Quadruple therapy is effective for eradicating Helicobacter pylori after failure of triple proton-pump inhibitor-based therapy: a detailed, prospective analysis of 21 consecutive cases

Background. Data regarding the effectiveness of second-line treatment of Helicobacter pylori infection are limited, especially if microbiological studies are considered.
Methods and Patients. We conducted a prospective, uncontrolled study of a consecutive series of 21 peptic ulcer patients with failure of 1-week lansoprazole, amoxicillin, and clarithromycin. H. pylori status was evaluated by urease test, histology, culture, and urea breath test. Susceptibility to amoxicillin, clarithromycin, and metronidazole was studied by E -test. Cure of infection was defined as negative results from endoscopy-based tests 1 month after treatment and negative results from a urea breath test at 2 months. Treatment consisted of a 1-week combination of lansoprazole (30 mg bid), tetracycline (500 mg qid), metronidazole (500 mg tid), and bismuth subcitrate (120 mg qid).
Results. H. pylori was resistant to metronidazole in three cases, to clarithromycin in three cases, and to both clarithromycin and metroinidazole in an additional three patients. No resistance to amoxicillin was found. Eradication was obtained in 20 cases (95.2% confidence interval [CI], 76.2–99.9). The only patient in whom infection was not eradicated harbored a metronidazole-resistant (minimum inhibitory concentration> 32 μg/ml) strain. No significant side effects were reported.
Conclusion. Quadruple therapy obtains a high eradication rate even in patients with clarithromycin- and metronidazole-resistant strains. Further randomized and controlled studies are warranted and are urgently needed.     

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

Background. Helicobacter pylori infection is associated with a wide range of digestive diseases and is very prevalent in developing countries, although few data exist on the susceptibility of H. pylori to antimicrobials commonly used in eradication schedules in these countries. The aim of this study was to evaluate the resistance of H. pylori to metronidazole, clarithromycin, amoxicillin, tetracycline, and furazolidone in dyspeptic Brazilian patients.
Material and Methods. Ninety consecutive H. pylori –positive patients were enrolled. Resistance was evaluated by an agar dilution test.
Results. Resistance to metronidazole was detected in 38 patients (42%); to amoxicillin in 26 individuals (29%); to clarithromycin in 6 patients (7%); to tetracycline in 6 patients (7%); and to furazolidone in 4 individuals (4%). Thirteen strains were resistant to two agents, and eight strains were resistant to three antimicrobials.
Conclusions. These results confirm the need for culture and susceptibility testing to define H. pylori resistance patterns in particular geographical areas before the general use of an eradication schedule. They also suggest the possibility of resistance to such antimicrobials as amoxicillin or tetracycline in geographical areas with a high prevalence of H. pylori infection and still not fully evaluated for antimicrobial susceptibility.     

Mutations in the 16S rRNA genes of Helicobacter pylori mediate resistance to tetracycline

Low-cost and rescue treatments for Helicobacter pylori infections involve combinations of several drugs including tetracycline. Resistance to tetracycline has recently emerged in H. pylori. The 16S rRNA gene sequences of two tetracycline-resistant clinical isolates (MIC = 64 microg/ml) were determined and compared to the consensus H. pylori 16S rRNA sequence. One isolate had four nucleotide substitutions, and the other had four substitutions and two deletions. Natural transformation with the 16S rRNA genes from the resistant organisms conferred tetracycline resistance on susceptible strains. 16S rRNA genes containing the individual mutations were constructed and tested for the ability to confer resistance. Only the 16S rRNA gene containing the triple mutation, AGA965-967TTC, was able to confer tetracycline resistance on H. pylori 26695. The MICs of tetracycline for the transformed strains were equivalent to those for the original clinical isolates. The two original isolates were also metronidazole resistant, but this trait was not linked to the tetracycline resistance phenotype. Serial passage of several H. pylori strains on increasing concentrations of tetracycline yielded mutants with only a very modest increase in tetracycline resistance to a MIC of 4 to 8 microg/ml. These mutants all had a deletion of G942 in the 16S rRNA genes. The mutations in the 16S rRNA are clearly responsible for tetracycline resistance in H. pylori.     

