Characterization of feline Helicobacter pylori strains and associated gastritis in a colony of domestic cats.

Twenty-four young adult domestic cats from a commercial vendor were found to be infected with Helicobacter pylori. Histopathologic analyses, selected electron microscopy, and urease mapping were performed on mucosal samples collected from the cardias and fundi, bodies, and antra of these cats' stomachs. H. pylori organisms were abundant in all areas of the stomach on the basis of histologic evaluation and urease mapping. H. pylori infection was associated with a moderate to severe lymphofollicular gastritis in 21 of 24 cats (88%). The gastritis was most pronounced in the antral region and consisted mainly of multifocal lymphoplasmacytic follicular infiltrates in the deep mucosa. The severity of gastritis in the antrum corresponded to high numbers of H. pylori there on the basis of the use of the urease assay as an indicator of H. pylori colonization. Ten of 24 cats (42%) also had small to moderate numbers of eosinophils in the gastric mucosa. All 24 cats had gastric lymphoid follicles, with follicles being most prevalent in the antrum. Electron microscopy of gastric tissue revealed numerous H. pylori organisms, some of which were closely adhered to the mucosal epithelium. Human H. pylori gene-specific primers to ureA and ureB amplified products of similar sizes from H. pylori cat isolates. Digestion of the products with restriction enzymes resulted in fragments characteristic of the restriction fragment length polymorphism patterns of H. pylori isolates from humans.(ABSTRACT TRUNCATED AT 250 WORDS)     

Helicobacter pylori isolated from the domestic cat: public health implications.

Helicobacter pylori has been directly linked with active chronic gastritis, peptic ulceration, and gastric adenocarcinoma in humans. Although a substantial portion of the human population is colonized with H. pylori, the patterns of transmission of the organism remain in doubt, and reservoir hosts have not been identified. This study documents the isolation of H. pylori from domestic cats obtained from a commercial vendor. The isolation of H. pylori from these cats was confirmed by morphologic and biochemical evaluations, fatty acid analysis, and 16S rRNA sequence analysis. H. pylori was cultured from 6 cats and organisms compatible in appearance with H. pylori were observed in 15 additional cats by histologic examination. In most animals, H. pylori was present in close proximity to mucosal epithelial cells or in mucus layers of the glandular or surface epithelium. Microscopically, H. pylori-infected cat stomachs contained a mild to severe diffuse lymphoplasmacytic infiltrate with small numbers of neutrophils and eosinophils in the subglandular and gastric mucosae. Lymphoid follicles were also noted, particularly in the antrum, and often displaced glandular mucosal tissue. Thus, the domestic cat may be a potential model for H. pylori disease in humans. Also, the isolation of H. pylori from domestic cats raises the possibility that the organism may be a zoonotic pathogen, with transmission occurring from cats to humans.     

Helicobacter pylori gastritis in cats with long-term natural infection as a model of human disease

A natural infection with Helicobacter pylori (H. pylori) in domestic cats (Felis cattus) less than 2 years of age has been well described in a closed colony of animals. Six cats from this colony that were serially evaluated by culture, polymerase chain reaction, and light and electron microscopy for a period of 3 years demonstrated persistent gastric colonization with a single cag(-) vac(+) strain of H. pylori. In these cats, as well as five other 5- to 6-year-old cats that were examined, a long-term infection resulted in chronic diffuse lymphofollicular atrophic gastritis with areas of mucosal dysplasia in the antrum and predominantly midsuperficial gastritis in the body and cardia. Topographically, the distribution of lesions was similar in both young and older cats and closely resembled that found in humans, with the most severe changes occurring in the gastric antrum. Few granulocytes and no significant elevation in mast cells were seen in older H. pylori-infected cats compared with uninfected controls; however, marked increases in interepithelial globule leukocytes and numerous active mucosal lymphoid follicles were present in infected animals. Indices of gastritis were significantly greater in older infected cats when compared with uninfected controls and younger cats (P < 0.05). The antral cell proliferation index of infected older cats was significantly (P = 0.021) greater than that of uninfected controls. Apoptotic indices of the gastric antrum and body of infected cats were significantly (P = 0.01) increased versus controls. Chronic infection with H. pylori in cats shares many features of long-term H. pylori infection in humans, including the development of preneoplastic processes. This similarity provides useful, comparative insights into host-pathogen interactions.     

