Clarithromycin resistance in Helicobacter pylori and its clinical relevance

Overcoming the effects of increasing antimicrobial resistance on Helicobacter pylori therapy

INTRODUCTION

Resistance to the antibiotics used to treat Helicobacter pylori (H. pylori) has risen to alarming levels worldwide emphasizing the need to reconsider the approach to therapy generally and to reconsider whether to continue use of many previously highly effective treatment regimens.

AREAS COVERED

This review covers current aspects management of the response to the effects of antimicrobial resistance on H. pylori therapy.

EXPERT OPINION

The prevalence of antimicrobial resistance to H. pylori is increasing and must now be integrated into management of the infection. Bacterial factors responsible for resistance include mutations, efflux pumps, and biofilm formation. Societal factors include overuse and misuse of antibiotics, including in the therapy of H. pylori infections. H. pylori infections should be managed as an infectious disease based on the principles of antimicrobial stewardship which should be incorporated into ongoing community-based and hospital programs of antibiotic stewardship to provide up-to-date advice regarding susceptibility and locally optimized best treatment practices (i.e. advice on which drugs, doses, formulation, frequency of administration, etc. The infection would best be managed in concert with infectious disease especially in asymptomatic patients. Gastroenterology's input remains critical for management of complications of the infection such as peptic ulcer disease.

Efficacy of a 2-week therapy with levofloxacin concomitant versus a levofloxacin sequential regimen for Helicobacter pylori infection in the Syrian population: a study protocol for randomized controlled trial

BACKGROUND

Treating Helicobacter pylori is becoming increasingly difficult with the development of bacterial resistance to many established treatment regimens. As a result, researchers are constantly looking for novel and effective treatments. This trial aims to establish the efficacy of levofloxacin-based sequential treatment regimen and concomitant levofloxacin-based regimen as empirical first-line therapy in the Syrian population.

METHOD

This is an open-label, prospective, single-center, parallel, active-controlled, superiority, randomized clinical trial. The recruitment will target Helicobacter pylori-positive males and females between the ages of 18 and 65 to evaluate the efficacy of empirical first-line therapy in the Syrian population. We are planning to recruit up to 300 patients which is twice the required sample size. One hundred fifty individuals will be randomly assigned to undergo either a sequential levofloxacin-based treatment regimen or a concomitant levofloxacin-based regimen. High-dose dual therapy (proton-pump inhibitor and amoxicillin) will be the rescue therapy in the event of first-line failure. The first-line eradication rate in both groups is the primary outcome, and one of the secondary outcomes is the overall eradication rate of high-dose dual therapy in the event of first-line treatment protocol failure. Intention-to-treat analysis and per-protocol analysis will be used to evaluate the eradication rates of Helicobacter pylori for first-line treatment protocols.

DISCUSSION

For the first time in the Syrian population, this randomized controlled trial will provide objective and accurate evidence about the efficacy of a sequential levofloxacin-based treatment regimen.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06065267 . Registered on October 3, 2023. Prospective registered. Enrollment of the first participant has not started yet.

Drug Resistance Patterns of Commonly Used Antibiotics for the Treatment of Helicobacter pylori Infection among South Asian Countries: A Systematic Review and Meta-Analysis

Background: In South Asia, resistance to commonly used antibiotics for the treatment of Helicobacter pylori infection is increasing. Despite this, accurate estimates of overall antibiotic resistance are missing. Thus, this review aims to analyze the resistance rates of commonly used antibiotics for the treatment of H. pylori in South Asia. Methods: The systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement. We searched five medical databases for relevant studies from inception to September 2022. A random effect model with a 95% confidence interval (CI) was used to calculate the pooled prevalence of antibiotic resistance. Results: This systematic review and meta-analysis included 23 articles, 6357 patients, 3294 Helicobacter pylori isolates, and 2192 samples for antibiotic resistance. The prevalences of antibiotic resistance to common antibiotics were clarithromycin: 27% (95%CI: 0.17–0.38), metronidazole: 69% (95%CI: 0.62–0.76), tetracycline: 16% (95%CI: 0.06–0.25), amoxicillin: 23% (95%CI: 0.15–0.30), ciprofloxacin: 12% (95%CI: 0.04–0.23), levofloxacin: 34% (95%CI: 0.22–0.47), and furazolidone: 14% (95%CI: 0.06–0.22). Subgroup analysis showed antibiotic resistances were more prevalent in Pakistan, India, and Bangladesh. Furthermore, a ten-year trend analysis showed the increasing resistance prevalence for clarithromycin (21% to 30%), ciprofloxacin (3% to 16%), and tetracycline (5% to 20%) from 2003 to 2022. Conclusion: This meta-analysis showed a high prevalence of resistance among the commonly used antibiotics for H. pylori in South Asian countries. Furthermore, antibiotic resistance has been increasing over the time of 20 years. In order to tackle this situation, a robust surveillance system, and strict adherence to antibiotic stewardship are required.

