Natural Competence Promotes Helicobacter pylori Chronic Infection

Animal models are important tools for studies of human disease, but developing these models is a particular challenge with regard to organisms with restricted host ranges, such as the human stomach pathogen Helicobacter pylori. In most cases, H. pylori infects the stomach for many decades before symptoms appear, distinguishing it from many bacterial pathogens that cause acute infection. To model chronic infection in the mouse, a human clinical isolate was selected for its ability to survive for 2 months in the mouse stomach, and the resulting strain, MSD132, colonized the mouse stomach for at least 28 weeks. During selection, the cagY component of the Cag type IV secretion system was mutated, disrupting a key interaction with host cells. Increases in both bacterial persistence and bacterial burden occurred prior to this mutation, and a mixed population of cagY⁺ and cagY mutant cells was isolated from a single mouse, suggesting that mutations accumulate during selection and that factors in addition to the Cag apparatus are important for murine adaptation. Diversity in both alleles and genes is common in H. pylori strains, and natural competence mediates a high rate of interstrain genetic exchange. Mutations of the Com apparatus, a membrane DNA transporter, and DprA, a cytosolic competence factor, resulted in reduced persistence, although initial colonization was normal. Thus, exchange of DNA between genetically heterogeneous H. pylori strains may improve chronic colonization. The strains and methods described here will be important tools for defining both the spectrum of mutations that promote murine adaptation and the genetic program of chronic infection.     

Chronic urticaria and Helicobacter pylori

Background: Helicobacter pylori (HP) have recently emerged as a novel eliciting factor for chronic urticaria (CU). The possible association between HP and CU has enormous potential, as eradicating HP could cure CU. Aims and Objectives: We conducted a study to assess the prevalence of HP infection and effect of bacterium eradication on skin lesions in patients of chronic idiopathic urticaria (CIU). Settings and Design: Four hundred sixty patients of CU attending the allergy clinic, SMS hospital, Jaipur during the period February 6, 2004, to February 6, 2006, were screened for possible eliciting factors. Patients with CIU were enrolled and others were excluded. Materials and Methods: Sixty-eight patients of CIU and similar number of age and sex matched controls, attending the allergy clinic, SMS Hospital, Jaipur were enrolled in the study. All patients underwent endoscopy with antral biopsy for urease and histopathology to identify HP-associated gastritis. Infected patients were given HP eradication therapy. Eradication of bacterium was confirmed by fecal antigen assay. Subjective response to treatment was judged using chronic urticaria quality-of-life questionnaire (CU-Q 2 oL) while objective response to treatment was judged by need for 'rescue medication' (antihistaminics). Statistical Analysis: Data were analyzed using Chi square and paired't' test for their level of significance. Results: HP associated gastritis was present in 48 (70.58%) patients, out of which 39 (81.25%) patients responded to eradication therapy. Ten (50.00%) patients without HP associated gastritis showed response to symptomatic therapy. Overall 49 (72.05%) patients responded and 19 (27.94%) showed no response. The value of chi2 was 28.571 (P = 0.003), which showed significant association between presence of HP and response to eradication regimen. Conclusion: The response of HP eradication therapy in infected patients of CIU is significant. HP should be included in diagnostic workup of patients with CIU.     

Chronic urticaria and Helicobacter pylori.

BACKGROUND: Although the clinical manifestations of chronic urticaria (CU) are similar in most patients, a variety of factors should be taken into consideration. In general, the cause of CU cannot be determined in most patients, and it is considered idiopathic. In the past several years, relationships between some patients with CU and hepatitis C or autoimmune thyroid diseases have been established. Similarly, other factors may also be considered as possible causes to explain certain patients with CU. Previously, some patients with CU have had their disease attributed to Helicobacter pylori (HP), but the relationship was only clinical. OBJECTIVE: None of the patients previously described included an immunological study. Thus, we studied a patient with CU, who showed marked clinical improvement after eradication of HP, to demonstrate an IgE relationship with this skin disease. METHODS: First, blood analytical parameters, roentgenograms, fecal examination for parasites, and skin tests were performed to try to establish an etiology. In addition, endoscopy with gastric biopsy confirmed HP colonization, and eradication treatment was prescribed. To investigate an immunological relationship, other tests performed included the following: HP-specific IgG, histamine release induced by HP, HP-specific IgE, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis with immunoblotting. RESULTS: The blood analytical parameters, roentgenograms, fecal examination for parasites, and skin tests were all negative. In contrast, the tests for HP-specific IgG, histamine release induced by HP, and HP-specific IgE were all positive. In addition, the sulfate-polyacrylamide gel electrophoresis with immunoblotting showed specific IgE binding to an extract of HP. CONCLUSIONS: Our results may indicate an immunological IgE relationship between HP colonization and CU in this particular patient.     