Helicobacter mustelae-induced gastritis and elevated gastric pH in the ferret (Mustela putorius furo).

Helicobacter mustelae has been cultured from the stomachs of ferrets with chronic gastritis; the lesions in the stomach have many of the same histological features seen in H. pylori gastritis in humans. To determine whether H. mustelae-negative ferrets with normal gastric mucosa were susceptible to colonization and whether gastritis developed after infection, four H. mustelae-negative ferrets treated with cimetidine were inoculated orally on two successive days with 3 ml (1.5 x 10(8) CFU) of H. mustelae; eight age-matched H. mustelae-negative ferrets served as controls. All four ferrets became colonized; H. mustelae persisted through week 24 of the study, as determined by positive gastric culture, tissue urease, and Warthin-Starry staining of gastric tissue. Superficial gastritis developed in the oxyntic gastric mucosa, and a full-thickness gastritis, composed primarily of lymphocytes and plasma cells plus small numbers of neutrophils and eosinophils, was present in the antrum. The inflammation was accompanied by an elevation of immunoglobulin G antibody to H. mustelae. At 4 weeks post-inoculation, the four infected (experimental) ferrets developed an elevated gastric pH (4.0 to 5.2) for 2 weeks. The eight control ferrets did not have gastritis; H. mustelae could not be demonstrated in gastric tissue via culture, nor was there an immune response to the bacteria. In ferrets, H. mustelae readily colonizes the stomach and produces a gastritis, a significant immune response, and, like H. pylori infection in humans, a transient elevated gastric pH after Helicobacter infection.     

Helicobacter felis gastritis in gnotobiotic rats: an animal model of Helicobacter pylori gastritis.

The gastric spirillum Helicobacter felis, originally isolated from the cat stomach, colonizes the stomachs of germfree rats. Studies were designed to examine the pathological and serological responses of germfree rats inoculated orally with H. felis. At 2 weeks postinoculation, the gastric mucosa of germfree rats had lymphocytes and eosinophils scattered in small foci throughout the subglandular region of the antrum. Small numbers of lymphocytes were present in the subglandular portion of the antral mucosa that focally extended through the lamina propria towards the luminal surface. Eight weeks postinoculation, the inflammation was confined to the antrum. It was characterized by increased numbers of lymphocytes and eosinophils in the subglandular areas, with focal aggregates of lymphocytes in the submucosa. Some lymphoid aggregates extended from the submucosa through the muscularis mucosa and lamina propria to the luminal surface. H. felis was demonstrated with the Warthin-Starry stain, bacterial culture, and urease assay, particularly in the antrum. H. felis also produced a significant immunoglobulin G antibody titer at 2, 4, and 8 weeks postinoculation as well as a transitory immunoglobulin M response at 2 to 4 weeks postinoculation. Contact control rats were not infected, inferring that fecal-oral spread of H. felis did not occur.     

Helicobacter pylori-mediated gastritis induces local downregulation of secretory leukocyte protease inhibitor in the antrum

Helicobacter pylori-infected subjects exhibited a strong decline in antral secretory leukocyte protease inhibitor (SLPI) levels compared to H. pylori-negative subjects and subjects from whom H. pylori had been eradicated (P = 0.002). This reduction was specific for the antrum, whereas SLPI expression in corpus and duodenum was not affected. Antral SLPI levels were inversely correlated with inflammatory scores of antrum-predominant gastritis.     

