A systematic review of Helicobacter pylori eradication therapy--the impact of antimicrobial resistance on eradication rates

Clarithromycin resistance of Helicobacter pylori has a major impact on the efficacy of the omeprazole-amoxicillin-clarithromycin therapy

Clarithromycin resistance of Helicobacter pylori is relatively frequent in France and is assumed to be the main cause of failure of the proton pump inhibitor-amoxicillin-clarithromycin (PPI-AC) therapy, which is the first-line regimen in our country. We determined the respective effects of clarithromycin primary and secondary resistances on efficacy of the PPI-AC regimen and examined whether failures were associated with persistence of the same strain or with emergence of a new one. Hundred and twenty three H. pylori-infected patients were treated for seven days with omeprazole 20 mg b.d., amoxicillin 1 g b.d., and clarithromycin 500 mg b.d. Eradication was assessed by breath test in 102 patients. MICs of clarithromycin were determined by E-test. Strain genotyping was performed by random amplified polymorphic DNA. The pre-treatment and post-treatment prevalences of clarithromycin resistance were 18.7% (23/123) and 69.2% (9/13), respectively. The rates of eradication were 67.6% (69/102), 78.8% (67/85), and 11.8% (2/17) for all, susceptible and resistant strains, respectively. The post-treatment isolate was available for six patients with a susceptible pre-treatment isolate and a persistent infection; resistance emerged in two patients and was associated with persistence of the pre-treatment strain in one and with selection of a new strain in the other. In conclusion, in our hospital, failures of the PPI-AC therapy are related to both clarithromycin primary and secondary resistances but emergence of secondary resistance does not explain all failures in the initial clarithromycin-susceptible group. In that group a new strain can emerge after failure.

Peptic ulcer disease

Peptic ulcer disease is a common gastrointestinal disease whose management and treatment has changed dramatically over the last 25 years. Treatment of peptic ulcer disease has evolved from dietary modifications and antacids to gastric acid suppression with H2-receptor antagonists and proton pump inhibitors to eradication of Helicobactor pylori infection. Treatment of patients infected with H pylori using antibiotics has changed the natural history of peptic ulcer disease. As a result of H pylori treatment and other unknown factors ulcer disease is declining and complications from ulcer disease have diminished significantly.

Quadruple therapy for symptomatic spontaneous duodenal ulcer disease

AIM

To investigate Helicobacter pylori eradication in duodenal ulcer patients with a new regimen, lansoprazole 30 mg daily for one or four weeks plus twice daily tetracycline 500 mg, clarithromycin 250 mg, and metronidazole 400 mg.

BACKGROUND

Spontaneous duodenal ulcer is regularly associated with H pylori, and permanent cure follows eradication of this bacterium. Numerous treatments have been proposed and none is ideal, possibly because of primary or acquired antibiotic resistance. Quadruple regimens with proton pump inhibitor therapy and three antibiotics offer promise as the most effective therapy.

METHODS

From November 1995 all patients with spontaneous duodenal ulcer were offered quadruple therapy. A month after completion a carbon 14 urea breath test (UBT) was performed. Sensitivity of H pylori to the antibiotics used was tested in 1992-3, 1996, and 1999.

RESULTS

A total of 331 patients were treated; 313 attended for a UBT, of which 299 were negative (95.5%). Of those patients who had an endoscopy with positive urease test immediately before treatment, 95/101 (94.0%) on lansoprazole for one week and 116/121 (95.8%) on lansoprazole for four weeks had a negative UBT. H pylori antibiotic sensitivity did not change.

CONCLUSION

This regimen produced some of the best results yet seen and may be generally recommended as first line therapy.