Antibody-Mediated Protection against Infection with Helicobacter pylori in a Suckling Mouse Model of Passive Immunity

Studies of active immunization against Helicobacter pylori indicate that antibodies play a minor role in immunity. There is also evidence, however, that the translocation of antibodies in the stomach may be insufficient to achieve functional antibody levels in the gastric lumen. We have used a suckling mouse model of passive immunity to determine if perorally delivered antibodies can protect against infection with H. pylori. Female C57BL/6 mice were immunized parenterally with formalin-fixed cells of three clinical isolates of H. pylori (3HP) or the mouse-adapted H. pylori strain SS1 before mating. Their pups were challenged with the SS1 strain at 4 days of age and left to suckle before determination of bacterial loads 14 days later. Compared to age-matched controls, pups suckled by 3HP-vaccinated dams were significantly protected against infection (>95% reduction in median bacterial load; P < 0.0001). Pups suckled by SS1-vaccinated dams were also significantly protected in terms of both median bacterial load (>99.5% reduction; P < 0.0001) and the number of culture-negative pups (28% versus 2% for immune and nonimmune cohorts, respectively; P < 0.0001). Similar results were obtained with pups suckled by dams immunized with a urease-deficient mutant of SS1. Fostering experiments demonstrated that protection was entirely attributable to suckling from an immunized dam, and antibody isotype analysis suggested that protection was mediated by the immunoglobulin G fraction of immune milk. Analysis of the bacterial loads in pups sampled before and after weaning confirmed that infection had been prevented in culture-negative animals. These data indicate that antibodies can prevent colonization by H. pylori and suppress the bacterial loads in animals that are colonized.Helicobacter pylori colonizes the gastric mucosa of humans and commandeers host defenses to establish chronic active gastritis while increasing the host''s susceptibility to gastroduodenal ulceration or certain gastric malignancies (37). Although H. pylori induces profound systemic and mucosal immune responses, clearance of infection is infrequent, and there is no protection against reinfection following eradication by antimicrobial chemotherapy (15). Consequently, there are no obvious parameters of natural immunity on which to base effective vaccination strategies.Vaccination studies of animal models have suggested that antibody development is not necessary for protective immunity to H. pylori (19) and may even enhance colonization (5, 6). Conversely, cellular immunity, possibly in concert with innate immune factors, such as defensins (59), elicits protection or eradication by exaggerating the gastric inflammatory response induced by H. pylori, thus interrupting colonization without a need to interact with the bacteria directly (3). The importance of the inflammatory response for protection against H. pylori is supported by the association of postimmunization gastritis with vaccine efficacy (6, 23). Nevertheless, the failure of antibody to limit H. pylori colonization is yet to be fully explained. One reason for this failure may be the relatively low level of antibodies in the gastric lumen due to the apparent inability of the mucosal immune system to translocate sufficient quantities of antibody across the gastric mucosa.Although well characterized in the intestine, relatively little is known about antibody secretion into the stomach. Some studies of H. pylori infection have reported that levels of immunoglobulin A (IgA) in gastric juice are significantly lower than those found in the saliva or intestinal contents (33, 34). Evidence that these low levels of IgA are due to inadequate antibody secretion in the stomach includes the following: (i) H. pylori-specific antibodies in gastric juice of infected individuals are predominantly nonsecretory IgA (10); (ii) equivalent amounts of IgG and IgA in the stomach suggest that IgA may leak across the mucosa rather than being actively secreted (14, 18); and (iii) much of the secretory IgA (sIgA) in the stomach is derived from swallowed saliva (17, 54). In addition, compared to the small intestine, the normal mammalian stomach has barely detectable secretory component (SC), suggesting a limited capacity for translocation of polymeric IgA across the gastric mucosa (8, 33). Moreover, despite considerable upregulation of SC by gamma interferon following the development of gastritis, there is no corresponding increase in the concentration of sIgA in gastric juice (4). Consequently, the concentration of sIgA in the stomach is unlikely to be sufficient to prevent or eradicate colonization by H. pylori.On the other hand, there is evidence that passive immunization with antibodies delivered perorally may reduce the extent of gastric colonization by Helicobacter species. This therapeutic approach has shown some promise in adult mice given monoclonal IgA or hyperimmune bovine colostrum against Helicobacter felis (14, 41) or urease-specific, chicken-derived IgY against H. pylori (44). In addition, reports of delayed acquisition of H. pylori by Gambian infants that corresponded to their mothers’ levels of breast milk IgA specific for H. pylori (58) and the protection of infant mice against full colonization by H. felis while suckling from immunized dams (13) suggest that orally delivered antibodies may be beneficial in controlling gastric Helicobacter infections. Despite these favorable reports, there are no tightly controlled studies that conclusively show prevention of H. pylori infection by orally delivered immune antibodies in the absence of additional factors, such as famotidine (44). Moreover, no studies have investigated the refinement of vaccine preparations for use in the production of anti-H. pylori polyclonal antibody products.In this study, we used a suckling mouse model of infection to investigate whether H. pylori-specific antibodies delivered during lactation to the gastric lumen of infant mice can protect against H. pylori infection. The route and adjuvant used to immunize the dams were selected to evoke an immune response similar to that required for the production of commercial quantities of polyclonal monomeric antibodies, such as from hyperimmune bovine colostrum. The model allowed us for the first time to quantify the contribution of passively acquired H. pylori-specific antibodies to protection against infection and provided an opportunity to examine different vaccine preparations for their ability to elicit these antibodies.     

