Helicobacter pylori and metronidazole resistance

Helicobacter pylori: perspectives and time trends

The discovery of Helicobacter pylori three decades ago is a modern medical success story. It markedly changed our understanding of the pathophysiology of gastroduodenal diseases and led to an improvement in the treatment of diseases related to H. pylori infection. Many of these diseases (such as ulcer disease and mucosal associated lymphoid tissue lymphoma) have become curable, and others (gastric cancer) might be preventable with the application of H. pylori eradication therapy. Since its discovery, H. pylori has also been identified as a trigger for some extragastric diseases. Promising results in this exciting field might have a clinical effect in the near future. This Timeline gives an overview of the success of clinical research on H. pylori to date and highlights some future trends in this area.

Drug resistance and Giardia

Giardiasis is a worldwide disease that can cause serious morbidity. Metronidozole is the current recommended drug for treatment, and is mostly still effective. However, Giardia duodenalis, the causative agent, is capable of developing resistance to high levels of metronidozole and other drugs, in vitro, via a number of mechanisms. Resistance, in vivo, has been reported and many cases of treatment failure have been variously attributed to a number of causes, including resistance. Here, Jacqueline and Peter Upcroft ask: is this the beginning of another chapter of drug resistance? or is the situation likely to remain as a 'few refractory cases'? Should we wait to find out or can we act positively to avert the possibility of yet another valuable drug in our limited pharmacopoeia becoming obsolete?

Helicobacter pylori: antibiotic resistance and eradication rates in Suffolk, UK, 1991-2001

Helicobacter pylori infection causes a number of gastrointestinal diseases and its current treatment is based on multidrug regimes including acid suppression and antimicrobials. The success of these regimes is determined by a number of factors including antibiotic resistance, which varies widely but is an increasing problem. Local data are important in establishing the most cost-effective eradication regime. Data have been collected prospectively on antibiotic resistance at Ipswich Hospital (Suffolk, UK) in all consecutive isolates of H. pylori from 1991 to 2001. The success of regimes consisting of a proton pump inhibitor, amoxycillin and metronidazole (PPI/A/M) has also been evaluated in patients found positive on serological testing in primary care using urea breath testing. Overall, metronidazole resistance was found in 31.7 % of isolates and clarithromycin resistance in 5.3 %. A significant increase in metronidazole resistance from 29.1 to 37.0 % (P = 0.022) and a decrease in clarithromycin resistance from 10.3 to 3.8 % (P = 0.014) was seen over the study period. Metronidazole resistance was significantly more common in women (P < 0.001) and young patients (P < 0.001). Eradication with PPI/A/M was successful in 89.9 % of patients and did not change significantly over the study period. Eradication rates were lower in young patients (P < 0.001). Whilst metronidazole resistance is increasing in Suffolk, this does not seem to have a significant effect on eradication rates. Metronidazole-based regimes are still effective first-line treatments in most patients.

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.

Antimicrobial susceptibility test of Helicobacter pylori isolated from Jos, Nigeria

Fifty-five strains of Helicobacter pylori isolated from November 1997 until October 1998 from 33 female and 22 male adults attending for endoscopy at the Evangel Hospital, Jos, Nigeria were assayed for antibiotic susceptibility to amoxycillin, clarithromycin, metronidazole and tetracycline by the E-test strip method. Minimum inhibitory concentration (MIC) within the attainable peak serum concentrations for each drug was used as the parameter to determine the susceptibility of H. pylori. The results showed 100% susceptibility for amoxycillin, 89.0% for tetracycline, 87.3% for clarithromycin and 60% for metronidazole. The MIC50 and MIC90 values were: 0.016 microgram/mL and 0.75 microgram/mL for amoxycillin, 0.016 microgram/mL and 2 micrograms/mL for clarithromycin, 0.094 microgram/mL and 12 micrograms/mL for tetracycline, and 2 micrograms/mL and > 48 micrograms/mL for metronidazole. The MIC90 values for metronidazole (> 48 micrograms/mL) and tetracycline (12 micrograms/mL) were in each case higher than the break-point value (peak serum concentrations) of 8 micrograms/mL for metronidazole and 3 micrograms/mL for tetracycline. This pattern of resistance to metronidazole and tetracycline has to be considered when therapeutic regimens against H. pylori contain either or both drugs.