Up-regulation of cathepsin X in Helicobacter pylori gastritis and gastric cancer

Recently, we identified increased cathepsin X expression in H. pylori-infected gastric mucosa. Here, we describe further up-regulation in gastric cancer and report on the role of inflammatory cytokines required for cathepsin X up-regulation in H. pylori-infected gastric mucosa, as well as on consequences for cellular invasion. Biopsy specimens were taken from the antrum, corpus and cardia of H. pylori-infected and non-infected patients. Gastric cancer samples were obtained from patients undergoing gastric surgery. Cathepsin X was detected in gastric mucosa by quantitative real-time RT-PCR, western blotting and immunohistochemistry. Induction of cathepsin X expression in epithelial and inflammatory cells caused by H. pylori infection was tested in in vitro contact and non-contact co-cultures of AGS cells and monocytic cells. Patients with H. pylori gastritis showed significantly higher cathepsin X mRNA (2.5-fold) and protein (1.6-fold) expression than H. pylori-negative patients. Cathepsin X was also up-regulated in gastric cancer (3-12-fold) compared to non-neoplastic mucosa. Cathepsin X was predominantly expressed by macrophages in the mucosal stroma and in glands of the antral mucosa. In addition, tumour cells stained for cathepsin X in 26 (68%) patients with gastric carcinoma. In general, staining was significantly more common (20 vs. 6 patients) and more intense (3.55 vs. 0.83) in intestinal type gastric cancer than in the diffuse type. In vitro cell culture experiments revealed that intercellular signalling between pathogenicity island (PAI)-positive H. pylori-infected epithelial cells and macrophages via soluble factors in the culture medium seems to be responsible for increased expression of cathepsin X in monocytes. Using antisense oligonucleotides, cathepsin X up-regulation was directly associated with higher invasiveness in vitro. Although no correlation of cathepsin X expression and TNM stage was found, our study demonstrates that cathepsin X plays a role not only in the chronic inflammation of gastric mucosa but also in the tumourigenesis of gastric cancer.     

Involvement of myeloid dendritic cells in the development of gastric secondary lymphoid follicles in Helicobacter pylori-infected neonatally thymectomized BALB/c mice

We previously described an animal model of Helicobacter pylori-induced follicular gastritis in neonatally thymectomized (nTx) mice. However, it is still not clear whether antigen-presenting dendritic cells (DCs) in the stomach have a role in the development of secondary follicles in H. pylori-infected nTx mice. We investigated the distribution of DC subsets using this model and examined their roles. To identify lymphoid and myeloid DCs, sections were stained with anti-CD11c (pan-DC marker) in combination with anti-CD8alpha (lymphoid DC marker) or anti-CD11b (myeloid DC marker) and were examined with a confocal microscope. Expression of macrophage inflammatory protein 3alpha (MIP-3alpha), which chemoattracts immature DCs, was analyzed by real-time PCR and immunohistochemistry. Follicular dendritic cells (FDCs) were stained with anti-SKY28 antibodies. In noninfected nTx mice, a few myeloid and lymphoid DCs were observed in the bottom portion of the lamina propria, whereas in H. pylori-infected nTx mice, there was an increased influx of myeloid DCs throughout the lamina propria. FDC staining was also observed in the stomachs of members of the infected group. MIP-3alpha gene expression was upregulated in the infected nTx group, and the immunohistochemistry analysis revealed MIP-3alpha-positive epithelial cells. These data suggest that H. pylori infection upregulates MIP-3alpha gene expression in gastric epithelial cells and induces an influx of myeloid DCs in the lamina propria of the gastric mucosa in nTx mice. Myeloid DCs and FDCs might contribute to the development of gastric secondary lymphoid follicles in H. pylori-infected nTx mice.     

Helicobacter pylori associated gastric diseases and lymphoid tissue hyperplasia in gastric antral mucosa

AIM: To investigate the relation between Helicobacter pylori associated gastroduodenal diseases and lymphoid tissue hyperplasia in the antral mucosa and to pursue its evolution after eradication of H pylori. METHODS: Gastric antral biopsy specimens were obtained from 438 patients with H pylori positive gastroduodenal diseases (185 chronic gastritis, 69 gastric ulcer, and 184 duodenal ulcer) and 50 H pylori negative healthy controls. Lymphoid follicles and aggregates were counted and other pathological features were scored according to the updated Sydney system for classification of chronic gastritis. After a course of anti-H pylori treatment, biopsy specimens were obtained at four to six weeks, 12 months, and 24 months in the chronic gastritis patient group. RESULTS: The total prevalence of lymphoid follicles and aggregates in the biopsies was 79.9% (350 of 438; 95% confidence intervals (CI), 0.76 to 0.84). The prevalence and density of lymphoid follicles and aggregates were significantly different in the various gastroduodenal diseases. The highest prevalence (89.9%; 95% CI, 0.83 to 0.97) and density (0.82) of lymphoid follicles and aggregates occurred in patients with gastric ulcers. The lowest prevalence of lymphoid follicles and aggregates was found in patients with chronic gastritis (74.6%; 95% CI, 0.68 to 0.81), and the lowest density of lymphoid follicles and aggregates (0.56) was seen in patients with duodenal ulcers. The prevalence and density of lymphoid follicles and aggregates correlated strongly with the activity and severity of gastric antral mucosal inflammation. The eradication of H pylori resulted in a decrease in the prevalence and density of lymphoid follicles and aggregates. CONCLUSION: The prevalence and density of lymphoid follicles and aggregates in gastric antral mucosal biopsies correlated closely with H pylori infection.     

