Serodiagnosis of Helicobacter pylori infection by immunoblot assay

We compared a noninvasive serological test using a commercial immunoblot assay (Helicoblot 2.0) to tissue-based methods [rapid urease test (CLO test), histology and culture] in eighty Thai patients undergoing upper endoscopy. A true positive test was defined as at least two of the biopsy-related tests being positive. The CLO test was the most accurate test with sensitivity and specificity as high as 100%, whereas histology and culture had sensitivity of 100% and 72.2%, respectively, and the specificity of 72.7% and 96%, respectively. The serological test had a high sensitivity (97.2%) but exhibited an unsatisfactory specificity (40.9%). We concluded that the rapid urease test using multiple gastric biopsies was the most appropriate method for diagnosing H. pylori status. The role of immunoblot assay as a serological screening test in our population remains doubtful, but it may identify patients who have been infected with certain strains of H. pylori.     

Serodiagnosis of Helicobacter pylori: comparison of enzyme-linked immunosorbent assays.

Enzyme-linked immunosorbent assays (ELISAs) have been developed to diagnose Helicobacter pylori infection. However, the methods are not standardized. We therefore prospectively evaluated the sensitivities and specificities of ELISAs developed in the United States and the United Kingdom in a study population comprising 41 consecutive symptomatic outpatients and 35 volunteers. At endoscopy, multiple biopsies were obtained for histology and culture and stained sections were graded for chronic gastritis, active chronic gastritis, and density of H. pylori. Serum samples were analyzed for H. pylori by ELISA. The first set of assays for immunoglobulin G (IgG) and IgA used a pool of sonicated isolates of H. pylori from five patients in the United States (antigen A). The second set of assays, developed in the United Kingdom, used three different antigens: antigen 1, an acid-extractable surface antigen; antigen 2, an acid-extractable antigen from an aflagellate variant; and antigen 3, a urease-containing fraction. Cutoff scores for positive results were determined a priori on the basis of previous serological studies. There was close agreement between histology and culture. In the study population, 36% of the individuals were H. pylori positive. The diagnostic value of the different ELISAs were highly comparable, and the crude antigens performed as well as the more purified antigens. The antigen A IgG had a sensitivity and specificity of 96 and 94%, respectively; the values for antigen 1 were 93 and 96%, respectively. The antigen A IgA and antigen 3 assays were the least sensitive tests.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serodiagnosis of Helicobacter pylori infection: comparison and correlation between enzyme-linked immunosorbent assay and rapid serological test results.

CLOser is a new, one-step, qualitative anti-Helicobacter pylori immunoglobulin G test having the advantage of convenience and simplicity. We aimed to evaluate its diagnostic accuracy and to compare it with a quantitative enzyme-linked immunosorbent assay (ELISA) (HEL-pTEST II) in a study of 86 adult dyspeptic patients by using the results from histology and urease testing of gastric biopsies as a "gold standard." Forty-six patients were H. pylori positive. The sensitivities, specificities, and positive and negative predictive values were 95.7, 72.5, 80.0, and 93.5%, respectively, for CLOser and 93.5, 92.5, 93.5, and 92.5%, respectively, for HEL-pTEST II. The grade of the colored test bands in CLOser was correlated with antibody titers in HEL-pTEST II (r = 0.71; p < 0.001). The mean antibody titers were 13, 74, 186, and 328 U/ml for the negative, faint, thin, and thick bands, respectively, of CLOser. We concluded that the CLOser rapid serological test yielded sensitivity similar to that of the conventional ELISA. Although CLOser is not suitable for epidemiologic screening for H. pylori infection on account of lower specificity, it is particularly convenient and very easy to perform. Therefore, it may eventually become widely used in the office-based care of patients and lead to more cost-effective patient management decisions.     