Significance of anaerobic preincubation of Helicobacter pylori for measuring metronidazole susceptibility by the Etest

The Etest is widely used for measuring the susceptibility of Helicobacter pylori to metronidazole. By using 55 H. pylori isolates from 55 patients and a standard H. pylori strain, NCTC11637, we compared metronidazole susceptibility results obtained from the Etest with or without anaerobic preincubation to those obtained from the agar dilution method. Mueller Hinton agar plates supplemented with 5% horse blood were used for both methods. For the Etest, plates were incubated for 72 hr at 35 C under microaerophilic conditions after 0-, 4- or 24-hr periods of anaerobic preincubation. For the agar dilution method, the plates were incubated at the same microaerophilic conditions as those for the Etest. Without anaerobic preincubation for the Etest, 39 of the 56 (70%) H. pylori isolates were categorized as resistant to metronidazole (minimal inhibitory concentration>8 mg/liter), whereas only one of the 56 (1.8%) isolates was resistant according to the agar dilution method. The resistant and susceptible agreement rate was 32%. Four-hour anaerobic preincubation did not alter the readings of the Etest significantly. However, when the Etest was performed with 24-hr anaerobic preincubation, the number of isolates categorized as resistant was reduced to six (11%), improving the agreement rate to 91%. For measuring the metronidazole susceptibility of H. pylori by the Etest, 24-hr anaerobic preincubation is necessary to agree with the results obtained by the agar dilution test.

H2-antagonist maintenance therapy versus Helicobacter pylori eradication in patients with chronic duodenal ulcer disease: a prospective study

BACKGROUND

Few outcome studies directly compare Helicobacter pylori eradication therapy with maintenance H2-antagonist therapy in duodenal ulcer disease.

AIM

To examine prospectively the efficacy of H. pylori eradication therapy with ranitidine maintenance therapy over 1 year in patients with confirmed chronic duodenal ulcer.

METHODS

One hundred and nineteen patients with active H. pylori infection were randomized to receive ranitidine, 150 mg/day initially (58 patients), or omeprazole, 40 mg/day, amoxycillin 2 g/day and metronidazole 1.2 g/day for 14 days, or omeprazole 40 mg/day and clarithromycin 1.5 g/day, for 14 days (if penicillin-allergic). Symptoms were assessed using the Gastrointestinal System Rating Scale (GSRS) and SF36 quality of life index.

RESULTS

13C urea breath testing confirmed overall treatment success in 100% of patients (58/58) per protocol and 95.1% (58/61) on an intention-to-treat basis. At 4 and 12 months there were no differences in any GSRS symptoms between treatment groups. SF36 analysis showed a perceived health improvement at 4 and 12 months in patients who received H. pylori eradication. However, despite successful H. pylori eradication, one-fifth of patients still required antisecretory therapy.

CONCLUSION

Following successful H. pylori eradication, chronic duodenal ulcer patients were at least as well symptomatically as when taking maintenance ranitidine. They perceived that their health had improved, but a subgroup was still acid-suppression dependent.

Assessment of a new triple agent regimen for the eradication of Helicobacter pylori and the nature of H. pylori resistance to this therapy in Japan

BACKGROUND

Multiple regimens for the eradication of Helicobacter pylori have been tested, but the best therapy has not been determined yet. To determine the efficacy of a new triple agent regimen using a combination of lansoprazole, amoxicillin, and clarithromycin against Helicobacter pylori (H. pylori), and to examine H. pylori resistance to this therapy in ineffective cases.

