Eradication of Helicobacter pylori

Role of Carbon Monoxide in Host-Gut Microbiome Communication

Nature is full of examples of symbiotic relationships. The critical symbiotic relation between host and mutualistic bacteria is attracting increasing attention to the degree that the gut microbiome is proposed by some as a new organ system. The microbiome exerts its systemic effect through a diverse range of metabolites, which include gaseous molecules such as H₂, CO₂, NH₃, CH₄, NO, H₂S, and CO. In turn, the human host can influence the microbiome through these gaseous molecules as well in a reciprocal manner. Among these gaseous molecules, NO, H₂S, and CO occupy a special place because of their widely known physiological functions in the host and their overlap and similarity in both targets and functions. The roles that NO and H₂S play have been extensively examined by others. Herein, the roles of CO in host-gut microbiome communication are examined through a discussion of (1) host production and function of CO, (2) available CO donors as research tools, (3) CO production from diet and bacterial sources, (4) effect of CO on bacteria including CO sensing, and (5) gut microbiome production of CO. There is a large amount of literature suggesting the "messenger" role of CO in host-gut microbiome communication. However, much more work is needed to begin achieving a systematic understanding of this issue.

Correlation between creatinine clearance and Helicobacter pylori infection eradication with sequential and triple therapeutic regimens: A randomised clinical trial

BACKGROUND AND STUDY AIMS

Uraemic patients show susceptibility to gastrointestinal mucosal lesions and colonisation by Helicobacter pylori (HP). Antibiotic resistance constitutes a problem in treatment and bismuth preparations are toxic in uraemic patients. This study aimed to assess the correlation between creatinine clearance (CrCl) and eradication of HP infection with new sequential and standard triple therapeutic regimens.

PATIENTS AND METHODS

A total of 120 HP-positive patients with renal function impairment and 60 control patients with HP infection were enrolled in this study. Patients were divided into four groups on the basis of CrCl and were randomly assigned to one of the two different regimens: A 14-day standard triple therapy with 20mg omeprazole bid, 1000mg amoxicillin bid and 500mg clarithromycin bid and a new sequential regimen with 20mg omeprazole bid and 1000mg amoxicillin bid both for 14 days, 500mg ciprofloxacin bid for the first 7 days and 200mg furazolidone bid for the last 7 days. Doses of amoxicillin, clarithromycin and ciprofloxacin were reduced to 50% in the cases of CrCl <30mgdl(-1).

RESULTS

One hundred and sixty two out of 180 HP-positive patients (54.3% male, 51.6±12.1 years) completed treatment in the four groups and were studied. According to renal function they were classified into group A (n=39), haemodialysis (HD) patients; group B (n=37), CrCl <30mgdl(-1) without HD; group C (n=36), CrCl between 30 and 60mgdl(-1); and group D (n=50), control subjects with CrCl >90mgdl(-1). HP was successfully eradicated in 77.7% of patients with standard triple therapy and in 81.4% of patients with the sequential therapy. There was no significant difference among the study groups in the rate of HP-infection eradication with both regimens.

CONCLUSION

HP eradication rates did not differ with both sequential and standard therapeutic regimens in uraemic and non-uraemic patients. We, therefore, prefer the standard triple therapy due to its simplicity and reported.

Phenylphosphonate transport by Helicobacter pylori

BACKGROUND

Helicobacter pylori can utilize phenylphosphonate as a sole source of phosphorus, and it is able to transport the phosphonate N-phosphonoacetyl-L-aspartate. However, H. pylori does not have any genes homologous to those of the known pathways for phosphonate degradation in bacteria, indicating that it must have novel pathways for the transport and metabolism of phosphonates.

METHODS

Phenylphosphonate transport by H. pylori was studied in strains LC20, J99 and N6 by the centrifugation through oil method using [(14)C]-labeled phenylphosphonate.

RESULTS

The Michaelis constants of transport K(t) and V(max) for phenylphosphonate showed similar kinetics in the three strains. The Arrhenius plot for phenylphosphonate transport rates at permeant concentrations of 50 micromol/L was linear over the temperature range 10-40 degrees C with an activation energy of 3.5 kJ/mol, and a breakpoint between 5 and 10 degrees C. Transport rates increased with monovalent cation size. The effects of various inhibitors were investigated: iodoacetamide, amiloride, valinomycin, and nigericin reduced the rate of phenylphosphonate transport; sodium azide and sodium cyanide increased the transport rate; and monensin had no effect.

CONCLUSIONS

The kinetics and properties of H. pylori phenylphosphonate transport were characterized, and the data suggested a carrier-mediated transport mechanism.

