Adding once-daily omeprazole 20 mg to metronidazole/amoxicillin treatment for Helicobacter pylori gastritis: a randomized, double-blind trial showing the importance of metronidazole resistance

A meta-analysis of the success rate of Helicobacter pylori therapy in Canada

BACKGROUND AND AIM

Helicobacter pylori treatment success rates have varied. A systematic review of the success rate of anti- H pylori therapy in Canada was performed.

METHODS

All clinical trials containing Canadian data on the success rate of H pylori treatment were identified using MEDLINE searches, through review of references of retrieved studies and by contacting key investigators. Both randomized and open-label trials were included. Treatment effect size was calculated using a variation of Cochran's Q method.

RESULTS

Seventeen papers met the inclusion criteria. Both triple therapies consisting of a proton pump inhibitor (PPI), clarithromycin and either amoxicillin or metronidazole performed well, achieving a success rate of 84% and 82%, respectively. The cure rate of PPI-amoxicillin + metronidazole was 76%. Quadruple therapy consisting of a PPI, bismuth, metronidazole and tetracycline, given for seven to 10 days, achieved a success rate of 87%.

CONCLUSION

Both PPI-based triple therapy and quadruple therapy perform well in Canada for the treatment of H pylori infection.

Efficacy of omeprazole and amoxicillin with either clarithromycin or metronidazole on eradication of Helicobacter pylori in Chinese peptic ulcer patients

AIM: One-week triple therapy with proton pump inhibitors, clarithromycin and amoxicillin has recently been proposed as the first-line treatment for Helicobacter pylori (H pylori) infection; however, data regarding the effects of this regimen in China are scarce. The aim of this prospective and randomized study was to compare the efficacy of clarithromycin and metronidazole when they were combined with omeprazole and amoxicillin on eradication of H pylori and ulcer healing in Chinese peptic ulcer patients.

METHODS: A total of 103 subjects with H pylori-positive peptic ulcer were randomly divided into two groups, and accepted triple therapy with omeprazole 20 mg, amoxicillin 1000 mg and either clarithromycin 500 mg (OAC group, n = 58) or metronidazole 400 mg (OAM group, n = 45). All drugs were given twice daily for 7 d. Patients with active peptic ulcer were treated with omeprazole 20 mg daily for 2-4 wk after anti-H pylori therapy. Six to eight weeks after omeprazole therapy, all patients underwent endoscopies and four biopsies (two from the antrum and two others from the corpus of stomach) were taken for rapid urease test and histological analysis (with modified Giemsa staining) to examine H pylori. Successful eradication was defined as negative results from both examination methods.

RESULTS: One hundred patients completed the entire course of therapy and returned for follow-up. The eradication rate of H pylori for the per-protocol analysis was 89.3% (50/56) in OAC group and 84.1% (37/44) in OAM group. Based on the intention-to-treat analysis, the eradication rate of H pylori was 86.2% (50/58) in OAC group and 82.2% (37/45) in OAM group. There were no significant differences in eradication rates between the two groups on either analysis. The active ulcer-healing rate was 96.7% (29/30) in OAC group and 100% (21/21) in OAM group (per-protocol analysis, P>0.05). Six patients in OAC group (10.3%) and five in OAM group (11.1%) reported adverse events (P>0.05).

CONCLUSION: One-week triple therapy with omeprazole and amoxicillin in combination with either clarithromycin or metronidazole is effective for the eradication of H pylori. The therapeutic regimen comprising metronidazole with low cost, good compliance and mild adverse events may offer a good choice for the treatment of peptic ulcers associated with H pylori infection in China.

A practical approach to patients with refractory Helicobacter pylori infection, or who are re-infected after standard therapy

The vast majority of recurrences of Helicobacter pylori infection after apparent eradication are observed during the first year. Almost all of these early recurrences are due to recrudescence rather than reinfection by a new strain. After the first year, the recurrence rates approximate to the rate of natural acquisition of H. pylori infection. By contrast, in developing countries, higher rates of recurrence suggest a major role of real reinfection. Important predictive factors of H. pylori treatment success are compliance and bacterial susceptibility to antibiotics. The new 1-week triple therapies, based on a proton pump inhibitor (PPI) and 2 antibiotics, lead to treatment discontinuation but rarely. If containing a nitroimidazole, their efficacy is reduced to 60 to 80% by pretreatment in vitro resistance. The prevalence of nitroimidazole resistance varies dependent on the geographical area, with rates over 50% in tropical regions. Resistance against macrolides hinders treatment success in 50 to 80% of patients. In the US, south-western Europe and Japan the prevalence of macrolide resistance amounts to about 10%, in other countries about 3%. After failed treatment, acquired resistance is frequent. Testing for resistance is recommended to facilitate the decision for an alternative triple therapy or for quadruple therapy comprising bismuth, metronidazole, tetracycline and a PPI. It seems reasonable to increase the dose of PPI in a retreatment regimen containing amoxicillin. Post-treatment double resistance against nitroimidazoles and macrolides reduces the success of most of the currently evaluated retreatment regimens. To overcome double resistance, high dose PPI plus amoxicillin is one approach, beside other experimental multidrug treatments.