Cytokine Expression in Pediatric Helicobacter pylori Infection

Helicobacter pylori infection is one of the most common gastrointestinal infections worldwide and almost invariably causes chronic gastritis in the infected host. A predominant Th1 profile has been demonstrated in H. pylori-infected mucosa from adults, but no previous study has evaluated in situ cytokine expression in children. We therefore examined expression of proinflammatory, anti-inflammatory, and regulatory cytokines by immunohistochemistry in cryopreserved antral biopsy specimens from 10 H. pylori-infected and 10 uninfected children and correlated expression of cytokines with histology scores. Concomitant expression of interleukin-8 (IL-8), gamma interferon (IFN-γ), IL-4, transforming growth factor β, and tumor necrosis factor alpha was seen in 8/10 H. pylori-infected cases and in 5/10 noninfected cases; all H. pylori-infected subjects showed staining for at least two of the cytokines. The proportion of epithelial cytokine-specific staining did not differ significantly between the groups, either in surface or glandular epithelium. Furthermore, no significant differences were noticed between intraepithelial or lamina propria lymphocyte staining in the groups. There was, however, a tendency of higher numbers of IFN-γ- and IL-8-positive cells in the H. pylori-infected group. IFN-γ and IL-8 lamina propria lymphocyte expression correlated significantly with antrum chronic inflammation, but there was no correlation between histology scores and epithelial cytokine expression. When the same techniques were used, the cytokine response appeared to be smaller in H. pylori-infected children than in adults, and there was no clear Th1 dominance. These results therefore suggest a different mucosal immunopathology in children. It remains to be determined whether the gastric immune response is downregulated in children with H. pylori infection and whether this is relevant to the outcome of infection.     

