Review article: treatment of Helicobacter pylori infection and factors influencing eradication

Trends in peptic ulcer pharmacotherapy

Considering the diseases of the stomach and duodenum, peptic ulcer has been the one with a significant clinical impact. The pathophysiology of peptic ulcer has centred on an imbalance between aggressive and protective factors. The discovery of Helicobacter pylori as a cause of peptic ulcer has changed our approach greatly towards this disease. Despite the decreasing frequency of H. pylori-induced peptic ulcers, peptic ulcer remains a major clinical problem partly because nonsteroidal anti-inflammatory drug (NSAID)-related ulcers and hospital admissions for ulcer complications associated with NSAIDs have increased in frequency. The interaction between H. pylori and NSAIDs is one of the most controversial issues in peptic ulcer. In this article, current concepts of peptic ulcer etiopathogenesis and the management of peptic ulcer according to the etiology were reviewed.

Treatment of Helicobacter pylori infection

Review of the recently published data on Helicobacter pylori management highlights various interesting aspects. Current H. pylori eradication guidelines generally suggest a noninvasive 'test and treat' strategy for all dyspeptic patients with certain age limits depending on the local gastric neoplasia risk. According to the 'Maastricht 2-2000 Consensus Report' treatment should be thought of as a 'package' considering first- and second-line eradication therapies together. Various centres have published their results using novel antimicrobial formulations and 'rescue' and 'sequential' therapies. Review suggests that care at the specialist level remains a challenge and guidelines are deficient particularly as regards the selection and duration of eradication therapies. Results indicate that differences for CYP2C19 genotype and the selection of proton pump inhibitors have no significant role in determining eradication rates whereas antibiotic resistance and socio-economic factors play a variable role according to different geographical areas. Compliance remains an important factor in determining clinical outcome at the primary and secondary levels worldwide.

Recurrent duodenal ulcer haemorrhage: a pharmacoeconomic comparison of various management strategies

BACKGROUND

Duodenal ulcer (DU) bleeding has a 7 - 13% mortality rate and bleeding often recurs. Prevention of recurrence is, therefore, an important goal. Eradication of Helicobacter pylori or maintenance treatment with a proton pump inhibitor (PPI) may reduce recurrent DU bleeding. Economic comparison of these options is sparse.

METHODS

After the control of index bleeding with endotherapy and drugs, three strategies were evaluated: empirical treatment for possible H. pylori infection followed by a PPI for 2 months; test for H. pylori, eradication if positive, maintenance PPI if negative; maintenance PPI alone. Probability and direct cost data were obtained from a Medline search and Indian hospitals, respectively. Cost-minimisation, cost-utility, one- and two-way sensitivity analyses and threshold values were evaluated.

RESULTS

Treatment of H. pylori, particularly empirical, was the preferred strategy and dominated maintenance treatment with PPI. The test-and-treat strategy was better than the empirical treatment strategy only when the probabilities of H. pylori eradication, ulcer healing following eradication and of frequency of H. pylori infection in bleeding DU were less than 58, 73 and 58%, respectively.

CONCLUSIONS

Eradication of H. pylori is preferred in preventing recurrent bleeding from DU.

The gastric biology of Helicobacter pylori

Helicobacter pylori is a neutralophilic, gram-negative, ureolytic organism that is able to colonize the human stomach but does not survive in a defined medium with a pH <4.0 unless urea is present. In order to live in the gastric environment, it has developed a repertoire of acid resistance mechanisms that can be classified into time-independent, acute, and chronic responses. Time-independent acid resistance depends on the structure of the organism's inner and outer membrane proteins that have a high isoelectric point, thereby reducing their proton permeability. Acute acid resistance depends on the constitutive synthesis of a neutral pH optimum urease that is an oligomeric Ni(2+)-containing heterodimer of UreA and UreB subunits. Gastric juice urea is able to rapidly access intrabacterial urease when the periplasmic pH falls below approximately 6.2 owing to pH-gating of a urea channel, UreI. This results in the formation of NH3, which then neutralizes the bacterial periplasm to provide a pH of approximately 6.2 and an inner membrane potential of -101 mV, giving a proton motive force of approximately -200 mV. UreI is a six-transmembrane segment protein, with homology to the amiS genes of the amidase gene cluster and to UreI of Helicobacter hepaticus and Streptococcus salivarius. Expression of these UreI proteins in Xenopus oocytes has shown that UreI of H. pylori and H. hepaticus can transport urea only at acidic pH, whereas that of S. salivarius is open at both neutral and acidic pH. Site-directed mutagenesis and chimeric analysis have identified amino acids implicated in maintaining the closed state of the channel at neutral pH and other amino acids that play a structural role in channel function. Deletion of ureI abolishes the ability of the organism to survive in acid and also to colonize the mouse or gerbil stomach. However, if acid secretion is inhibited in gerbils, the deletion mutants do colonize but are eradicated when acid secretion is allowed to return, showing that UreI is essential for gastric survival and that the habitat of H. pylori at the gastric surface must fall to pH 3.5 or below. The chronic response is from increased Ni(2+) insertion into the apo-enzyme, which results in a threefold increase in urease, which is also dependent on expression of UreI. This allows the organism to live in either gastric fundus or gastric antrum depending on the level of acidity at the gastric surface. There are other effects of acid on transcript stability that may alter levels of protein synthesis in acid. Incubation of the organism at acidic pH also results in regulation of expression of a variety of genes, such as some outer membrane proteins, that constitutes an acid tolerance response. Understanding of these acid resistance and tolerance responses should provide novel eradication therapies for this carcinogenic gastric pathogen.