Helicobacter pylori infection in Korea

Helicobacter pylori is a gram-negative bacterium that was first isolated in 1982. Since then, H. pylori infection in humans has been shown to be associated with gastritis, peptic ulcer disease, gastric carcinoma, and mucosa-associated lymphoid tissue (MALT) lymphoma as well. The epidemiology, transmission, and pathogenicity of H. pylori has been a subject of intensive study. Successful treatment improves the cure rate of peptic ulcerations and treatment with antimicrobials also decreases the recurrence rate of these diseases. Better regimens having less toxicity and a good eradication rate have also been developed. A better understanding of the pathophysiologic mechanisms relating to H. pylori induced mucosal damages would result in more options for the prevention of peptic ulcers and carcinogenesis. Korea has a relatively high incidence of H. pylori infection and gastric cancer. Growing interest has developed in view of its importance in being associated with various gastroduodenal diseases. Furthermore, along with a high incidence of H. pylori-related disease in Korea, because the interaction between H. pylori, host factors and environmental factors is important in disease pathogenesis, we need to have precise data on the characteristics of H. pylori-related diseases that occur in Korea. In the present report we review the epidemiology, transmission route, diagnosis, pathogenesis, treatment methods and relationship with gastroduodenal diseases with in special references to basic and clinical data that have been published.     

Gastric cancer and Helicobacter pylori infection.

AIMS--To identify differences in the prevalence of Helicobacter pylori infection in different groups of patients with gastric cancer. METHODS--In total 224 cases of gastric cancer were studied: 120 (53.6%) intestinal; 69 (30.8%) diffuse; and 35 (15.6%) unclassified. Site of tumour, presence and severity of gastritis, presence and extent of intestinal metaplasia, and age and sex were also recorded. Infection by H pylori was assessed using modified Giemsa staining. RESULTS--H pylori infection was found in 96 (43%) cases. There was no significant association between infection and histological type of tumour, nor was there any significant association between infection and site of tumour, the presence of intestinal metaplasia, age, or sex. The only significant association identified was between infection and gastritis. CONCLUSIONS--These results are in broad agreement with those of other similar studies, although the overall prevalence of infection, at 43%, was lower than has been reported in some series. The findings do not support a role for H pylori in any particular subgroup of patients with gastric cancer but do not exclude a role for the organism in the pathogenesis of gastric cancer as a whole.     

Serodiagnosis of Helicobacter hepaticus infection in mice by an enzyme-linked immunosorbent assay.

Helicobacter hepaticus is a newly recognized bacterium associated with chronic active hepatitis, hepatic carcinoma, and inflammatory bowel disease in mice. Currently, fecal or tissue PCR, fecal culture, or histologic examination of silver-stained liver sections is used to diagnose H. hepaticus infection. In this report, we describe an enzyme-linked immunosorbent assay (ELISA) for serodiagnosis of H. hepaticus infection in mice with a membrane digest preparation of H. hepaticus as the antigen. Sera from mice positive for H. hepaticus by PCR or histologic examination (n = 88), positive for Helicobacter bilis by PCR (n = 13), positive for other helicobacters (not identifiable to species level) by PCR (n = 25), or negative for all Helicobacter species by PCR (n = 162) were used to evaluate the ELISA. Results indicated that ELISA provided 93.2% sensitivity, 94% specificity, 87.2% positive predictive value, and 96.9% negative predictive value. Cross-reactive antibodies were detected in some mice infected with helicobacters not identifiable to species level. To further define ELISA sensitivity and specificity, groups of 10 C57BL/6 mice were inoculated per os with H. hepaticus, Helicobacter muridarum, or H. bilis. Sera were collected and examined by the ELISA. H. hepaticus-infected mice seroconverted by 2 weeks and maintained ELISA reactivity throughout the 18-week study, while mice infected with H. muridarum and H. bilis were negative by ELISA. These results indicate that this reported ELISA is highly sensitive and specific for the serodiagnosis of H. hepaticus infection in mice.     

Pathogenesis of Helicobacter pylori infection

Helicobacter pylori induces chronic gastritis, the strongest known risk factor for peptic ulcer disease and distal gastric cancer, yet only a fraction of colonized individuals ever develop clinical disease. H. pylori isolates possess substantial genotypic diversity, which engenders differential host inflammatory responses that influence pathologic outcome. However, clinical sequelae are not completely dependent upon bacterial virulence factors, and disease is also influenced by host genetic diversity, particularly within immune response genes. The focus of this article will be to provide an understanding of mechanisms that underlie H. pylori persistence and pathogenesis as a framework for understanding disease processes that develop from chronic inflammation. Identification of mechanisms that regulate ongoing H. pylori–host interactions will not only improve targeted diagnostic and therapeutic modalities, but may also provide insights into other diseases that arise within the context of pathogen-initiated inflammatory states.     