Infection with Helicobacter pylori and Leukocyte Response in Patients with Myocardial Infarction

 To test whether Helicobacter pylori may contribute to the inflammatory response following myocardial infarction, the levels of IgG antibodies to Helicobacter pylori and some parameters of leukocyte activity were measured in 63 patients and 61 comparable controls. Helicobacter pylori-positive patients showed a significantly higher expression of the adhesion molecule LFA-1 on neutrophils than Helicobacter pylori-negative patients (433±29.0 vs. 398.8±38.9 mean fluorescence channels; P<0.0001), whereas no significant difference for any parameters tested was found in control subjects. These data suggest a role of Helicobacter pylori in inducing a leukocyte response following myocardial infarction.     

Immune Responses of Specific-Pathogen-Free Mice to Chronic Helicobacter pylori (Strain SS1) Infection

A model permitting the establishment of persistent Helicobacter pylori infection in mice was recently described. To evaluate murine immune responses to H. pylori infection, specific-pathogen-free Swiss mice (n = 50) were intragastrically inoculated with 1.2 × 10⁷ CFU of a mouse-adapted H. pylori isolate (strain SS1). Control animals (n = 10) received sterile broth medium alone. Animals were sacrificed at various times, from 3 days to 16 weeks postinoculation (p.i.). Quantitative culture of gastric tissue samples from inoculated mice demonstrated bacterial loads of 4.0 × 10⁴ to 8 × 10⁶ CFU per g of tissue in the animals. Infected mice had H. pylori-specific immunoglobulin M (IgM) and IgG antibodies in serum (at day 3 p.i.) and IgG and IgA antibodies in their gastric contents (weeks 4 and 16 p.i.) and saliva (week 16 p.i.). Mucosal IgM antibodies were not detected. Histological examination of the gastric mucosae from control and infected mice revealed mild chronic gastritis, characterized by the presence of polymorphoneutrophil cell infiltrates and submucosal lymphoid aggregates, in infected animals at 16 weeks p.i. Differences in the quantities of IgG1 and IgG2a subclass antibodies detected in the sera of mouse strains (Swiss, BALB/c, and C57BL/6) infected by H. pylori suggested that host factors influence the immune responses induced against this bacterium in the host. In conclusion, immune responses to H. pylori infection in mice, like those in chronically infected humans, appear to be ineffective in resolving the infection.The presence of Helicobacter pylori bacteria in human gastric mucosae induces marked immune responses in the host (for a review, see reference 10). Volunteer ingestion experiments and case reports have shown that individuals develop severe polymorphonuclear leukocyte inflammation of the stomach mucosa soon after infection by H. pylori (23, 29). In addition, acutely infected individuals were reported to have anti-H. pylori immunoglobulin A (IgA) and IgM class antibodies in their gastric juice and/or sera within several weeks after having been infected (26, 27, 33). Though there has been some evidence of spontaneous eradication of H. pylori by the host (2, 26), most untreated individuals remain infected with the organism. In such cases, subjects develop a chronic gastritis which is characterized by the formation of gastric lymphoid tissue (10).Various animal models have been developed for study of H. pylori pathogenesis, and, until recently, those using large animal hosts such as gnotobiotic piglets, nonhuman primates, and cats have been the most successful at reproducing the pathology associated with human infection (for a review, see reference 14). Nevertheless, such models are relatively cumbersome and have a restricted applicability because of difficulties in handling large numbers of infected animals for significant periods and because of the limited availability of immunological reagents for these host species.In 1991, Karita and colleagues (18) established transient H. pylori infections in immunodeficient BALB/c animals, thus demonstrating for the first time that it was possible to colonize a small laboratory animal with H. pylori. More recently, there have been reports of the colonization of immunocompetent mice with mouse-adapted H. pylori isolates (19, 22, 24). By screening various H. pylori clinical isolates for their capacity to colonize mice, Lee and colleagues (21) identified one H. pylori strain (named SS1, or the Sydney strain) that, after adaptation to mice, was able to colonize mouse gastric mucosae in high numbers and for long periods (≤8 months).Data on host immune responses to H. pylori in humans have, for the most part, arisen from investigations of chronically infected individuals (2, 5, 6, 31), while studies with animal models have tended to focus on responses associated with acute or short-term H. pylori infections (18, 19, 22, 24). In this study, we sought to evaluate host immune responses to H. pylori in a murine infection model. To this end, mice were infected with H. pylori SS1 and the humoral immune responses of the animals were assessed over time. The findings demonstrated that chronic H. pylori SS1 infection in mice induced humoral immune responses that closely mimicked those observed in human H. pylori infections. As has been found to be the case for infected humans, adaptive immune responses do not appear to be effective in eradicating an existent H. pylori infection in mice. This is the first report detailing the humoral responses of mice to a persistent H. pylori infection.     

