What role does Helicobacter pylori play in dyspepsia and nonulcer dyspepsia? Arguments for and against H. pylori being associated with dyspeptic symptoms

Review article: nitroimidazole resistance in Helicobacter pylori

The efficacy of a nitroimidazole-containing regimen for the treatment of Helicobacter pylori infection is decreased by nitroimidazole resistance. Nitroimidazoles are meta- bolized by H. pylori by several nitro-reductases of which an oxygen-insensitive NADPH nitroreductase encoded by the rdxA gene is the most important. Null mutations in this gene are associated with resistance. Susceptibility testing to nitroimidazoles may give variable results. This is not only related to the slow growth under specific conditions, but also to variability in the activity of the other nitroreductases and the ability to deactivate toxic metabolites of an NI and to repair DNA damage. Moreover, co-infections with resistant and susceptible bacteria are frequently found. The presence of nitroimidazole resistance is related to the previous use of this drug. The prevalence of resistance is rising and nowadays 10-50% of the isolates are resistant. Resistance reduces the efficacy of a treatment regimen to a variable degree. This is related to efficacy of the other components of the regimen and the treatment duration. Whether a nitroimidazole is still effective in resistant strains remains unresolved. When nitroimidazole resistance is present, a nitro-imidazole-containing regimen should be avoided or a regimen with other highly effective components should be used.

Lack of association of Helicobacter pylori infection with gastric hypersensitivity or delayed gastric emptying in functional dyspepsia

OBJECTIVE

We evaluated the relationship between Helicobacter pylori (H. pylori) infection and gastric sensitivity to distention or gastric emptying rate to define the role of H. pylori in the pathogenesis of functional dyspepsia.

METHODS

Gastric barostat, gastric emptying scintigraphy, and 13C urea breath test were performed in 34 consecutive patients with functional dyspepsia.

RESULTS

Between H. pylori-positive and -negative patients with functional dyspepsia, there were no significant differences in basal tone (57.2 +/- 15.0 ml vs 66.8 +/- 18.3 ml), compliance (41.0 +/- 11.2 ml/mm Hg vs 38.2 +/- 11.8 ml/mm Hg), threshold of first sense (3.6 +/- 2.7 mm Hg vs 2.3 +/- 1.5 mm Hg), threshold of abdominal discomfort (9.4 +/- 4.0 mm Hg vs 7.3 +/- 1.9 mm Hg), and postprandial receptive relaxation (115.4 +/- 89.7 ml vs 99.0 +/- 88.7 ml), measured by gastric barostat. Half gastric emptying time (88.6 +/- 24.5 min vs 91.4 +/- 21.6 min) and retention rate at 120 min (32.8 +/- 17.8% vs 41.9 +/- 20.1%) were also similar between the two groups.

CONCLUSION

H. pylori infection was not associated with gastric hypersensitivity to distention or delayed gastric emptying.

Helicobacter pylori eradication in patients with non-ulcer dyspepsia

Epidemiological and pathophysiological studies, as well as clinical trials, attempting to identify a relationship between Helicobacter pylori infection and non-ulcer dyspepsia (NUD), or a subset of NUD, have produced inconsistent and confusing results. While it is possible that H. pylori eradication may be beneficial for symptom relief in a small proportion of patients, routine H. pylori testing and treatment in documented NUD is not currently widely accepted. Despite the lack of convincing evidence, the European Helicobacter pylori Study Group, an Asian Pacific Consensus Meeting, the American Digestive Health Foundation and the American Gastroenterology Association have all recommended considering H. pylori eradication in patients with NUD on a patient-by-patient basis. Recently, large prospective, randomised, double-blind, controlled clinical trials applying highly effective antimicrobial therapy have been conducted with 12 months follow-up. Although these well-designed studies have reached differing conclusions, the results have been largely negative. H. pylori eradication therapy in NUD will fail to relieve symptoms in most patients in the long term.

Is Helicobacter pylori associated with non-ulcer dyspepsia and will eradication improve symptoms? A meta-analysis

OBJECTIVES

To examine the association between Helicobacter pylori infection and non-ulcer dyspepsia, and to assess the effect of eradicating H pylori on dyspeptic symptoms in patients with non-ulcer dyspepsia.

DESIGN

Systematic review and meta-analysis of (a) observational studies examining the association between Helicobacter pylori infection and non-ulcer dyspepsia (association studies), and (b) therapeutic trials examining the association between eradication of H pylori and dyspeptic symptoms in patients with non-ulcer dyspepsia (eradication trials).

DATA SOURCES

Randomised controlled trials and observational studies conducted worldwide and published between January 1983 and March 1999.

MAIN OUTCOME MEASURES

Summary odds ratios and summary symptom scores.

RESULTS

23 association studies and 5 eradication trials met the inclusion criteria. In the association studies the summary odds ratio for H pylori infection in patients with non-ulcer dyspepsia was 1.6 (95% confidence interval 1.4 to 1.8). In the eradication trials the summary odds ratio for improvement in dyspeptic symptoms in patients with non-ulcer dyspepsia in whom H pylori was eradicated was 1.9 (1.3 to 2.6).

CONCLUSIONS

Some evidence shows an association between H pylori infection and dyspeptic symptoms in patients referred to gastroenterologists. An improvement in dyspeptic symptoms occurred among patients with non-ulcer dyspepsia in whom H pylori was eradicated.

Eradication of Helicobacter pylori in functional dyspepsia: randomised double blind placebo controlled trial with 12 months' follow up. The Optimal Regimen Cures Helicobacter Induced Dyspepsia (ORCHID) Study Group

OBJECTIVES

To determine whether eradication of Helicobacter pylori relieves the symptoms of functional dyspepsia.