Pathogenicity of Helicobacter pylori infection

Numerous Helicobacter pylori virulence factors, including various enzymes (urease, catalase, lipase, phospholipase and proteases), vacuolating cytotoxin (a product of expression of the vacA gene), and the immunogenic protein CagA, encoded by the cagA gene localised in the H. pylori pathogenicity island, are involved in the pathomechanism of infection caused by these organisms. This review presents the current state of knowledge concerning the molecular mechanisms and epidemiology of H. pylori infection, based on the published literature and recent unpublished observations.     

Pathogenesis of Helicobacter pylori infection

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori.     

Helicobacter pylori gastric infection in gnotobiotic beagle dogs.

Establishment of infection with Helicobacter pylori and gastritis in nonhuman species is currently only successful in gnotobiotic piglets. This study was designed to determine whether H. pylori will colonize the gastrointestinal tract of gnotobiotic dogs. Gnotobiotic beagle pups were derived by standard methods. Group A (five dogs) was orally challenged with 3 x 10(8) H. pylori at 7 days of age. Group B (two dogs) received only peptone water but was contact-exposed beginning on day 23 postinfection (p.i.). Necropsy was performed on dogs on day 30 p.i. H. pylori colonized the stomach of all dogs (groups A and B). Urease map analysis correlated with the microbiologic findings and indicated that the density of colonization was less than that observed in human tissue. Organisms were also recovered from the pharynx, esophagus, duodenum, and rectum of 1, 2, 2, and 1 dog, respectively. All group A and one group B dog developed serum immunoglobulin G specific for H. pylori by day 30 p.i. Gross lesions were restricted to the stomach and consisted of small (less than 1 mm) lymphoid follicles. Microscopically, there were focal to diffuse lymphoplasmacytic infiltrates with follicle formation and mild to moderate infiltration of neutrophils and eosinophils in the gastric lamina propria. With the Warthin-Starry silver stain, organisms were seen on the surface of the gastric epithelial cells, beneath the mucus layer. We conclude that H. pylori colonizes the stomachs of gnotobiotic dogs for at least 1 month and the lesions resemble those seen in humans. H. pylori is transmissible by contact from infected to noninfected dogs.     

Antibody to cytotoxin in infection by Helicobacter pylori.

Gastrointestinal disease and colonization by Helicobacter pylori were determined in 36 asymptomatic volunteers and 30 symptomatic individuals undergoing endoscopy and biopsy. Serum antibody immunoglobulin G (IgG) and IgA to H. pylori were measured by enzyme-linked immunosorbent assay. Serum antibody to a cytotoxin produced by H. pylori was detected with a neutralization assay. Serum IgG was 95% predictive of infection by H. pylori, and serum IgA was 88% predictive. Antibody to the cytotoxin was detected in 12 of 18 infected individuals. Antibody to the cytotoxin was a highly specific (96%), but not a very sensitive (67%), indicator of infection by H. pylori. The neutralization assay was 87% predictive of infection. These data confirm the diagnostic value of serum antibody to H. pylori for the detection of infection. The toxin-neutralizing activity of sera from individuals infected with H. pylori suggests that the cytotoxin is produced in vivo. It may therefore contribute to disease associated with H. pylori.     

细胞自噬与幽门螺杆菌感染

幽门螺杆菌是一种广泛定植于人胃黏膜的革兰阴性菌,它通过逃逸机体局部免疫杀灭而持续感染,最终导致胃上皮损伤,与多种胃部疾病相关.自噬是进化过程中保留的细胞机制,既能清除胞质内容物,又不影响细胞的生存.幽门螺杆菌能够入侵胃上皮细胞和某些免疫细胞,诱导自噬的发生,并在自噬体中自我复制后被清除,推测自噬可能在幽门螺杆菌感染中扮...     

Diversity of Helicobacter pylori among Chinese persons with H. pylori infection

To determine whether there is diversity among clinical isolates of Helicobacter pylori in Chinese patients with peptic ulcer disease, 40 strains of H. pylori were isolated from antral biopsy specimens obtained at the gastroenterology clinic of Xiangya Hospital from January 1996 to June 1998. Total protein profile by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and DNA diversity by polymerase chain reaction-random amplified polymorphic DNA (PCR-RAPD) fingerprinting were performed with these isolates. All the isolates from peptic ulcer disease were relatively homogeneous in protein profiles, but they showed a great DNA sequence diversity by PCR-RAPD fingerprinting. In Chinese patients H. pylori demonstrated an enormous diversity. The diversity among clinical isolates of H. pylori could be distinctly demonstrated and this observation will be helpful in the management of intrafamilial and recurrent H. pylori infection. PCR-RAPD fingerprinting is an efficient method of distinguishing between clinical isolates of H. pylori.     