Clarithromycin-susceptible and -resistant Helicobacter pylori isolates with identical randomly amplified polymorphic DNA-PCR genotypes cultured from single gastric biopsy specimens prior to antibiotic therapy

Of the Helicobacter pylori populations from 976 patients, six contained clarithromycin-resistant as well as -susceptible colonies. In each heterogeneous H. pylori population, resistant H. pylori colonies harbored identical 23S ribosomal DNA (rDNA) mutations associated with clarithromycin resistance, while the susceptible H. pylori colonies all had wild-type 23S rDNA. The resistant and susceptible colonies of each of the heterogeneous H. pylori populations had identical randomly amplified polymorphic DNA-PCR genotypes. In conclusion, evaluation of antimicrobial susceptibility can be misinterpreted if only a single colony from the primary H. pylori population is used to test for clarithromycin susceptibility.

Helicobacter pylori: strategies for treatment

Helicobacter pylori (Hp) is a Gram-negative bacteria able to live in the human stomach, a very surprising fact considering the acid environment of gastric mucosa. Identified by Marshall and Warren in 1982 [1,2], this bacterium seems aetiologically related to many gastric diseases, previously known as 'acid related diseases'. Compelling evidence demonstrates that Hp is the most important aetiological agent of gastritis [3], the principal causal factor in peptic ulcer [4], contributes to the genesis of gastric cancer [5] and has a critical role in the development of many mucosa-associated lymphoid tissue (MALT) lymphomas [6]. Although experimental data have recently provided hard evidence to support the role of Hp in the genesis of gastritis, ulcer and carcinoma [7], a critical argument for Hp generating peptic ulcer disease has been, in fact, the change in the natural history of peptic ulcer that follows the cure of the infection.

High efficacy of ranitidine bismuth citrate, amoxicillin, clarithromycin and metronidazole twice daily for only five days in Helicobacter pylori Eradication

AIM

The combination of a proton pump inhibitor (PPI) or ranitidine-bismuth-citrate (Rbc) and two antibiotics for 7-10 days are, at present, the preferred treatments in Helicobacter pylori eradication. However, therapies for fewer than 7 days have been scarcely evaluated and it is unknown whether the length of treatment can be shortened, without a lost of efficacy, if three instead of two antibiotics are used. The aim of our study was to evaluate the efficacy of Rbc plus three antibiotics for only 5 days in H. pylori eradication.

METHODS

We prospectively studied 80 patients (34% duodenal ulcer, 66% functional dyspepsia) infected by H. pylori. At endoscopy, biopsies were obtained for histological study and rapid urease test, and a 13C-urea breath test was carried out. Urea breath test was repeated 4 weeks after completing eradication treatment with Rbc [400 mg twice a day (bid)], amoxicillin (1 g bid), clarithromycin (500 mg bid) and metronidazole (500 mg bid). All drugs were administered together after breakfast and dinner for 5 days only, and no treatment was administered thereafter. Compliance with therapy was determined from the interrogatory and the recovery of empty envelopes of medications.

RESULTS

In 79 out of the 80 patients, H. pylori eradication success or failure was assessed after therapy (one patient was lost from follow-up). All but one of these 79 patients took all the medications (one patient stopped treatment on the day 3 due to nausea/vomiting). Per protocol eradication was achieved in 72/78 (92%; 95% CI, 84-96%) and in 72/80 (90%; 81-95%) by intention-to-treat. Therapy was more effective in patients with duodenal ulcer than in those with functional dyspepsia [100% (87-100%) vs. 85% (73-92%) by intention-to-treat; p <.05]. Adverse effects were described in ten patients (12%), and included the perception of a metallic taste (eight patients), nausea/vomiting (two patients, one of them abandoned the treatment due to this), and diarrhea (two patients).

CONCLUSION

The combination of Rbc, amoxicillin, clarithromycin and metronidazole for only 5 days represents a promising therapy for H. pylori infection, due to its high efficacy, simple posology, low cost and excellent tolerance.

Resistance of Helicobacter pylori to antibiotics and its impact on treatment options

The treatment of Helicobacter pylori infection is jeopardized by resistance to the antibiotics used, which turns out to be the main risk factor for failure. Resistance is due to point mutations. For clarithromycin only two sites in the 23S rRNA sequence are concerned and can be easily detected by molecular methods, while for metronidazole several mutations on rdxA and other genes can be responsible and so do not allow such detection. The situation for the rare cases of amoxicillin resistance is not fully determined. The impact of resistance on the clinical outcome is dramatic for clarithromycin while it only decreases the success by 20% for metronidazole.