Experimental Infection of Mongolian Gerbils with Wild-Type and Mutant Helicobacter pylori Strains

Experimental Helicobacter pylori infection was studied in Mongolian gerbils with fresh human isolates that carry or do not carry cagA (cagA-positive or cagA-negative, respectively), multiply passaged laboratory strains, wild-type strain G1.1, or isogenic ureA, cagA, or vacA mutants of G1.1. Animals were sacrificed 1 to 32 weeks after challenge, the stomach was removed from each animal for quantitative culture, urease test, and histologic testing, and blood was collected for antibody determinations. No colonization occurred after ≥20 in vitro passages of wild-type strain G1.1 or with the ureA mutant of G1.1. In contrast, infection occurred in animals challenged with wild-type G1.1 (99 of 101 animals) or the cagA (25 of 25) or vacA (25 of 29) mutant of G1.1. Infection with G1.1 persisted for at least 8 months. All 15 animals challenged with any of three fresh human cagA-positive isolates became infected, in contrast to only 6 (23%) of 26 animals challenged with one of four fresh human cagA-negative isolates (P < 0.001). Similar to infection in humans, H. pylori colonization of gerbils induced gastric inflammation and a systemic antibody response to H. pylori antigens. These data confirm the utility of gerbils as an animal model of H. pylori infection and indicate the importance of bacterial strain characteristics for successful infection.     

Expression of the BabA Adhesin during Experimental Infection with Helicobacter pylori

The Helicobacter pylori babA gene encodes an outer membrane protein that mediates binding to fucosylated ABH antigens of the ABO blood group. We recently demonstrated that BabA expression is lost during experimental infection of rhesus macaques with H. pylori J166. We sought to test the generality of this observation by comparison of different H. pylori strains and different animal hosts. Challenge of macaques with H. pylori J99 yielded output strains that lost BabA expression, either by selection and then expansion of a subpopulation of J99 that had a single-base-pair mutation that encoded a stop codon or by gene conversion of babA with a duplicate copy of babB, a paralog of unknown function. Challenge of mice with H. pylori J166, which unlike J99, has 5′ CT repeats in babA, resulted in loss of BabA expression due to phase variation. In the gerbil, Leb binding was lost by replacement of the babA gene that encoded Leb binding with a nonbinding allele that differed at six amino acid residues. Complementation experiments confirmed that change in these six amino acids of BabA was sufficient to eliminate binding to Leb and to gastric tissue. These results demonstrate that BabA expression in vivo is highly dynamic, and the findings implicate specific amino acid residues as critical for binding to fucosylated ABH antigens. We hypothesize that modification of BabA expression during H. pylori infection is a mechanism to adapt to changing conditions of inflammation and glycan expression at the epithelial surface.Helicobacter pylori is a gastric bacterial pathogen of humans that chronically infects an estimated 50% of the world''s population (19). The consequence of long-term infection with H. pylori is typically asymptomatic gastritis, but ca. 10 to 15% of those infected will develop peptic ulcer disease or gastric adenocarcinoma (19). Several bacterial virulence factors are found more commonly in H. pylori strains that are associated with disease, the best studied of which are the cytotoxin-associated gene pathogenicity island (cag PAI) and certain alleles of the vacuolating cytotoxin, VacA. Another bacterial factor that is associated with disease, rather than asymptomatic infection, is the capacity for adherence. Approximately 4% of the H. pylori genome encodes a diverse repertoire of outer membrane proteins (OMPs), the largest of which is the 21-gene Hop family (1). BabA is a member of the Hop family that binds Lewis b (Leb) and related terminal fucose residues found on blood group O (H antigen), A, and B antigens that are expressed on the gastric epithelium (3, 6). Some studies suggest that patients infected with strains that express BabA are more likely to present with ulcer or gastric cancer, particularly if they also have the cag PAI and the s1m1 allele of vacA (12, 35).DNA sequence analysis suggests that among the genes encoding Hop family proteins there is considerable potential for both antigenic variation, in which combinatorial DNA shuffling creates antigenically distinct proteins, and phase variation, in which there is reversible on/off switching of gene expression. For example, there is extensive 5′ and 3′ homology between babA and two other H. pylori OMPs of unknown function called babB and babC (1). The greater similarity among bab paralogues (within a genome) than among orthologues (across genomes) suggests that there is frequent recombination and concerted evolution among these genes (27). Regions of dinucleotide CT repeats in the 5′ coding region of babA, babB, and other Hop genes may promote phase variation by slipped-strand mispairing during DNA replication. Finally, polynucleotide (A or T) tracts in babA and other Hop promoters might alter expression by subtle changes in the spacing between −35 and −10 hexamers. BabA proteins are also highly polymorphic in the variable midregion (26, 27), and they differ by more than 1,500-fold in their affinity for Leb (3).We recently showed that H. pylori strains recovered from experimentally challenged rhesus macaques had lost expression of BabA and the capacity to attach to Leb (33). In some cases the strains underwent a gene conversion event in which the babA gene was replaced by a duplicate copy of babB. In other cases the babA gene was present in H. pylori strains recovered from macaques, but it was not expressed due to phase variation that resulted from gain or loss of one CT repeat in the 5′ coding region of babA. These results demonstrate that H. pylori regulates OMP expression in vivo using both antigenic variation and phase variation. Here we sought to extend these observations by comparison of different animal hosts, including primate, mouse, and gerbil, and different H. pylori strains. The results indicate that loss of BabA expression and Leb attachment is a robust phenomenon that occurs via multiple genetic mechanisms in different H. pylori strains and across diverse animal models. Furthermore, analysis of subtle BabA variants that emerge during colonization permitted the identification of six amino acid changes that are sufficient to eliminate binding to Leb.     

