Breath and string test: A diagnostic package for the identification of treatment failure and antibiotic resistance of Helicobacter pylori without the necessity of upper gastrointestinal endoscopy

AIM: Helicobacter pylori (H pylori) resistance after failed eradication has a major impact on the outcome of a further treatment regimen. The aim of this study was to assess the validity of a non-invasive strategy using the 13C-urea breath test (UBT) and the gastric string test in identifying post-treatment resistance of H pylori. METHODS: The UBT was routinely performed 4 to 6 wk after H pylori eradication therapy. Forty-two patients (24 females, 18 males, mean age 48 years) with a positive UBT were included in the study. A gastric string test using a capsule containing a 90 cm-long nylon fiber was performed. Before the capsule was swallowed, the free end of the string was taped to the cheek. After one hour in the stomach, the string was withdrawn. The distal 20 cm of the string was inoculated onto an agar plate and processed under micro-aerophilic conditions. Following the string test, upper gastrointestinal endoscopy was performed to obtain gastric biopsies for conventional culture. RESULTS: H pylori was successfully cultured from the gastric string in 34 patients (81%), but not in 5 patients due to contamination with oropharyngeal flora. H py/oriwas cultured from the gastric biopsies obtained at endoscopy in 39 patients (93%). CONCLUSION: The UBT followed by the gastric string test in the case of treatment failure is a valid diagnostic strategy with the aim of determining the post-therapeutic antibiotic resistance of H pylori with little inconvenience to the patient. Upper Gl-endoscopy can be avoided in several cases by applying consequently this diagnostic package.

Lewis blood genotypes of peptic ulcer and gastric cancer patients in Taiwan

AIM： The Lewis b （Le^b） antigen has been implicated as a possible binding site for attachment of Helicobacter pylori （H pylon） to gastric mucosa. However, studies both supporting and denying this association have been reported in the literature. Differences in secretor （Se） genotype have been suggested as a possible reason for previous discrepancies. Therefore, we investigated the relationship between Le and Se genotypes and Hpylori infection rates in people with peptic ulcer or gastric cancer. METHODS： Peripheral blood samples were obtained from 347 patients with endoscopic evidence of peptic ulcer disease （235 cases of duodenal ulcer, 62 of gastric ulcer, and 50 of combined duodenal ulcer/gastric ulcer） and 51 patients with gastric cancer on endoscopy. Peripheral blood specimens from 101 unrelated normal volunteers were used as controls. Lewis phenotype was determined using an antibody method, whereas Le and Se genotypes were determined by DNA amplification and restriction enzyme analysis. Gastric or duodenal biopsies taken from patients with endoscopic evidence of peptic ulcer or gastric cancer were cultured for Hpylotri Isolates were identified as Hpylori by morphology and production of urease and catalase. The Hpyloriinfection status was also evaluated by rapid urease test （CLO test）, and urea breath test （13^C-UBT）. Results of studies were analyzed by chi-square test （taken as significant）. RESULTS： Hpyloriwas isolated from 83.7% （303/347） of patients with peptic ulcer disease. Statistical analysis did not show any significant difference in Lewis phenotype or genotype between patients with and without Hpylori infection. No significant association was found between Lewis genotype and peptic ulcer or gastric cancer.CONCLUSION： Lewis blood genotype or phenotype may not play a role in the pathogenesis of Hpyloriinfection. However, bacterial strain differences and the presence of more than one attachment mechanism may limit the value of epidemiological studies in elucidating this matter.

