Furazolidone-containing short-term triple therapies are effective in the treatment of Helicobacter pylori infection

Application of furazolidone in Helicobacter pylori infection eradication

Increasing antibiotic resistance is the primary reason for treatment failure of Helicobacter pylori (H. pylori) infection. To enhance the eradication rate, minimize the development of secondary resistance, and alleviate the socioeconomic burden, it is crucial to select H. pylori-sensitive antibiotics carefully. Furazolidone has been used for H. pylori eradication in developing countries for decades due to its affordability and low resistance rate. Numerous studies have demonstrated that furazolidone-containing regimens are more efficacious than those containing other antibiotics, as both first- and second-line therapies, and are also well tolerated. However, utility of furazolidone is restricted or not optimal in certain countries due to its infrequent but potentially severe adverse effects. The decision to discontinue usage of furazolidone because of concerns regarding adverse effects may be misguided. Here we comprehensively reviewed the studies on furazolidone at different dosages and treatment durations for H. pylori eradication. Further research on the mechanisms of action and clinical trials of furazolidone are of great practical importance.

Safety of furazolidone-containing regimen in Helicobacter pylori infection: a systematic review and meta-analysis

OBJECTIVES

Furazolidone containing regimen is effectivefor Helicobacter pylori (H. pylori) infection, but its safetyremains controversial. To assess the safety of furazolidone containing regimenin H. pylori infection.

DESIGN

A systematic review and meta-analysis.

DATA SOURCES

PubMed, Embase, Cochrane Library, Web of Science and Scopus databases were systematically searched for eligible randomised controlled trials.

ELIGIBILITY CRITERIA

Studies comparing furazolidone with non-furazolidone-containing regimen, variable durations or doses of furazolidone were included.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently selected studies and extracted data. Primary outcomes were the risk of total adverse events (AEs), serious AEs and severe AEs, expressed as relative risk (RR) with 95% CI. Secondary outcomes contained the incidence of individual adverse symptoms, AE-related treatment discontinuation and compliance.

RESULTS

Twenty-six articles were identified from 2039 searched records, of which 14 studies (n=2540) compared furazolidone with other antibiotics. The eradication rates of furazolidone-containing regimen were higher than those of other antibiotics in both intention-to-treat (RR 1.06, 95% CI 1.01 to 1.12) and per-protocol analysis (RR 1.05, 95% CI 1.00 to 1.10). Only two serious AEs were reported in furazolidone group (2/1221, 0.16%). No significant increased risk was observed for the incidence of total AEs (RR 1.04, 95% CI 0.89 to 1.21) and severe AEs (RR 1.81, 95% CI 0.91 to 3.60). Twelve studies (n=3139) compared different durations of furazolidone, and four studies (n=343) assessed variable doses. Elevated risk of total AEs and severe AEs were only found in a high daily dose of furazolidone rather than prolonged duration. The incidence of AE-related treatment discontinuation and compliance of patients were all similar, irrespective of dose and duration adjustments.

CONCLUSION

Furazolidone-containing regimen has a similar risk of AEs and compliance as non-furazolidone-containing regimen. A low daily dose of 200 mg is well-tolerated for 14 day regimen and should be first considered.

PROSPERO REGISTRATION NUMBER

CRD42019137247.

The effect of antibiotic resistance on Helicobacter pylori eradication efficacy: A systematic review and meta-analysis

BACKGROUND

The occurrence of antibiotic-resistant strains has been rapidly increasing due to the wide use of antibiotics. To evaluate the current effects of antibiotic resistance on Helicobacter pylori eradication efficacy, we conducted this systematic review and meta-analysis.

METHODS

Literature searches were conducted in the following databases: PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials. Statistical analysis was performed using STATA version 12.0 (StataCorp LP, College Station, TX, USA).

RESULTS

A total of 120 studies, including 28 707 patients, were assessed. Only first-line therapy was considered. The pooled RR of eradication rate in patients with Helicobacter pylori strains sensitive versus resistant to clarithromycin was 0.682 (95% CI: 0.636-0.731). The pooled RR of eradication rate in patients with Helicobacter pylori strains sensitive versus resistant to metronidazole was 0.843 (95% CI: 0.810-0.877). The pooled RR of eradication rate in patients with Helicobacter pylori strains sensitive versus resistant to levofloxacin was 0.794 (95% CI: 0.669-0.941). The pooled RR of eradication rate in patients with Helicobacter pylori strains sensitive versus resistant to dual clarithromycin and metronidazole was 0.674 (95% CI: 0.590-0.770).

CONCLUSION

Antibiotic resistance causes a decrease in the eradication rate of H pylori today. Quadruple concomitant therapy may overcome the declining H pylori eradication rate caused by metronidazole-only resistance.

Furazolidone treatment for Helicobacter Pylori infection: A systematic review and meta-analysis

Antibiotic resistance is a major cause of Helicobacter pylori (H. pylori) treatment failures. Because the resistance rate of H. pylori to furazolidone is low, we aimed to assess the efficacy and safety of furazolidone. We searched the PubMed, Web of Science, Cochrane Library, and Embase databases and included randomized controlled trials (RCT) that either compared furazolidone to other antibiotics or changed the administered dose of furazolidone. A total of 18 articles were included in the meta-analysis. According to the intention-to-treat (ITT) analysis, the total eradication rates of furazolidone-containing therapy were superior to those of other antibiotic-containing therapies (relative risk [RR] 1.07, 95% confidence interval [CI] 1.01-1.14) (13 RCTs). Specifically, the eradication rates of furazolidone-containing therapy were better than those for metronidazole-containing therapy (RR 1.10, 95% CI: 1.01-1.21 for ITT). The eradication rate of furazolidone-containing bismuth-containing quadruple therapy was 92.9% (95% CI: 90.7%-95.1%) (PP). In addition, a higher daily dose of furazolidone increased the eradication rate (RR 1.17, 95% CI: 1.05-1.31). And the incidence of some adverse effects, such as fever and anorexia, was higher in the furazolidone group than in the control group, the overall incidences of total side effects and severe side effects showed no significant differences between the groups. Furazolidone-containing treatments could achieve satisfactory eradication rates and did not increase the incidence of total or severe adverse effects, but the incidence of milder side effects, such as fever and anorexia, should be considered when prescribing furazolidone-containing treatments to patients.