METHODS

We studied a total of 71 patients infected with H. pylori who had gastric ulcer (n = 37) or duodenal ulcer (n = 34) as confirmed by endoscopy. Patients received 1500 mg amoxicillin, 400 mg clarithromycin and 30 mg lansoprazole for 2 weeks followed by 30 mg lansoprazole for 6 weeks in patients with gastric ulcer or for 4 weeks in those with duodenal ulcer. Endoscopic examination was performed before treatment and at 1 month, 2 months, and 5 months after initiating treatment to check the status of ulceration and H. pylori infection.

RESULTS

The eradication rate of H. pylori was 92% (CI, 83-100%) in the gastric ulcer group and 94% (CI, 86-100%) in the duodenal ulcer group at 5 months, as determined by per-protocol analysis. Resistance to clarithromycin was present in 1 of 71 (1%) patients before treatment and in 2 of 5 (40%) patients after treatment. No resistance to amoxicillin and lansoprazole was found in patients before or after treatment. The resistance to clarithromycin changed during the observation period.

CONCLUSIONS

The new triple agent regimen was effective against H. pylori. Resistance to clarithromycin may not be permanent and it might be one of the risk factors which affect the efficacy of a clarithromycin-based therapy.

A simple method for determining metronidazole resistance of Helicobacter pylori

The reliability of methods for determination of Helicobacter pylori resistance to metronidazole has been found to depend upon the incubation time. Because the disk diffusion method is more vulnerable than other methods to prolonged incubation, this method has not been recommended for H. pylori. However, because media designed for rapid growth of H. pylori have been introduced, the time has come to look at the clinical usefulness of this inexpensive and simple method again. The correlation of readings obtained with the E test (AB Biodisk, Solna, Sweden) and Rosco's (Taastrup, Denmark) disk diffusion method for in vitro metronidazole resistance determination for H. pylori with a short incubation time (24 to 31 h) was studied. Plates which could not be read after 24 to 31 h were reincubated for another night. Fifty-seven consecutive clinical strains were tested. Because the rate of regrowth of H. pylori depends upon the age of the colonies inoculated, the reproducibility of resistance test results for young colonies versus old colonies was also studied. Resistance plates could be read after 24 to 31 h of incubation for 28 of 29 strains when the inoculum consisted of young colonies (3 to 4 days old). For these 29 strains, a high correlation (r = -0.937) was found between results obtained with the E test and those obtained with the disk diffusion test. A poorer correlation was found for old colonies (> or = 5 days old) (r = -0.742), which required a prolonged incubation for 8 of 23 strains. In conclusion, short incubation was successfully applied with young colonies. Results obtained with the simple and inexpensive disk diffusion method correlated well with those obtained with the E test.

Rapid increase in the prevalence of metronidazole-resistant Helicobacter pylori in the Netherlands

The prevalence of primary metronidazole resistance of Helicobacter pylori was studied in one Dutch hospital from 1993 to 1996 and in two additional Dutch hospitals in 1993 and 1996. All cultures of antral biopsy specimens yielding H. pylori in the study period were evaluated, except those from patients who had received anti-H. pylori treatment; 1,037 H. pylori strains, all from different patients were included. Metronidazole resistance was determined by disk diffusion in 1993 and by Epilipsometer-test in 1994 to 1996. Metronidazole resistance increased from 7% (18/245) in 1993 to 32% (161/509) in 1996. More patients with nonulcer dyspepsia and more non-Western European patients were seen in 1996 than in 1993, but age and sex differences were not observed. A comparable increase in metronidazole resistance was observed in both nonulcer dyspepsia patients and peptic ulcer patients, and the prevalence of metronidazole resistance in Western Europeans increased from 5% in 1993 to 28% in 1996.

An increase in Helicobacter pylori strains resistant to metronidazole: a five-year study

BACKGROUND

Metronidazole is one of the most commonly used antimicrobial agents for the treatment of Helicobacter pylori infection. Resistance to metronidazole has been reported worldwide but with a wide range of prevalence. We started using the classical triple therapy (bismuth, tetracycline, and metronidazole) for H. pylori infection in 1991 but recently have experienced a decline in its efficacy in curing the infection. Thus our aim was to investigate in a single center the prevalence of metronidazole-resistant H. pylori over a period of 5 years.