Helicobacter pylori infection in hemodialysis patients: Susceptibility to amoxicillin and clarithromycin

AIM: To evaluate susceptibility of Helicobacter pylori to amoxicillin and clarithromycin in end-stage renal disease (ESRD) patients and non-uremic controls.

METHODS: The subjects with dyspeptic complaints were 33 ESRD patients and 46 age- and sex-matched non-uremic controls who exhibited H pylori on antral biopsy specimens. The two groups were age and sex matched. The H pylori strains’ pattern of susceptibility to amoxicillin and clarithromycin was investigated with the agar dilution technique.

RESULTS: None of the H pylori strains from either group showed resistance to amoxicillin with the agar dilution method. Twelve (36.4%) of the ESRD group strains and 7 (15.2%) of the control group strains showed resistance to clarithromycin, and this difference was statistically significant (P<0.05).

CONCLUSION: Resistance to amoxicillin does not appear to be an important problem in H pylori-infected ESRD and non-uremic patients in our region. In contrast, the rates of resistance to clarithromycin are high, particularly in the ESRD population.

Double-blind comparison of absorbable colloidal bismuth subcitrate and nonabsorbable bismuth subnitrate in the eradication of Helicobacter pylori and the relief of nonulcer dyspepsia

BACKGROUND

Bismuth is widely used for the eradication of H. pylori, especially in developing countries, although there are concerns over its neurotoxicity. Whether bismuth has to be absorbed in humans to act against H. pylori is not known. In this study, we compared "absorbable" (colloidal bismuth subcitrate) and "nonabsorbable" (bismuth subnitrate) bismuth as part of triple therapy in the eradication of H. pylori.

MATERIALS AND METHODS

A double-blind, randomized, placebo-controlled trial was carried out with 120 H. pylori-positive patients with nonulcer dyspepsia. Group CBS + Ab (n = 35) received colloidal bismuth subcitrate (one tablet qds), amoxicillin (500 mg qds), and metronidazole (400 mg tds). Group BSN + Ab (n = 35) received bismuth subnitrate (two tablets tds) and the same antibiotics. Group Ab (n = 35) received placebo bismuth (two tablets tds) and the antibiotics. Group BSN (n = 15) received bismuth subnitrate (two tablets tds) and placebo antibiotics. Bismuth was taken for 4 weeks and the antibiotics for the first 2 weeks. H. pylori eradication, side effects, compliance, pre- and post-treatment symptom scores, and bismuth absorption were assessed.

RESULTS

H. pylori eradication was 69%, 83%, 31%, and 0% in CBS + Ab, BSN + Ab, Ab, and BSN, respectively. Side effects, compliance, and symptom relief were similar in all groups, but blood bismuth levels were significantly greater in CBS + Ab than the other three groups.

CONCLUSION

The efficacy of bismuth-based therapies as part of triple therapy in the eradication of H. pylori is unrelated to absorption. Hence, the use of effective but poorly absorbed bismuth preparations should be encouraged for bismuth-based eradication therapies.

Metronidazole-resistant Helicobacter pylori in an urban Asian population

BACKGROUND

Helicobacter pylori eradication is the mainstay in the treatment of H. pylori-associated peptic ulcer disease. Metronidazole is an important component in most eradication regimens. However, the presence of metronidazole-resistant H. pylori adversely affects the efficacy of such regimens. We aimed to study the prevalence of metronidazole resistance in our population, and the factors associated with its presence.

METHODS AND RESULTS

From September 1993 to September 1996, 459 H. pylori isolates were collected and analysed. The overall resistance rate was 62.7%. The rate was significantly higher among women compared with men (P < 0.05). When the results were analysed according to each year, there was a significant increase in the resistance rate from 50.5% in the first year to 72.7% in the third year (P = 0.0039).

CONCLUSIONS

There was a significant rise in the prevalence of metronidazole resistance over a 3-year period. The presence of metronidazole resistance adversely affects the eradication rates of nitroimidazole-based regimens. Hence, in a population with a high prevalence of metronidazole resistance, the use of non-nitroimidazole-based therapy may be more efficacious. This information on resistance rates is important for the empirical choice of antibiotic against H. pylori in a population.

Effects of ranitidine bismuth citrate on Helicobacter pylori motility, morphology and survival

AIM

The effects of the anti-ulcer agents ranitidine bismuth citrate (RBC), ranitidine hydrochloride (R) and colloidal bismuth citrate (BC), on Helicobacter pylori motility, morphology and survival were examined to determine whether the clinical effectiveness of RBC might be linked to a specific action that inhibits bacterial motility.