Retreatment of Helicobacter pylori infection after initial treatment failure

OBJECTIVES

Helicobacter pylori treatment regimens fail to cure the infection in at least 10-20% of patients undergoing initial treatment. Retreatment strategies for patients who have failed initial treatment for H. pylori infection remain poorly described.

METHODS

The literature describing the frequency of H. pylori treatment failure and factors leading to failure is reviewed. The role of antibiotic resistance is discussed and clinical studies assessing success rates according to antibiotic resistance are described. Clinical trials evaluating the treatment success rates for a second episode of treatment are discussed.

RESULTS

The literature describing retreatment of failed H. pylori infection remains limited. The existing data support the use of bismuth-based quadruple therapy or ranitidine bismuth citrate (RBC)-based triple therapy as the preferred agents after initial treatment failure.

CONCLUSION

Further studies are needed to better define the optimal second treatment regimen after failed H. pylori treatment.

A systematic comparison of triple therapies for treatment of Helicobacter pylori infection with proton pump inhibitor/ ranitidine bismuth citrate plus clarithromycin and either amoxicillin or a nitroimidazole

BACKGROUND

Triple therapies with proton pump inhibitor/ranitidine bismuth citrate (RBC), clarithromycin (C) and either amoxicillin (A) or a nitroimidazole (I) are widely accepted as treatment for Helicobacter pylori infection. However, it is not clear which of these antibiotic combinations should be preferred.

AIM

To evaluate whether there is a difference in efficacy between triple therapies with proton pump inhibitor/RBC, clarithromycin and either amoxicillin or a nitroimidazole.

METHODS

The literature was examined for randomized trials comparing proton pump inhibitor/RBC-C-A and proton pump inhibitor/RBC-C-I. Studies were grouped according to the type of acid inhibitor used (proton pump inhibitor or RBC) and differences between pooled cure rates were calculated.

RESULTS

Forty-seven studies were identified: seven using RBC, 39 using proton pump inhibitor, one using both. RBC-C-I was somewhat superior to RBC-C-A, although this difference only reached statistical significance in intention-to-treat analysis. Overall, proton pump inhibitor-C-I and proton pump inhibitor-C-A were equally effective, but in nitroimidazole-susceptible strains, proton pump inhibitor-C-I performed better, in nitroimidazole-resistant strains, proton pump inhibitor-C-A performed better. No serious side-effects were reported and pooled drop-out rates were equal.

CONCLUSIONS

In general, proton pump inhibitor-C-I and proton pump inhibitor-C-A are equally effective and therefore other factors such as local prevalence of resistant strains, cost of therapy and options for second-line treatment should determine which regimen should be preferred. When using RBC, the RBC-C-I combination is somewhat superior to RBC-C-A.

Impact of Helicobacter pylori resistance to clarithromycin on the efficacy of the omeprazole-amoxicillin-clarithromycin therapy

BACKGROUND

Helicobacter pylori resistance to clarithromycin is relatively frequent in France and is assumed to be the main cause of failure of the proton pump inhibitor-amoxicillin-clarithromycin (proton pump inhibitor-AC) therapy, which is the first-line regimen in France.

AIM

To determine the respective effects of clarithromycin primary and secondary resistances on efficacy of the proton pump inhibitor-AC regimen and to determine whether failures are associated with persistence of the same strain or with emergence of a new one.

METHODS

A total of 123 H. pylori-infected patients were treated for 7 days with omeprazole 20 mg b.d., amoxicillin 1 g b.d., and clarithromycin 500 mg b.d. Eradication was assessed by breath test in 102 patients. Minimal inhibitory concentrations of clarithromycin were determined by E-test. Strain genotyping was performed by random amplified polymorphic DNA.