Modified Sequential Therapy Regimen versus Conventional Triple Therapy for Helicobacter Pylori Eradication in Duodenal Ulcer Patients in China: A Multicenter Clinical Comparative Study

Objective. Antimicrobial resistance has decreased eradication rates for Helicobacter pylori infection worldwide. To observe the effect of eradicating Helicobacter pylori (H. pylori) and the treatment of duodenal ulcer by 2 kinds of modified sequential therapy through comparing with that of 10-day standard triple therapy. Methods. A total of 210 patients who were confirmed in duodenal ulcer active or heal period by gastroscopy and H. pylori positive confirmed by rapid urease test, serum anti-H. pylori antibody (ELASE), or histological examination enrolled in the study. All the patients were randomly divided into three groups: group A (70 cases) and group B (70 cases) were provided 10-day modified sequential therapy; group C (70 cases) was provided 10-day standard triple therapy. Patients of group A received 20 mg of Esomeprazole, 500 mg of Clarithromycin for the first 5 days, followed by 20 mg of Esomeprazole, 500 mg of Clarithromycin, and 1000 mg of Amoxicillin for the remaining 5 days. Group B received 20 mg of Esomeprazole, 1000 mg of Amoxicillin for the first 5 days, followed by 20 mg of Esomeprazole, 500 mg of Clarithromycin, and 1000 mg of Amoxicillin for the remaining 5 days. Group C received 20 mg of Esomeprazole, 500 mg of Clarithromycin, and 1000 mg of Amoxicillin for standard 10-day therapy. All drugs were given twice daily. H. pylori eradication rate was checked four to eight weeks after taking the medicine by using a ¹³C urea breath test. In the first, second, third, seventh, twenty-first, thirty-fifth days respectively, the symptoms of patients such as epigastric gnawing, burning pain, and acidity were evaluated simultaneously. Results. Overall, 210 patients accomplished all therapy schemes, 9 case patients were excluded. The examination result indicated that the H. pylori eradication rate of each group was as follows: group A 92.5% (62/67), group B 86.8% (59/68), and group C 78.8% (52/66). The H. pylori eradication rate of group A was slightly higher than group B (P < 0.05) and both of them were obviously higher than group C (P < 0.05). Modified sequential therapy was significantly more effective in patients with clarithromycin-resistant strains (80%/67% versus 31%; P = 0.02). Symptoms improvement: all the three groups could improve the symptoms such as epigastric gnawing, burning pain, and acidity since the first day. There was no significant difference in total score descending of symptoms between each group (P > 0.05). Conclusions. All the three therapy schemes could alleviate symptoms of duodenal ulcer patients in China efficiently. But as far as eradicating H. pylori is concerned, the modified sequential therapy was better than standard triple therapy, especially the therapy scheme used in group A.

Short-duration furazolidone therapy in combination with amoxicillin, bismuth subcitrate, and omeprazole for eradication of Helicobacter pylori

BACKGROUND/AIM

Resistance to metronidazole is one of the most common reasons for Helicobacter pylori treatment failure with the classic triple therapy. The clarithromycin-based regimen is not cost-effective for use in developing countries. Though furazolidone is a great substitute it has many side effects. Decreasing the duration of treatment with furazolidone to 1 week may help decrease the drug's side effects.

AIM

To study the efficacy and side effects of furazolidone when given for 1 week in combination with bismuth subcitrate, amoxicillin, and omeprazole.

MATERIALS AND METHODS

One hundred and seventy-seven patients with duodenal ulcer were randomly divided into two groups. Group I received omeprazole 2 Chi 20 mg + amoxicillin 2 Chi 1 g + bismuth subcitrate 4 Chi 120 mg for 2 weeks, with furazolidone 2 Chi 200 mg in the first week only. Group II received the same regimen, except that 1 week of furazolidone was followed by 1 week of metronidazole in the second week. Control endoscopy was performed after 6 weeks. Three biopsies from the antrum and three from the corpus were taken for urease testing and histology. Eradication was concluded if all tests were negative for H pylori.

RESULTS

One hundred and fifty-seven patients completed the study. Two subjects from group I and three from group II did not tolerate the regimen and were excluded from the analysis. No serious complication was detected in any patient. The eradication rates by per-protocol (PP) analysis and intention-to-treat (ITT) analysis were 89% and 79.3% in group I and 86.6% and 74.4% in group II, respectively.

CONCLUSION

One week of furazolidone in combination with 2 weeks of amoxicillin, omeprazole, and bismuth subcitrate is a safe and cost-effective regimen for the eradication of H pylori. Adding metronidazole to the above regimen does not increase the eradication rate.

Azithromycin-containing versus standard triple therapy for Helicobacter pylori eradication: A meta-analysis

AIM: To evaluate whether adding azithromycin to first-line Helicobacter pylori (H pylori) eradication improved eradication and reduced side effects.

METHODS: Eligible articles were identified by searches of electronic databases. We included all randomized trials that compared azithromycin-containing with standard triple-therapy regimens for first-line treatment of H pylori infection. Statistical analysis was performed with Review Manager 5.0.10. Sub-analyses were also performed.

RESULTS: We identified 14 randomized trials (1431 patients). Pooled H pylori eradication rates were 72.01% (95% CI: 58.09%-85.93%) and 69.78% (95% CI: 66.47%-73.09%) for patients with or without azithromycin by intention-to-treat analysis, and the odds ratio (OR) was 1.17 (95% CI: 0.64-2.14). The occurrence of side effects differed significantly and was 15.81% (95% CI: 12.50%-19.12%) and 25.20% (95% CI: 21.44%-28.96%) for treatment with or without azithromycin, respectively, and the summary OR was 0.58 (95% CI: 0.41-0.82). Furthermore, the azithromycin-containing group had a lower occurrence of diarrhea, nausea and taste disturbance.

CONCLUSION: Our review suggests that azithromycin-containing triple-therapy regimens could be equally effective in eradication of H pylori compared with standard first-line triple-therapy regimens.