Exposure to metronidazole in vivo readily induces resistance in Helicobacter pylori and reduces the efficacy of eradication therapy in mice

The Helicobacter pylori SS1 mouse model was used to characterize the development of resistance in H. pylori after treatment with metronidazole monotherapy and to examine the effect of prior exposure to metronidazole on the efficacy of a metronidazole-containing eradication regimen. Mice colonized with the metronidazole-sensitive H. pylori SS1 strain were treated for 7 days with either peptone trypsin broth or the mouse equivalent of 400 mg of metronidazole once a day or three times per day (TID). In a separate experiment, H. pylori-infected mice were administered either peptone trypsin broth or the mouse equivalent of 400 mg of metronidazole TID for 7 days, followed 1 month later by either peptone trypsin broth or the mouse equivalent of 20 mg of omeprazole, 250 mg of clarithromycin, and 400 mg of metronidazole twice a day for 7 days. At least 1 month after the completion of treatment, the mice were sacrificed and their stomachs were cultured for H. pylori. The susceptibilities of isolates to metronidazole were assessed by agar dilution determination of the MICs. Mixed populations of metronidazole-resistant and -sensitive strains were isolated from 70% of mice treated with 400 mg of metronidazole TID. The ratio of resistant to sensitive strains was 1:100, and the MICs for the resistant strains varied from 8 to 64 micrograms/ml. In the second experiment, H. pylori was eradicated from 70% of mice treated with eradication therapy alone, compared to 25% of mice pretreated with metronidazole (P < 0.01). Mice still infected after treatment with metronidazole and eradication therapy contained mixed populations of metronidazole-resistant and -sensitive isolates in a ratio of 1:25. These results demonstrate that H. pylori readily acquires resistance to metronidazole in vivo and that prior exposure of the organism to metronidazole is associated with failure of eradication therapy. H. pylori-infected mice provide a suitable model for the study of resistance mechanisms in H. pylori and will be useful in determining optimal regimens for the eradication of resistant strains.

The DU-MACH study: eradication of Helicobacter pylori and ulcer healing in patients with acute duodenal ulcer using omeprazole based triple therapy

AIM

To investigate the efficacy of two omeprazole triple therapies for the eradication of Helicobacter pylori, ulcer healing and ulcer relapse during a 6-month treatment-free period in patients with active duodenal ulcer.

METHODS

This was a double-blind, randomized study in 15 centres across Canada. Patients (n = 149) were randomized to omeprazole 20 mg once daily (O) or one of two 1-week b. d. eradication regimens: omeprazole 20 mg, metronidazole 400 mg and clarithromycin 250 mg (OMC) or omeprazole 20 mg, amoxycillin 1000 mg and clarithromycin 500 mg (OAC). All patients were treated for three additional weeks with omeprazole 20 mg once daily. Ulcer healing was assessed by endoscopy after 4 weeks of study therapy. H. pylori eradication was determined by a 13C-urea breath test and histology, performed at pre-entry, at 4 weeks after the end of all therapy and at 6 months.

RESULTS

The intention-to-treat (intention-to-treat) analysis contained 146 patients and the per protocol (per protocol) analysis, 114 patients. The eradication rates were (intention-to-treat/per protocol): OMC-85% and 92%, OAC-78% and 87% and O-0% (O). Ulcer healing (intention-to-treat) was greater than 90% in all groups. The differences in the eradication and relapse rates between O vs. OMC and O vs. OAC were statistically significant (all, P < 0.001). Treatment was well tolerated and compliance was high.

CONCLUSION

The OMC and OAC 1-week treatment regimens are safe and effective for eradication, healing and the prevention of relapse in duodenal ulcer patients.

Omeprazole. A review of its use in Helicobacter pylori infection, gastro-oesophageal reflux disease and peptic ulcers induced by nonsteroidal anti-inflammatory drugs

Omeprazole is a well studied proton pump inhibitor that reduces gastric acid secretion. This review examines its use in Helicobacter pylori infection, gastro-oesophageal reflux disease (GORD) with or without oesophagitis and gastrointestinal damage caused by nonsteroidal anti-inflammatory drugs (NSAIDs). Optimal omeprazole regimens for anti-H. pylori therapy are those that administer the drug at a dosage of 40 mg/day (in 1 or 2 divided doses) for 7, 10 or 14 days in combination with 2 antibacterial agents. As a component of 3-drug regimens in direct comparative studies, omeprazole was at least as effective as lansoprazole, pantoprazole, bismuth compounds and ranitidine. However, a meta-analysis suggests that triple therapies with omeprazole are more effective than comparable regimens containing ranitidine, lansoprazole or bismuth. Omeprazole also appears to be successful in triple therapy regimens used in children with H. pylori infection. In patients with acute GORD with oesophagitis, omeprazole is at least as effective as lansoprazole or pantoprazole in promoting healing, and superior to ranitidine, cimetidine or cisapride in oesophagitis healing and symptom relief. Omeprazole was similar to lansoprazole and superior to ranitidine in preventing oesophagitis relapse in patients with all grades of oesophagitis, but may be superior to lansoprazole or pantoprazole in patients with more severe disease. More patients with symptomatic GORD without oesophagitis experienced symptom relief after short term treatment with omeprazole than with ranitidine, cisapride or placebo, and symptoms were more readily prevented by omeprazole than by cimetidine or placebo. Omeprazole was effective in healing and relieving symptoms of reflux oesophagitis in children with oesophagitis refractory to histamine H2 receptor antagonists. Omeprazole is superior to placebo in preventing NSAID-induced gastrointestinal damage in patients who must continue to take NSAIDs. It is also similar to misoprostol and superior to ranitidine in its ability to heal NSAID-induced peptic ulcers and erosions, and superior to misoprostol, ranitidine or placebo in its ability to prevent relapse. In long and short term studies, omeprazole was well tolerated, with diarrhoea, headache, dizziness, flatulence, abdominal pain and constipation being the most commonly reported adverse events. Usual omeprazole dosages, alone or combined with other agents, are 10 to 40 mg/day for adults and 10 to 20 mg/day for children.

CONCLUSIONS

Omeprazole is a well studied and well tolerated agent effective in adults or children as a component in regimens aimed at eradicating H. pylori infections or as monotherapy in the treatment and prophylaxis of GORD with or without oesophagitis or NSAID-induced gastrointestinal damage.