RESULTS

The pre-treatment and post-treatment prevalences of clarithromycin resistance were 19% (23 out of 123) and 69% (nine out of 13), respectively. The rates of eradication were 68% (69 out of 102), 79% (67 out of 85), and 12% (two out of 17) for all, susceptible and resistant strains, respectively. The post-treatment isolate was available for six patients with a susceptible pre-treatment isolate and a persistent infection. Resistance emerged in two patients and was associated with persistence of the pre-treatment strain in one and with selection of a new strain in the other.

CONCLUSIONS

In our hospital, failures of the proton pump inhibitor-AC therapy are related to both clarithromycin primary and secondary resistances, but the emergence of secondary resistance does not explain all of the failures in the initial clarithromycin-susceptible group. In that group a new strain can emerge after failure.

Accurate prediction of macrolide resistance in Helicobacter pylori by a PCR line probe assay for detection of mutations in the 23S rRNA gene: multicenter validation study

Helicobacter pylori strains from 299 patients were tested in six laboratories in different countries. Macrolide susceptibility of the strains was determined by agar dilution (17.4%) or the epsilometer test (82.6%). Mutations in the 23S ribosomal DNA (rDNA) that are associated with macrolide resistance were analyzed by PCR and reverse hybridization (PCR-line probe assay [LiPA]). This method identifies A2115G, G2141A, A2142G, A2142C, A2142T, A2143G, and A2143C mutations in the 23S rDNA. vacA s-region (s1a, s1b, s1c, and s2) and m-region (m1, m2a, and m2b) genotypes and cagA status were also determined using another PCR-LiPA system. Of the 299 strains investigated by MIC testing, 130 (43.5%) were resistant and 169 (56.5%) were susceptible to clarithromycin. Of the 130 resistant strains, 127 (97.7%) contained 23S rDNA mutations, whereas 167 (98.8%) of the 169 susceptible strains contained wild-type sequences. The predominant mutations were A2143G (45.2%) and A2142G (33.3%). Twenty-eight (19.8%) strains contained multiple 23S rDNA mutations. Only five resistant strains contained the A2142C mutation (three of these in combination with the A2142G mutation), and the A2115G, G2141A, A2142T, and A2143C mutations were not found. MICs of clarithromycin for the A2142G mutant strains were significantly higher than MICs for the A2143G strains. Although there was no significant association between 23S rDNA mutations and the vacA and cagA status, clarithromycin-susceptible strains more often contained mixed vacA genotypes, indicating the presence of multiple H. pylori strains. In conclusion, our data confirmed the very strong association between 23S rDNA mutations and macrolide resistance and showed that the PCR-LiPA permits accurate and reliable diagnosis of macrolide resistance in H. pylori.

Treatment of Helicobacter pylori

Helicobacter pylori causes several gastroduodenal diseases. Various antibiotic regimens are available that eradicate H. pylori in 80 to 90% of patients, but no regimen cures all patients. Dual therapy is now obsolete. Triple therapy with two antibiotics and either a proton pump inhibitor or bismuth is the regimens of choice. Metronidazole and clarithromycin are the two key antibiotics. Antibiotic resistance against these two drugs is becoming more problematic and should be taken into consideration when choosing a regimen. Antibiotic resistance is usually induced after failure. Quadruple therapy has been used as a salvage regimen in failed cases but it is also the most complicated regimen. Several new agents are being studied including a single capsule that contains bismuth, metronidazole, and tetracycline.

Six regimens for the eradication of Helicobacter pylori (Hp) in duodenal ulcer patients: three consecutive trials (1995-1999)

AIM

to present our experience in eradicating Hp in three consecutive trials performed between 1995 and 1999.

METHODS

320 duodenal ulcer outpatients have been enrolled in three open, prospective controlled trials. Hp infection was confirmed by Giemsa stain and Rut. In Trial I, 52 cases received 20 mg omeprazole + 2 x 250 mg clarithromycin + 2 x 500 mg tinidazole (OCT), 48 patients were given 20 mg omeprazole, 2 x 1000 mg amoxicillin + 2 x 500 mg metronidazole (OAM) for 7 days; in Trial II, 48 cases received 40 mg pantoprazole + 2 x 1000 mg amoxicillin + 2 x 500 mg clarithromycin (PAC) for 7 days and 5l cases 2 x 400 mg ranitidin bismuth citrate + 2 x 500 mg clarithromycin for 14 days (RBC-C); in Trial III, 60 cases were treated with 2 x 30 mg lansoprazole + 2 x 250 mg clarithromycin + 2 x 500 mg metronidazole and 6l patients received 2 x 400 mg ranitidin bismuth citrate+2 x 250 mg clarithromycin + 2 x 500 mg metronidazole (RBC-CM). The patients were controlled within 4-6 weeks by endoscopy in trials I-II and 13C-urea breath test in trial III.

