Metronidazole resistance: a predictor of failure of Helicobacter pylori eradication by triple therapy

The nonadherence and risk factors of eradication failure by sequential therapy as first-line anti-Helicobacter pylori treatment in real-world clinical practice

BACKGROUND

The eradication rates of sequential therapy are high in clinical trials; however, the adherence for follow-up or the patient population in a real-world setting might be different from those in trails. This study investigates the effectiveness of sequential therapy in a real-world setting and the factors that lead to treatment failure.

MATERIALS AND METHODS

In this retrospective study, patients receiving sequential therapy as a first-line anti-Helicobacter pylori (H. pylori) treatment in a real-world setting were reviewed. The age adjusted Charlson Comorbidity Index (age-CCI) and baseline variety of medications were reviewed to determine factors correlated with nonadherence for post-treatment testing and H. pylori eradication failure.

RESULTS

A total of 1053 patients were reviewed. A total of 579 patients receiving sequential therapy were included in the analyses. Among them, 462 received post-treatment testing and were placed into the follow-up group. Thus, the post-treatment testing rate was 79.8%. Stroke was an independent factor of nonadherence for post-treatment testing. In the follow-up group, the eradication failure rate was 8.2%. Female sex (odds ratio [OR] 2.41 [95% CI 1.16-5.03], p = 0.02) and age-CCI ≥2 (OR 3.16 [1.05-9.48], p = 0.04) were independent factors of H. pylori eradication failure. The eradication failure rates were 14.4%, 7.8%, 7.1%, and 3.1% for the females with age-CCI ≥2, females with age-CCI <2, males with age-CCI ≥2, and males with age-CCI <2 subgroups, respectively (p = 0.027).

CONCLUSIONS

In a real-world setting, the adherence rate of post-treatment testing for sequential therapy as a first-line anti-H. pylori treatment was found to be suboptimal. Female sex and age-CCI ≥2 were independent factors of eradication failure.

Antibiotic resistance of Helicobacter pylori in Australia and New Zealand: A systematic review and meta-analysis

OBJECTIVE

While the global prevalence of antibiotic-resistant Helicobacter pylori (H. pylori) is increasing, there is much regional variation, and local data are required to guide eradication therapy. We performed a systematic review and meta-analysis to determine rates of H. pylori antibiotic resistance in Australia and New Zealand.

STUDY DESIGN

Random effects meta-analysis of data from 15 published studies and three published abstracts reporting prevalence of primary or secondary H. pylori antibiotic resistance in Australasia.

DATA SOURCES

PubMed, EMBASE, MEDLINE, PROSPERO, and the Cochrane Library were searched until August, 2020.

DATA SYNTHESIS

Fifteen published studies and three published abstracts were identified; one study was excluded due to high risk of bias. Seventeen studies conducted between 1996 and 2013 were included in the final analysis, 12 reporting primary and five reporting secondary antibiotic resistance. Prevalence of primary resistance was clarithromycin 7.4% (95% confidence interval [CI], 5.3-9.7%), metronidazole 50.0% (95%CI, 23.9-56.1%), fluoroquinolones 3.7% (95%CI, 0.004-14.8%), and both amoxicillin and tetracycline <0.5%. Subgroup analysis (last 20 years) showed doubling of clarithromycin resistance to 16.1% (95%CI 11.2-21.7%) with other resistance stable. Prevalence of secondary resistance was high for all antibiotics, particularly clarithromycin 78.7% (95%CI, 64.1-90.1%) and metronidazole 68.3% (95%CI, 59.9-76.1%).

CONCLUSIONS

The outcomes reveal an increase in primary H. pylori clarithromycin resistance since the year 2000, while metronidazole resistance has remained stable and primary resistance to amoxicillin, tetracycline, and fluoroquinolones is low. Rates of secondary resistance to metronidazole and clarithromycin are high. The results highlight the need for contemporary local data on antibiotic resistance in Australia and New Zealand.

Anti-Helicobacter pylori activity of acomplex mixture of Lactobacillus paracasei HP7 including the extract of Perilla frutescens var. acuta and Glycyrrhiza glabra

The effect of standard therapeutic strategies on Helicobacter pylori infection is diminished over time owing to the emergence of drug resistant strains. In this study, we would like to confirm the enhanced effect of L. paracasei HP7, which has been reported to exert antibacterial and gastric mucosal protective effects, in combination with Perilla frutescens var. acuta (P. frutescens)and Glycyrrhiza glabra (G. glabra) extracts.

P. frutescens extract and G. glabra extract were found to inhibit the growth of H. pylori in a concentration-dependent manner, and the combination of L. paracasei HP7 and P. frutescens extract and G. glabra extract effectively inhibited H. pylori from attaching to AGS a gastric epithelial cells. Moreover, L. paracasei HP7 complex mixture containing P. frutescens and G. glabra extracts has been shown to inhibit H. pylori virulence genes such as AlpA, CagA, FlaA and UreA. When H. pylori-infected mice were administered a complex mixture of L. paracasei HP7 containing P. frutescens and G. glabra extract, the infection rate of H. pylori was significantly reduced. In addition, the L. paracasei HP7 complex mixture significantly reduced serum IL-8 levels and stomach inflammation in H. pylori infected mice.

These results suggest that a complex mixture of L. paracasei HP7 containing P. frutescens and G. glabra extracts may be an alternative to treating diseases caused by H. pylori infection.

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.

In vitro and in vivo inhibition of Helicobacter pylori by Lactobacilllus paracasei HP7

The efficacy of standard therapeutic strategies for Helicobacter pylori (H. pylori) infection is decreasing over time due to the emergence of drug-resistant strains. As an alternative, the present study investigated the capacity of Lactobacilllus paracasei (L. paracasei) HP7, isolated from kimchi, to inhibit H. pylori growth. The effects of L. paracasei HP7 on H. pylori adhesion and H. pylori-induced inflammation were examined in AGS human gastric adenocarcinoma epithelial cells and a mouse model of H. pylori SS1 infection. L. paracasei HP7 reduced H. pylori adhesion to AGS cells and suppressed the inflammatory response in infected cells by downregulating interleukin-8. H. pylori colonization in the stomach of C57BL/6 mice was demonstrated by rapid urease test, and results showed significant decrease in mice post-treated with L. paracasei HP7. Additionally, L. paracasei HP7 decreased gastric inflammation and epithelial lesions in the stomach of H. pylori-infected mice. These results demonstrate that L. paracasei HP7 treatment can inhibit H. pylori growth and is thus a promising treatment for patients with gastric symptoms such as gastritis that are caused by H. pylori infection.