Performance of Native and Recombinant Antigens for Diagnosis of Helicobacter pylori Infection

 The aim of this study was to evaluate the performance of three antigenic preparations for serological diagnosis of Helicobacter pylori infection: (i) native antigens from Helicobacter pylori strain N6 or its aflagellated isogenic mutant N6flbA ^–, or an acellular extract (antigen AgFA) from a pool of six clinical strains; (ii) recombinant antigens consisting of CagA fused to MS2 polymerase and HspA or recombinant UreA and UreB fused to the maltose-binding protein, and (iii) the preparations provided with two commercial kits, the Cobas Core (Roche Diagnostic Systems, France) and the Pylori Stat (BioWhittaker, Belgium). All preparations were used in an enzyme immunoassay to test 92 sera from dyspeptic patients for whom the status of Helicobacter infection was established. Sensitivities were higher (90 to 100%) for the native antigens and the commercial kits than for the recombinant antigens. Specificities were higher than 90%, except with UreA + UreB (42%). The most useful antigens were those extracted from strains N6 and N6flbA ^–.     

Treatment of Helicobacter pylori Infection in Korea: A Systematic Review and Meta-analysis

The efficacy of seven-day clarithromycin-based standard triple therapy (STT) for Helicobacter pylori has decreased in Korea over the past decade. The aim of this meta-analysis was to clarify the efficacy of first-line and second-line therapies in Korea. This systematic review will provide an overview of H. pylori eradication and present new therapeutic strategies used in Korea. An extensive search of the literature concerning STT, sequential therapy (SET), concomitant therapy (CT), bismuth-containing quadruple therapy (BCQT) and various other therapies used in Korea was performed. All selected studies were randomized controlled trials (RCTs). Eighteen RCTs were eligible for systematic review. The alternative regimens comparing seven-day STT as a first-line therapy include SET, CT, levofloxacin-based therapy (LBT), BCQT, and STT with prolonged duration. The results of the meta-analysis suggest that SET is superior to seven-day STT. The overall eradication rate by intention to treat (ITT) analysis was 69.8% for STT and 79.7% for SET. The overall eradication rate by per-protocol (PP) analysis was 77.0% for STT and 85.0% for SET. The odds ratios for the ITT and PP eradication rate were 0.57 (95% confidence interval [CI], 0.43 to 0.74) and 0.52 (95% CI, 0.35 to 0.76), respectively. In the subgroup analysis, however, there were no significant differences between SET and STT with prolonged durations. Alternative regimens to seven-day BCQT as second-line therapy include LBT, moxifloxacin-based therapy and 14-day BCQT. The eradication rates of these alternative regimens were not superior to that of the conventional treatment. SET is superior to seven-day STT but not to STT with prolonged duration.