RESULTS

Eradication rates on ITT/PP basis were: OCT: 72.3/80.2% vs OAM 51.2/63.5% (P = 0.02/P = 0.03); PAC: 80.8/88.3% vs RBC-C 80.3/85.4% (P = 0.65/0.67) and LCM 78.3/92.1% vs RBC-CM 78.7/90.5% (P = 0.86/P = 0.93). Side effects occurred in 5.2, 8.6, 9.5, 14.5, 13.5 and 18.3% of the cases.

CONCLUSION

Regimens using 2 x l PPI or RBC + 2 antibiotics for l week proved to be the most effective for Hp eradication in duodenal ulcer patients.

Strategies to treat patients with antibiotic resistant Helicobacter pylori

Increased resistance to clarithomycin and metronidazole, the two main antibiotics used to treat Helicobacter pylori infection, has led to a search for alternatives to the proton pump inhibitor based triple therapies commonly used. The main rescuse therapy is a bismuth-based quadruple therapy. However, triple therapies with tetracycline and metronidazole or amoxicillin and metronidazole can be considered in the case of clarithomycin resistance. They can also be used in the case of metronidazole resistance by increasing the dose and duration of metronidazole. The only therapy without clarithomycin and metronidazole includes rifabutin and amoxicillin. Dual therapies with amoxicillin and a proton pump inhibitor at high dose can also be used.

How to treat Helicobacter pylori. First-line, second-line, and future therapies

Numerous trials were performed in the 1990s to define the optimal therapy for Helicobacter pylori infections. The proposed proton-pump inhibitor (PPI)-based and ranitidine bismuth citrate (RBC)-based triple therapies led to satisfactory results. Their first drawback is cost, and, for this reason, many people worldwide cannot benefit from these regimens. Failures of first-line therapies essentially are because of antimicrobial resistance, which increases with the selection pressure resulting from the use of these drugs. Second-line treatments using antimicrobial agents for which H. pylori resistance is low or nonexistent are being tested to find alternatives to the quadruple therapy. There is a need for new drugs, which should be highly effective, nonselective of resistant strains, and without side effects, to improve current regimens. These drugs may be the results of postgenomic studies.

Proton pump inhibitor, clarithromycin and either amoxycillin or nitroimidazole: a meta-analysis of eradication of Helicobacter pylori

AIM

To perform a meta-analysis of studies comparing twice daily, one-week triple therapy with a proton pump inhibitor, clarithromycin (C) and amoxycillin (A) (PCA) vs. those using proton pump inhibitor, clarithromycin and a nitroimidazole (N) (PCN) for H. pylori eradication.

REVIEW METHODS

SELECTION CRITERIA

Comparative randomized trials of PCA vs. PCN were included.

DATA SOURCES

PubMed database and abstracts from congresses until September 1999.

STATISTICS

Meta-analysis was performed combining the Odds Ratios (OR) of the individual studies in a global OR (Peto method) both on an intention-to-treat (ITT) and on a per protocol (PP) basis.

RESULTS

Twenty-two studies fulfilled the inclusion criteria. Eighteen studies reported ITT and 20 PP analysis. Mean H. pylori eradication rates were 81% (95% CI: 79-83%) ITT, and 84% (82-86%) PP with PCA, and 81% (78-83%) ITT and 84% (82-86%) PP with PCN; the odds ratio for the effect of PCA vs. PCN was 1 (0.83-1.22) on an ITT, and 0.98 (0.8-1.2) on a PP basis. Subanalysis showed that mean H. pylori eradication efficacy with PC(250 b.d.)A was 81% (78-85%) ITT, vs. 86% (83-89%) with PC(250 b.d.)N. The odds ratio for this comparison was 0.68 (0.48-0.98). Finally, when comparing PC(500 b.d. )A against PC(250 b.d.)N ITT cure rates were 77% (74-80%), and 75% (72-78%) with an odds ratio of 1.18 (0.93-1.5).