Treatment of Helicobacter pylori Infection: A Review of the World Literature

Background. None of the currently used anti- Helicobacter pylori drug regimens cures the infection 100%, and cure results still vary considerably. The present article reviews the effectiveness of currently used antimicrobial regimens, aimed to cure H. pylori infection.
Methods. Data collection started from the beginning of the anti- H. pylori -therapy era until May 1995. No attempt at formal metanalysis has been made, because many studies have been published only in abstract form. Attempts were made to exclude duplicates of studies by comparison to previously reported ones; the authors of suspected duplicates were contacted. After amalgamation of the number of included patients and the number of successfully treated patients, the mean values of eradication rates and the 95% confidence intervals were calculated.
Results. A total of 237 treatment arms were analyzed. Bismuth triple therapy continues to reach high eradication rates worldwide (78–89%). Side effects leading to diminished patient compliance and the marked decline of eradication efficacy in cases of metronidazole resistance are considered to be the major drawbacks of this therapy. Proton pump inhibitor (PPI) dual therapy is better tolerated with fewer side effects than is bismuth triple therapy. The mean eradication rates vary from 55 to 75%, and the extremes lie between 24 and 93%. PPI triple therapies have been shown to be very effective against H. pylori (eradication rates, 80–89%). Quadruple therapy leads to a mean eradication rate of 96%.
Conclusion. Based on efficacy, PPI triple or bismuth triple therapy are recommended as first-line treatment for H. pylori infection. Quadruple therapy could serve as second-line treatment for eradication of initial failures and in case of metronidazole resistance.     

High Level of Antimicrobial Resistance in French Helicobacter pylori Isolates

Background:  Helicobacter pylori is a human pathogen responsible for serious diseases including peptic ulcer disease and gastric cancer. The recommended triple therapy included clarithromycin but increasing resistance has undermined its effectiveness. It is therefore important to be aware of the local prevalence of antimicrobial resistance to adjust treatment strategy.
Materials and Methods:  Overall, 530 biopsies were collected between 2004 and 2007. The antimicrobial susceptibility of H. pylori was determined by E-test and molecular methods.
Results:  Among these, 138/530 (26%) strains were resistant to clarithromycin, 324/530 (61%) to metronidazole and 70/530 (13.2%) to ciprofloxacin. Whereas no resistance against amoxicillin and tetracycline was observed, only one strain was resistant to rifampicin. Compared to the patients never treated for H. pylori infection, the prevalence of resistance was significantly higher in patients previously treated (19.1% vs 68% for clarithromycin; 13.2% vs 53.3% for both clarithromycin and metronidazole). The trend analysis revealed an increase of primary resistance to ciprofloxacin between 2004 and 2005 (7.3%) vs 2006–2007 (14.1%) ( p  = .04) and the secondary resistance reached 22.7% in 2007. Interestingly, 27 biopsies (19.6%) contained a double population of clarithromycin-susceptible and -resistant strains.
Conclusions:  The reported high prevalence of clarithromycin and multiple resistances of H. pylori suggest that the empiric therapy with clarithromycin should be abandoned as no longer pretreatment susceptibility testing has assessed the susceptibility of the strain. As culture and antibiogram are not routinely performable in most clinical laboratories, the use of molecular test should be developed to allow a wide availability of pretreatment susceptibility testing.     

Primary resistance of Helicobacter pylori to antimicrobial agents in Polish children

Helicobacter pylori resistance to antimicrobial agents is an important factor compromising the efficacy of treatment. Therefore the aims of our study were: to determine the prevalence of H. pylori resistance to clarithromycin, metronidazole, amoxycillin and tetracycline in children prior to eradication therapy, to compare different methods of susceptibility testing and to detect mutations responsible for clarithromycin resistance. During 1996-2000, 259 H. pylori strains were isolated from antral gastric biopsies. Susceptibility to antimicrobials was determined by the agar dilution method and the Etest. Mutations in the 23S rRNA gene associated with clarithromycin resistance were analysed by PCR-RFLP and direct sequencing. Overall, ninety-six strains (37%) were resistant to metronidazole, 50 strains (19.3%) were resistant to clarithromycin, and 20 strains (7.7%) were simultaneously resistant to both drugs. All cultured isolates were sensitive to amoxycillin and only one isolate (0.4%) was resistant to tetracycline. The agar dilution method and the Etest showed a perfect category correlation for clarithromycin and 4% discrepancies for metronidazole. Primary resistance to clarithromycin was mainly associated with an A2143G mutation in the 23S rRNA gene of H. pylori. The study highlights the high prevalence of H. pylori primary resistance to clarithromycin in Polish children, which implies a need for pretreatment susceptibility testing.     