Gastroprotective effects of Hwanglyeonhaedok-tang against Helicobacter pylori-induced gastric cell injury

ETHNOPHARMACOLOGICAL RELEVANCE

Helicobacter pylori, which is found in the stomachs of approximately half of the world's population, has been associated with the development of chronic gastritis and gastric cancer. Hwanglyeonhaedok-tang (HHT) is a popular traditional medicine for the therapies of gastric ulcers and gastritis.

AIM OF THE STUDY

The emerging resistance of H. pylori to antibiotics arouses requirement on alternative nonantibiotic-based therapies. In the present study, we investigated the anti-inflammatory activity and anti-microbial activity of HHT against H. pylori in vitro and in an H. pylori-infected mouse model.

MATERIALS AND METHODS

H. pylori were treated with various concentrations of HHT and then incubated with human gastric carcinoma AGS cells. For the in vivo study, mice were orally infected with H. pylori three times over the course of 1 week, and then subjected to daily administration of HHT (120 or 600 mg/kg) for 4 weeks or standard triple therapy for 1 week. At the scheduled termination of the experiment, all mice were killed and their stomachs were collected for histological examination, quantitative real-time PCR, and Western blot analysis.

RESULTS

Our in vitro studies showed that HHT treatment inhibited the adhesion of H. pylori to AGS cells and suppressed the H. pylori-induced increases of inflammatory regulators, such as interleukin (IL)-8, cyclooxygenase 2 (COX-2), and inducible nitric oxide synthase (iNOS). In the mouse model, HHT treatment significantly reduced H. pylori colonization, inflammation, and the levels of IL-1β, IL-6, C-X-C motif chemokine ligand 1 (CXCL1), tumor necrosis factor alpha (TNF-α), COX-2, and iNOS in gastric mucosa. Further investigation showed that HHT treatment reduced the H. pylori-induced phosphorylations of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinases 1/2 (ERK1/2), c-Jun N-terminal protein kinase (JNK), and nuclear factor-kappa B (NF-κB).

CONCLUSIONS

Our findings collectively suggest that HHT has anti-inflammatory activity and antibacterial activity against H. pylori and could be an alternative to antibiotics for preventing H. pylori infection.

Rapid identification of Helicobacter pylori and assessment of clarithromycin susceptibility from clinical specimens using FISH

Helicobacter pylori remains one of the most common bacterial infections worldwide. Clarithromycin resistance is the most important cause of H. pylori eradication failures. Effective antibiotic therapies in H. pylori infection must be rapidly adapted to local resistance patterns. We investigated the prevalence of clarithromycin resistance due to mutations in positions 2142 and 2143 of 23SrRNA gene of H. pylori by fluorescence in situ hybridisation (FISH), and compared with culture and antimicrobial susceptibility testing in 234 adult patients with dyspepsia who were enrolled. Antrum and corpus biopsy specimens were obtained for rapid urease test, histopathology and culture. Epsilometer test was used to assess clarithromycin susceptibility. H. pylori presence and clarithromycin susceptibility were determined by FISH in paraffin‐embedded biopsy specimens. We found that 164 (70.1%) patients were positive for H. pylori based on clinical criteria, 114 (69.5% CI 62.5–76.6%) were culture positive, and 137 (83.5% CI 77.8–89.2%) were FISH positive. Thus the sensitivity of FISH was significantly superior to that of culture. However specificity was not significantly different (91.4 versus 100.0%, respectively). The resistance rate to clarithromycin for both antrum and corpus was detected in H. pylori‐positive patients; 20.2% by FISH and 28.0% by E‐test.The concordance between E‐test and FISH was only 89.5% due to the presence of point mutations different from A2143G, A2142G or A2142C. We conclude that FISH is significantly more sensitive than culture and the E‐test for the detection of H. pylori and for rapid determinination of claritromycin susceptibility. The superior hybridisation efficiency of FISH is becoming an emerging molecular tool as a reliable, rapid and sensitive method for the detection and visualisation of H. pylori, especially when the management of H. pylori eradication therapy is necessary. This is particularly important for the treatment of patients with H. pylori eradication failure.