Serum pepsinogen and Helicobacter pylori infection—a Japanese population study

The decreased ratio of serum pepsinogen (PG) I and II has good correlation with the presence of atrophic gastritis. A total of 1,540 residents aged 30-89?years were enrolled into this study to investigate which serum PG level of residents with Helicobacter pylori infection would represent an adjunct to the diagnosis and progression of atrophic gastritis. All participants received esophagogastroduodenoscopy. Serum antibody to H. pylori (anti-H. pylori) was measured by an enzyme-linked immunosorbent assay (ELISA). Serological atrophic gastritis was defined as serum PG I isozyme level ≤70?ng/ml and a PG I/II ratio of ≤3.0. Of the 1,540 participants, 923 (59.9%) were positive for anti-H. pylori. Serological atrophic gastritis was found significantly more often in anti-H. pylori-positive participants (40.8%) than in anti-H. pylori-negative participants (7.9%) (p?≤?0.0001). The endoscopic findings of anti-H. pylori-positive participants with serological atrophic gastritis were significantly more frequent by 4.06 times for atrophic gastritis (p?≤?0.0001) than anti-H. pylori-negative participants without serological atrophic gastritis. Eight anti-H. pylori-positive participants were diagnosed with gastric cancer, but no cancer was found in anti-H. pylori-negative participants without serological atrophic gastritis. Serum PG testing is clinically useful for the prediction of gastric lesions in H. pylori-infected persons.     

Role of activated protein C in Helicobacter pylori-associated gastritis

The protein C (PC) pathway has recently been suggested to play a role in the regulation of the inflammatory response. To further extend the anti-inflammatory effect of activated PC (APC) in vivo, particularly its biological relevance to human disease, the activity of APC in the mucosa of patients with Helicobacter pylori-associated gastritis and the effect of vacuolating cytotoxin (VacA), cytotoxin-associated antigen (CagA), and H. pylori lipopolysaccharide (LPS) on PC activation were evaluated. This study comprised 35 patients with chronic gastritis. There were 20 patients with and 15 without H. pylori infection. The levels of PC and APC-PC inhibitor (PCI) complex were measured by immunoassays. The level of PC was significantly decreased and the level of APC-PCI complex was significantly increased in biopsy specimens from gastric corpus and antrum in patients with H. pylori-associated gastritis as compared to H. pylori-negative subjects. The concentrations of VacA, CagA, and LPS were significantly correlated with those of the APC-PCI complex in biopsy mucosal specimens from the gastric corpus and antrum. H. pylori LPS, VacA, and CagA induced a dose-dependent activation of PC on the surface of monocytic cells. APC inhibited the secretion of tumor necrosis factor alpha (TNF-alpha) induced by H. pylori LPS. Overall, these results suggest that H. pylori infection is associated with increased APC generation in the gastric mucosa. The inhibitory activity of APC on TNF-alpha secretion may serve to protect H. pylori-induced gastric mucosal damage.     

Lymphoid aggregates in gastric biopsies: relationship to other mucosal lesions

The purpose of this study is to estimate the prevalence of lymphocyte aggregates (precursor of MALT lymphomas) in gastric mucosal biopsies and to associate gastric lymphoid tissue with the age of patients, Helicobacter-associated gastritis and other gastric mucosal pathology. A consecutive series of gastric mucosal samples from 150 children and 256 adults were assessed for the presence of lymphoid aggregates as well as morphological characteristics, Helicobacter pylori status, signs of gastritis, mucosal atrophy and lymphoepithelial lesions. Fifteen selected samples with prominent lymphoid aggregates and 10 controls were examined immunohistochemically for the immunoglobulins A, G, M, lymphocytes B and T, clonality of B cell population, atypical lymphocytes and Epstein-Barr virus (EBV) antigen. There was an increase of H. pylori infection and mucosal lymphoid aggregates (MALT) rates in parallel with the increasing age of patients noted in the histological assessment of the mucosal samples. A close association of lymphoid aggregates with H. pylori infection and prominent active gastritis was found, but in adults with chronic non-active, particularly atrophic gastritis this association became weaker. No morphological and immunohistochemical signs of MALT lymphoma were present. Lymphoid aggregates in children were larger, with follicles, but less numerous and tended to be located in the intermediate and deeper parts of the gastric mucosa. Immunohistochemical studies showed an increase of IgA, IgM and lymphocytes T in the deeper part of the lamina propria in H. pylori-associated gastritis and lymphocyte T accumulation in the periphery of the lymphoid follicles. No evidence of monoclonality, CD31 positive lymphocytes or EBV antigen was detected. Lymphoid aggregates are related, but not exclusively, to H. pylori infection. Their detection rates achieve a peak in young adults with H. pylori infection. Lymphocytic aggregates are also present in chronic atrophic gastritis without H. pylori infection and may relate to autoimmune inflammatory response to other factors.     