Effectiveness of Quadruple Therapy Using Lansoprazole, Instead of Omeprazole, in Curing Helicobacter pylori Infection

Background. Omeprazole enhances the efficacy of bismuth-based triple therapy. It is unknown whether the same is true for other proton pump inhibitors. Lansoprazole has superior anti- Helicobacter activity in vitro and possibly also in vivo; therefore we investigated quadruple therapy with lansoprazole.
Materials and Methods. In two studies performed in separate hospitals, a total of 67 Helicobacter pylori –positive patients were treated with 7-day quadruple therapy (lansoprazole, colloidal bismuth subcitrate, tetracycline, and metronidazole) after 3 days of lansoprazole pretreatment. Testing for cure was done by endoscopy in study 1 and by breath test in study 2.
Results. Cure rates per protocol were 31 of 31 (100%) in study 1 and 30 of 32 (94%) in study 2. Intention-to-treat cure rates were 31 of 35 (89%) in study 1 and 30 of 32 (94%) in study 2. Cured overall were 32 of 34 with a metronidazole sensitive strain and 3 of 3 with a metronidazole-resistant strain. Data on side effects were collected from 51 patients. Twelve (21%) had no side effects, 27 (53%) had mild side effects, 10 (20%) had moderate side effects, but only 2 (4%) had severe side effects. Side effects, never were the reason that a patient stopped taking the medication.
Conclusions. The results with lansoprazole-quadruple therapy are comparable to the historic control group treated with omeprazole-quadruple therapy. The cure rate is very high, and although mild to moderate side effects occured in many patients, everybody finished the treatment regime.     

Characterization and Therapy for Experimental Infection by Helicobacter mustelae in Ferrets

Background. Numerous clinical trials evaluating the efficacy of various antimicrobial compounds against Helicobacter pylori infection have been performed in humans. A convenient animal model for Helicobacter infection would facilitate the evaluation of novel therapies. These experiments were performed to evaluate the use of ferrets as a model of Helicobacter infection.
Materials and Methods. Ferrets were infected experimentally with Helicobacter mustelae and subsequently treated with bismuth subsalicylate (BSS) triple therapy (BSS, metronidazole, and amoxicillin), or left untreated. The status of infection and serology was assessed during treatment and for 8 weeks posttreatment. Seven ferrets successfully treated with triple therapy were challenged with H. mustelae and monitored for infection for an additional 5 weeks.
Results. Infection of ferrets by H. mustelae was accompanied by gastritis and a specific antibody response. Treatment of H. mustelae -infected ferrets with BSS suppressed bacterial growth in four of nine animals but did not eradicate infection. Triple therapy eradicated infection in all nine ferrets with a reduction in gastric inflammation. No relapse of infection occurred up to 8 weeks posttherapy. Challenge with H. mustelae of ferrets successfully treated with triple therapy resulted in a 100% rate of reinfection.
Conclusions. H. mustelae infection can be eliminated by triple therapy, but this does not result in protective immunity against reinfection by H. mustelae. This model, using a strain of Helicobacter indigenous to the host, may be useful for assessing therapeutic efficacy of novel therapies for the treatment of human infection by H. pylori.     