Is antimicrobial susceptibility testing necessary before second-line treatment for Helicobacter pylori infection?

BACKGROUND

An antimicrobial susceptibility test for Helicobacter pylori before second-line treatment is often performed, although whether the test is truly necessary remains unknown.

PATIENTS AND METHODS

Eighty-two patients with H. pylori infection for whom first-line treatment with a 1-week proton pump inhibitor/amoxicillin-clarithromycin (AC) regimen had failed were randomly assigned to two groups: those having or not having the susceptibility test before re-treatment. The cure rates for these two groups were compared.

RESULTS

Five of the 82 patients were excluded from the analysis. For 38 patients in the susceptibility-test group, we used what we considered the best regimen based on susceptibility testing: 10 patients [no resistance to clarithromycin (CAM)] received the lansoprazole-amoxicillin-clarithromycin regimen, 22 patients [19 CAM resistant, metronidazole (MNZ) susceptible; three failure of culture] were given the lansoprazole-amoxicillin-metronidazole (LAM) regimen, and six patients (both MNZ and CAM resistant) received dual therapy with omeprazole (OPZ) and amoxicillin (AMOX) in which the OPZ dose was determined by the CYP2C19 gene polymorphism. For 39 patients in the group with no susceptibility testing, LAM regimens were prescribed. The intention-to-treat (ITT)-based cure rates in the groups with and without susceptibility testing were 81.6% (95% confidence interval; 66-92%) and 92.4% (79-98%), respectively, and there was no significant difference between these two groups.

CONCLUSION

Susceptibility testing is not necessarily required before second-line therapy if the first-line treatment has been performed using proton pump inhibitor/AC regimens.

Review article: diagnosis and treatment of Helicobacter: a 2002 updated review

The year 2002 saw advances on many fronts in the study of Helicobacter and gastroduodenal disease. Several studies have confirmed endoscopy as a valuable management procedure with confirmation of the diagnostic utility of the rapid urease test and the description of a new formulation of the test, which is more rapid in giving a result. Serology has been re-confirmed as a useful investigation in selected populations. Some commercial kits for near patient testing have also been assessed and although generally regarded as less accurate than laboratory based tests some have shown acceptable accuracy. The recent exciting development in diagnostic serology is the availability of the faecal antigen test; further studies have confirmed its usefulness as recommended screening tests. There have been several studies demonstrating that a test and treat policy has a significant patient benefit, both economic and medical, although there is some doubt if eradication of Helicobacter leads to regression of atrophy and metaplasia. However, in low Helicobacter-prevalence areas the test and treat policy is being challenged as an effective management strategy. Further studies have shown that compliance with treatment regimens is an important determinant of successful eradication. Finally several new eradication regimens have been reported particularly for use in patients who have had previous unsuccessful eradication attempts.

Gastric and duodenal ulcers during pregnancy

The frequency, symptoms, and complication rate of PUD seem to decrease during pregnancy. Yet clinicians often have to treat dyspepsia or pyrosis of undetermined origin during pregnancy because the frequency of pyrosis significantly increases during pregnancy, and clinicians reluctantly perform EGD during pregnancy for pyrosis to differentiate reliably between GERD and PUD. Dyspepsia or pyrosis during pregnancy is initially treated with dietary and lifestyle modifications. If the symptoms do not remit with these modifications, sucralfate or antacids, preferably magnesium-containing or aluminum-containing antacids, should be administered. Histamine2 receptor antagonists are recommended when symptoms are refractory to antacid or sucralfate therapy. Ranitidine seems to be a relatively safe H2 receptor antagonist. If symptoms continue despite H2 receptor antagonist therapy, the patient should be evaluated for possible EGD or PPI therapy. Pregnant women with hemodynamically significant upper gastrointestinal bleeding or other worrisome clinical findings should undergo EGD. Indications for surgery include ulcer perforation, ongoing active bleeding from an ulcer requiring transfusion of six or more units of packed erythrocytes, gastric outlet obstruction refractory to intense medical therapy, and a malignant gastric ulcer without evident metastases.