CONCLUSION

Overall, one-week combination regimens of PCA and PCN present similar H. pylori eradication efficacy. Nevertheless, the PCN regimen obtains significantly better results when using low doses of C (250 mg b.d.).

Helicobacter pylori eradication: proton pump inhibitor vs. ranitidine bismuth citrate plus two antibiotics for 1 week-a meta-analysis of efficacy

OBJECTIVE

To compare the efficacy of proton pump inhibitor vs. ranitidine bismuth citrate (RBC) with two antibiotics for 1 week in Helicobacter pylori eradication.

METHODS

Randomized trials comparing 1-week regimens with (i) proton pump inhibitor plus two antibiotics [clarithromycin (C) and amoxycillin (A) or a nitroimidazole (N)]; or (ii) RBC plus the same antibiotics. Eradication was confirmed by histology or 13C-urea breath test at least 4 weeks after therapy. Data sources included PubMed database and abstracts from congresses until October 1999. Statistical analysis was by meta-analysis combining the odds ratios (OR) of the individual studies in a global OR (Peto method).

RESULTS

Twelve studies met the selection criteria. Nine compared proton pump inhibitor vs. RBC plus C and A, and five compared proton pump inhibitor vs. RBC plus C and N. With RBC, C and A, mean H. pylori eradication efficacy by intention-to-treat analysis (pooled data) was 76.6% (95% CI: 72-81%) and 73.7% (95% CI: 69-78%) with proton pump inhibitor, C and A. The OR for the effect of RBC vs. proton pump inhibitor (plus C and A) on H. pylori eradication was 1.15 (95% CI: 0.8-1.64%). Mean H. pylori eradication with RBC, C and N was 87. 2% (95% CI: 83-91%), and 74.9% (95% CI: 74-84%) with proton pump inhibitor plus these two antibiotics. The OR for the effect of RBC vs. proton pump inhibitor (plus C and N) on H. pylori eradication was 1.76 (95% CI: 1.08-2.85%).

CONCLUSION

RBC and proton pump inhibitor have similar efficacy for H. pylori eradication when given with C and A for 1 week, but RBC seems to have a higher efficacy than proton pump inhibitor when C and N are the co-prescribed antibiotics.

Analysis of rdxA and involvement of additional genes encoding NAD(P)H flavin oxidoreductase (FrxA) and ferredoxin-like protein (FdxB) in metronidazole resistance of Helicobacter pylori

Metronidazole (Mtz) is a critical ingredient of modern multidrug therapies for Helicobacter pylori infection. Mtz resistance reduces the effectiveness of these combinations. Although null mutations in a rdxA gene that encodes oxygen-insensitive NAD(P)H nitroreductase was reported in Mtz-resistant H. pylori, an intact rdxA gene has also been reported in Mtz-resistant H. pylori, suggesting that additional Mtz resistance mechanisms exist in H. pylori. We explored the nature of Mtz resistance among 544 clinical H. pylori isolates to clarify the role of rdxA inactivation in Mtz resistance and to identify another gene(s) responsible for Mtz resistance in H. pylori. Mtz resistance was present in 33% (181 of 544) of the clinical isolates. There was marked heterogeneity of resistance, with Mtz MICs ranging from 8 to >/=256 microg/ml. rdxA inactivation resulted in Mtz MICs of up to 32 microg/ml for 6 Mtz-sensitive H. pylori strains and 128 microg/ml for one Mtz-sensitive strain. Single or dual (with rdxA) inactivation of genes that encode ferredoxin-like protein (designated fdxB) and NAD(P)H flavin oxidoreductase (frxA) also increased the MICs of Mtz for sensitive and resistant strains with low to moderate levels of Mtz resistance. fdxB inactivation resulted in a lower level of resistance than that from rdxA inactivation, whereas frxA inactivation resulted in MICs similar to those seen with rdxA inactivation. Further evidence for involvement of the frxA gene in Mtz resistance included the finding of a naturally inactivated frxA but an intact rdxA in an Mtz-resistant strain, complementation of Mtz sensitivity from an Mtz-sensitive strain to an Mtz-resistant strain or vice versa by use of naturally inactivated or functional frxA genes, respectively, and transformation of an Mtz-resistant Escherichia coli strain to an Mtz sensitive strain by a naturally functional frxA gene but not an inactivated frxA gene. These results are consistent with the hypothesis that null mutations in fdxB, frxA, or rdxA may be involved in Mtz resistance.