Adverse events with bismuth salts for Helicobacter pylori eradication: systematic review and meta-analysis

AIM

To assess the safety of bismuth used in Helicobacter pylori (H pylori) eradication therapy regimens.

METHODS

We conducted a systematic review and meta-analysis. MEDLINE and EMBASE were searched (up to October 2007) to identify randomised controlled trials comparing bismuth with placebo or no treatment, or bismuth salts in combination with antibiotics as part of eradication therapy with the same dose and duration of antibiotics alone or, in combination, with acid suppression. Total numbers of adverse events were recorded. Data were pooled and expressed as relative risks with 95% confidence intervals (CI).

RESULTS

We identified 35 randomised controlled trials containing 4763 patients. There were no serious adverse events occurring with bismuth therapy. There was no statistically significant difference detected in total adverse events with bismuth [relative risk (RR) = 1.01; 95% CI: 0.87-1.16], specific individual adverse events, with the exception of dark stools (RR = 5.06; 95% CI: 1.59-16.12), or adverse events leading to withdrawal of therapy (RR = 0.86; 95% CI: 0.54-1.37).

CONCLUSION

Bismuth for the treatment of H pylori is safe and well-tolerated. The only adverse event occurring significantly more commonly was dark stools.

Adverse events with bismuth salts for Helicobacter pylori eradication: Systematic review and meta-analysis

AIM: To assess the safety of bismuth used in Helicobacter pylori (H pylori) eradication therapy regimens.

METHODS: We conducted a systematic review and meta-analysis. MEDLINE and EMBASE were searched (up to October 2007) to identify randomised controlled trials comparing bismuth with placebo or no treatment, or bismuth salts in combination with antibiotics as part of eradication therapy with the same dose and duration of antibiotics alone or, in combination, with acid suppression. Total numbers of adverse events were recorded. Data were pooled and expressed as relative risks with 95% confidence intervals (CI).

RESULTS: We identified 35 randomised controlled trials containing 4763 patients. There were no serious adverse events occurring with bismuth therapy. There was no statistically significant difference detected in total adverse events with bismuth [relative risk (RR) = 1.01; 95% CI: 0.87-1.16], specific individual adverse events, with the exception of dark stools (RR = 5.06; 95% CI: 1.59-16.12), or adverse events leading to withdrawal of therapy (RR = 0.86; 95% CI: 0.54-1.37).

CONCLUSION: Bismuth for the treatment of H pylori is safe and well-tolerated. The only adverse event occurring significantly more commonly was dark stools.

Nitrofuran-based regimens for the eradication of Helicobacter pylori infection

Several aspects of Helicobacter pylori eradication have been meta-analyzed; however, nitrofuran-based therapies constitute an exception. The aim of this study was the systematic review and meta-analysis of the effect of furazolidone- and nitrofurantoin-based regimens in the eradication of infection. Studies evaluating the effects of nitrofurans on H. pylori were identified from Medline, EMBASE, the Cochrane Controlled Trials Register and congress abstracts. The studies were classified into groups based on first-, second- and third-line regimens. The pooled eradication rates and combined odd ratios of the individual studies were calculated and compared with the published meta-analysis. The factors influencing the efficiency of the regimens were also analyzed. Side-effects of nitrofuran-based regimens were also analyzed. The pooled eradication rate of primary proton pump inhibitor-based regimens containing furazolidone was 76.3% (CI 67.8-84.2). The odds ratio for furazolidone-based regimens versus standard triple therapies was 2.34 (CI 0.76-3.92). Ranitidine bismuth citrate + furazolidone-based triple regimens were equally efficient (83.5%, CI 74.0-93.0, P = 0.06 versus triple therapies). Schedules including a H(2) antagonist + furazolidone + one other antibiotic achieved pooled eradication rates of 79.9% (CI 67.8-89.9, P = 0.04). Bismuth-based triple therapies achieved 84.5% (CI 72.6-93.0, P = 0.002). Primary quadruple regimens containing furazolidone were superior to triple therapies (83.4%, CI 69.7-92.3, P = 0.01). Second-line schedules containing furazolidone obtained eradication rates of 76.1% (CI 66.4-85.0, P = 0.28 versus primary regimens). Third-line 'rescue' therapies were efficient in 65.5% of the cases (CI 56.3-75.5, P = 0.0001). Side-effects of the regimens containing furazolidone were more frequent than in standard therapies (P = 0.02). The combined odds ratio of side-effects for furazolidone-based versus standard therapies was 0.74 (CI 0.32-1.98). The duration of treatment, but not the furazolidone dose, influenced the treatment outcome. Primary triple regimens containing furazolidone are slightly less efficient than the standard primary combinations; primary quadruple regimens were more efficient than triple therapies. Furazolidone is also efficient as a component of second-line or rescue therapies.

Meta-analysis: the effect of antibiotic resistance status on the efficacy of triple and quadruple first-line therapies for Helicobacter pylori

BACKGROUND

Information regarding the effects of drug resistance on therapies for Helicobacter pylori is limited.

AIMS

To determine the effect of drug resistance on the efficacy of first-line treatment regimens for H. pylori and identify the most efficacious treatments in the presence of drug resistance.

METHODS

We searched for studies using the keywords: 'Helicobacter pylori','resistance' and 'treatment' or 'therapy'. Multilevel meta-regression models were used to determine the effect of drug resistance on treatment efficacy.

RESULTS

We analysed data from 93 studies with 10,178 participants. For triple therapies, clarithromycin resistance had a greater effect on treatment efficacy than nitroimidazole resistance. Metronidazole resistance reduced efficacy by 26% in triple therapies containing a nitroimidazole, tetracycline and bismuth, while efficacy was reduced by only 14% when a gastric acid inhibitor was added to the regimen. Quadruple therapies containing both clarithromycin and metronidazole were the most efficacious; >80% of H. pylori infections were consistently eradicated with these regimens.

CONCLUSIONS

Drug resistance was a strong predictor of efficacy across triple therapies for the eradication of H. pylori in adults. Resistance to either clarithromycin or metronidazole, but not both simultaneously, may be overcome by using quadruple therapies, especially those containing both clarithromycin and metronidazole.