Pretreatment antimicrobial susceptibilities of paired gastric Helicobacter pylori isolates: antrum versus corpus

Background. Antimicrobial susceptibility testing of Helicobacter pylori isolates is the most useful tool for guiding specific therapy, especially when primary resistance is suspected. However, the most informative gastric biopsy site for detection of resistant H. pylori isolates is uncertain. We sought to determine whether susceptibilities to commonly used antimicrobials (amoxicillin, clarithromycin, minocycline, and metronidazole) were related to biopsy site.
Methods. H. pylori isolates were obtained from patients who had duodenal ulcer and had not received any therapy directed against H. pylori. Agar-dilution minimum inhibitory concentrations of each antimicrobial were compared between paired H. pylori isolates from the antrum and the proximal corpus.
Results. Differences in minimum inhibitory concentrations exceeding twofold were observed within the pairs of H. pylori isolates in 5 of the 40 patients tested. In three patients with clarithromycin-resistant isolates and two with metronidazole-resistant isolates, both antral and corporeal specimens revealed resistance. However, no patient had pairs of isolates categorized as resistant at one site and sensitive at the other.
Conclusions. While we found that an individual may have a mixed H. pylori infection with respect to differing antimicrobial susceptibility in different parts of the stomach, a single biopsy specimen from either the antrum or the corpus should provide reliable detection of H. pylori isolates with primary resistance.     

Helicobacter pylori: new developments and treatments

The authors highlight new developments in research on Helicobacter pylori. There is now consensus that all patients with newly diagnosed or recurrent duodenal or gastric ulcers who have a positive test result for H. pylori should be treated for the infection. Patients presenting with complications of ulcers, such as bleeding, should also be treated. H. pylori has recently been classified as a definite human carcinogen by the International Agency for Research on Cancer. In treatment, new combination regimens, consisting of 3 or 4 different drugs, cure the infection in more than 80% of patients. Currently, the best combinations are: (1) omeprazole (or another proton-pump inhibitor), clarithromycin and metronidazole, (2) omeprazole (or another proton-pump inhibitor), clarithromycin and amoxicillin, (3) bismuth subsalicylate, tetracycline and metronidazole, and (4) omeprazole, bismuth subsalicylate, tetracycline and metronidazole.     

The Ideal Therapy Must Be Def ined in Each Geographical Area: Experience with a Quadruple Therapy in Spain

Background. Multiple therapeutic combinations have been tested to determine the optimal regimen(s) for Helicobacter pylori eradication, leading to very different results depending on the geographical area. Our goal was to evaluate the efficacy of a "quadruple" therapy with omeprazole, tetracycline, bismuth and metronidazole in our area.
Materials and Methods. We investigate 106 consecutive patients with active peptic ulcer disease (duodenal, gastric or both) and Helicobacter pylori infection. One-week therapy with omeprazole 20 mg b.i.d., tetracycline hydrochloride 500 mg q.i.d., colloidal bismuth subcitrate 120 mg q.i.d., and metronidazole 250 mg t.i.d was prescribed. Between the days 30 and 40 after treatment ended follow-up endoscopy was performed. Eradication was defined as both negative urease test and histology. Between days 90 and 360 a ¹³C urea breath test was performed in 100 patients.
Results. Of the 106 patients in the study, 91 had duodenal ulcer, 12 had gastric ulcer, and 3 had both. Side effects were observed in 25% of the cases. Eradication was achieved in 87.7% (93/106; CI 79.9–93.3). Healing was obtained in 95.2% (100/105; CI 89.2–98.4); 97.8% (CI 92.4–99.7) in those eradicated and 75% (CI 42.8–94.5) in non-eradicated ( p < .01).
Conclusions. Quadruple therapy with omeprazole, tetracycline, bismuth subcitrate and metronidazole achieves healing rates up to 95–100%. The 87.7% eradication rate obtained suggests that the regimen we used is a reasonable therapeutic alternative in our area.     