In vivo bactericidal activities of Japanese rice-fluid against H. pylori in a Mongolian gerbil model

PURPOSE

The antibiotic effect of rice-fluid on Helicobacter pylori infection was investigated using a Mongolian gerbil model.

METHODS

Gerbils were divided into four groups: H. pylori -infected, rice-fluid-treated animals (group A); H. pylori -infected, untreated animals (group B); uninfected, rice-fluid-treated animals (group C); and uninfected, untreated animals (group D). Group A and B animals were killed 14 weeks after H. pylori infection and group C and D animals were killed at the same age. The stomachs were examined for histology, 5'-bromo-2'-deoxyuridine (BrdU) labeling, and the bacterial burden. Serum anti-H. pylori antibody titers were also tested.

RESULTS

The positive incidence of H. pylori -culture was 25 and 84 % in groups A and B, respectively (p<0.01). Both the degree of inflammation and the BrdU labeling index in group A were significantly lower than those in group B.

CONCLUSIONS

Rice-fluid showed an antibiotic effect on H. pylori and an anti-inflammatory effect on the H. pylori -associated gastritis.

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.

Does delayed gastric emptying shorten the H pylori eradication period? A double blind clinical trial

AIM: To evaluate the gastric emptying inhibitory effects of sugar and levodopa on H pylori eradication period.

METHODS: A total of 139 consecutive patients were randomized into 6 groups. The participants with peptic ulcer disease or non-ulcer dyspepsia non-responding to other medications who were also H pylori-positive patients either with positive rapid urease test (RUT) or positive histology were included. All groups were pretreated with omeprazole for 2 d and then treated with quadruple therapy regimen (omeprazole, bismuth, tetracycline and metronidazole); all drugs were given twice daily. Groups 1 and 2 were treated for 3 d, groups 3, 4 and 5 for 7 d, and group 6 for 14 d. Groups 1 to 4 received sugar in the form of 10% sucrose syrup. Levodopa was prescribed for groups 1 and 3. Patients in groups 2 and 4 were given placebo for levodopa and groups 5 and 6 received placebos for both sugar and levodopa. Upper endoscopy and biopsies were carried out before treatment and two months after treatment. Eradication of H pylori was assessed by RUT and histology 8 wk later.

RESULTS: Thirty patients were excluded. Per-protocol analysis showed successful eradication in 53% in group 1, 56% in group 2, 58% in group 3, 33.3% in group 4, 28% in group 5, and 53% in group 6. Eradication rate, patient compliance and satisfaction were not significantly different between the groups.

CONCLUSION: It seems that adding sugar or levodopa or both to anti H pylori eradication regimens may lead to shorter duration of treatment.

Bactericidal activity of wasabi (Wasabia japonica) against Helicobacter pylori

In this study, the bactericidal activity of Korean and Japanese wasabi roots, stems and leaves against Helicobacter pylori were examined. Allyl isothiocyanate (AIT) in roots, stems and leaves of Korean wasabi were 0.75, 0.18 and 0.32 mg/g, respectively. AIT in roots, stems and leaves of Japanese wasabi were 1.18, 0.41 and 0.38 mg/g, respectively. All parts of wasabi showed bactericidal activities against H. pylori strain NCTC 11637, YS 27 and YS 50. The leaves of both wasabi showed the highest bactericidal activities with the minimum bactericidal concentration of 1.05-1.31 mg of dry weight/ml against three strains of H. pylori. The roots showed a little lower bactericidal activity with 2.09-4.17 mg of dry weight/ml against them. The main component related to antimicrobial activity in wasabi is well known to be AIT. In this study, the bactericidal activity of leaves was higher than that of roots, although AIT amount of leaves was lower than that of roots. These results suggest that certain components besides AIT in wasabi are effective in killing H. pylori.

Laboratory handling of Helicobacter pylori critically influences the results of in-vitro metronidazole resistance determination

In-vitro metronidazole resistance rates of Helicobacter pylori determined by Etest are high, and the predictive value of metronidazole resistance is low. It was hypothesised that altered laboratory methods could reduce the overestimation of resistance and improve the predictive value of the Etest. Pre-treatment isolates (n = 150) of H. pylori from 150 patients were investigated by Etest with incubation for 72 h. Treatment with metronidazole, tetracycline and bismuth for 10 days failed to eradicate H. pylori in 23 patients. After isolate storage for 3 years, resistance determination results by agar dilution and Etest, with incubation for 72 and 31 h, were compared. The rate of metronidazole resistance was reduced significantly during storage, and instability of resistance was associated significantly with treatment outcome. Isolates that retained in-vitro resistance had significantly (p 0.008) higher treatment failure rates (n = 13; 42%) than isolates that lost resistance (n = 3; 9%). The reproducibility achieved by dual testing with agar dilution and Etest was 41% and 70% for +/- 1 and +/- 2 log2 dilutions, respectively, after incubation for 72 h, and 85% and 92%, respectively, after incubation for 31 h. Thus, the predictive value was improved from 25% to 50% by the altered laboratory conditions (p 0.04). MIC values of 2-8 mg/L signified an intermediate risk of treatment failure.

Metronidazole-resistant Helicobacter pylori is more prevalent in patients with nonulcer dyspepsia than in peptic ulcer patients in a multiethnic Asian population

The trend of increasing prevalence of antibiotic resistance among Helicobacter pylori strains has been suggested as a cause of the failure of treatment of H. pylori infections. In this study, 120 of 211 antral biopsy specimens from patients with dyspeptic symptoms were found to harbor H. pylori. The isolates from the 120 specimens were tested by the agar dilution method, and 38 (31.7%) were found to be metronidazole resistant. Among the 211 subjects, 81 of 115 (70.4%) patients with peptic ulcer (PU) were infected with H. pylori, whereas 39 of 96 (40.6%) patients with nonulcer dyspepsia (NUD) were infected with H. pylori. Interestingly, significantly more NUD patients than PU patients harbored metronidazole-resistant H. pylori (22 of 39 [56.4%] and 16 of 81 [19.8%], respectively; P < 0.001). A similar pattern was also observed among NUD patients of different ethnicities but not between male and female patients (23 of 78 [29.5%] and 15 of 42 [35.7%], respectively; P = 0.54). In the posttreatment follow-up, five of six patients who had positive urea breath test results, indicating treatment failure, were NUD patients. Of these, four harbored metronidazole-resistant H. pylori strains. This further illustrates the relevance of metronidazole-resistant H. pylori in NUD patients. The significantly higher percentage of metronidazole-resistant H. pylori isolates in NUD patients may be attributed to the protection offered by the mucus layer of the nonulcerated stomach to the bacteria that reside below it, resulting in organism exposure to sublethal concentrations of metronidazole and leading to the induction of metronidazole resistance. The results demonstrate that the H. pylori isolates colonizing NUD patients are more likely to be resistant to metronidazole. It will therefore be useful to reevaluate the use of metronidazole in the treatment of NUD patients infected with H. pylori.