Nifuratel-containing initial anti-Helicobacter pylori triple therapy in children

BACKGROUND

Proton pump inhibitor-containing triple therapy with amoxicillin and metronidazole is recommended as initial treatment of Helicobacter pylori in childhood. However, eradication rate with this "classic" regimen is relatively low in Russia.

AIM

To evaluate empiric nifuratel, amoxicillin, and bismuth triple therapy for H. pylori gastritis in childhood.

MATERIALS AND METHODS

Pediatric outpatients with H. pylori-associated chronic gastritis who underwent endoscopy for dyspeptic symptoms received the combination of bismuth subcitrate (8 mg/kg/day, q.d.s.), nifuratel (30 mg/kg/day, q.d.s.), and amoxicillin (50 mg/kg/day, q.d.s.) for 10 days. H. pylori status was determined before and after the treatment (in 4-6 weeks) by modified Giemsa staining.

RESULTS

Seventy-three children (48 boys, 25 girls, age range 9-14) were entered. H. pylori was eradicated in 63 patients (86%; 95% confidence interval: 76.6-93.2; intention-to-treat and per protocol). There were no serious adverse reactions and were no withdrawals due to any side-effects. All of side-effects were self-limiting (dark stools, urine discoloration, blackening of the tongue, and others).

CONCLUSIONS

The combination of nifuratel, bismuth subcitrate, and amoxicillin was an effective and tolerable regimen for H. pylori eradication.

Helicobacter pylori eradication using tetracycline and furazolidone versus amoxicillin and azithromycin in lansoprazole based triple therapy: an open randomized clinical trial

BACKGROUND

Optimal anti-Helicobacter pylori treatment has not yet been established.

AIM

To evaluate H. pylori eradication using tetracycline and furazolidone versus amoxicillin and azithromycin in lansoprazole based triple therapy in northeastern of Brazil.

PATIENTS AND METHODS

One hundred and four patients with H. pylori infection, as determined by rapid urease testing and histology, were randomly assigned to receive either: lansoprazole (30 mg q.d.), tetracycline (500 mg q.i.d.), and furazolidone (200 mg t.i.d.) for 7 days (LTF; n = 52); or lansoprazole (30 mg b.i.d.) and amoxicillin (1 g b.i.d.) for 1 week, plus azithromycin (500 mg q.d.) for the first 3 days (LAAz; n = 52). H. pylori eradication was assessed 3 months following completion of therapy by means of rapid urease testing, histology and a 14C-urea breath test.

RESULTS

H. pylori eradication was achieved in 46 of 52 (88.4%, 95% CI: 77.5%-95.1%) patients in LTF group and in 14 of 52 (26.9%, 95% CI: 16.2%-40,1%) patients in LAAz group. On a per-protocol analysis, eradication rates were 91.8% (95% CI: 81.4%-97.3%) and 28.5% (95% CI: 17.2%-42.3%), respectively in LTF and LAAz groups.

CONCLUSION

The LAAz regimen yielded unacceptably low eradication rates. On the other hand, the LTF scheme represents a suitable alternative for H. pylori eradication.

Low-dose furazolidone in triple and quadruple regimens for Helicobacter pylori eradication

BACKGROUND

Furazolidone-based regimens for the eradication of Helicobacter pylori are low cost and effective. Unfortunately, the usual dose of furazolidone is not tolerable in many patients. Lower doses of furazolidone are expected to cause fewer adverse effects.

AIM

To investigate the efficacy of low-dose furazolidone in the eradication of H. pylori.

METHODS

One hundred and fifty patients with duodenal ulcer and H. pylori infection were randomly assigned to one of three treatment groups: omeprazole 20 mg b.d., amoxicillin 1000 mg b.d. and furazolidone 100 mg b.d. for 14 days (OAF); omeprazole 20 mg b.d., amoxicillin 1000 mg b.d., furazolidone 100 mg b.d. and bismuth subcitrate 240 mg b.d. for 14 days (OABF1); or omeprazole 20 mg b.d., amoxicillin 1000 mg b.d., furazolidone 200 mg b.d. and bismuth subcitrate 240 mg b.d. for 14 days (OABF2).

RESULTS

Of the 150 patients, 145 completed treatment. The intention-to-treat and per protocol eradication rates were 54% (27/50), 72% (36/50) and 92% (46/50) for the OAF, OABF1 and OABF2 groups, respectively. The OAF and OABF1 groups showed significantly lower eradication rates than the OABF2 group (P<0.001 and P<0.01, respectively).

CONCLUSIONS

Triple and quadruple furazolidone-based H. pylori eradication regimens do not yield acceptable success rates when a low dose of furazolidone (100 mg b.d.) is used.

Effect of different doses of furazolidone with amoxicillin and omeprazole on eradication of Helicobacter pylori

BACKGROUND

Resistance to metronidazole is one of the most common reasons for Helicobacter pylori treatment failure with classic triple therapy. In contrast, the clarithromycin-based regimen is not cost-effective for developing countries. Furazolidone is a very good substitute for metronidazole and clarithromycin, but its many side-effects limit widespread use. The aim of the present study was to assess the efficacy of two different doses of furazolidone in combination with amoxycillin and omeprazole.

METHODS

A total of 123 patients with duodenal ulcer were randomized and received the following medications for two weeks. Group A: furazolidone 2 x 200 mg + amoxycillin 2 x 1 g + omeprazole 2 x 20 mg/day. Group B: furazolidone 2 x 50 mg + amoxycillin 2 x 1 g + omeprazole 2 x 20 mg/day. Control endoscopy was performed after 6 weeks and two biopsy specimens from the antrum and two from the corpus were taken for a urease test and histology. Eradication was concluded if all tests were negative for H. pylori.

RESULTS

In total, 110 patients completed the study. Four patients in group A did not tolerate the regimen on day 8 of therapy and were excluded from the study. Serious complications such as fever, and fatigue and dizziness, which occurred in the beginning of the second week of treatment (days 8-10), were more common in group A than in group B (19%, 15.9% and 14.3%, respectively, in group A vs 0% in group B). The eradication rate by per protocol analysis was significantly higher in group A than in group B (88.9%vs 67.9%, respectively, P = 0.008). However, this difference was low and not statistically significant by intention-to-treat analysis (76.2% in group A and 62.3% in group B, P = 0.09).

