Campylobacter pyloridis: a new organism to explain an old problem?

The Possible Role of Helicobacter pylori in Gastric Cancer and Its Management

Helicobacter pylori (HP) is a facultative anaerobic bacterium. HP is a normal flora having immuno-modulating properties. This bacterium is an example of a microorganism inducing gastric cancer. Its carcinogenicity depends on bacteria-host related factors. The proper understanding of the biology of HP inducing gastric cancer offers the potential strategy in the managing of HP rather than eradicating it. In this article, we try to summarize the biology of HP-induced gastric cancer and discuss the current pharmacological approach to treat and prevent its carcinogenicity.

Helicobacter pylori: review of research findings

Helicobacter pylori attracted widespread interest from gastroenterologists because of its potential aetiologic role in disorders of the upper gastrointestinal tract. Based on extensive microbiological studies, Campylobacter pylori was renamed Helicobacter pylori, and the organism represents a new genus of bacteria. It is generally accepted that H. pylori causes chronic, non-specific gastritis (type B gastritis). The inflammatory response occurs even though the bacterium does not penetrate the gastric epithelium; it is found on the surface of and adjacent to the epithelium. The clinical significance of histological gastritis is unknown. The bacterium is often found in asymptomatic subjects. In Caucasian adults, the prevalence of infection increases with increasing age. Higher rates of infection are found in blacks and Hispanics than would be expected for their age. Whether these different rates are the result of racial or socioeconomic factors is not known. It is theorized, but not proven, that high rates of infection with H. pylori at an early age may explain the high incidence of gastric carcinoma found in Hispanic populations. H. pylori is found in almost every patient with duodenal ulcer disease, although no direct evidence for a causal relationship exists. Indirect evidence is based on the findings that if H. pylori infection is eradicated, ulcer recurrence is less likely (up to one year of follow-up). A small percentage of patients have a relapse despite eradication of the organism, suggesting a role for other factors in duodenal ulcer disease. The role of H. pylori in gastric ulcer disease is unknown. Seventy to eighty per cent of patients with gastric ulcer have evidence of H. pylori infection, and preliminary data seem to support the existence of two distinct aetiologic groups: those with gastric ulcers related to H. pylori infection and those with gastric ulcers related to use of non-steroidal anti-inflammatory drugs. The role of H. pylori in non-ulcer dyspepsia is unknown. Some clinicians believe that H. pylori causes non-ulcer dyspepsia and treat these patients for H. pylori infection. However, the data supporting this practice are poor. Treatment is only recommended for patients with resistant duodenal ulcers and patients who have frequent relapses of duodenal ulcers and who are willing to take triple-drug therapy (bismuth compounds, metronidazole, tetracycline) for the infection. As 95% of patients with duodenal ulcer have evidence of H. pylori infection, there is probably little need to confirm the diagnosis of H. pylori infection.

Helicobacter pylori CagA status associated with gastric cancer incidence rate variability in Costa Rican regions

BACKGROUND

We evaluated several risk factors for gastric cancer in Costa Rican regions having contrasting gastric cancer incidence rates, despite the small dimensions of the country.

METHODS

A total of 180 dyspeptic patients were classified into two groups according to the gastric cancer incidence (GCI) rate in their Costa Rican region: group A, with a high GCI rate (n = 91) and group B, with a low GCI rate (n = 89). Helicobacter pylori infection was detected by rapid urease test, Gram staining, and histological observation. Antral and corpus specimens were obtained to assess the grade of inflammation, topography of gastritis, gastric atrophy, and intestinal metaplasia by histological examination. Serum CagA antibody was measured by an antigen-specific enzyme-linked immunosorbent assay.

RESULTS

There was no significant difference in H. pylori prevalence between groups A (73%) and B (63%); however, serum CagA antibody was more frequently detected in group A (79%) than in group B (54%) [P = 0.02; odds ratio (OR), 2.68]. Among patients under 60 years of age, serum CagA antibody was even more frequently detected in group A (81%) than in group B (49%) (P < 0.01; OR, 4.50). The prevalence of corpus-predominant gastritis, atrophic gastritis, and moderate/severe grades of neutrophilic infiltration was higher in serum CagA antibody-positive patients than in CagA antibody-negative patients (P = 0.003, 0.04, and 0.002, respectively).

CONCLUSIONS

Infection with H. pylori possessing the cagA gene is associated with the development of severe gastric damage such as gastric atrophy, leading to gastric cancer, and probably influences the differences in GCI between Costa Rican regions.

Helicobacter pylori infection in two areas in Japan with different risks for gastric cancer

BACKGROUND

We evaluated the relationship between Helicobacter pylori and various factors associated with gastric cancer in two areas in Japan with different risks for mortality due to gastric cancer.

METHODS

A total of 250 sera from Niigata and 209 from Okinawa were used. H. pylori antibody and CagA antibody were measured by antigen-specific ELISAs. Serum gastrin and pepsinogen levels were determined by RIA.