Antimicrobial resistance in Helicobacter pylori isolates from children

OBJECTIVE

To determine the resistance rate to four antimicrobial agents commonly used in the treatment of Helicobacter pylori infection in children.

METHODS

Between July 1997 and January 2000, all H. pylori isolates from children undergoing gastroscopy were prospectively collected and subcultured to yield the susceptibility to four antimicrobial agents by E-test. In all, 23 isolates were tested. Demographic data, presenting symptoms, treatment regimen and clinical improvement after treatment were collected retrospectively.

RESULTS

The resistance rate of H. pylori to metronidazole and clarithromycin were 43.5% and 8.7%, respectively. No H. pylori strains were resistant to amoxycillin or tetracycline. There were no statistically significant differences in age, sex, ethnicity, presenting symptoms or clinical improvement after treatment between antimicrobial-susceptible and antimicrobial-resistant groups.

CONCLUSIONS

The frequent resistance of H. pylori to metronidazole and moderate resistance to clarithromycin in children are comparable with local adult data. The incidence of resistance tended to be higher in patients of non-European ethnicity, but this was not statistically significant. Given that the primary goal of therapy is eradication, and that local resistance rates are high, recommendations for H. pylori management may need to be modified to include sensitivity testing and/or determination of eradication in all patients.

Antimicrobial activity of essential oils against Helicobacter pylori

BACKGROUND

Helicobacter pylori is an important pathogen responsible for gastroduodenal diseases in humans. Although the eradication of H. pylori using antibiotics often improves gastroduodenal diseases, resistance to the antibiotics is emerging.

MATERIALS AND METHODS

The antimicrobial effect of essential oils and the development of resistance to the essential oils were evaluated in vitro and in vivo.

RESULTS

Thirteen essential oils used in this study completely inhibited the growth of H. pylori in vitro at a concentration of 0.1% (v/v). Cymbopogon citratus (lemongrass) and Lippia citriodora (lemon verbena) were bactericidal against H. pylori at 0.01% at pH 4.0 and 5.0. Resistance to lemongrass did not develop even after 10 sequential passages, whereas resistance to clarithromycin developed under the same conditions. In in vivo studies, the density of H. pylori in the stomach of mice treated with lemongrass was significantly reduced compared with untreated mice.

CONCLUSIONS

These results demonstrate that the essential oils are bactericidal against H. pylori without the development of acquired resistance, suggesting that essential oils may have potential as new and safe agents for inclusion in anti-H. pylori regimens.

Helicobacter pylori in children and adolescents: increase of primary clarithromycin resistance, 1997-2000

BACKGROUND

The authors evaluate the prevalence of Helicobacter pylori resistance in 117 children and demonstrate the changes over a 4-year period.

METHODS

In 117 children and adolescents, H. pylori-positive gastritis was revealed by diagnostic upper endoscopy. Biopsies from the antrum and body of the stomach were tested by histology, urease test, and culture. H. pylori was isolated using standard culture techniques, and susceptibility to amoxicillin, clarithromycin, and metronidazole was tested using the E-test (AB-Biodisk, Sweden).

RESULTS

Endoscopy revealed gastric ulcers in 2 of 117 subjects, duodenal ulcers in 6 of 117, and erosive gastritis or duodenitis in 23 of 117. Almost all patients showed antral nodularity. Histology always showed chronic gastritis with different degrees of activity. During the 4-year study period, the authors noticed an increase of primary clarithromycin-resistant H. pylori strains, from 14.3% to 27.6% (mean, 20.3%). Metronidazole resistance varied between 5% and 25%. No resistance to amoxicillin was found.

CONCLUSION

Eradication of H. pylori should take place only after testing of susceptibility. The general use of clarithromycin in children should be restricted to better-defined indications. Resistance to clarithromycin of H. pylori may also become a future problem for the treatment of adults.

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.

High prevalence of mixed infections by Helicobacter pylori in Hong Kong: metronidazole sensitivity and overall genotype

BACKGROUND

Diversity in metronidazole susceptibility and genotypes of Helicobacter pylori have been reported with varying results in different areas.

AIMS

To investigate the prevalence of multiple strain infection in a symptomatic Chinese population and to determine the metronidazole susceptibility pattern and genotypic characteristics of these infecting strains.

METHODS

Gastric biopsies from antrum, body and cardia were taken during upper endoscopy in symptomatic patients referred to our department. Pooled cultures and single colony isolates were obtained and tested for metronidazole susceptibility and random amplified polymorphic DNA (RAPD) fingerprint patterns.

RESULTS

A total of 461 isolates were successfully cultured from 46 patients. Fifty-seven per cent of subjects had metronidazole-resistant strains. Among them, 77% carried a mixture of sensitive and resistant strains, non-uniformly distributed in the gastric mucosa. Mixed genotypes were found by RAPD typing in 24% of subjects. These did not correlate with the metronidazole susceptibility/resistance pattern.

CONCLUSION

H. pylori infections with mixed metronidazole sensitive/resistant strains and mixed genotypes are common in Hong Kong. This makes it prudent to use bacterial strains from several biopsy sites when testing for traits such as drug resistance or virulence in relation to disease.