Local immune response in Helicobacter pylori-infected cats and identification of H. pylori in saliva, gastric fluid and faeces.

Helicobacter pylori-infected cats were screened by culture and polymerase chain reaction (PCR) for the presence of H. pylori in salivary secretions, gastric juice, gastric tissue and faeces. H. pylori was cultured from salivary secretions in six of 12 (50%) cats and from gastric fluid samples in 11 of 12 (91%) cats. A 298 base pair polymerase chain reactions (PCR) product specific for an H. pylori 26000 MW surface protein was amplified from dental plaque samples from five of 12 (42%) cats and from the faeces of four of five (80%) cats studied. Analyses of serum and mucosal secretions by enzyme-linked immunosorbent assay (ELISA) revealed an H. pylori-specific immunoglobulin G (IgG) response, and elevated IgA anti-H. pylori antibody levels in salivary and local gastric secretions. Immunohistochemical analyses of gastric tissue revealed the presence of IgM+ B cells assembled into multiple lymphoid follicles surrounded by clusters of CD4+ and CD8+ T cells. The lamina propria also contained single cells or aggregates of IgA+ and IgM+ B cells. These observations show that H. pylori can be identified in feline mucosal secretions, and that a localized IgA immune response develops in gastric tissue of H. pylori-infected cats. The findings suggest a zoonotic risk from exposure to personnel handling H. pylori-infected cats in vivaria.     

Experimental gastritis induced by Helicobacter pylori in Japanese monkeys.

We used Japanese monkeys (Macaca fuscata) to establish an experimental model in order to clarify the pathogenicity of Helicobacter pylori in gastric and duodenal disorders. A suspension (5 ml; 10(9) CFU/ml) of H. pylori cells isolated from humans was sprayed around the antrum of the stomach of each of 12 of 17 animals with an endoscope. The remaining five animals were not inoculated; they served as a control group. On days 7, 14, and 28 after inoculation, the gastric mucosa samples were examined grossly and were biopsied for microscopic examination with an endoscope. H. pylori was recovered from 7 of the 12 inoculated animals (58%), and infiltration by neutrophils and monocytes was observed histologically. Macroscopic gastritis with erythema and erosions were noted for five of these animals. On day 28 after inoculation, five animals in the infected group were treated with ampicillin. In two infected but untreated animals, the bacteria persisted for more than 6 months. The result of the gastritis scoring of the antral mucosa and the ammonia concentration in the gastric secretion were significantly higher (P < 0.01 to 0.001) for the infected group than for the control group; however, these values decreased to levels comparable to those for the control group after treatment with ampicillin. Urease activity was positive in gastric biopsy specimens from five of the seven animals in the infected group after 7 days and from four of these animals after 14 days but was negative in all specimens from animals in the control group. The level of antibody (immunoglobulin G) in serum for the infected group was elevated but changed very little for the control group. These results suggest that this M. fuscata model can be used to study H. pylori infection and that H. pylori can induce gastritis.     

Two- to four-year histological follow-up of gastric mucosa after Helicobacter pylori eradication.