Helicobacter pylori and Peptic Ulcer Disease Therapies: A Survey of Gastroenterologists in Israel

Background. Eradication of Helicobacter pylori has become a therapeutic option in the treatment of patients with peptic ulcer disease. The aim of this study was to evaluate the current management strategies of Israeli gastroenterologists in the diagnosis and treatment of H. pylori- related peptic ulcer disease, 14 years after the discovery of H. pylori.
Materials and Methods. A questionnaire was mailed to all specialists in gastroenterology, members of the Israel Gastroenterological Association (IGA). Replies were received from 60% of Israel Board-certified gastroenterology specialists.
Results. Over 89% of the gastroenterologists (89.1%) noted that they recommend anti- H. pylori treatment. 94.5% said that they treat duodenal ulcer in the first presentation with anti- H. pylori medication and 75% said that they do so in cases of recurrent duodenal ulcer. According to the replies received, there is a strong consensus towards triple treatment as the favored anti -H. pylori treatment; no one noted the use of dual treatment. Seven-day triple treatment was prescribed by 83.6% of the gastroenterologists who responded. Of these, the great majority, 89.1%, stated that they use proton pump inhibitors (PPI) in combination with any two of the following antibiotics: metronidazole (47.3%), tinidazole (29.1%), clarithromycin (61.8%), and amoxicillin (40%).
Conclusion. At the time of the survey, most Israel Board-certified gastroenterology specialists prescribed triple anti- H. pylori treatment of one-week's duration.     

Seven-Day Triple Therapy with Lansoprazole, Clarithromycin, and Metronidazole for the Cure of Helicobacter pylori Infection: A Short Report

Background To refine our understanding of anti- Helicobacter pylori treatment regimens further, we evaluated the efficacy and safety of lansoprazole given in combination with clarithromycin and metronidazole for 7 days in an open-label, multicenter study.
Materials and Methods. H. pylori -positive patients self-administered lansoprazole, 30 mg; clarithromycin, 500 mg; and metronidazole, 500 mg bid for 7 days. Patients were assessed at pretreatment, at which time the presence of H. pylori was documented by rapid urease test or histology and culture, following study drug administration (week 1) for a brief evaluation only, and at least 4 weeks posttreatment (week 5), including endoscopy with collection of biopsy specimens for culture and histology testing.
Results. Of the 60 patients enrolled in the study, 59 had confirmed H. pylori infection, and 51 were included in an intent-to-treat analysis of efficacy. Primary metronidazole and clarithromycin resistance were observed in 84% and 8% of study patients, respectively. One month after the end of therapy, H. pylori infection was cured in 40 of 51 patients (78%); 95% confidence interval, 65%–89%). The triple-therapy regimen was well-tolerated, with only 2 patients (4%) requiring premature withdrawal from the study due to treatment-related adverse events. Taste perversion (15.0%) and diarrhea (11.7%) were the most frequently reported adverse events possibly or probably related to study medication during the treatment period.
Conclusion. Despite a high prevalence of metronidazole resistance, a 1-week, triple-drug combination of lansoprazole, clarithromycin, and metronidazole is effective treatment for and well-tolerated by patients with H. pylori infection.     

Antibiotic resistance of Helicobacter pylori in Mazandaran, North of Iran

Background: The aim of this study was to investigate the prevalence of resistances in Helicobacter pylori against commonly used antibiotics including metronidazole, clarithromycin, amoxicillin, and tetracycline in Iranian patients. Methods: H. pylori isolates were collected from gastric biopsies from patients referred for upper gastrointestinal endoscopy at Tooba Medical Center, Sari, Iran, from 2007 to 2010. None of them had been using antibiotics for at least 8 months. H. pylori was identified based on morphological shape and positive biochemical tests for catalase, oxidase, and urease activity. Antibiotic resistance for metronidazole, clarithromycin, amoxicillin, and tetracycline was investigated by using epsilometer test. Resistance was defined by minimal inhibitory concentration (MIC) > 0.5 mg/L for amoxicillin (AMX), >4 mg/L for tetracycline (TET), >8 mg/L for metronidazole (MTZ), and >1 mg/L for clarithromycin (CLR). Results: Strains were collected from 132 patients, mean age 45.8 years, 52 (39%) were women. Patients had diverse diagnoses: gastritis 42 (31.8%), duodenal ulcer 45 (34%), gastric cancer 15 (11.3%), or gastric ulcer 30 (22.7%). The prevalences of resistance of H. pylori strains isolated from the patients were 73.4% for metronidazole, 30% for clarithromycin, 6.8% for amoxicillin, and 9% for tetracycline. Twenty‐eight (21.2%) were double resistant to MTZ‐CLR, 16 (12.1%) showed triple resistance to MTZ‐CLR‐AMX, and 8 (6%) were resistant to all four tested antibiotics (MTZ‐CLR‐AMX‐TET). No associations were detected between multiple resistant strains and clinical manifestations (p > .05). Conclusions: The prevalence of H. pylori antibiotic resistance to metronidazole and clarithromycin was high in Iran consistent with the reported low success rates for H. pylori treatment in this country.     