RESULTS

Although there was no significant difference in H. pylori prevalence among the persons in Niigata (50%) and Okinawa (42%), CagA prevalence in these populations was significantly different, at 41% and 26%, respectively (OR = 1.98, 95%CI: 1.33-2.95, P < 0.01). Serum gastrin levels in Niigata were significantly lower than those in Okinawa in H. pylori-negative persons (P < 0.01). The serum pepsinogen I/II ratio in Niigata was significantly lower than that in Okinawa in H. pylori positive persons (P < 0.01), whereas there was no significant difference in H. pylori-negative persons. Among those positive for H. pylori, serum pepsinogen I/II ratio in Niigata was significantly lower than that in Okinawa in CagA-negative persons (P < 0.01), whereas no significant difference was observed in CagA-positive persons.

CONCLUSIONS

These results suggest that the difference in the mortality ratio of gastric cancer between Niigata and Okinawa is mainly associated with the difference between areas in the prevalence of cagA-positive strains rather than that of H. pylori itself.

Effect of Helicobacter pylori eradication on malignant transformation of gastric adenoma

BACKGROUND

A nonrandomized trial of Helicobacter pylori eradication was conducted in patients with endoscopically diagnosed gastric adenoma to determine the long-term effect of antimicrobial treatment on progression of the adenoma.

METHODS

Of 64 patients with an endoscopically diagnosed gastric adenoma and H pylori infection, 32 were treated with omeprazole and antibiotics to eradicate the infection, and 32 were not.

RESULTS

During 2 years of follow-up, 4 (12.5%) of the 32 patients in the untreated group developed an early stage, intestinal-type gastric cancer, whereas no gastric cancer was found in the 32 patients in the treated group.

CONCLUSION

H Pylori eradication may inhibit progression of gastric adenoma to carcinoma.

Helicobacter pylori

H pylori is now recognised as a treatable primary cause of both gastric ulcers and gastric adenocarcinoma. Most infections remain asymptomatic. Persons with signs and symptoms which correlate with potential infection with H pylori should be tested and, if positive, treated with a recognised triple antibiotic regimen. Evaluation of the response to the treatment regimen should be undertaken.

What role does Helicobacter pylori play in gastric cancer?

Several lines of evidence support an association between Helicobacter pylori infection and gastric cancer. The natural history of H. pylori-associated gastritis is inexorable progression ultimately leading to gastric atrophy. In general, this process requires between 20 and 40 years to complete. Atrophic gastritis is widely considered to be a precursor lesion of the intestinal type of gastric cancer. Moreover, areas with a high prevalence of H. pylori infection also have a high prevalence of gastric cancer. Strong evidence from three prospective studies shows the risk of gastric cancer to be increased fourfold in H. pylori-positive persons. Several retrospective studies have also confirmed that H. pylori infection is associated with development of gastric cancer, especially in the younger generation, early gastric cancer, and noncardiac gastric cancer. H. pylori alone is not likely responsible for gastric cancer. Rather, it may provide a suitable environment, including chronic gastritis and intestinal metaplasia, for neoplastic change. Recognition of an association between H. pylori infection and gastric cancer has led to a major shift in emphasis on the cause of the disease. Research into H. pylori has focused attention on the importance of chronic inflammation and impaired host defense mechanisms as factors in the development of gastric cancer. H. pylori infection leads to changes in many factors that are important to the pathogenesis of gastric cancer, including vitamin C content of gastric juice, reactive oxygen metabolites, and epithelial cell proliferation. Eradication of the organism may reverse these changes. Therefore, eradication of H. pylori in infected persons might be a route to preventing gastric cancer, although many questions still remain as to the effectiveness of this strategy.

Possible role of Helicobacter pylori infection in early gastric cancer development

BACKGROUND

Gastric cancer is the most frequently diagnosed malignancy in Japan. The possible relationship between Helicobacter pylori infection and gastric cancer in Japan was evaluated.

METHODS

H. pylori infection was identified by the presence of anti-H. pylori IgG. The frequency of H. pylori infection was compared in 213 patients with gastric cancer and the same number of asymptomatic control subjects matched for age and sex.

RESULTS

The presence of IgG antibody to H. pylori was significantly more prevalent (P < 0.001) in those with gastric cancer compared with asymptomatic control subjects (88.2% versus 74.6%). H. pylori positive rates were significantly greater in patients with the intestinal type (90.4%, P < 0.001) and diffuse type (86.4%, P < 0.05) of gastric cancer than in control subjects. Ninety-three percent of the patients with early gastric cancer tested positive for H. pylori (P < 0.001 compared with control subjects), whereas no significant difference was observed between those with advanced gastric cancer and control subjects. The intestinal type of early gastric cancer showed only the significantly increased frequency of high titer (optical density > 1.50) of H. pylori IgG antibody (P < 0.001) compared with control subjects without cancer.

CONCLUSIONS

These results suggest that H. pylori infection may be associated with the development of early gastric cancer in Japan.