Graphical Abstract

相似文献   

Seroprevalence of Helicobacter pylori Infection in Urban and Rural Vietnam

Helicobacter pylori-associated diseases, such as peptic ulcer and gastric cancer, are common in Vietnam, but the prevalence of the infection is largely unknown. A validated enzyme-linked immunosorbent assay was used for seroepidemiology with 971 samples from the general population, ages 0 to 88 years, with 546 samples from an urban population (Hanoi), and with 425 samples from a poor, rural province (Hatay). The overall seroprevalence of the infection was 746 per 1,000, with a prevalence of 788 per 1,000 in Hanoi and 692 per 1,000 in Hatay (P = 0.0007). The risk for infection in the rural area of Hatay was 40% lower than in the urban population of Hanoi, with the odds ratio being 0.59 (95% confidence interval, 0.43 to 0.81). The study shows that the prevalence of H. pylori infection is high in Vietnam and especially high in a large urban area, such as the city of Hanoi.     

Immunization against Natural Helicobacter pylori Infection in Nonhuman Primates

Helicobacter pylori infection is widespread in some breeding groups of a rhesus monkey colony (71% H. pylori positive by 1 year), and the rate of seroconversion is also high. As a result, these groups can be used to test the safety and efficacy of an anti-H. pylori vaccine. Nine-month-old female animals were randomized to receive either 8 mg of recombinant urease (rUre) plus 25 μg of Escherichia coli heat-labile enterotoxin (LT) (n = 26) or placebo plus LT (n = 29), given four times at 1-week intervals followed by a booster 1 month later. Ten months after the start of the immunization, the animals were subjected to endoscopy and biopsy samples were obtained. H. pylori negativity was defined as no H. pylori growth by culture and no H. pylori observed at histology. By this criterion, 2 (7%) of 29 animals receiving placebo and 8 (31%) of 26 immunized animals were H. pylori negative (P < 0.035). In addition, antral gastritis score was significantly less in H. pylori-negative immunized monkeys than in H. pylori-positive animals, whether they were given rUre plus LT or placebo plus LT (P < 0.02 or P < 0.01, respectively). Interestingly, antral gastritis was also significantly less in H. pylori-positive animals given rUre plus LT than in H. pylori-positive animals given placebo plus LT (P < 0.02). However, quantitative cultures did not demonstrate significant differences between the two latter groups. It is concluded that oral administration of rUre vaccine plus LT significantly protects nonhuman primates against H. pylori infection while not causing undesirable side effects.     

4214名健康体检者幽门螺杆菌检验结果分析

目的 探讨大连地区体检人群幽门螺杆菌尿素酶抗体阳性率及分布特点.方法 用胶体金法对2013年9月至2015年9月期间在大连市第三人民医院做体检的4214名健康体检者的幽门螺杆菌尿素酶抗体进行检测,以性别和年龄进行分组,对其检验结果进行统计学分析.结果 4214名健康体检者幽门螺杆菌总阳性率为21.76％ (917/4214);其中男性和女性健康体检者阳性率分别为23.98％ (480/2002)、19.76％ (437/2212),男性和女性健康体检者幽门螺杆菌阳性率比较,差异有统计学意义(P＜0.05);再将这些体检者分为＜45岁、45～ 59岁、60 ～ 74岁和75～ 89岁4个组,幽门螺杆菌阳性率在4个年龄组分别为19.13％ (447/2337)、24.77％(357/1441)、26.09％(102/391)和24.44％(11/45),组间幽门螺杆菌尿素酶抗体阳性率差异具有统计学意义(P＜0.05).结论 大连地区体检人群幽门螺杆菌尿素酶抗体阳性率分布与性别和年龄有关.     