MATERIALS AND METHODS

A total of 1,015 different H. pylori strains collected over a period of 5 years were tested for sensitivity against metronidazole, ampicillin, tetracycline, and imipenem. Antibiotic sensitivity was tested by the disk diffusion and agar dilution methods. To elucidate further the possible relationship between these metronidazole-resistant strains, genomic DNA digestion by the Hae III endonuclease and ribotyping were undertaken in a selected group of isolates.

RESULTS

In 1991, 29 of 132 (22.0%) tested strains of H. pylori were found to be resistant to metronidazole. Since our initiation at that time of a triple therapy of bismuth, metronidazole, and tetracycline, the prevalence of metronidazole-resistant strains rose rapidly to 73.2% in 1995. All H. pylori isolates were sensitive to ampicillin, tetracycline, and imipenem. A high degree of genomic heterogeneity was found among these isolates. Thus it is unlikely that the resistant strains of H. pylori were originated from a single clone.

CONCLUSIONS

This study shows a rapid increase in metronidazole-resistant H. pylori with the use of an anti-Helicobacter regimen that contains metronidazole. We anticipate that the efficacy of metronidazole-containing anti-Helicobacter regimens will decline with the rapid rise in resistant strains of H. pylori.

Metronidazole, ranitidine and clarithromycin combination for treatment of Helicobacter pylori infection (modified Bazzoli's triple therapy)

BACKGROUND

Multi-drug regimens are generally required to reliably cure Helicobacter pylori infection. Metronidazole, clarithromycin and omeprazole has proven to be an effective combination therapy with a cure rate of 90% or greater.

METHODS

We evaluated a 14-day combination regimen for H.pylori infection consisting of metronidazole 500 mg b.d., clarithromycin 250 mg b.d. and ranitidine 300 mg b.d. (MRC) instead of omeprazole. Ranitidine alone was continued for an additional 4 weeks. H. pylori status was determined by rapid urease testing, histopathology using the Genta stain, and by culture at entry and 4 weeks after completing antimicrobial therapy.

RESULTS

Twenty-seven patients with documented peptic ulcer disease and H. pylori infection were treated. Five had previously failed macrolide-based antimicrobial therapy; none had received metronidazole. All ulcers were healed at week 6 except one patient taking naproxen; his H. pylori infection was cured. Overall, H. pylori infection was cured in 78% (95% CI = 58-91%). In patients with clarithromycin-sensitive isolates, the cure rate was 20 of 23 (87%, 95% C.I. = 66-97%); only one of four patients (25%) with clarithromycin-resistant isolates was cured. In contrast, four of five patients with metronidazole-resistant isolates were cured (80%). In patients with isolates sensitive to both antibiotics, the cure rate was 16 of 18 (89%, 95% C.I. = 65-99%). Mild side effects were reported by 27%, including diarrhoea and altered taste. Compliance averaged 98%.

CONCLUSION

These results suggest that the combination of metronidazole, ranitidine and clarithromycin results in high cure rates in patients with clarithromycin-sensitive isolates. Omeprazole may not be required for Bazzoli's triple therapy; and large multicentre comparative trials are indicated.

Antimicrobial susceptibility testing of Helicobacter pylori. Comparison of E-test, broth microdilution, and disk diffusion for ampicillin, clarithromycin, and metronidazole

