vacA s1a and s1c strains were found in significantly more cases of duodenal ulcer than gastritis (p < 0.05). For iceA, subtype iceA1 reached a frequency of 60%, whereas subtype iceA2 was only 24%.