Studies on the development and stability of resistance of Helicobacter pylori to metronidazole and clarithromycin

Thirty-one strains of Helicobacter pylori, susceptible to metronidazole and clarithromycin, were isolated from 31 biopsy samples from patients with various gastric pathologies. We investigated the possibility of selecting resistant strains and the stability of resistance by exposing isolates to increasing subinhibitory concentrations of metronidazole and clarithromycin using a serial passages technique. Resistance to metronidazole was obtained in 100% of the isolates, while 32.2% displayed resistance to clarithromycin. Resistance to metronidazole was stable in 93.5% (29 of 31) of the isolates, whereas 100% (10 of 10) of the strains were stably resistant to clarithromycin. The stability of the resistance that occurred after three passages on medium containing the two drugs was statistically significant (P <0.001). Thus, the technique of serial passages in vitro could be useful as a first screening in selecting drugs for use in therapeutic protocols for clinical trials.

High levels of resistance to metronidazole and clarithromycin in Helicobacter pylori strains in children

The aim of the study was to evaluate the prevalence of resistance to amoxicillin, metronidazole, and clarithromycin before treatment of Helicobacter pylori infection in children and to assess the evolution of resistance with time. The study was carried out between 1994 and 1999 with 150 H. pylori-positive children through gastric culture (antimicrobial susceptibility) and histology. All cultured H. pylori strains were sensitive to amoxicillin, 64 (43%) were resistant to metronidazole, 32 (21%) were resistant to clarithromycin, and 14 (9%) were resistant to both metronidazole and clarithromycin. The overall prevalence of resistance to metronidazole and clarithromycin did not change significantly with time. The study highlights the generalized high-level and stable metronidazole and clarithromycin resistance of H. pylori strains from children.

High prevalence of Helicobacter pylori infection with dual resistance to metronidazole and clarithromycin in Hong Kong

BACKGROUND

Metronidazole resistance is a common problem in most Asian countries, and clarithromycin has been widely used in Hong Kong.

AIM

To determine the prevalence of Helicobacter pylori strains resistant to metronidazole and clarithromycin in Hong Kong and to assess the effect on eradication rates. Also to determine the genetic mutation in relation to phenotypic divergence in clarithromycin-resistant strains.

METHODS

H. pylori were cultured from gastric biopsies obtained from 87 patients during upper endoscopy. Minimal inhibitory concentrations of metronidazole and clarithromycin were determined by Etest and agar dilution methods. Mutations in clarithromycin-resistant strains were identified by polymerase chain reaction and restriction analysis. Random amplified polymorphic DNA fingerprinting was performed on clarithromycin-resistant and susceptible isolates.

RESULTS

The prevalences of H. pylori strains resistant to metronidazole and clarithromycin were 49.4% and 10.8%, respectively, in Hong Kong. Dual resistance to metronidazole and clarithromycin were found in 7. 2% of patients. The agreement between E-test and agar dilution methods was determined by error-rate bound analysis as 95.4% for metronidazole and 100% for clarithromycin. Dual resistant strains reduced the eradication rate to 66.7%. Among clarithromycin-resistant strains tested, all were due to A2144G point mutation in 23S rRNA gene. Random amplified polymorphic DNA fingerprinting suggested various phenotypically mixed populations.

CONCLUSIONS

The prevalence of metronidazole-resistant H. pylori strains remained static whilst the prevalence of clarithromycin-resistant strains was not rare in Hong Kong. An alarming 7.2% of patients were resistant to both the antimicrobials, which had a definite impact on treatment success. All cases of resistance to clarithromycin were due to A2144G mutation in 23S rRNA of H. pylori.

Detection of clarithromycin-resistant helicobacter pylori strains by a preferential homoduplex formation assay

It has been shown that resistance to clarithromycin, a major cause of failure in Helicobacter pylori eradication therapy, is associated with point mutations in the 23S rRNA gene. We sought to apply the preferential homoduplex formation assay (PHFA), a novel technique for the efficient detection of point mutations, to detection of the mutations. PHFA was performed on streptavidin-coated microtiter plates with biotin- and dinitrophenyl-labeled amplicons to detect the wild-type gene or each mutant gene. DNA samples were extracted from gastric juice specimens of 412 patients with H. pylori infection and were applied to the assay. The detection threshold of PHFA was as few as 10 gene copies. The sensitivity of PHFA for the detection of H. pylori infection was higher than those of culture and the rapid urease test. A total of 337 (81.8%) samples had the wild-type gene, 38 (9.2%) had the A2144G mutation, and 37 (9.0%) contained both the wild type and a mutation (A2144G in 30 samples, A2143G in 5 samples, and A2143G plus A2144G in 2 samples). About half the strains isolated from patients with mixed infection were susceptible by the agar dilution method (MIC, <0.1 mg/liter). Therefore, PHFA can detect clarithromycin-resistant H. pylori strains, even in patients with mixed infections with the wild type, that are not detectable by the agar dilution method.

In vitro and in vivo activities of tea catechins against Helicobacter pylori

The catechin epigallocatechin gallate showed the strongest activity of the six tea catechins tested against Helicobacter pylori (MIC for 50% of the strains tested, 8 microg/ml). It had bactericidal activity at pH 7 but not at pH </=5.0. In infected Mongolian gerbils, H. pylori was eradicated in 10 to 36% of the catechin-treated animals, with significant decreases in mucosal hemorrhage and erosion. Tea catechins, therefore, may have therapeutic effects on H. pylori infection.

Helicobacter pylori treatment and antibiotic susceptibility: results of a five-year audit

BACKGROUND

Helicobacter pylori eradication treatment has been a rapidly evolving field. Audit of treatment results provides reassurance that trial data can be translated into routine clinical practice.

METHODS

Data were collected prospectively over five years. Patients were given four different treatment regimens over the audit period 'standard' triple therapy, two types of clarithromycin-based treatment or ranitidine, amoxycillin and metronidazole. Eradication was proven by a urea breath test at least four weeks after completing treatment.