Resistance pattern of Helicobacter pylori strains to clarithromycin, metronidazole, and amoxicillin in Isfahan, Iran

BACKGROUND

Helicobacter pylori (H. pylori) resistance to antibiotics has become a global problem and is an important factor in determining the outcome of treatment of infected patients. The purpose of this study was to determine the H. pylori resistance to clarithromycin, metronidazole, and amoxicillin in gastrointestinal disorders patients.

MATERIALS AND METHODS

In this study, a total of 260 gastric antrum biopsy specimens were collected from patients with gastrointestinal disorders who referred to Endoscopy Section of the Isfahan Hospitals. The E-test and Modified Disk Diffusion Method (MDDM) were used to verify the prevalence of antibiotic resistance in 78 H. pylori isolates to the clarithromycin, metronidazole, and amoxicillin.

RESULTS

H. pylori resistance to clarithromycin, metronidazole, and amoxicillin were 15.3, 55.1, and 6.4%, respectively. In this study, we had one multidrug resistance (MDR) isolates from patient with gastritis and peptic ulcer disease.

CONCLUSION

Information on antibiotic susceptibility profile plays an important role in empiric antibiotic treatment and management of refractive cases. According to the results obtained in this study, H. pylori resistance to clarithromycin and metronidazole was relatively high. MDR strains are emerging and will have an effect on the combination therapy.

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

BACKGROUND AND STUDY AIMS

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSION

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

Isolation of Helicobacter pylori in gastric mucosa and susceptibility to five antimicrobial drugs in Southern chile

Helicobacter pylori colonizes more than 50% of the world population thus, it is considered an important cause of gastric cancer. The aim of this study was to determine the isolation frequency of H. pylori in Southern Chile from patients with symptomatology compatible with gastritis or gastric ulcer and to correlate these findings with demographic parameters of infected patients and the susceptibility profiles of the isolated strains to the antimicrobial drugs used in the eradication treatments. A total of 240 patients were enrolled in the study. Each gastric biopsy was homogenized and seeded onto blood agar plates containing a selective antibiotics mixture (DENT supplement). Plates were incubated at 37° C in a microaerophilic environment for five days. The susceptibility profiles to amoxicillin, ciprofloxacin, clarithromycin, tetracycline and metronidazole were determined using the E-test method. H. pylori was isolated from 99 patients (41.3%) with slightly higher frequency in female (42% positive cultures) than male (40.2% positive cultures). With regard to age and educational level, the highest isolation frequencies were obtained in patients between 21-30 (55%) and 41-50 (52.6%) years old, and patients with secondary (43.9%) and university (46.2%) educational levels. Nineteen (21.6%) strains showed resistance to at least one antimicrobial drug. Tetracycline was the most active antimicrobial in vitro, whereas metronidazole was the less active. One strain (5.3%) showed resistance to amoxicillin, clarithomycin and metronidazole, simultaneously.

Effect of esomeprazole triple therapy on eradication rates of Helicobacter pylori, gastric ulcer healing and prevention of relapse in gastric ulcer patients

OBJECTIVES

To compare esomeprazole-based triple therapy with esomeprazole alone for the eradication of Helicobacter pylori (H. pylori), healing of ulcer and prevention of relapse in H. pylori-related gastric ulcer (GU) diseases.

METHODS

In this double-blind study, 401 H. pylori-positive patients with more than or equal to two GUs were randomized to: esomeprazole (20 mg) twice daily (bid) and amoxicillin (1000 mg) bid and clarithromycin (500 mg) bid (EAC) for 1 week, followed by placebo for 3 weeks (EAC and placebo); EAC for 1 week, followed by esomeprazole (20 mg) once daily (E20) for 3 weeks (EAC and E20); or esomeprazole (20 mg) bid and placebo antimicrobials for 1 week, followed by E20 for 3 weeks (E20 bid and E20). Patients with unhealed GUs at 4 weeks received E20 for an additional 4 weeks. Healed patients were followed up for 12 months.

RESULTS

Eradication rates at 4 weeks or 8 weeks were 82% for EAC and E20, 77% for EAC and placebo and 9.5% for E20 bid and E20 (intention-to-treat analysis). Significantly more patients receiving EAC than those receiving esomeprazole alone remained free of GUs during follow-up [EAC and E20, 90%; EAC and placebo, 87%; P=0.0005 for combined group vs. esomeprazole alone [E20 bid and E20 (74%)]. All treatments were well tolerated.