CONCLUSION

The regimen with a non-reduced dose of furazolidone in combination with amoxycillin and omeprazole was effective when the patients tolerated the drugs and completed the study.

Low Helicobacter pylori eradication rates with 4- and 7-day regimens in an Iranian population

BACKGROUND

In Iran, there is insufficient information on the efficacy of Helicobacter pylori eradication regimens shorter than 10 days. This study aims at assessing the efficacy of 4- and 7-day H. pylori eradication regimens in a high-incidence area of gastric cancer in Iran.

METHODS

Subjects with an endoscopic diagnosis of gastritis, positive urease test, and a histological diagnosis of chronic gastritis were enrolled. Patients were randomly assigned to one of three groups: AOC7 (1000 mg amoxicillin, 20 mg omeprazole, and 500 mg clarithromycin twice daily for 7 days), FOT4 (200 mg furazolidone, 20 mg omeprazole, and 500 mg tetracycline twice daily for 4 days) and FOT7 (the same treatment as the FOT4 group but for 7 days). Sensitivity to these antibiotics was determined in all isolates recovered from culture. The efficacy of eradication was assessed 8 weeks after the end-of-treatment by the 14C-urea breath test.

RESULTS

One hundred and twenty-eight patients were enrolled in the study. Culture was positive for 84 patients and none of these were resistant to amoxicillin, tetracycline or furazolidone, 1.2% were resistant to clarithromycin and 32.1% to metronidazole. Forty-five, 41 and 42 patients were randomly allocated to the AOC7, FOT4, and FOT7 groups, respectively. The intention-to-treat eradication rates were 35.5, 17.1, and 23.8% for the AOC7, FOT4, and FOT7 groups, respectively.

CONCLUSION

Treatment regimens of 4 or 7 days are unacceptable for H. pylori infection in Iran, even in the presence of a favorable sensitivity profile.

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.

Impact of furazolidone-based quadruple therapy for eradication of Helicobacter pylori after previous treatment failures

BACKGROUND

One week of quadruple therapy including metronidazole is recommended for Helicobacter pylori treatment failures after first line therapy regardless of resistance status. This study investigated whether a quadruple regimen containing furazolidone could be effective as a third-line (salvage) therapy.

METHODS

All patients with previous H. pylori treatment failure after a clarithromycin-metronidazole +/- amoxicillin combination plus acid suppression were given lansoprazole 30 mg twice a day (bid), tripotassiumdicitratobismuthate 240 mg bid, tetracycline 1 g bid, metronidazole 400 mg (PPI-B-T-M) three times a day (tid) for 1 week. In the case of treatment failure with this second-line therapy, the same regimen was applied for 1 week except for using furazolidone 200 mg bid (PPI-B-T-F) instead of metronidazole (sequential study design).

RESULTS

Eighteen consecutive patients were treated with PPI-B-T-M. Eleven of those 18 remained H. pylori positive (38.9% cured). Pretherapeutic metronidazole resistance was associated with a lower probability of eradication success (10% vs. 75%, p=.04). Ten of these 11 patients agreed to be retreated by PPI-B-T-F. Final cure of H. pylori with PPI-B-T-F was achieved in 9/10 patients (90%) nonresponsive to PPI-B-T-M.

CONCLUSIONS

In the presence of metronidazole resistance, PPI-B-T-M as a recommended second-line therapy by the Maastricht consensus conference achieved unacceptable low cure rates in our metronidazole pretreated population. In this population, metronidazole based second-line quadruple therapy may be best suited in case of a metronidazole-free first line-regimen (e.g. PPI-clarithromycin-amoxicillin) or a low prevalence of metronidazole resistance. Furazolidone in the PPI-B-T-F combination does not have a cross-resistance potential to metronidazole and is a promising salvage option after a failed PPI-B-T-M regimen.

Furazolidone-based triple 'rescue therapy' vs. quadruple 'rescue therapy' for the eradication of Helicobacter pylori resistant to metronidazole

BACKGROUND

The optimal treatment of patients with Helicobacter pylori resistant to metronidazole has not been established.

AIM

To compare the efficacy of quadruple and furazolidone-based triple therapy in the eradication of H. pylori resistant to metronidazole.

METHODS

Duodenal ulcer patients (n = 70) in whom initial eradication therapy failed and who harboured H. pylori strains resistant to metronidazole were randomized to receive one of the following 7-day regimens: colloidal bismuth subcitrate, 240 mg, tetracycline, 750 mg, and furazolidone, 200 mg, each given twice daily (BTF), or omeprazole, 20 mg b.d., colloidal bismuth subcitrate, 240 mg b.d., tetracycline, 500 mg q.d.s., and metronidazole, 500 mg b.d. (OBTM). H.pylori status was assessed by culture, histology and rapid urease test before treatment and 4-6 weeks after therapy. Susceptibility to metronidazole was assessed by the agar dilution method.

RESULTS

H. pylori eradication rates with intention-to-treat/per protocol analyses were: BTF, 85.7%/90.9%; OBTM, 74.2%/89.6%. Duodenal ulcers were healed in nine of 10 (90%) patients in the BTF group and in all patients (12/12) (100%) in the OBTM group (P = N.S.). A significantly lower rate of adverse events was observed in the BTF group than in the OBTM group (31.4% vs. 60%, P = 0.03), but there was no difference in terms of discontinuation of treatment (2/35 vs. 6/35, P = N.S.).

CONCLUSIONS

The 1-week BTF regimen was as effective as the OBTM regimen, and produced less adverse events. Thus, it may be used in patients in whom resistance of H. pylori to metronidazole is suspected.

One-week omeprazole, furazolidone and amoxicillin rescue therapy after failure of Helicobacter pylori eradication with standard triple therapies

AIM

To test the efficacy of omeprazole, furazolidone and amoxicillin triple therapy for the treatment of Helicobacter pylori infection after failure of standard first-line therapy recommended by the Asia-Pacific Consensus on the management of H. pylori infection.