RESULTS

Eradication treatment for H. pylori was given to 665 patients; 89% had follow-up data. H. pylori eradication was significantly associated with treatment type (p<0.0001) and smoking (p=0.04) by univariate analysis, but was not associated with sex, age, alcohol consumption, endoscopic diagnosis, recent treatment with anti-secretory drugs or NSAIDs. By logistic regression analysis, only treatment type was significant (p=0.0001). H. pylori culture and sensitivities were available for 255 patients. Metronidazole resistance was shown for 84 isolates (32%) and clarithromycin resistance for 18 isolates (6.8%). Metronidazole resistance was significantly associated with younger age (p=0.02), ethnicity (p=0.02), female sex (p=0.02), and year of endoscopy (p=0.04), but was not associated with clarithromycin resistance. Clarithromycin resistance was not associated with age, sex, or ethnicity. Metronidazole resistance significantly affected H. pylori eradication for regimens containing metronidazole without clarithromycin. Eradication with metronidazole without clarithromycin was achieved in 90% of sensitive strains but only 55% of resistant strains (p<0.001). Metronidazole resistance was not significantly associated with treatment failure when metronidazole was combined with clarithromycin. Eradication with metronidazole and clarithromycin was achieved in 86% of sensitive strains and 78% of resistant strains (p=0.42).

CONCLUSION

Treatment type and antibiotic susceptibility are the most important determinants of treatment success.

Metronidazole and clarithromycin resistance amongst Helicobacter pylori isolates from a large metropolitan hospital in the United States

BACKGROUND

Metronidazole and clarithromycin-based therapies are among the most efficacious treatment regimens for H. pylori infection. Resistance to metronidazole or clarithromycin is associated with impaired therapy with these agents. We conducted a retrospective review of susceptibility data to determine the frequency of primary metronidazole and clarithromycin resistance among H. pylori isolates from a single metropolitan hospital in the United States. The database comprised 933 patients who presented at the Digestive Diseases Clinic at the Veterans Affairs Medical Center in Houston between September 1988 and January 1997 with complaints of dyspepsia, abdominal pain and peptic ulcer disease. One hundred and seventy-nine of these patients had both pharmaceutical records available for evaluation and culture and antimicrobial susceptibility data for analysis. The MICs were determined by both E-test and broth microdilution tests. The frequency of primary metronidazole resistance was 37.4% (67/179). The level of primary clarithromycin resistance was 6.1%. Dual metronidazole and clarithromycin resistance was present in approx. 3%. The high level of primary metronidazole and clarithromycin resistance in H. pylori isolates from this metropolitan hospital is such that antimicrobial susceptibility data should be available so that informed choice can be made for specific eradication therapies, especially in patients who fail treatment.

The influence of in vitro nitroimidazole resistance on the efficacy of nitroimidazole-containing anti-Helicobacter pylori regimens: a meta-analysis

OBJECTIVE

The aim of this study was to determine the influence of nitroimidazole resistance (NIR) on the efficacy of treatment for Helicobacter pylori (H. pylori) infections by meta-analysis of the world literature.

METHODS

A MEDLINE search, a manual search of all major gastroenterological journals from 1993 to 1997, and abstracts of gastroenterological and H. pylori meetings from 1993 to 1997 were performed. All treatment studies using a nitroimidazole and providing data about the medication used, dose frequency, total daily dose, duration of treatment, and eradication results in relation to NIR were included. Eradication had to be assessed by two biopsy-based tests or a urea breath test > or = 4 wk after treatment. Individual studies were pooled into groups according to the medication used and the duration of treatment. The pooled estimate of the odds ratio (OR) of NIR for treatment failure and its 95% confidence interval (95% CI) were calculated for each group using the logit method. To detect any possible bias, funnel plots (plots of effect estimates against sample size) were constructed.

RESULTS

A total of 91 treatment arms, including a total of 4823 patients, were evaluated. The pooled ORs of NIR for treatment failure (95% CI) of proton pump inhibitors, bismuth, and quadruple regimens were 5.2 (3.8-7.1), 5.9 (4.1-8.3), and 7.0 (3.1-16.0), respectively. Eradication rates were 90% in susceptible strains but <75% in resistant strains. In susceptible strains, neither treatment duration nor the choice of the second antibiotic influenced efficacy. In resistant strains, tetracycline was more effective than amoxicillin (bismuth regimens), and the longer the duration of regimens (bismuth-amoxicillin regimens) the more effective they were. Only quadruple regimens given for > or = 1 wk were effective in resistant strains.

CONCLUSIONS

NIR decreases treatment efficacy. Treatment duration and choice of other drugs influence the impact of NIR on treatment efficacy. If NIR is present, a nitroimidazole-containing regimen should be avoided or a quadruple regimen should be given for > 1 wk.

In vitro and in vivo activities of tea catechins against Helicobacter pylori

The catechin epigallocatechin gallate showed the strongest activity of the six tea catechins tested against Helicobacter pylori (MIC for 50% of the strains tested, 8 microg/ml). It had bactericidal activity at pH 7 but not at pH </=5.0. In infected Mongolian gerbils, H. pylori was eradicated in 10 to 36% of the catechin-treated animals, with significant decreases in mucosal hemorrhage and erosion. Tea catechins, therefore, may have therapeutic effects on H. pylori infection.

The effect of antibiotic resistance on the outcome of three 1-week triple therapies against Helicobacter pylori

BACKGROUND

Resistance of Helicobacter pylori to antibiotics may be a major reason for treatment failure.

AIM

To evaluate the effect of primary H. pylori resistance to antibiotics on the cure rates of three anti-H. pylori 1-week triple therapies.

METHODS

One hundred and sixteen consecutive patients diagnosed H. pylori-positive by gastric histology, rapid urease test and culture were enrolled. Activity of tested antibiotics was determined by means of the E-test. Patients were treated for 7 days with: (i) pantoprazole 40 mg o.d. plus amoxycillin 1 g b.d. and metronidazole 250 mg q.d.s. (PAM); (ii) pantoprazole 40 mg o.d. plus clarithromycin 250 mg b.d. and metronidazole 250 mg q.d.s. (PCM); or (iii) pantoprazole 40 mg o.d. plus amoxycillin 1 g b.d. and clarithromycin 250 mg b.d. (PAC). Two months after completion of therapy, endoscopy and gastric biopsies were repeated.

RESULTS

Primary resistance rates to metronidazole, clarithromycin and amoxycillin were 17.2, 6.9 and 0%, respectively. Overall H. pylori cure rates expressed as intention-to-treat and per protocol analyses were, respectively, 79% and 86% with PAM, 82% and 89% with PCM, and 85% and 85% with PAC. Significantly lower cure rates were observed in metronidazole-resistant patients treated with PAM (56% vs. 96%, P = 0.01) or PCM (50% vs. 97%, P = 0.01). A trend towards lower H. pylori cure rates was observed in clarithromycin-resistant patients treated with PCM (67% vs. 91%, P = 0.74) or PAC (50% vs. 87%, P = 0.68).