The optimal method for the determination of the minimum inhibitory concentration (MIC) of antimicrobials against Helicobacter pylori has not been established. The epsilometer agar diffusion gradient test (E-Test; AB Biodisk, Solna, Sweden) was compared with broth microdilution, the reference method, and disk diffusion for the antimicrobial susceptibility testing of 122 clinical isolates of H. pylori to ampicillin, clarithromycin, and metronidazole. Isolates were considered to be resistant when the MIC values was > 8 micrograms/ml for either ampicillin or metronidazole and > 2 micrograms/ml for clarithromycin. For an individual isolate, the MICs for ampicillin and clarithromycin determined by broth microdilution and the E-test were highly reproducible, with replicate results being within +/- 1 log2 dilution. The correlation between the MICs determined by E-test and broth microdilution was excellent for both ampicillin and clarithromycin (90.1% and 88.5% were within +/- log2 dilution, and 98.3% and 96.7% of the values were within +/- 2 log2 dilution, respectively). In no instance did the interpretation of "sensitive" or "resistant" differ. Conversely, only 70.5% of the E-test results of metronidazole were within +/- 1 log2 dilution of the broth microdilution results. In addition, 15 (12.3%) of the H. pylori isolates interpreted as resistant by the E-test were sensitive by the broth microdilution method. All discrepancies occurred when the E-test MIC values fell between 8 and 32 micrograms/ml. The results of the ampicillin and clarithromycin disk diffusion assay correlated 100% with the results of the broth microdilution. However, these data suggest that when the E-test MIC results of metronidazole yield values between 8 and 32 micrograms/ml, the MIC should be reevaluated by another method.

Metronidazole, omeprazole and clarithromycin: an effective combination therapy for Helicobacter pylori infection

BACKGROUND

Successful treatment of Helicobacter pylori infection results in cure of peptic ulcer disease. Multi-drug regimens are needed to cure this infection. We studied the effectiveness and side effect profile of two antibiotics active against Helicobacter pylori, metronidazole and clarithromycin, combined with omeprazole.

METHODS

We evaluated a combination therapy for H. pylori infection consisting of metronidazole (500 mg b.d.), omeprazole (20 mg b.d.), and clarithromycin (250 mg b.d.) for 2 weeks, followed by ranitidine 300 mg daily for 4 weeks.

RESULTS

Thirty-three patients with documented H. pylori infection were studied. Twenty had previously failed antimicrobial therapy, including one with metronidazole-based triple therapy and eight with macrolide-based therapy (five with clarithromycin-based therapy), and 11 with amoxycillin, tetracycline, and bismuth. H. pylori status was determined by histopathology using the Genta stain and by culture. H. pylori status was determined at entry and 4 weeks after completing antimicrobial therapy. The H. pylori infection was cured in 88% (95% CI = 72%-96%) including 90% of those who had failed previous anti-H. pylori therapies. Mild side effects were reported by 18%.

CONCLUSION

We conclude that the combination of metronidazole, omeprazole and clarithromycin is an effective treatment for H. pylori infection.

Rapid eradication of Helicobacter pylori infection

BACKGROUND/AIMS

Current Helicobacter pylori eradication therapy for peptic ulcer disease usually involves a 2-week course of either a bismuth preparation or omeprazole in combination with antibiotics. We have studied a shorter, 7-day course of treatment to assess efficacy and tolerability.

METHODS

Four hundred and thirty-six patients, in three non-randomized groups, received omeprazole (40 mg mane), amoxycillin (500 mg t.d.s.) and metronidazole (400 mg t.d.s.): 308 patients received the triple combination for 14 days; 80 patients were treated for 7 days; and 48 patients received omeprazole and amoxycillin for 7 days but metronidazole for only 5 days.

RESULTS

Helicobacter pylori was eradicated in 89.5%, 91.1% and 87.5%, respectively (98.3%, 92.9% and 100% of metronidazole-sensitive isolates and 75.6% and 88.2% of metronidazole-resistant isolates in the first two groups). Side effects were significantly more frequent in patients who received 14 days (49%) compared with 7 days of treatment (33%); only 8/308 and 1/128 patients, respectively, failed to complete the course.

CONCLUSIONS

On the basis of efficacy, tolerability and cost, we conclude that a 7-day course of the omeprazole (40 mg mane), amoxycillin (500 mg t.d.s.) plus metronidazole (400 mg t.d.s.) combination is effective therapy for the eradication of H. pylori.