Helicobacter pylori eradication lowers serum homocysteine level in patients without gastric atrophy

AIM: To determine whether Helicobacter pylori (H pylori) infection caused hyperhomocysteinemia by altering serum vitamin B_(12), serum folate and erythrocyte folate levels and whether eradication of this organism decreased serum homocysteine level. METHODS: The study involved 73 dyspeptic H pylork positive patients, none of them had gastric mucosal atrophy based on rapid urease test and histology. Out of 73 patients, 41 (56.2%) showed a successful eradication of H pylori 4 wk after the end of treatment. In these 41 patients, fasting serum vitamin B_(12) folate and homocysteine levels, and erythrocyte folate levels before and 4 wk after H pylori eradication therapy were compared. RESULTS: The group with a successful eradication of H pylori had significantly higher serum vitamin B_(12) and erythrocyte folate levels in the post-treatment period compared to those in pre-treatment period (210±97 pg/mL vs 237±94 pg/mL,P＜0.001 and 442±212 ng/mL vs 539±304 ng/mL, P=0.024, respectively), but showed no significant change in serum folate levels (5.6±2.6 ng/mL vs 6.0+2.4 ng/mL, P=0.341). Also, the serum homocysteine levels in this group were significantly lower after therapy (13.1±5.2 μmol/L vs 11.9±6.2 μmol/L, P=0.002). Regression analysis showed that serum homocysteine level was positively correlated with age (P=0.01) and negatively with serum folate level before therapy (P=0.003). CONCLUSION: Eradication of H pylori decreases serum homocysteine even in patients who do not exhibit gastric mucosal atrophy. It appears that the level of homocysteine in serum is related to a complex interaction among serum vitamin B_(12), serum folate and erythrocyte folate levels.

Effect of Helicobacterpyloriinfection on gastric mucosal pathologic change and level of nitric oxide and nitric oxide synthase

AIM： To investigate the level of nitric oxide （NO） and nitrous oxide synthase （NOS） enzyme and its effect on gastric mucosal pathologic change in patients infected with Helicobacter pylori （H pylori）, and to study the pathogenic mechanism of H pylori. METHODS： The mucosal tissues of gastric antrum were taken by endoscopy, then their pathology, H pylori and anti-CagA-IgG were determined. Fifty H pylori positive cases and 35 H pylori negative cases were randomly chosen. Serum level of NO and NOS was detected. RESULTS： One hundred and seven cases （71.33%） were anti-CagA-IgG positive in 150 H pyloripositive cases. The positive rate was higher especially in those with preneoplastic diseases, such as atrophy, intestinal metaplasia and dysplasia. The level of NO and NOS in positive group was higher than that in negative group, and apparently lower in active gastritis than in pre-neoplastic diseases such as atrophy, intestinal metaplasia and dysplasia. CONCLUSION： H pylori is closely related with chronic gastric diseases, and type I H pylori may be the real factor for H pylori-related gastric diseases. Infection with H pylori can induce elevation of NOS, which produces NO.

Association of the myeloperoxidase ^(468)G→K polymorphism with gastric inflammation and duodenal ulcer risk

AIM: To elucidate the relations between the myeloperoxidase ^(-468)G→a polymorphism and the development of duodenal ulcer (DU), and to investigate the impacts of this host genetic polymorphism on the histopathological features of Helicobacter pylori (H py/ori)-related gastritis. METHODS: In a case-control study of 115 consecutive DU patients and 182 controls, the myeloperoxidase ^(-468)G→A polymorphism was genotyped. Additionally, gastric mucosal changes were examined according to the updated Sydney System. RESULTS: The two study groups differed in the distributions of myeloperoxidase genotypes (P=0.008). All six individuals carrying myeloperoxidase A/A genotypes were in the DU group. The carriage of myeloperoxidase allele A and H pylori infection were associated with an increased risk of DU with odds ratios (OR) of 2.3 and 5.8, respectively. The combined risk of the carriage of myeloperoxidase allele A and H pylori infection for DU was 8.7 (95% CI, 3.5-21.8). In the H pylori-infected individuals, allele A carriers displayed higher bacterial density scores (P=0.04) in the antrum than did non-carriers. CONCLUSION: This work verifies for the first time the association of myeloperoxidase ^(-468)G→A polymorphism with antral H pylori density and DU disease. The mechanisms underlying this genetic polymorphism in developing DU disease merit further investigations.