METHODS

Patients with failed H. pylori eradication received omeprazole, 20 mg, furazolidone, 100 mg, and amoxicillin, 1 g, all twice daily for 1 week. Endoscopy (CLO test, histology and culture) was performed before treatment. Post-treatment H. pylori status was determined by 13C-urea breath test 6 weeks later.

RESULTS

Fifty patients were recruited. Resistance to metronidazole, clarithromycin and both drugs was in the range of 50-64%, 60-75% and 40-50%, respectively, after failure of first-line therapy. Amoxicillin resistance was not found. The intention-to-treat and per protocol H. pylori eradication rates were 52% and 53%, respectively. Patients with double resistance to metronidazole and clarithromycin showed the lowest eradication rate (38%), which was significantly lower than that of patients with sensitive strains (88%). Side-effects were minimal and compliance was excellent (98%).

CONCLUSIONS

One-week omeprazole, furazolidone and amoxicillin rescue therapy achieved a high eradication rate in strains sensitive to metronidazole and clarithromycin. This is a cheap and safe rescue regimen when guided by pre-treatment sensitivity testing.

Increased primary resistance to recommended antibiotics negatively affects Helicobacter pylori eradication

OBJECTIVE

To evaluate the efficacy of two commonly employed treatments for Helicobacter pylori infection and the impact of bacterial resistance to antibiotics on eradication rate.

METHODS

Ninety-two consecutive H. pylori-positive patients with active peptic ulcer disease were randomly enrolled to receive a 7-day treatment with either lansoprazole 30 mg plus amoxicillin 1 g and clarithromycin 500 mg [all twice a day (b.i.d.), Group A, n = 46]; or bismuth subcitrate 125 mg four times a day (q.i.d.) plus tetracycline 500 mg q.i.d and furazolidone 200 mg b.i.d. (Group B, n = 46) H. pylori status was reassessed 30 days after completion of the therapy and bacterial resistance to the antibiotics was investigated using an in vitro assay.

RESULTS

Five patients from each study group were lost to follow up. Both treatments resulted in similar H. pylori eradication rate: 66-60% (per protocol), 59-52% (intention-to-treat) in Groups A and B, respectively (non significant). However, eradication improved to 79% in the absence of H. pylori resistance to clarithromycin or amoxicillin.

CONCLUSION

Primary resistance to clarithromycin or amoxicillin may underscore a potentially serious problem for the eradication of H. pylori infection. Testing for bacterial resistance may become necessary to improve therapeutic efficacy.

One-week regimens containing ranitidine bismuth citrate, furazolidone and either amoxicillin or tetracycline effectively eradicate Helicobacter pylori: a multicentre, randomized, double-blind study

BACKGROUND

The metronidazole resistance of Helicobacter pylori strains has increased rapidly.

AIM

To evaluate the efficacy and safety of new 1-week regimens containing ranitidine bismuth citrate, furazolidone and either amoxicillin or tetracycline.

METHODS

One hundred and twenty patients with H. pylori-positive inactive duodenal ulcer or non-ulcer dyspepsia diagnosed by endoscopy were recruited randomly to receive one of two regimens for 7 days: ranitidine bismuth citrate, 350 mg b.d., furazolidone, 100 mg b.d., and either amoxicillin, 1000 mg b.d. (n=60), or tetracycline, 500 mg b.d. (n=60). H. pylori infection was identified by rapid urease testing and histology. 13C-Urea breath test was performed to evaluate the cure of H. pylori infection at least 4 weeks after completion of triple therapy.

RESULTS

The eradication rates of H. pylori by ranitidine bismuth citrate-furazolidone-amoxicillin and ranitidine bismuth citrate-furazolidone-tetracycline regimens were 82% and 85% (P > 0.05), respectively, by intention-to-treat analysis, and 85% and 91% (P > 0.05), respectively, by per protocol analysis. Adverse effects were mild in both ranitidine bismuth citrate-furazolidone-amoxicillin and ranitidine bismuth citrate-furazolidone-tetracycline groups.

CONCLUSIONS

One-week regimens containing ranitidine bismuth citrate, furazolidone and amoxicillin or tetracycline are well tolerated and effective for the eradication of H. pylori.

Review article: alternative antibacterial agents for Helicobacter pylori eradication

Standard eradication therapies against Helicobacter pylori appear to be effective in most cases, but in clinical practice a failure rate higher than the 5-10% reported in clinical trials is often observed. Among the various reasons responsible for therapeutic failure, antibiotic resistance is becoming a major issue in some countries. A range of different antibacterial agents is currently under investigation: several macrolides, new fluoroquinolones, furazolidone and rifabutin. Although not formally tested in refractory cases, azithromycin, spiromycin, levofloxacin and furazolidone represent the most promising antibacterial agents for possible inclusion in eradication regimens. Rifabutin has been evaluated in H. pylori infections resistant to standard therapies. Although very effective, the drug is expensive and its use should be restricted to the most difficult cases to avoid the development of rifabutin resistance in Mycobacterium spp.

Effect of acid secretion blockade by omeprazole on the relative bioavailability of orally administered furazolidone in healthy volunteers

AIMS

The administration of omeprazole may interfere with the absorption of orally administered drugs by reducing gastric pH and hence tablet dissolution. The aim of this study was to investigate the effects of a 5 day administration of omeprazole on the pharmacokinetics of furazolidone.

METHODS

Eighteen healthy (nine male and nine female) volunteers were selected. The study had an open randomized two-period crossover design with a 21 day washout period between the phases. Serum concentrations of furazolidone were measured by reversed-phase h.p.l.c. with ultraviolet detection.

RESULTS

Administration of omeprazole caused a significant reduction of Cmax [0.34 microg x ml(-1) (range 0.25-0.43) vs 0.24 microg x ml(-1) (range 0.15-0.34)] with no significant delay in absorption tmax [2.5 h (range 1.85-3.0) vs 2.4 h (range 2.06-2.71)].