In a 2- to 4-year prospective study, the reversibility of gastritis after Helicobacter pylori eradication was analysed. Sixty-three H. pylori-positive, chronic duodenal ulcer patients were studied after the successful eradication of bacteria in the period from 1990 to 1993. H. pylori eradication was obtained by triple antimicrobial regimens (colloidal bismuth subcitrate, amoxycillin, and metronidazole) applied for at least 14 days. The criteria for eradication were the absence of bacteria from two antral and two body of stomach biopsies stained with haematoxylin, eosin, and Warthin Starry, and a negative antral biopsy culture. The same diagnostic procedures were repeated, at regular follow-up endoscopies, each year for up to 4 years. Neutrophil-granulocyte infiltration of gastric mucosa disappeared in 2 months after bacterial eradication. Mononuclear cellular infiltration was disappearing with statistical significance up to the second year and normal mucosa was observed in the majority of patients in the fourth year of follow-up. Degeneratively changed lymphoid aggregates were also present in the fourth year in the antrum (12.5 per cent of patients) and in the body of stomach (14 per cent of patients). There was no significant change in antral intestinal metaplasia during the 4 years of follow-up. Antral atrophy declined significantly in the period from 1 to 3 years of follow-up. In conclusion, 3-4 years are needed for gastric mucosa to become normal after H. pylori eradication, although some residual lymphoid aggregates persist even after that period.     

Enhanced disease severity in Helicobacter pylori-infected mice deficient in Fas signaling

Recent evidence suggests that immune-mediated gastric epithelial cell apoptosis through Fas-Fas ligand interactions participates in Helicobacter pylori disease pathogenesis. To define the role of Fas signaling in vivo, H. pylori strain SS1 infection in C57BL/6 mice was compared to that in mice deficient in the Fas ligand (gld). gld mice had a degree of gastritis similar to that of C57BL/6 mice after 6 weeks (gastritis score, 5.2 +/- 0.6 [mean +/- standard error] versus 3.5 +/- 0.8) and 12 weeks (4.0 +/- 0.7 versus 3.4 +/- 0.5) of infection. Bacterial colonization was comparable in each group of mice at 12 weeks of infection (2.1 +/- 0.3 versus 1.6 +/- 0.3 for gld and C57BL/6, respectively; the difference is not significant). Sixty-seven percent of H. pylori-infected gld mice displayed atrophic changes in the gastric mucosa, compared with 37% of infected C57BL/6 mice, at 12 weeks. In addition, atrophic changes were more severe in H. pylori-infected gld mice (P < 0.05). Splenocytes isolated from H. pylori-infected C57BL/6 mice had a twofold increase in production of the Th1 cytokine gamma interferon (IFN-gamma) in response to H. pylori antigens at both 6 and 12 weeks compared to controls (143 +/- 65 versus 69 +/-26 pg/ml and 336 +/- 73 versus 172 +/- 60, respectively). In contrast, there was a lack of detectable IFN-gamma in gld mice infected with the bacterium. H. pylori-infected C57BL/6 mice had increased epithelial cell apoptosis compared with sham-infected C57BL/6 mice (35.0 +/- 8.9 versus 12.3 +/- 6.9; P < 0.05). Epithelial cell apoptosis did not differ between H. pylori-infected and control gld mice (5.2 +/- 1.6 versus 6.5 +/- 2.9 [not significant]). These data demonstrate that mice with mutations in the Fas ligand develop more severe premalignant mucosal changes in response to infection with H. pylori in association with both an impaired gastric epithelial cell apoptotic response and IFN-gamma production. The Fas death pathway modulates disease pathophysiology following murine infection with H. pylori. Deregulation of the Fas pathway could be involved in the transition from gastritis to gastric cancers during H. pylori infection.     

Sampling efficiency in the diagnosis of Helicobacter pylori infection and chronic active gastritis.

The methods and sampling procedures used in the diagnosis of Helicobacter pylori infection and chronic active gastritis were evaluated. Five biopsy specimens for bacteriological cultivation and three specimens for histological examination were obtained endoscopically from a defined area of the gastric antral mucosae of 83 patients. An increase in the number of biopsy specimens for cultivation from one to five revealed only one more H. pylori-infected patient. H. pylori was isolated from 31 of 83 patients. Three technically adequate samples for histological examination were obtained from each of 74 patients. Of these 74 patients, chronic active gastritis was diagnosed by demonstration of typical histological changes in all three specimens from each of 20 patients, in two of three specimens from each of 3 patients, and in one of three specimens from 1 patient. The results indicate that one biopsy specimen is sufficient for the isolation of H. pylori, whereas several specimens may be necessary for the histological diagnosis. Chronic active gastritis was found in four patients not infected with H. pylori; on the other hand, H. pylori was isolated from nine patients who showed no signs of chronic active gastritis in any of three samples.