CONCLUSION

Primary resistance to metronidazole influences the H. pylori cure rate of anti-H. pylori proton pump inhibitor-based triple therapies which include this antibiotic. A similar trend exists for primary clarithromycin resistance.

The attenuated Salmonella vaccine approach for the control of Helicobacter pylori-related diseases

The Gram-negative bacterium Helicobacter pylori is a widespread human pathogen that colonizes the gastric mucosa and is associated with gastro-intestinal illnesses such as gastritis, peptic ulcer, gastric lymphoma and gastric cancer. Current pharmacological therapies are becoming less reliable for the control of H. pylori due to the elevated costs and to the increasing number of antibiotic resistant strains. New vaccination strategies utilizing H. pylori antigens combined with adjuvants or delivery of antigens by attenuated Salmonella strains have been successful in protecting mice against H. pylori infections. Oral immunization with single doses of urease-expressing Salmonella vaccine strains elicits mucosal and systemic antibody responses and fully protects different mouse strains against challenge infections with H. pylori. The high efficacy in the mouse model, combined with remarkable immunogenicity, safety and low-cost production, makes attenuated live recombinant Salmonella promising vaccine candidates for the control of H. pylori-related diseases in humans.

Three treatment schemes with colloidal bismuth subcitrate (Q-ULCER) in peptic ulcer with Helicobacter pylori

BACKGROUND

Since the discovery, several decades ago, of the infection of the gastric mucosa with Helicobacter pylori and its association with chronic antral gastritis and peptic ulcer, the treatment of ulcer illness has recently been revolutionized.

METHODS

In this study, the clinical effectiveness of three schemes of treatment with colloidal bismuth subcitrate (CBS) were compared. Fifty-three patients suffering from gastroduodenal peptic ulcer with Helicobacter pylori were distributed randomly into three groups. Group I (n = 17) received 240 mg CBS every 12 h for 6 weeks. Group II (n = 17) received 240 mg CBS every 12 h for 6 weeks, pus metronidazole 500 mg every 8 h plus tetracycline 500 mg every 8 h for 10 days. Group III (n = 19) received 240 mg CBS every 12 h for 6 weeks, plus metronidazole 500 mg every 8 h plus amoxicillin 750 mg every 12 h for 10 days. A duodenoscopy investigation with antrum biopsy for a morphologic study and detection of the germ was carried out by means of urease test and histological study (Warthin-Sarry and hematoxylin-eosin).

RESULTS

The three schemes of treatment were effective for ulcerous healing with 70.5%, 82.3%, and 78.2%, respectively, without significant differences. The highest clearing index (52.6%) was obtained in group III.

CONCLUSIONS

With these treatments, the Helicobacter pylori eradication was only observed in 47.3% of the patients studied.

Prevalence of Helicobacter pylori resistance to several antimicrobial agents in a region of Germany

To evaluate the prevalence of resistance among Helicobacter pylori in Germany, the minimum inhibitory concentrations of amoxicillin, tetracycline, clarithromycin, and metronidazole were determined by means of the E test, for 271 Helicobacter pylori isolates cultured from biopsies taken during routine endoscopies in 1996 and 1997. The prevalence of metronidazole resistance was 32.1%, with resistance found more frequently in women (38.5%) than in men (24.4%). Clarithromycin resistance was rare (3.3%). Eight of nine strains resistant to clarithromycin were also resistant to metronidazole. Resistance to either metronidazole or clarithromycin was significantly (P=0.022) higher in patients with duodenal ulcer. No strain was found to be resistant to amoxicillin or tetracycline.

Prevalence and demographic determinants of metronidazole resistance by Helicobacter pylori in a large cosmopolitan cohort of Australian dyspeptic patients

BACKGROUND

The pre-treatment sensitivity of Helicobacter pylori to metronidazole is a key determinant of successful eradication therapy and should influence local choice of therapy. However, there are few data defining the prevalence of metronidazole resistance (MR) in Australia.

AIM

To determine prospectively the prevalence and demographic determinants of MR in H. pylori isolates from a large and cosmopolitan cohort of dyspeptic patients in Sydney.

METHODS

Consecutive dyspeptic patients undergoing endoscopy had gastric biopsies for histology, urease test and culture. Metronidazole resistance was determined by E-test after subculture. An MIC > 8 micrograms/mL defined MR. Patient age, gender, birthplace and history of previous nitroimidazole use were recorded.

RESULTS

In 732 patients, H. pylori was present in 46.4%. Culture was successful in 81% and subculture for MR in 88% of these. In 237 evaluable patients the overall MR rate was 59.1%. Five patients had had prior triple therapy for H. pylori (of which four of five had MR). Therefore, the primary MR rate in the study population was 58.6% (136/232). MR was more prevalent in younger patients (p = 0.0002). The MR rate was 70.4% in patients 18-39 years, 66.7% in those aged 40-59 years and lowest (38.9%) in those 60 years or older (p = 0.002). The MR rate was highest in patients born in Southeast Asia (72.8%, 59/81) and significantly higher than in Australian born (48.1%, 26/54), or Southern European (46.2%, 24/52) born patients (p = 0.002). There was no gender difference. Logistic regression to determine the impact of each variable (birthplace, age and gender) on MR identified Southeast Asia birthplace as a factor associated with greater likelihood of harbouring an MR isolate (OR 1.88, p = 0.02). Southern European born patients had the lowest risk of MR (OR 0.70, p = 0.02) as did patients older than 60 years (OR 0.56, p = 0.04). A definite history of prior metronidazole use was infrequent and not predictive of MR.

CONCLUSIONS

While a high rate of MR is not unexpected in patients born in developing countries, the high rate in Australian born patients is surprising and of concern. This may relate to the high local usage of nitroimidazoles as monotherapy and has important implications for the effectiveness of metronidazole containing triple therapies.