Treatment of Helicobacter pylori infection

Helicobacter pylori infects the human stomach and is associated with chronic gastritis, peptic ulcer disease and gastric cancer. Most patients with peptic ulcers are infected with H pylori. These patients suffer a high relapse rate following initial healing of the ulcer with anti-secretory agents. The rate of relapse can be greatly diminished following successful eradication of the organism. Although experience is still being accumulated, it is reasonable to use eradication therapy in any patient with H pylori positive active peptic ulcer disease. Combination triple and dual therapy regimens are effective but the search continues for better therapies. This review outlines the current evidence regarding which, when, how and with what H pylori infected patients should be treated.

Helicobacter pylori infection in children with recurrent abdominal pain

Helicobacter pylori was cultured and Helicobacter-like organisms (HLO) were seen in 6 (16%) of 37 children with recurrent abdominal pain. Five children had concomitant histological inflammation, but none had endoscopic changes. All 6 children demonstrated positive serology. Compared with the total group, they were more often from developing countries, larger families and lower social groups. Treatment with phenoxymethyl penicillin and colloidal bismuth subcitrate did not result in side effects or elevated serum levels of serum bismuth. Three children demonstrated metronidazole-resistant strains and the treatment of these children remained an unsolved problem. Among the 31 H. pylori/HLO negative children 8 (26%) demonstrated histological changes, 5 (16%) endoscopic changes and 11 (35%) had positive serology. In conclusion, pathological findings at upper gastrointestinal endoscopy are common in children with recurrent abdominal pain. Because of disconcordance between endoscopy, histology and culture, we recommend that biopsies should always be taken to clarify the diagnosis.

Clarithromycin-amoxycillin therapy for Helicobacter pylori infection

BACKGROUND

More convenient therapies are needed to treat Helicobacter pylori infection successfully. Clarithromycin and amoxycillin are effective against H. pylori both in vivo and in vitro. Recent success with a high dose amoxycillin-metronidazole combination therapy led us to evaluate clarithromycin-amoxycillin dual therapy for H. pylori infection.

METHODS

We tested the combination of clarithromycin 500 mg t.d.s. with meals plus amoxycillin 750 mg t.d.s. with meals for 10 days for its effect on H. pylori infection in 29 patients with documented H. pylori peptic ulcers. There were 27 men and 2 women, ranging in age from 23 to 77 years. H. pylori and ulcer status were evaluated at entry and at least 4 weeks after ending antimicrobial therapy. For ulcer healing, ranitidine 300 mg was given each evening for 6 weeks. H. pylori status was determined by CLOtest and histology.

RESULTS

H. pylori infection was cured in 86% (95% CI = 78-99%). Compliance averaged 93% by pill count. Ten patients (34%) experienced mild side effects: eight reported dysgeusia and two had mild diarrhoea; none discontinued therapy because of side effects.

CONCLUSION

We conclude that dual therapy with clarithromycin and amoxycillin is a safe and effective alternative regimen for the successful treatment of H. pylori infections.

Impact of metronidazole resistance on the eradication of Helicobacter pylori

We investigated how often Helicobacter pylori was resistant to metronidazole before treatment in 283 H. pylori positive patients and whether the in vitro susceptibility to metronidazole could predict the clinical outcome of several drug regimens containing metronidazole. Metronidazole susceptibility was tested using either disc diffusion or plates containing metronidazole. Metronidazole-resistant strains were found in 41% of patients before their first anti-H. pylori treatment course. In patients with metronidazole-susceptible isolates, eradication was achieved in 74% after colloidal bismuth subcitrate (CBS) with metronidazole and in 91% after triple therapies consisting of CBS, metronidazole and amoxicillin or tetracycline. Dual therapies of 1 or 4 weeks' duration and triple therapies lasting 1 week were ineffective in patients with metronidazole-resistant strains. A 4-week course of triple therapy could still eradicate H. pylori in 68% of patients with metronidazole-resistant strains, but at the cost of significant side-effects. It is concluded that metronidazole resistance is common and is generally associated with a poor outcome of anti-H. pylori therapies containing metronidazole. Alternative drug schedules are urgently needed for patients with metronidazole-resistant H. pylori.