Polymerase chain reaction: A sensitive method for detecting Helicobacter pyloriinfection in bleeding peptic ulcers

AIM: To assess the sensitivity and specificity of polymerase chain reaction (PCR) in detecting Helicobacter pylori(H pylon) infection in patients with bleeding peptic ulcers, and to compare its diagnostic efficacy with other invasive and non-invasive tests. METHODS: From April to September 2002, H pylori status in 60 patients who consecutively presented with gastroduodenal ulcer bleeding was examined by rapid urease tests (RUT), histology, culture, PCR, serology and urea breath tests (UBT). RESULTS: The sensitivity of PCR was significantly higher than that of RUT, histology and culture (91% vs 66%, 43% and 37%, respectively; P = 0.01, <0.001, <0.001, respectively), but similar to that of serology (94%) and UBT (94%). Additionally, PCR exhibited a greater specificity than serology (100% vs 65%, P<0.01). However, the specificity of PCR did not differ from that of other tests. Further analysis revealed significant differences in the sensitivities of RUT, culture, histology and PCR between the patients with and those without blood in the stomach (P<0.01, P= 0.09, P<0.05, and P<0.05, respectively). CONCLUSION: PCR is the most accurate method among the biopsy-based tests to detect H pylori infection in patients with bleeding peptic ulcers. Blood may reduce the sensitivities of all biopsy-based tests.

Mutation of cytotoxin-associated gene A affects expressions of antioxidant proteins of Helicobacter pylori

AIM: To determine if disruption of the cagA gene of Helicobacter pylori (H pylori) has an effect on the expression of other proteins at proteome level. METHODS: Construction of a cagA knock out mutant Hp27 _△cagA (cagA -) via homologous recombination with the wild-type strain Hp27 (cagA+) as a recipient was performed. The method of sonication-urea-CHAPS-DTT was employed to extract bacterial proteins from both strains. Soluble proteins were analyzed by two-dimensional electrophoresis (2-DE). Images of 2-DE gels were digitalized and analyzed. Only spots that had a statistical signif icance in differential expression were selected and analyzed by matrix-assisted laser desorption/ionizationtime of flight mass spectrometry (MALDI-TOF-MS). Biological information was used to search protein database and identify the biological function of proteins. RESULTS: The proteome expressions between wild-type strain and isogenic mutant with the cagA gene knocked-out were compared. Five protein spots with high abundance in bacteria proteins of wild-type strains, down-regulated or absently expressed in bacteria proteins of mutants, were identified and analyzed. From a quantitative point of view, the identified proteins are related to the cagA gene and important antioxidant proteins of H pylori , including alkyl hydroperoxide reductase (Ahp), superoxide dismutase (SOD) and modulator of drug activity (Mda66), respectively, suggesting that cagA is important to maintain the normal activity of antioxidative stress and ensure H pylori persistent colonization in the host. CONCLUSION: cagA gene is relevant to the expressions of antioxidant proteins of H pylori, which may be a novel mechanism involved in H pylori cagA pathogenesis.

Detection of T lymphocyte subsets of children with Helicobacter pylori infection

AIM: To study the transformation of T lymphocyte subsets in children with Heliobacter pylori (H pylori) infection. METHODS: The H pylori infection status were determined by a combination of ELISA and Western blot (immunoblot) technique in 98 children and T lymphocyte subsets in peripheral blood were determined by flow cytometrical analysis.RESULTS: There were 75 children positive with H pylori infection and 23 negative in 98 children. Comparing the proportion of peripheral blood T lymphocytic subsets in children with H pylori infection and without H pylori infection, it was found that a higher proportion of CD4 T-cells in infected children (39.02±7.71 vs34.25±10.73,t = 2.246,P＜0.05) and higher value of CD4 to CD8 T-cells ratio (1.51±0.52 vs 1.25, t= 2.104,P＜0.05) were present, but there were not significant differences in CD3 T-cells and CD8 T-cells (73.11±10.02 vs69.49±17.08, 27.22±6.07vs 28.27±8.67, P＞0.05).CONCLUSION: Th1 cell-mediated immune responses may be induced by H pylori infection in children.