Immunoglobulin G Antibody Response to Infection with Coccoid Forms of Helicobacter pylori

An increasing number of studies support a potential role for coccoid forms in Helicobacter pylori infection. Evidence for this was obtained through scanning microscopy, genetic analysis for virulence traits, examination of the presence and activity of key enzymes, and other methods. We studied the serum immunoglobulin G responses to coccoid H. pylori forms by enzyme-linked immunosorbent assay (ELISA) and immunoblotting and compared them with those of bacillary cells. Sera from a total of 295 infected individuals were studied; these included sera from 100 patients with duodenal ulcers, 98 patients with nonulcer dyspepsia, 11 patients with gastroduodenal cancer, and 86 asymptomatic individuals. Initially, we characterized and selected coccoid and bacillary antigenic preparations by one-dimensional (1-D) and 2-D gel electrophoresis and immunoblotting. Data showed that coccoid and bacillary preparations with comparable protein contents have similar patterns in 1-D and 2-D electrophoresis gels and antigenic recognition at blotting. These results revealed that coccoid and spiral antigens in ELISA can equally recognize specific antibodies to H. pylori in sera from infected individuals. The analysis of the spiral and coccoid preparations by Western blotting showed no major differences in antigen recognition. No specific bands or profiles associated with a single gastric condition were identified.     

Serological Methods for Diagnosis of Helicobacter pylori Infection and Monitoring of Eradication Therapy

 Several methods can be used to diagnose Helicobacter pylori infection. Invasive methods include detection of the bacterium in gastric biopsy specimens by culture, immunohistochemistry, rapid urease tests, or the polymerase chain reaction. Noninvasive or less invasive detection methods include the urea breath test and serological methods. The urea breath test is based on the detection of ¹³CO₂ or ¹⁴CO₂ in breath, produced by bacterial urease in the stomach after labelled urea is swallowed. Serological methods are based on the detection of Helicobacter pylori-specific antibodies in serum, saliva, or urine. In this review, the performance and diagnostic value of several serological methods, such as enzyme immunoassay, rapid office-based assays, and Western blot, will be discussed in relation to biopsy-based methods and the urea breath test. In addition, the value of serological assays for monitoring eradication of Helicobacter pylori infection following treatment will be discussed. The diagnostic performance of properly evaluated serological assays is comparable to that of biopsy-based methods and the urea breath test. To monitor eradication of Helicobacter pylori infection following therapy, quantitative enzyme immunoassays can be used, especially in patients with high pretreatment antibody titres.     

Chronic inactive gastritis and coccoid Helicobacter pylori in patients treated for gastroesophageal reflux disease or with H pylori eradication therapy

Gastric biopsy specimens from 105 consecutive adults with persistent dyspepsia who did not have changes due to esophageal reflux disease changes or gastric or duodenal ulcers at endoscopy were scored using the updated Sydney gastritis classification system. The medication history of proton pump inhibitors (PPIs) or Helicobacter pylori eradication therapy during the month before endoscopy was retrieved. Of the patients, 72 (68.6%) had chronic inactive gastritis, and 7 (6.7%) had antral-predominant, chronic mild active gastritis. H pylori infection was present in 36 patients (34.3%), of whom 29 had chronic inactive gastritis. Forty-six patients (43.8%) had a positive medication history, including 40 (56%) of 72 with chronic inactive gastritis. The most common morphologic feature associated with H pylori infection was moderate chronic inactive gastritis, which was found most often in patients who had received recent PPIs or H pylori eradication therapy. Pathologists should be aware of the extensive use of these medications, their association with chronic inactive gastritis, and rare H pylori thatfrequently are coccoid shaped. Modified Giemsa stain may not be the optimal method to detect H pylori in this group of patients.