Relationship of Helicobacter pylori to serum pepsinogens in an asymptomatic Japanese population

A seroepidemiologic study of the prevalence of Helicobacter pylori infection in Japan was performed, and the relationship between serum pepsinogen I and II levels (markers of gastritis and gastric atrophy) and H. pylori infection was investigated. Four hundred and eighteen asymptomatic children and adults were studied. The prevalence of anti-H. pylori immunoglobulin G antibody increased with age. For persons born after 1950, the frequency of H. pylori infection increased at approximately 1% per year; for those born before 1950 the prevalence was high (70%-80%) and relatively constant. Serum pepsinogen I and II levels were significantly higher in H. pylori-infected volunteers than in H. pylori-uninfected volunteers [51.6 +/- 3 vs. 42.9 +/- 2 ng/mL (P less than 0.05) for pepsinogen I; 16.0 +/- 1 vs. 7.5 +/- 0.8 ng/mL (P less than 0.001) for pepsinogen II]. The ratio of pepsinogen I to pepsinogen II was significantly lower in H. pylori-infected volunteers (3.5 +/- 0.2) than in uninfected volunteers (6.3 +/- 0.3; P less than 0.001). The apparent decrease in prevalence of H. pylori accompanying the Westernization of Japan may eventually be accompanied by a reduction in the frequency of atrophic gastritis, the precursor lesion of the epidemic form of gastric carcinoma, and ultimately result in a decrease in the incidence of gastric carcinoma in Japan.

Prevalence of Helicobacter pylori infection and histologic gastritis in asymptomatic persons

We estimated the prevalences of Helicobacter pylori (formerly called Campylobacter pylori) infection and histologic gastritis in 113 asymptomatic persons, using endoscopic biopsy of the gastric antrum and corpus. Unsuspected lesions, mainly mucosal erosions, were revealed at endoscopy in 16 subjects (14 percent). Gastritis was found in 42 subjects (37 percent), of whom 36 (32 percent of the total) were found to be infected with H. pylori on the basis of hematoxylin-eosin staining. H. pylori was not found in any of the 71 subjects with normal histologic features. Gastritis and H. pylori were noted in both the antrum and corpus in 75 percent of those infected (n = 27). The prevalence of H. pylori infection increased from 10 percent (2 of 20 subjects) in those between the ages of 18 and 29, to 47 percent (7 of 15) in those between the ages of 60 and 69, but the effect of age did not reach statistical significance. The prevalence of gastritis increased significantly with advancing age. Stepwise logistic regression analysis revealed that the relative risk for H. pylori infection associated with recent (within six months) antibiotic use was 5.8 (95 percent confidence interval, 1.5 to 22.1), whereas the relative risk was 6.5 (95 percent confidence interval, 1.4 to 29.2) for those who had never used bismuth compounds. We conclude that histologic gastritis and H. pylori infection commonly occur in the stomach of apparently normal persons and increase in prevalence with advancing age. All the subjects with H. pylori infection had gastritis, suggesting a possible etiologic role for the bacterium in the histologic lesion.

Campylobacter pylori and ulcer disease--a causal connection?

A strong positive correlation has been demonstrated between the (antral mucosal) presence of Campylobacter pylori and active duodenal and gastric ulceration. Moreover, both duodenal and gastric ulcers heal, and remain in remission, as a consequence of therapeutic measures which eradicate C. pylori. However, the Henle-Koch postulates have not been fulfilled, because C. pylori has not been shown to produce ulcers. As for the claim that ulcer disease represents an infection with C. pylori because therapeutic eradication heals ulcers, it has been shown that antibiotics and metronidazole, as well as bismuth subcitrate, exert antiulcer actions by mechanisms which do not involve their antibacterial effects. The association between C. pylori and ulcer disease, which was noted half a century ago, remains unexplained now as it did then.

Campylobacter pylori: prospective analysis of clinical and histological factors associated with colonization of the upper gastrointestinal tract

The association of Campylobacter pylori (C.p.) colonization of the upper gastrointestinal tract with five predefined anamnestic variables, seven symptoms of dyspepsia, and various blindly evaluated histological criteria, was prospectively investigated in a consecutive series of 149 patients submitted to upper gastrointestinal tract endoscopy. Colonization was determined by biopsy urease tests and histological searches. Significant differences (P less than 0.05) between C.p.-positive and C.p.-negative patients were found for smoker status and the frequency of therapy with ulcer-healing drugs (positive association with C.p.) and antibiotics (negative association), but not for any other of the anamnestic data or symptoms. These data were further submitted to stepwise multiple logistic regression analyses. Concerning histological findings, C.p. colonization was significantly associated with the degree of antrum and body gastritis (P less than 0.01), and also with lymphocellular infiltration in antrum and body biopsies and neutrophil cellular grading in gastric antra. We conclude that C.p. colonization of the upper gastrointestinal tract is associated with gastritic change of the antrum and, albeit to a lesser extent, of the body mucosa. However, a specific pattern of symptoms to predict C.p. colonization could not be established.