DESIGN

Multicentre randomised double blind placebo controlled trial.

SUBJECTS

278 patients infected with H pylori who had functional dyspepsia.

SETTING

Predominantly secondary care centres in Australia, New Zealand, and Europe.

INTERVENTION

Patients randomised to receive omeprazole 20 mg twice daily, amoxicillin 1000 mg twice daily, and clarithromycin 500 mg twice daily or placebo for 7 days. Patients were followed up for 12 months.

MAIN OUTCOME MEASURES

Symptom status (assessed by diary cards) and presence of H pylori (assessed by gastric biopsies and 13C-urea breath testing using urea labelled with carbon-13).

RESULTS

H pylori was eradicated in 113 patients (85%) in the treatment group and 6 patients (4%) in the placebo group. At 12 months follow up there was no significant difference between the proportion of patients treated successfully by intention to treat in the eradication arm (24%, 95% confidence interval 17% to 32%) and the proportion of patients treated successfully by intention to treat in the placebo group (22%, 15% to 30%). Changes in symptom scores and quality of life did not significantly differ between the treatment and placebo groups. When the groups were combined, there was a significant association between treatment success and chronic gastritis score at 12 months; 41/127 (32%) patients with no or mild gastritis were successfully treated compared with 21/123 (17%) patients with persistent gastritis (P=0. 008).

CONCLUSION

No convincing evidence was found that eradication of H pylori relieves the symptoms of functional dyspepsia 12 months after treatment.

Prescription of acid-suppressing drugs in relation to endoscopic diagnosis: a record-linkage study

BACKGROUND

Although widely used, few data are available on the appropriateness of prescribing of acid-suppressing drugs (ASDs), despite guidelines on the investigation and treatment of dyspeptic patients.

METHODS

We created a database of 62 000 endoscopy examinations and record-linked these to a prescribing database. Endoscopic diagnoses were classified into peptic, nonpeptic and others. The H2-antagonists, omeprazole and misoprostol, were studied.

RESULTS

35 000 patients had one or more endoscopies during 1978-93; two-thirds were over 45 years of age at first endoscopy. A quarter of all patients who had been endoscoped had consistently normal examinations. Peptic oesophageal pathology was the commonest positive finding. A quarter of those prescribed ASDs between 1989 and 1993 had been endoscoped between 1978 and 1993. In those with a peptic diagnosis prescribed any ASD, the pathologies found were: oesophageal (42.9%), duodenal (36.3%) and gastro-pyloric (21.3%). Patients prescribed omeprazole were more likely to have undergone endoscopy than those prescribed other ASDs, and they were also more likely to have peptic oesophageal pathology. Long-term prescribing (>56 days per year) occurred in two-thirds of patients prescribed ASDs and 40% had at least one endoscopy. In those prescribed short-term ASDs, 20% had undergone at least one endoscopy. Peptic and nonpeptic endoscopic pathology was associated with increased ASD prescribing, but a normal endoscopy did not reduce prescribing.

CONCLUSION

ASD prescribing appeared to be mainly symptom-driven. Positive endoscopic findings increased the prescribing of ASDs, but normal findings did not reduce it.

Treatment of functional dyspepsia

Many functional dyspepsia treatment trials have until recently suffered from important weaknesses in study design. A major problem has been the low number of studies that have used validated outcome measures. Fortunately, progress has been made in this area. The evidence for the efficacy of antacids, H2-receptor antagonists, omeprazole, domperidone, cisapride and anti-Helicobacter therapy is reviewed. Although several of these have shown benefit, it is unclear whether this may be a result of the inclusion of patients with unrecognized gastro-oesophageal reflux disease. The data on anti-Helicobacter therapy are conflicting.

Report of the 1997 Asia Pacific Consensus Conference on the management of Helicobacter pylori infection

While European and United States guidelines for the management of Helicobacter pylori infection have been developed, there are no guidelines for the Asian Pacific. International experts and recognised local authorities met in Singapore in 1997 to develop appropriate guidelines, taking into account the high background prevalence of infection, high incidence rates of gastric cancer and resource limitations. Recommendations were made based on randomised controlled trials or where this was not possible, they were based on the current best available evidence or on good clinical practice. A number of acceptable diagnostic tests for infection are available throughout the region. The non-endoscopic methods of choice are the urea breath test or a locally validated antibody test. If endoscopy was to be performed, a biopsy urease test was recommended as the test of first choice, with histology recommended only if this was negative. Post treatment testing was not recommended for all patients; a urea breath test was considered the test of choice if available. All gastric and duodenal ulcer patients who are infected with H. pylori should be treated for H. pylori whether the ulcer is active or in remission. Patients requiring long term non-steroidal anti-inflammatory drug therapy who have a current or recent history of dyspepsia, patients with early gastric cancer or low grade gastric mucosa associated lymphoid tissue lymphoma, and patients with a family history of gastric cancer should be treated. However, it was concluded that there wasn't sufficient evidence that cure of H. pylori infection reduces the risk or prevents the development of gastric adenocarcinoma. Many patients with dyspepsia in the region will request or require early upper endoscopy because of an inherent fear of gastric cancer. However, where endoscopy is not available or is too costly, alternative acceptable approaches were recommended in high risk cancer regions. While evidence is inconclusive to support treatment of H. pylori infection in non-ulcer dyspepsia, it was agreed that treatment be offered to patients with documented infection on a case-by-case basis. Treatment regimens need to attain an eradication rate of 90% or greater by per protocol analysis and 80% or greater by intention-to-treat analysis. A number of 7-day regimens were recommended based on available evidence. These regimens were considered likely to maximize the chances of successful eradication with one course of treatment, thereby reducing the risk of acquired antibiotic resistance and leading to long term cost savings.