Metronidazole- and clarithromycin-resistant Helicobacter pylori in dyspeptic patients in western Sydney as determined by testing multiple isolates from different gastric sites

It is unknown whether antibiotic susceptibility testing of antral isolates alone is representative of Helicobacter pylori susceptibility. We aimed to determine: (i) the prevalence of metronidazole- and clarithromycin-resistant strains in infected dyspeptic patients; and (ii) whether there is consistency in the susceptibility to metronidazole and clarithromycin among isolates cultured from different gastric sites. Antral, body and fundus biopsies were taken from 242 consecutive patients and cultured on blood agar under micro-aerophilic conditions for 5-7 days. Isolates from 66 patients (13 had one, 15 had two and 38 had three isolates) were tested for susceptibility to metronidazole and clarithromycin using previously validated disc diffusion tests. Of the 66 patients, 42 (64%) had strains resistant to metronidazole while four (6.1%) had clarithromycin-resistant strains. The prevalence of metronidazole resistance was not significantly different between men and women (65% vs 60%) or across different age groups. In five (9.4%) of the 53 patients with multiple isolates, discrepant results for metronidazole susceptibility were observed: susceptible antral and body isolates but resistant fundus isolates in two cases and susceptible antral isolates but resistant body and fundus isolates in the others. Clarithromycin susceptibilities were consistent among the isolates cultured from different gastric sites in all patients. It is concluded that metronidazole-resistant strains of H. pylori are common while clarithromycin-resistant strains are rare. Metronidazole susceptibility testing of antral isolates does not appear to be representative of isolates from the body and fundus in a subset of patients.

A prospective randomized trial comparing the use of omeprazole-based dual and triple therapy for eradication of Helicobacter pylori

BACKGROUND

Controversy surrounds the optimal composition, dosage, and duration of therapies for eradication of Helicobacter pylori. We prospectively compared omeprazole-based dual and triple therapies in the eradication of H. pylori in a randomized manner.

METHODS

Between June 1995 and March 1997, 1000 consecutive patients with acid-peptic disease associated with H. pylori infection (duodenal ulcer, 388 patients, gastric ulcer, 179 patients; duodenitis, 173 patients; gastritis, 260 patients) were prospectively recruited. They were randomized to either a 2-wk (OA) course of omeprazole 20 mg and amoxicillin 1 g, both given twice daily, or treatment for 1 wk (OCM) with omeprazole 20 mg once daily, clarithromycin 500 mg twice daily, and metronidazole 400 mg twice daily.

RESULTS

The age of these 1000 patients ranged from 16 to 90 yr, with a mean of 54.9 yr. Side effects occurred in 29.6% (95% confidence interval [CI] 25.6-33.8%) and 10.6% (95% CI 8.0-13.6%) of patients taking OCM and OA, respectively (p < 0.0001). Apart from taste disturbance, however, there were no significant differences in the incidences of side effects between the two groups. One patient in the OA group and four patients of the OCM group could not tolerate the medications, and therefore did not complete treatment (p = 0.37). Seven and 13 patients in the OA and OCM groups, respectively, refused a second endoscopy (p = 0.25). The remaining 975 patients underwent a second endoscopy. Positive endoscopic findings were significantly more common in the OA group (51/492; 10.4%; 95% CI 7.8-13.4%) than in the OCM group (25/483; 5.2%; 95% CI 3.4-7.5%) in the per-protocol (PP) analysis (p = 0.004). On intent-to-treat (ITT) analysis, the overall eradication rates in the OA and OCM groups were 73.6% (95% CI 69.5-77.4%) and 92% (95% CI 89.3-94.2%), respectively (p < 0.0001). On PP analysis, the corresponding rates were 74.8% (95% CI 70.7-78.6%) and 95.2% (95% CI 92.9-97.0%), respectively (p < 0.0001).

CONCLUSIONS

A course of omeprazole, clarithromycin, and metronidazole for 1 wk is a safe, well-tolerated, efficacious, and cost-effective treatment for H. pylori infection.

Prevalence of Helicobacter pylori resistance to several antimicrobial agents in a region of Germany

To evaluate the prevalence of resistance among Helicobacter pylori in Germany, the minimum inhibitory concentrations of amoxicillin, tetracycline, clarithromycin, and metronidazole were determined by means of the E test, for 271 Helicobacter pylori isolates cultured from biopsies taken during routine endoscopies in 1996 and 1997. The prevalence of metronidazole resistance was 32.1%, with resistance found more frequently in women (38.5%) than in men (24.4%). Clarithromycin resistance was rare (3.3%). Eight of nine strains resistant to clarithromycin were also resistant to metronidazole. Resistance to either metronidazole or clarithromycin was significantly (P=0.022) higher in patients with duodenal ulcer. No strain was found to be resistant to amoxicillin or tetracycline.

Effect of metronidazole resistance on bacterial eradication of Helicobacter pylori in infected children

A prospective study was performed with 23 Helicobacter pylori-infected children (mean age, 9.5 +/- 4.4 years) with clinical symptoms of gastritis and positive results of culture and histologic examination of gastric biopsy specimens to evaluate the influence of antibiotic resistance on eradication. Positive children were treated for 4 weeks with lansoprazole and for 2 weeks with either amoxicillin-metronidazole or spiramycin (a macrolide)-metronidazole. At endoscopy 1 month after the discontinuation of therapy, the eradication rate and improvement of histologically related gastritis were significantly dependent on the susceptibility or the resistance of the infecting organism to metronidazole (83 versus 17% and 88 versus 16.6%, respectively). Pretreatment determination of the susceptibility is appropriate in any anti-H, pylori regimen, including one with metronidazole.

Risk of development of in vitro resistance to amoxicillin, clarithromycin, and metronidazole in Helicobacter pylori

We have studied initial killing, morphological alterations, the frequency of occurrence, and the selective growth of resistant subpopulations of Helicobacter pylori during exposure to amoxicillin, clarithromycin, or metronidazole by bioluminescence assay of intracellular ATP levels, microscopy, and a viable count assay. We found an induction of spheroplasts and a decrease in intracellular ATP levels after 21 h of exposure to high concentrations of amoxicillin. During clarithromycin exposure the onset of a decrease in intracellular ATP levels started after prolonged incubation, and with the highest concentration of clarithromycin an induction of coccoid forms was seen after 68 h. Metronidazole exposure resulted in the strongest initial decrease in intracellular ATP levels, and coccoid forms were seen after 21 h of exposure to high concentrations of metronidazole. Amoxicillin caused a low-level increase in resistant subpopulations, which indicates a need for surveillance of the amoxicillin susceptibility of H. pylori in order to detect decreasing susceptibility. No increase in the numbers of resistant subpopulations was demonstrated during clarithromycin exposure. Metronidazole selected resistant subpopulations, which caused high-level resistance in H. pylori.