METHODS

H. pylori from patients with duodenal ulcer or non-ulcer dyspepsia were exposed to RBC and BC at bismuth concentrations ranging from 12.5 to 50 microg/mL, and R at ranitidine concentrations ranging from 12.5 to 50 microg/mL for a brief period (< 15 min), 6 h and 24 h. Bacterial motility was assessed with a Hobson BacTracker, bacterial morphology by transmission electron microscopy, and growth inhibition by counting colony-forming units.

RESULTS

H. pylori motility was diminished with RBC and BC but not R. However, the effect of RBC was markedly greater than that of BC at each bismuth concentration and time of exposure tested: (i) brief exposure to RBC/bismuth 50 microg/mL but not to BC, resulted in a significant loss of motility without loss of viability or change in cell morphology, and (ii) bacteria were immobilized, and lost viability after exposure to RBC/bismuth 50 microg/mL for 24 h but not to BC. Morphological destruction caused by RBC differed from that by BC: after 24 h exposure to the highest concentration tested, cell fragmentation and flagella detachment occurred more frequently with BC than RBC, but the latter produced greater disruption of intracellular structures.

CONCLUSIONS

RBC suppresses growth of H. pylori, and has a specific inhibitory effect on the bacterial motor mechanism. These pharmacological actions are likely to contribute to the clinical effectiveness of the agent.

Lansoprazole and secnidazole with clarithromycin, amoxycillin or pefloxacin in the eradication of Helicobacter pylori in a developing country

BACKGROUND

A number of triple drug regimens using proton pump inhibitors and two antibiotics have been evaluated in the West and reported to achieve Helicobacter pylori eradication rates of over 90%. In developing countries however, these combinations have neither been well evaluated, nor the optimum treatment for H. pylori infection well defined.

AIM

To compare the combination of a proton pump inhibitor with a nitroimidazole and another antibiotic in eradicating H. pylori infection and healing duodenal ulcer.

METHODS

Sixty consecutive patients with active duodenal ulcer who were positive for H. pylori (by rapid urease test and 14C-urea breath test) were randomized into three treatments groups: (1) LAS (n=21): lansoprazole 30 mg o.m., amoxycillin 500 mg q.d.s. and secnidazole 2 g on alternate days for 2 weeks; (2) LCS (n=18): lansoprazole 30 mg o.m., clarithromycin 500 mg b.d. and secnidazole 2 g on alternate days for 1 week; (3) LPS (n=21): lansoprazole 30 mg o.m., pefloxacin 400 mg o.m. and secnidazole 2 g on alternate days for 2 weeks. Urease and breath tests were performed at 0, 6 and 12 weeks to check for H. pylori eradication.

RESULTS

Intention-to-treat eradication rates were as follows: LAS 86%, LCS 83%, LPS 71%; the overall ulcer healing rate was 90% at 6 weeks.

CONCLUSIONS

High H. pylori eradication rates were achieved using the amoxycillin- and clarithromycin-based therapies. Fewer side-effects, better compliance and low cost favoured the amoxycillin-based therapy.

New options in Helicobacter pylori eradication: efficacy, resistance and synergy

The eradication of Helicobacter pylori has become the focus of much attention since the first attempts at developing effective therapies some 10 years ago. This review focuses on ranitidine bismuth citrate (RBC), the first new drug to be introduced for use in the eradication of H. pylori. RBC when combined with clarithromycin gives consistently high eradication rates (above 80% intention-to-treat assessment in double-blind, international studies) as a simple dual therapy for 14 days or when combined with two antibiotics as a triple therapy for 7 days. RBC enhances the in vitro killing of H. pylori by antibiotics, such as clarithromycin, metronidazole or tetracycline, in a synergistic manner. This effect is seen even when the H. pylori strains are 'resistant' to the antibiotics. Such a synergistic effect probably explains the increased efficacy of RBC-clarithromycin dual therapies compared with clarithromycin dosed with acid-suppressive agents such as H2-receptor antagonists or proton-pump inhibitors.

Review: Helicobacter pylori. Current issues and new directions

The present review outlines current management issues and controversies related to Helicobacter pylori infection. Clearance of this infection markedly reduces the likelihood of duodenal and gastric ulcer recurrence and may result in the regression of low grade primary gastric lymphoma. Recent therapeutic advances have seen the development of simpler drug regimens to treat H. pylori that have fewer side effects and are shorter in duration. Clearance of the infection can be achieved in 80-95% of patients treated, depending on the drug regimen used, compliance with medications and antibiotic sensitivity. In developed nations reinfection is uncommon after successful treatment. Data do not currently support treatment of this infection for non-ulcer dyspepsia or for the prevention of gastric cancer, although whether certain individuals or populations may benefit from such treatment remains to be clarified.