Levofloxacin based regimens for the eradication of Helicobacter pylori

BACKGROUND

A 7 day treatment scheme based on rabeprazole/levofloxacin/amoxycillin or tinidazole achieved an eradication rate over 90%. However, the combination of drugs and duration of treatment for the correct use of levofloxacin in the eradication of are still unclear.

OBJECTIVE

To compare the efficacy and tolerability of rabeprazole/levofloxacin based dual therapies given for 5, 7 or 10 days with rabeprazole/levofloxacin/amoxycillin triple therapy for 7 days.

METHODS

One hundred and sixty patients with infection documented by the C-urea breath test and histology were included in this prospective, open label study. Subjects were randomized in four groups: (1) levofloxacin (500 mg o.d.), amoxycillin (1 g b.d.) and rabeprazole (20 mg o.d.) for 7 days; (2) levofloxacin (500 mg o.d.) and rabeprazole (20 mg o.d.) for 5 days; (3) levofloxacin (500 mg o.d.) and rabeprazole (20 mg o.d.) for 7 days; and (4) levofloxacin (500 mg o.d.) and rabeprazole (20 mg o.d.) for 10 days. Six weeks after the end of therapy status was checked by using the C-urea breath test.

RESULTS

All patients completed the therapeutic regimens. The eradication rate was not significantly modified by treatment duration in the dual therapy schemes (5 days: 20/40, 50%; 7 days: 28/40, 70%; 10 days: 26/40, 65%). The eradication rate of the 1 week levofloxacin based triple therapy was significantly higher than that observed using any dual therapies (36/40). No major adverse effects were observed.

CONCLUSIONS

A rabeprazole/levofloxacin dual eradication regimen is simple and well tolerated but does not achieve an acceptable eradication rate when compared to a 1 week rabeprazole/levofloxacin/amoxycillin triple therapy. The eradication rate did not increase with a longer regimen.

Helicobacter pylori infection in geriatrics

The prevalence of Helicobacter pylori infection increases with age worldwide. However, the percentage of H. pylori-positive elderly patients who are tested and treated for their infection remains very low. We now have data that demonstrate the benefit of curing H. pylori infection in elderly patients with H. pylori-associated peptic ulcer disease and severe chronic gastritis. Furthermore, the cure of H. pylori may prevent progression of intestinal metaplasia and gastric atrophy. Studies are needed to clarify the role of eradication for elderly patients who have nonulcer dyspepsia, gastroesophageal reflux disease and who use nonsteroidal anti-inflammatory drugs. H. pylori infection may be easily diagnosed by histological evaluation, rapid urease test or culture performed on gastric biopsies taken during endoscopy. However, the biopsy site must be carefully selected in elderly patients. For noninvasive monitoring of H. pylori infection after treatment, the 13C-urea breath test has significantly higher accuracy than serology in the elderly. The role of the H. pylori stool antigen test in old age still needs to be clarified. One-week PPI-based triple therapy regimens including clarithromycin, amoxycillin and/or nitroimidazoles are highly effective and well tolerated in elderly patients. Low doses of both PPIs and clarithromycin (in combination with standard doses of amoxycillin or nitroimidazoles) are sufficient. Antibiotic resistance and low compliance are the main factors related to treatment failure at any age.

Alternative and rescue treatment regimens for Helicobacter pylori eradication

Eradication therapy has been incorporated into clinical practice. The regimens currently recommended for first-line treatment include a 2-week bismuth-based triple therapy (mainly in developing countries), a 1 - 2 week proton pump inhibitor (PPI)-based triple therapy and a 1-week ranitidine bismuth citrate (RBC)-based triple therapy. However, these regimens fail to eradicate Helicobacter pylori in up to 20% of patients due to poor compliance, inadequate treatment duration, smoking, old age and bacterial resistance to nitroimidazoles and/or macrolides in particular. Therefore, alternative regimens that avoid nitroimidazoles and/or macrolides or overcome bacterial resistance to these drugs, improve compliance, minimise side effects and/or reduce costs have been evaluated. One-week quadruple therapy, which adds a PPI or histamine receptor 2-blocker to bismuth-based triple therapy, usually achieves an eradication rate of 90% when used as an alternative first-line therapy but the efficacy decreases when used as a rescue therapy. Several new triple therapies that may be used as alternative and/or rescue therapies have been evaluated. Among these are furazolidone-based (furazolidone plus an antibiotic and a bismuth salt, a PPI or RBC), fluoroquinolone-based (levofloxacin or moxifloxacin plus an antibiotic and a PPI) and ecabet sodium-based (ecabet plus two antibiotics) triple therapies. Recently, rifabutin has been used in combination with a PPI and amoxycillin as a rescue therapy, with satisfactory eradication rates. In addition, a number of new antimicrobial agents are currently under investigation in in vitro studies but the clinical values of these agents needs to be confirmed.