CONCLUSIONS

Furazolidone was rapidly absorbed after oral administration. Short-term treatment with omeprazole did alter the relative bioavailability of this drug, probably through an effect on absorption kinetics or first-pass metabolism.

Helicobacter pylori infection--current treatment practice

Helicobacter pylori infection, which is present in 30 - 60% of the population in developed countries and in more than 60% in developing countries, is established to be a major cause of gastritis, peptic ulcer disease and gastric cancer. Eradication therapy has been incorporated into clinical practice over the past 15 years. Treatment regimens include a 2 week bismuth-based triple therapy (a bismuth compound plus metronidazole, tetracycline or amoxycillin), a 1 week proton-pump inhibitor (PPI)-based triple therapy and a 1 week ranitidine bismuth citrate (RBC)-based triple therapy (a PPI or RBC plus any two of the three antibiotics, metronidazole, amoxycillin and clarithromycin). These regimens achieve eradication rates of >> 80%. H. pylori resistance to metronidazole and clarithromycin decreases the clinical efficacy of most regimens, despite the high eradication rates for resistant strains achieved by the RBC-triple therapy in some recent trials. The dose of antibiotics (especially clarithromycin) and the duration of treatment may also influence the eradication rate. Doctors' beliefs impact on clinical practice and, thus, influence the clinical application of eradication therapy. Whereas peptic ulcer disease and primary gastric low-grade B-cell mucosa-associated lymphoid tissue lymphoma (MALToma) have become established as definite indications for eradication therapy, there remain controversies surrounding non-ulcer dyspepsia, gastro-oesophageal reflux disease, atrophic gastritis, intestinal metaplasia, use of non-steroidal anti-inflammatory drugs (NSAIDs) and H. pylori-related extradigestive diseases.

A multicentre study on eradication of Helicobacter pylori using four 1-week triple therapies in China

BACKGROUND

Short-term proton pump inhibitor-based triple therapies for the eradication of Helicobacter pylori are used widely. The eradication rates vary greatly from country to country and from region to region.

AIM

To assess the efficacy at eradicating H. pylori of 1-week regimens containing three medications: omeprazole (O) or colloidal bismuth subcitrate (B), furazolidone (F) or metronidazole (M), and amoxicillin (A) or clarithromycin (C).

METHODS

A multicentre study involving 20 hospitals in different regions of China. A total of 892 patients with H. pylori-positive non-ulcer dyspepsia or healed duodenal ulcer confirmed by endoscopy were recruited to receive, randomly, one of four regimens: OMC, OFC, OFA, and BFC, b.d. for 7 days. 13C-urea breath test was performed 4-8 weeks after completion of treatment.

RESULTS

The eradication rates with per protocol/intention-to-treat analyses were: OMC (n=217/219) 66%/65%; OFC (n=227/229) 69%/69%; OFA (n=223/225) 87%/86%; and BFC (n=214/219) 80%/78%. The eradication rate (per protocol analysis) in duodenal ulcer (79%) was higher than that in non-ulcer dyspepsia (73%, P=0.033). Patient compliance was good. The adverse events of the four regimens were mild, and mainly gastrointestinal.

CONCLUSIONS

The omeprazole, furazolidine and amoxicillin regimen achieves a high H. pylori eradication rate in different geographical regions of China.

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.

A new quadruple therapy for Helicobacter pylori using tripotassium dicitrato bismuthate, furazolidone, josamycin and famotidine

BACKGROUND

In our previous study, a triple therapy using tripotassium dicitrato bismuthate (TDB), josamycin and furazolidone achieved a suboptimal cure rate of Helicobacter pylori infection.

AIM

To investigate whether the addition of an antisecretory agent raises the cure rate using this regimen.

METHODS

One hundred and twenty H. pylori positive patients with peptic ulcer disease or functional dyspepsia were randomly assigned to receive 1-week quadruple therapy of TDB 240 mg b.d., furazolidone 100 mg b.d., josamycin 1000 mg b.d. and famotidine 20 mg b.d. (BFJF group), or triple therapy of TDB 240 mg b.d., furazolidone 100 mg b.d. and clarithromycin 250 mg b.d. (BFC group). H. pylori status was assessed by histology and culture of gastric biopsy specimens before and at least 4 weeks after completion of therapy.

RESULTS

Seven patients (three in the BFJF group and four in the BFC group) dropped out. Eradication rates (intention-to-treat/per protocol) were 90%/95% in the BFJF group and 82%/88% in the BFC group, respectively (P > 0.05). Duodenal ulcer healing rates were 94% (16/17) in the BFJF group and 80% (20/25) in the BFC group, respectively (P > 0.05). Mild side-effects occurred in 11 (18%) patients in the BFJF group and 10 (17%) in the BFC group (P > 0.05).

CONCLUSIONS

One-week quadruple therapy consisting of TDB, furazolidone, josamycin and famotidine achieves a high cure rate of H. pylori infection.

Evaluation of nitrofurantoin combination therapy of metronidazole-sensitive and -resistant Helicobacter pylori infections in mice

The main objectives of this study were to determine whether the nitroreductase enzyme encoded by the rdxA gene of Helicobacter pylori was responsible for reductive activation of nitrofurantoin and whether a triple-therapy regimen with nitrofurantoin was able to eradicate metronidazole-sensitive and -resistant H. pylori infections from mice. The susceptibilities to nitrofurantoin of parent and isogenic rdxA mutant strains (three pairs), as well as a series of matched metronidazole-sensitive and -resistant strains isolated from mice (30) and patients (20), were assessed by agar dilution determination of the MIC. Groups of mice colonized with the metronidazole-sensitive H. pylori SS1 strain or a metronidazole-resistant rdxA SS1 mutant were treated with either metronidazole or nitrofurantoin as part of a triple-therapy regimen. One month after the completion of treatment the mice were sacrificed and their stomachs were cultured for H. pylori. The nitrofurantoin MICs for all strains tested were between 0.5 and 4.0 microg/ml. There was no significant difference between the susceptibility to nitrofurantoin of the parental strains and those of respective rdxA mutants or between those of matched metronidazole-sensitive and -resistant H. pylori isolates. The regimen with metronidazole eradicated infection from all eight SS1-infected mice and from one of eight mice inoculated with the rdxA mutant (P < or =0.001). The regimen with nitrofurantoin failed to eradicate infection from any of the six SS1-infected mice (P < or =0.001) and cleared infection from one of seven mice inoculated with the rdxA mutant. These results demonstrate that, despite the good in vitro activity of nitrofurantoin against H. pylori and the lack of cross-resistance between metronidazole and nitrofurantoin, eradication regimens involving nitrofurantoin are unable to eradicate either metronidazole-sensitive or -resistant H. pylori infections from mice.