Short report: treatment of Helicobacter pylori-associated duodenal ulcer with omeprazole plus antibiotics

Omeprazole heals most duodenal ulcers after 4 weeks of treatment but relapse is common. Eradication of Helicobacter pylori is associated with reduced rate of ulcer relapse. This study investigates the effect of omeprazole with antibiotics in H. pylori-associated duodenal ulceration. Forty-three patients with endoscopically proven duodenal ulcer and H. pylori entered this study. Treatment consisted of 20 mg omeprazole daily (four weeks) and seven days (first week) treatment with 400 mg metronidazole t.d.s. and 500 mg tetracycline t.d.s. Four weeks after completing the treatment, 81% (35/43) had a healed duodenal ulcer, and 58% (25/43) had H. pylori eradication. In those who healed, at one year 21 remained H. pylori-negative, 12 had persistent H. pylori infection and 2 had re-infection. The ulcer relapse rate at one year was 26%: of the 9 who relapsed, 6 had persistent infection, 2 were re-infected, and only 1 was H. pylori-negative. This combination therapy of antibiotics with omeprazole successfully eradicates Helicobacter pylori and has a lower ulcer relapse than omeprazole alone.

Results of a multicentre European survey in 1991 of metronidazole resistance in Helicobacter pylori. European Study Group on Antibiotic Susceptibility of Helicobacter pylori

In 1991 a multicentre survey on the prevalence of metronidazole resistance in Helicobacter pylori in vitro was carried out in 12 hospitals in 11 different European countries. The susceptibility of Helicobacter pylori to metronidazole was determined in each centre by measuring the MIC on agar with the PDM E-test (AB Biodisk) according to a standard procedure. Overall, 122 of 443 (27.5%) strains tested were resistant to metronidazole (MIC > 8 micrograms/ml). The level of resistance to metronidazole varied markedly between centres (from 7% to 49%) and was found to be substantially higher in Africans and other non-Caucasian subjects than in natives from European countries. The overall rate of resistance to metronidazole was higher in females (34.7%) than in males (23.9%), and varied according to the age group, being highest among women aged 20 to 39 (50%). Previous use of metronidazole was reported in only 16 patients, 11 of whom (68.8%) harboured resistant Helicobacter pylori strains. Although differences in the rate of metronidazole resistance in Helicobacter pylori most probably relate to variations in use of this drug in different populations, such use may frequently go unrecognized. This study emphasises the importance of monitoring the drug resistance of Helicobacter pylori on a local basis. Standardisation of the methods for testing the susceptibility of Helicobacter pylori in vitro is clearly needed for this purpose.

Eradication of Helicobacter pylori and its effect in peptic ulcer disease

Since Helicobacter pylori was first cultured 10 years ago, there have been remarkable changes in our approach to the therapy of peptic ulcer disease. We now know that 90% of duodenal ulcer patients and 70% of all gastric ulcer patients are infected with H. pylori. Evidence is presented that the relapse rate of both duodenal and gastric ulcers can be substantially reduced if the bacterium is eradicated from the patient's stomach. Some of the anti-H. pylori eradication regimens currently available are discussed, with particular emphasis on the relative merits of standard triple therapy and an omeprazole/amoxycillin combination.