Review article: treatment of Helicobacter pylori infection with ranitidine bismuth citrate- or proton pump inhibitor-based triple therapies

Triple therapy, combining a proton pump inhibitor with clarithromycin (C) and either amoxycillin (A) or a nitro-imidazole (I) is the standard in Helicobacter pylori eradication therapy. Recently, triple therapies based on ranitidine bismuth citrate (RBC) have emerged as an alternative. This review examines the current literature for studies directly comparing proton pump inhibitor- with RBC-based triple therapies. Seventeen studies were identified, of which three have been published as a full paper. Eradication rates in an intention-to-treat analysis ranged from 51 to 98%. No large difference in cure rates between the different regimens was demonstrated, although the RBC-I-C combination was somewhat superior. No definite conclusions could be made about the impact of metronidazole or clarithromycin resistance since only three studies performed a formal resistance analysis. No serious side-effects were reported, and dropout rates were equal for the two regimens. Both RBC- and proton pump inhibitor-based triple therapies are highly effective. If one prefers a imidazole/clarithromycin combination the evidence presented here suggests that RBC should be used instead of a proton pump inhibitor. Larger studies comparing both forms of triple therapy, using proper resistance analysis, are needed before final conclusions can be reached regarding efficacy in the setting of bacterial resistance.

The impact of antibiotic resistance on the efficacy of three 7-day regimens against Helicobacter pylori

BACKGROUND

Antibiotic resistance affects the success of anti-Helicobacter pylori therapies and varies greatly from country to country.

AIM

To compare the efficacy of three short-term triple regimens in relation to H. pylori primary resistance in our region.

METHODS

We enrolled 210 H. pylori-positive dyspeptic patients for this randomized, open, parallel-group study. Three arms of 70 patients each received the following 1-week regimens: (1) ranitidine bismuth citrate 400 mg b.d. + clarithromycin 250 mg b.d. + metronidazole 500 mg b.d. (RCM); (2) bismuth subcitrate 240 mg b.d. + amoxycillin 1000 mg b.d. + metronidazole 500 mg b.d. (BAM); (3) omeprazole 20 mg o.d. + clarithromycin 250 mg b.d. + metronidazole 500 mg b.d. (OCM). H. pylori was assessed by CLO-test and histology before and 4 weeks after therapy. Antibiotic resistance was assessed by E-test.

RESULTS

On intention-to-treat analysis RCM was more effective than OCM (84% vs. 69%; P < 0.03) and BAM (84% vs. 63%; P < 0.004). MIC determination was successful in 117 out of 210 patients (55%); metronidazole resistance was present in 52 out of 117 patients (44%) and clarithromycin resistance was present in 17 out of 117 patients (14%). Excellent cure rates were achieved when strains were sensitive to both antibiotics (100% with RCM and BAM and 90% with OCM), whereas RCM was superior to OCM (P=0.009) and BAM (P=0.001) with respect to overall resistant strains (94% vs. 57% and 38%, respectively).

CONCLUSIONS

One-week RCM is the best regimen to eradicate H. pylori in our geographical area. This seems to be linked to the better ability of RCM compared to OCM and BAM in overcoming the high prevalence of H. pylori resistance to both metronidazole and clarithromycin in our region.