Challenges to therapy in the future

Quadruple therapy (with a proton pump inhibitor (PPI), metronidazole, tetracycline and bismuth) is generally reserved for second-line treatment; however, studies using this regimen for 7 days have found it to be effective even in metronidazole-resistant strains. Resistance is an ongoing problem with antimicrobial therapy but considerable progress has now been made into understanding the underlying genetic mechanisms of this process. Metronidazole resistance in Europe is usually in the range of 20-30% of strains but may be as high as 70% in some countries. One genetic mechanism involved is thought to be a mutation of the rdxA gene. Macrolide resistance appears to be on the increase in Europe, varying from 1% in some countries to 13% in others. The genetic mechanism involved has been shown to be a point mutation of a ribosomal RNA. Amoxicillin resistance is an emerging problem that has an adverse effect on eradication rates in clinical practice. Resistance has been shown to be caused by the absence of one of the four binding proteins in the cell wall. Few novel antibiotics have been developed for use in eradication therapy, although rifabutin, secnidazole and furazolidone have shown some success as part of combination therapy. Alternative therapies that have been tested include mucosal protective agents which have been used in place of a PPI in some eradication regimens with some success, and the somatostatin analog, octreotide, that has been used as part of quadruple therapy in place of a PPI and produced eradication rates of approximately 88%. The ultimate challenge is still to develop a safe and effective vaccine against Helicobacter pylori. Current and future research will also focus on identifying genetic targets for therapy, adhesion molecule analogs to prevent binding of the bacterium, and urease inhibitors. The current triple therapy treatment options available for the eradication of Helicobacter pylori infection are over 90% effective in susceptible organisms and there are very few medical conditions to which we can offer such efficacious treatment. Unfortunately, the recommendations made at consensus conferences are not always put into practice and physicians in primary care may be unaware of the true efficacy of eradication therapy. Treatment is very simple: three drugs, twice a day for 1 week. The main focus for both primary care physicians and gastroenterologists should be to reinforce the need for patient compliance, otherwise we will see an increase in antibiotic resistance. Patients should be prewarned that they may experience some mild side effects and should be encouraged to complete the course of treatment. The real challenge for the future will be the management of patients who do not respond to first-line treatment. This paper will focus on potential problems with therapy, such as antibiotic resistance, and possible future solutions, such as novel antibiotics and vaccines.

Equally high efficacy of 4, 7 and 10-day triple therapies to eradicate Helicobacter pylori infection in patients with ulcer disease

BACKGROUND

In patients with ulcer disease the optimal dose and duration of Helicobacter pylori treatment containing omeprazole (O), metronidazole (M) and clarithromycin (C) has yet to be established. The efficacy might be influenced by metronidazole- and clarithromycin-resistance.

AIM

To study the effect of duration of OMC treatment on its efficacy and influence of metronidazole-resistance and clarithromycin-resistance on the optimal duration.

MATERIALS AND METHODS

Ulcer patients (n=76) were randomized to three double-blind treatments of 10 days: OMC 4 consisted of 4 days b.d. 20 mg omeprazole, 400 mg metronidazole and 250 mg clarithromycin switched over to 6 days b.d. 20 mg omeprazole and placebo antibiotics (n=27); OMC 7 consisted of 7 days b.d. omeprazole 20 mg, metronidazole 400 mg and clarithromycin 250 mg and 3 days b.d. omeprazole 20 mg and placebo antibiotics (n=25); OMC 10 consisted of 10 days b.d. omeprazole 20 mg, metronidazole 400 mg and clarithromycin 250 mg (n=24). H. pylori was assessed by biopsies for culture and histology pre- and 4-6 weeks after OMC therapy. Metronidazole-resistance and clarithromycin-resistance were assessed by the E-test.

RESULTS

Intention-to-treat-eradication rates were: OMC 4, 96%; OMC 7, 92%; and OMC 10, 96% (N.S.). All of the three per protocol eradication rates were 100% (95% CI: 85.2-100). Of 75 isolates, 16 were metronidazole-resistant and one was clarithromycin-resistant.

CONCLUSION

In H. pylori-positive ulcer patients, OMC 4 is highly efficacious and as effective as OMC 7 and OMC 10. No influence of metronidazole-resistance or clarithromycin-resistance was observed.

Prevalence of Helicobacter pylori resistance to metronidazole, clarithromycin, amoxicillin, tetracycline, and furazolidone in Brazil

BACKGROUND

Helicobacter pylori infection is associated with a wide range of digestive diseases and is very prevalent in developing countries, although few data exist on the susceptibility of H. pylori to antimicrobials commonly used in eradication schedules in these countries. The aim of this study was to evaluate the resistance of H. pylori to metronidazole, clarithromycin, amoxicillin, tetracycline, and furazolidone in dyspeptic Brazilian patients. Material and Methods. Ninety consecutive H. pylori-positive patients were enrolled. Resistance was evaluated by an agar dilution test.

RESULTS

Resistance to metronidazole was detected in 38 patients (42%); to amoxicillin in 26 individuals (29%); to clarithromycin in 6 patients (7%); to tetracycline in 6 patients (7%); and to furazolidone in 4 individuals (4%). Thirteen strains were resistant to two agents, and eight strains were resistant to three antimicrobials.

CONCLUSIONS

These results confirm the need for culture and susceptibility testing to define H. pylori resistance patterns in particular geographical areas before the general use of an eradication schedule. They also suggest the possibility of resistance to such antimicrobials as amoxicillin or tetracycline in geographical areas with a high prevalence of H. pylori infection and still not fully evaluated for antimicrobial susceptibility.

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.