Guidelines for the Management of Helicobacter pylori Infection in Japan: 2009 Revised Edition

Background:  Over the past few years, the profile of Helicobacter pylori infection has changed in Japan. In particular, the relationship between H. pylori and gastric cancer has been demonstrated more clearly. Accordingly, the committee of the Japanese Society for Helicobacter Research has revised the guidelines for diagnosis and treatment of H. pylori infection in Japan.
Materials and Methods:  Four meetings of guidelines preparation committee were held from July 2007 to December 2008. In the new guidelines, recommendations for treatment have been classified into five grades according to the Minds Recommendation Grades, while the level of evidence has been classified into six grades. The Japanese national health insurance system was not taken into consideration when preparing these guidelines.
Results:  Helicobacter pylori eradication therapy achieved a Grade A recommendation, being useful for the treatment of gastric or duodenal ulcer, for the treatment and prevention of H. pylori -associated diseases such as gastric cancer, and for inhibiting the spread of H. pylori infection. Levels of evidence were determined for each disease associated with H. pylori infection. For the diagnosis of H. pylori infection, measurement of H. pylori antigen in the feces was added to the tests not requiring biopsy. One week of proton-pump inhibitor-based triple therapy (including amoxicillin and metronidazole) was recommended as second-line therapy after failure of first-line eradication therapy.
Conclusion:  The revised Japanese guidelines for H. pylori are based on scientific evidence and avoid the administrative restraints that applied to earlier versions .     

Frame-shift mutations in NAD(P)H flavin oxidoreductase encoding gene (frxA) from metronidazole resistant Helicobacter pylori ATCC43504 and its involvement in metronidazole resistance

Metronidazole is a critical ingredient for combination therapies of Helicobacter pylori infection, the major cause of peptic ulcer and gastric cancer. It has been recently reported that metronidazole resistance from H. pylori ATCC43504 is caused by the insertion of a mini-IS605 sequence and deletion of sequences in an oxygen insensitive NAD(P)H nitroreductase encoding gene (rdxA). We also found that an additional gene (frxA) encoding NAD(P)H flavin oxidoreductase in the same strain was truncated by frame-shift mutations. To assess whether the frxA truncation is also involved in metronidazole resistance, metronidazole sensitive H. pylori strains ATCC43629 and SS1 were transformed by the truncated frxA gene cloned from strain ATCC43504. All transformed cells grew on agar plates containing 16 microg ml(-1) of metronidazole. The involvement of the frxA gene in metronidazole resistance was also confirmed by insertion inactivation of frxA and/or rdxA genes from strain ATCC43629 and one metronidazole sensitive clinical isolate H. pylori 2600. In addition, the frxA gene cloned from the H. pylori 2600 showed metronidazole nitroreductase activity in Escherichia coli and rendered ordinary metronidazole resistant E. coli to metronidazole sensitive cell. These results indicate that the frxA gene may also be involved in metronidazole resistance among clinical H. pylori isolates.     

Helicobacter pylori in gastric biopsies of Taiwanese patients with gastroduodenal diseases