Short report: omeprazole plus antibiotic combinations for the eradication of metronidazole-resistant Helicobacter pylori

Twenty-eight Helicobacter pylori-positive patients with metronidazole-resistant isolates and 25 with metronidazole-sensitive isolates were treated for 14 days with 40 mg omeprazole nocte plus 500 mg amoxycillin t.d.s. Eradication of H. pylori, defined as absence of the organism one month after cessation of treatment, was assessed using the [14C]urea breath test. The eradication rate in patients with metronidazole-resistant isolates was 14/28 (50%) while that in patients was metronidazole-sensitive isolates was 12/25 (48%). In contrast to these encouraging eradication rates, very poor results were obtained with a 7-day course of omeprazole (40 mg nocte) in combination with erythromycin ethylsuccinate (500 mg q.d.s.) and tripotassium dicitrato bismuthate tablets (120 mg q.d.s.). The latter eradication rates were 3/20 (15%) in patients taking erythromycin tablets and 3/19 (16%) in those taking a liquid formulation of erythromycin. All treatment regimens were well tolerated and all patients completed the prescribed course of therapy.

Experience with 'triple' anti-Helicobacter pylori eradication therapy: side effects and the importance of testing the pre-treatment bacterial isolate for metronidazole resistance

At the 1990 World Congresses of Gastroenterology, the Working Party on Helicobacter pylori (H. pylori) recommended that, in suitable patients, the bacterium should be eradicated using a therapeutic regimen comprising a bismuth salt, tetracycline and metronidazole for two weeks. We have treated 40 patients infected with H. pylori with 'triple' therapy consisting of 120 mg tripotassium dicitrato bismuthate q.d.s., 500 mg tetracycline q.d.s. and 400 mg metronidazole t.d.s. for two weeks. The success rate, in terms of bacterial eradication, was 19/21 (90.5%) in patients with metronidazole-sensitive organisms, compared with only 6/19 (31.6%) in patients whose H. pylori were resistant to metronidazole (P less than 0.01). Side effects, particularly diarrhoea and vomiting/nausea, were common: 23/40 patients reported such symptoms during the 14-day course of therapy. Fifteen of these 23 patients completed the entire 14-day course, although suffering from significant side effects, while the remaining eight patients had to discontinue the treatment because side effects became intolerable. If a form of triple therapy is going to be widely used to eradicate H. pylori infection, the regimen will have to be simpler, shorter, produce fewer side effects and be more effective in patients with metronidazole-resistant bacteria.

Does a previous course of tripotassium dicitrato bismuthate affect the subsequent chances of successful Helicobacter pylori eradication?

We have performed a retrospective study of 103 patients with either peptic ulcer or non-ulcer dyspepsia, infected with metronidazole-sensitive strains of Helicobacter pylori (H. pylori), who were treated with a combination of tripotassium dicitrato bismuthate and metronidazole for a period of at least two weeks. Dual therapy with tripotassium dicitrato bismuthate plus metronidazole showed similarly high eradication rates (greater than or equal to 80%) of H. pylori from patients irrespective of age, gender or clinical diagnosis. Most importantly, dual therapy achieved a similar eradication rate of H. pylori infection in 41 patients who had previously been treated with tripotassium dicitrato bismuthate alone or in combination with an antibiotic other than metronidazole. It therefore appears that H. pylori does not become resistant to treatment with tripotassium dicitrato bismuthate.

One week eradication regimen for Helicobacter pylori

Although Helicobacter pylori is both a frequent cause of gastritis and an important factor in duodenal ulcer recurrence, no treatment regimen exists that is completely safe and effective. We have studied a short eradication regimen of tripotassium dicitrato bismuthate 120 mg four times daily and amoxycillin 500 mg four times daily for seven days with metronidazole 400 mg five times daily for three days (days 5-7). 106 patients with peptic ulceration and non-ulcer dyspepsia, who were also infected with H pylori, were entered into the study. H pylori was successfully eradicated in 76/106 (72%) patients (median follow-up 9.3 months). The rate of eradication was higher among patients with metronidazole-sensitive H pylori (40/43, 93%). In 17/30 patients in whom eradication failed, pretreatment metronidazole-resistant strains were subsequently isolated. Side-effects were mild, the commonest (24/106, 24%) being taste disturbance with metronidazole. A one-week eradication regimen is a safe, effective, cheap, and well-tolerated treatment for metronidazole-sensitive H pylori.