Intrafamilial clustering of Helicobacter pylori infection

Colonization of the gastric antrum by Helicobacter pylori (formerly Campylobacter pylori) has been associated with primary gastritis. We determined the frequency of colonization by H. pylori in gastric-antrum biopsy specimens from 93 children undergoing gastroscopy for the evaluation of upper gastrointestinal symptoms. We also determined H. pylori IgG antibody levels by enzyme-linked immunosorbent assay in coded serum samples from these children, family members, and control subjects of comparable ages. Among 27 children with primary, or unexplained, gastritis, H. pylori was identified by silver staining in 24 biopsy specimens and by culture in 22; specific antibodies were present in 23 children (96 percent). Three children with unexplained gastritis had no evidence of H. pylori in the antrum, nor did any of 13 children with secondary gastritis or any of 53 children with normal antral histologic features; specific antibodies were present in only 1 of these 69 children. H. pylori antibody was detected in 25 of 34 parents of colonized children, but in only 8 of 33 parents of noncolonized children (P less than 0.001). Of 22 siblings of children colonized by H. pylori, 18 had specific antibodies, as compared with only 5 of 37 controls (P less than 0.001). We conclude that H. pylori-specific IgG antibodies are associated with bacterial colonization of the gastric antrum by this organism. The intrafamilial clustering of H. pylori infection suggests that there may be person-to-person spread of these bacteria.     

Eradication therapy of Helicobacter pylori infection

Helicobacter pylori(H. pylori) infection is recognized to be a pathogen of various gastro-duodenal diseases. Eradication therapy of H. pylori reduces the recurrence of gastro-duodenal ulcer, and improves gastritis histologically. Recently, proton pump inhibitor(PPI) based triple therapy, that combining PPI, clarithromycin, amoxicillin is widely accepted throughout the world, and shows high eradication rate which ranged about 80-90%. In Japan, one week triple therapy is recommended for the treatment of gastro-duodenal ulcer, though it is expected the improvement of recurrent peptic ulcer. In the present studies, the rate of clarithromycin resistant strains has been increased gradually, and this fact may lead to the development of failure of PPI based triple therapy. Another problem is suggested by several studies that gastro-esophageal reflux disease(GERD) may increase after successful eradication of H. pylori. Reflux esophagitis and Barrett's esophagus are recognized as precancerous lesion of esophageal adenocarcinoma, but the association of newly occurrence of GERD after H. pylori eradication and increase of esophageal adenocarcinoma is not clear. Merits and demerits of H. pylori eradication need to be observed carefully over a long term.     

Helicobacter pylori infection and chronic gastritis in gastric cancer.

AIMS: To investigate the prevalence of Helicobacter pylori associated chronic gastritis in patients with gastric cancer. METHODS: Serum IgG antibodies for H pylori were determined in 54 consecutive patients with gastric carcinoma. The prevalence of H pylori in gastric mucosa was also examined histologically (modified Giemsa) in 32 patients from whom adequate biopsy specimens of the antrum and corpus were available. Thirty five patients with gastrointestinal tumours outside the stomach and 48 with non-gastrointestinal malignancies served as controls. RESULTS: Of the 54 patients, 38 (70%) had H pylori antibodies (IgG) in their serum (three additional patients had H pylori antibodies IgA, class specific but not IgG specific). This prevalence was significantly higher (p less than 0.05) than that (49%) in the 35 controls. No differences in prevalence of H pylori antibodies were found between gastric cancer cases of intestinal (IGCA) or diffuse (DGCA) type, both these types showing H pylori antibodies (IgG) in 71% of the patients. In the subgroup of 32 subjects, five patients had normal gastric mucosa and four showed corpus limited atrophy ("pernicious anaemia type" atrophy of type A). All of these nine patients had no evidence of current or previous H pylori infection in serum (no IgG antibodies) or in tissue sections (negative Giemsa staining). The remaining 23 patients had antral or pangastritis, and all had evidence of current or previous H pylori infection. CONCLUSIONS: H pylori associated chronic gastritis was the associated disease in 75% of the patients with gastric cancer occurring equally often in both IGCA and DGCA groups. About 25% of cases seem to have a normal stomach or severe corpus limited atrophy, neither of which showed evidence of concomitant H pylori infection.