This study was designed to study the in vivo prevalence and the heterogeneity of H. pylori in patients with gastroduodenal diseases in central Taiwan. H. pylori infection was detected in 74.1% (575/776) of the symptomatic population studied. The prevalence of H. pylori infection increased from 11.1% in those between the ages of one to 20, to 82.9% in those between the ages of 41 and 50, and to 84% in those between the ages of 51 and 60. There was no significant difference in the prevalence of H. pylori infection between men and women. Among different blood types, the prevalence and relative risk of H. pylori infection was significantly higher in blood group O patients (90.3%) than in blood group A (41%), blood group B (27.4%), or blood group AB (62%) patients. Metronidazole resistance was found in 6.7% of the primary isolates. The prevalence of metronidazole-resistant H. pylori strains was higher in women (7.69%) than in men (6.25%), but this difference was not significant. A total of 88% of H. pylori strains were cagA-positive. CagA gene-positive strains were present in 90.1% of duodenal ulcers, 90% of duodenal ulcers combined with gastric ulcer, 85.8% of gastric ulcers, and 69.2% of gastritis patients, and was significantly higher in peptic ulcer disease groups than in the gastritis group. In conclusion, there was a low incidence (6.7%) of metronidazole-resistant H. pylori strains and a high prevalence (88%) of H. pylori cagA-positive strains in central Taiwan. This study also demonstrated a significant in vivo correlation between active H. pylori infection and blood group O-positive patients, and showed a significant association between cagA gene-positive H. pylori strains and the development of peptic ulcers.     

Conservation and Diversity of the Helicobacter pylori Copper-Transporting ATPase Gene (copA) Sequence Among Helicobacter Species and Campylobacter Species Detected by PCR and RFLP

Background Helicobacter pylori is a causative pathogen of such human stomach diseases as chronic type B gastritis, ulcer, and possibly gastric carcinoma. As a co-factor in various redox enzymes and an essential trace metal required for the synthesis of metalloproteins, copper might play a role in the pathogenesis of H. pylori. A gene, copA , associated with copper transport, has been isolated from H. pylori UA802. In this study, conservation and diversity of this gene were analyzed among some Helicobacter and Campylobacter species.
Materials and Methods. Twenty-one clinical isolates and strains of helicobacters and campylobacters were used in this study. Methods including polymerase chain reaction (PCR) amplification, restriction fragment-length polymorphisms (RFLPs), and hybridization were employed to carry out this work.
Results. The copA gene was highly conserved in all the H. pylori isolates tested ( Helicobacter nemestrinae and Helicobacter felis but not in Helicobacter mustelae and the Campylobacter species), whereas the sequence downstream of the copA appears to diverge among H. pylori isolates. In addition, two restriction patterns of the PCR-amplified copA fragments from seven H. pylori isolates and H. nemestrinae were identified, and the RFLP of H. nemestrinae was identical to that of one of the H. pylori isolate group.
Conclusions. The adenosine triposphatase-derived copper-transporting mechanism is employed by various H. pylori strains, H. nemestrinae, H. felis , and perhaps by other Helicobacter species. The nucleotide mutations have risen in the copA gene. It appears that there is a genetic relatedness of the copA gene to H. pylori and H. nemestrinae.     

Mixed-infection of antibiotic susceptible and resistant Helicobacter pylori isolates in a single patient and underestimation of antimicrobial susceptibility testing

Antibiotic resistance among Helicobacter pylori has been increasing worldwide and has begun to affect the overall efficacy of current antibiotic regimens adversely. We examined 220 pairs of H. pylori isolates obtained from both the antrum and corpus of separate patients; 109 (50%) harbored antibiotic-resistant H. pylori: amoxicillin (0.5%), clarithromycin (5.9%), furazolidone (1.4%), metronidazole (45.5%), nitrofurantoin (1.4%), and tetracycline (6.8%). Heteroresistance among the two biopsy sites from each patient was present in 41 of the 109 patients (38%) with antibiotic resistant H. pylori (e.g. 34% with resistant strains would be misclassified as susceptible if a biopsy of the antrum alone used for antimicrobial susceptibility testing). DNA fingerprinting genotype analysis was carried out on the 41 pairs of isolates with heteroresistance. While different patients had different fingerprinting patterns, each pair of isolates showed identical or similar fingerprinting patterns. These results suggest that antibiotic-resistant H. pylori typically develop from pre-existing susceptible strain rather than coinfection with a different strain. The minor differences in genotype (degeneration of genotype) seen reflect one of the processes for development of genetic diversity in H. pylori. No biopsy single site can be considered representative for antimicrobial susceptibility testing.