Comparison of culture, histopathology and urease testing for the diagnosis of Helicobacter pylori gastritis and susceptibility to amoxycillin, clarithromycin, metronidazole and tetracycline

Gastric biopsy specimens were taken from 737 patients undergoing upper gastrointestinal endoscopy and assessed for Helicobacter pylori infection. The diagnostic utilities of H. pylori culture (733 patients), detection of urease production (724 patients) and histopathological examination (469 patients) were compared. Since each of these techniques may fail to diagnose patients infected with H. pylori, an attempt was made to estimate the true rate of infection using a mathematical approach that combined the results of culture, histopathology and urease testing; 34% of the 733 patients were thought to be infected. Using this figure as a benchmark, the sensitivity, specificity, positive predictive value and negative predictive value of H. pylori culture were 73.2%, 100%, 100% and 86.3%, respectively, compared with 58.7%, 100%, 100% and 89.6%, respectively for urease production and 77.0%, 100%, 100% and 82.4%, respectively for histopathology. Thus, histopathological examination was the single most reliable test. A combination of histopathological examination and H. pylori culture diagnosed 99.5% of patients that were estimated to be truly infected. The minimum inhibitory concentrations of a number of antibiotics were measured for 135 isolates of H. pylori. All isolates were susceptible to amoxycillin and tetracycline whereas 5.2% were resistant to clarithromycin and 60% were resistant to metronidazole.

What other regimens are under investigation to treat Helicobacter pylori infection?

The most common infection in the world, Helicobacter pylori infection, is very specific, and present experience in treating infectious diseases is not applicable in general for this infection. Animal models (e.g., mouse and ferret) are thus far inadequate as reliable screening models. Old-fashioned trial-and-error treatment of infected humans is still the screening model and the gold standard in the evaluation of regimens aimed at eradication of H. pylori. A variety of studies on treatment of H. pylori infection have been performed with varying results. This pooled analysis of the following therapeutic combinations: proton pump inhibitor (PPI) plus two antibiotics or antimicrobials, quadruple therapies, and nonantibiotic regimens is an attempt to make a fair comparison of tested therapeutic strategies aimed at eradicating H. pylori. Data from treatment groups including specified drug combinations are pooled, regardless of dose or duration. Search methods are: MEDLINE 1984-1996, Digestive Disease Week 1988-1996, United European Gastroenterology Week 1992-1996, European Helicobacter pylori Study Group 1988-1996, Asia Pacific Congress 1996, H. pylori International Workshop Hong Kong 1996, and miscellaneous. Eradication rates (efficacy) are presented as intention-to-treat data (i.e., worst-case analysis). Separate subanalyses with regard to study quality, dose, and duration are performed for some groups. A general cost-efficacy analysis is performed based on pooled efficacy data. Convenience data are presented as total number of tablets, total number of intake occasions, and duration of therapy. Drugs evaluated in the analysis are bismuthdicitrate, tetracycline, amoxicillin, nitroimidazoles, macrolides, H2-receptor antagonists, PPIs, sucralfate, and sofalcone. The most effective and convenient drug combinations are the PPI-based triple therapies. No significant difference was observed between the three PPIs. The cure rate did not improve after addition of bismuth. Cost-effectiveness is closely associated with efficacy.

Antimicrobial resistance testing of Helicobacter pylori: a comparison of Etest and disk diffusion methods

Routine antimicrobial resistance testing of Helicobacter pylori is more commonly performed since the correlation between metronidazole resistance and failure to eradicate using this drug, has been made. While resistance testing of H. pylori by Etest is simple to perform, it is expensive compared to disk diffusion methods. In this study the Etest was compared with a modified Kirby-Bauer disk diffusion (NCCLS) method for routine resistance screening of H. pylori. Fifty one pre-treatment isolates were tested against amoxycillin, metronidazole, tetracycline and erythromycin by both Etest and disk diffusion using NCCLS guideline strength disks. Clarithromycin was tested by Etest only. Nitroimidazole and macrolide resistance were detected using the modified Kirby-Bauer disk diffusion method which correlated with Etest minimum inhibitory concentration (MIC). Resistance rates were 49% for metronidazole and 8% for clarithromycin. Cross resistance occurs with macrolides against H. pylori and allows testing of erythromycin to predict resistance to clarithromycin. The very low MICs obtained with H. pylori against amoxycillin and tetracycline require the use of Etest or lower strength disk methods to be used.

Doubling the omeprazole dose (40 mg b.d. vs. 20 mg b.d.) in dual therapy with amoxycillin increases the cure rate of Helicobacter pylori infection in duodenal ulcer patients

BACKGROUND

Several studies have shown that dual therapy with omeprazole and amoxycillin may cure Helicobacter pylori infection. However, the optimum dose of omeprazole has still to be established.

METHODS

An international, randomized, double-blind multicentre trial was conducted in patients with duodenal ulcers to compare the H. pylori cure rates obtained by dual therapy consisting of either omeprazole 20 mg b.d. plus amoxycillin 750 mg b.d. or omeprazole 40 mg b.d. plus amoxycillin 750 mg b.d. for 2 weeks. Dual therapy was followed by omeprazole 20 mg once daily for 2 weeks. Before entering the trial and 4 weeks after cessation of treatment H. pylori infection was assessed by histology and a 13C-urea breath test.

RESULTS

381 patients were randomized into the study, of whom 345 were evaluable for the all-patients-treated analysis of efficacy and 378 were valid for the evaluation of safety. Histology results showed that H. pylori infection was cured in 64 out 174 patients treated with omeprazole 20 mg b.d. plus amoxycillin and in 102 out of 171 patients treated with omeprazole 40 mg b.d. plus amoxycillin (37% vs. 60%; P < 0.001). Both treatment regimens were well tolerated, with adverse events reported by 29 (15.2%) and 35 patients (18.7%), respectively.

CONCLUSIONS

This study has shown that dual therapy with amoxycillin 750 mg b.d. and omeprazole 40 mg b.d. is superior to dual therapy with amoxycillin and omeprazole 20 mg b.d. in patients with H. pylori-positive duodenal ulcers. Thus, a true dose-response relationship exists between omeprazole and treatment success. However, a combination of omeprazole with two of amoxycillin, clarithromycin and nitroimidazole is a preferable alternative for routine clinical use.

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.