CONCLUSION

Esomeprazole-based triple therapy is effective for the eradication of H. pylori, healing of GU and prevention of relapse. Esomeprazole monotherapy for 3 weeks after triple therapy may be beneficial in terms of healing.

Clinical role and importance of fluorescence in situ hybridization method in diagnosis of H pylori infection and determination of clarithromycin resistance in H pylori eradication therapy

H pylori is etiologically associated with gastritis, gastric and duodenal ulcers, gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Eradicating H pylori may convert rapidly the outcome of related diseases with the use of more accurate diagnostic molecular tests. Indeed some of the tests cannot give the evidence of current infection; H pylori can be detected by noninvasive and invasive methods, the latter requiring an endoscopy. Eradication failure is a big problem in H pylori infection. Recently, clarithromycin resistance in H pylori strains is increasing and eradication therapy of this bacterium is becoming more difficult. Molecular methods have frequently been applied besides phenotypic methods for susceptibility testing to detect clarithromycin resistance due to mutations in the 2143 and 2144 positions of 23S rRNA gene. Fluorescence in situ hybridization (FISH) method on paraffin embedded tissue is a rapid, accurate and cost-effective method for the detection of H pylori infection and to determine clarithromycin resistance within three hours according to the gold standards as a non-culture method. This method can also be applied to fresh biopsy samples and the isolated colonies from a culture of H pylori, detecting both the culturable bacillary forms and the coccoid forms of H pylori, besides the paraffin embedded tissue sections. This technique is helpful for determining the bacterial density and the results of treatment where clarithromycin has been widely used in populations to increase the efficacy of the treatment and to clarify the treatment failure in vitro.

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

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

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

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

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

Comparison of the efficacy of 250 mg and 500 mg clarithromycin used with lansoprazole and amoxicillin in eradication regimens forHelicobacter pylori infection

AIMS AND METHODS

The aim of this study was to compare the efficacy of 250 mg and 500 mg clarithromycin used with lansoprazole and amoxicillin in eradication of H. pylori infection. 235 patients with H. pylori infections and non-ulcer dyspepsia were randomly assigned to one of the following regimens: lansoprazole 30 mg, amoxicillin 1000 mg, clarithromycin 250 mg (LAC250) and lansoprazole 30 mg, amoxicillin 1000 mg, clarithromycin 500 mg (LAC500). All drugs were given twice daily for 7 days. The patients were assessed for prevalence of H. pylori with the CLO test. Gastric biopsy samples obtained during upper gastrointestinal endoscopy before randomization and 4-6 weeks after completion of therapy were used for histology and culture. Bacterial sensitivity to clarithromycin and amoxicillin was determined with the E-test.

RESULTS

101 patients in the LAC250 mg group and 102 in the LAC500 group completed the study. On intention-to-treat analysis, eradication rates were 81% with LAC250 and 82% with LAC500 (p=0.88). On per-protocol analysis, eradication rates were 92% with LAC250 and 96% with LAC500 (p=0.23). Among the 203 patients (86% of the entire study group) for whom H. pylori antibiotic-sensitivity testing was technically feasible, primary resistance to clarithromycin was found in 9% and to amoxicillin in 0%. Eradication of clarithromycin sensitive/resistant strains was 94%/38% for LAC250 (p < 0.001) and 93%/40% for LAC500 (p < 0.001).

CONCLUSIONS

The cure rates for the two regimens were similar, although adverse effects were more frequent with the LAC500 regimen, suggesting that 250 mg of clarithromycin b.d. may be sufficient in our patient population.

Geographical difference in antimicrobial resistance pattern of Helicobacter pylori clinical isolates from Indian patients: Multicentric study

AIM

To assess the pattern of antimicrobial resistance of Helicobacter pylori isolates from peptic ulcer disease patients of Chandigarh, Delhi, Lucknow, Hyderabad and Chennai in India, and to recommend an updated anti-H. pylori treatment regimen to be used in these areas.

METHODS

Two hundred and fifty-nine H. pylori isolates from patients with peptic ulcer disease reporting for clinical management to the Post Graduate Institute of Medical Education and Research, Chandigarh; All India Institute of Medical Sciences, New Delhi; Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow; Deccan College of Medical Sciences and Allied Hospitals, Hyderabad; and hospitals in Chennai in collaboration with the Dr ALM Post Graduate Institute of Basic Medical Sciences were analyzed for their levels of antibiotic susceptibility to metronidazole, clarithromycin, amoxycillin, ciprofloxacin and tetracycline. The Epsilometer test (E-test), a quantitative disc diffusion antibiotic susceptibility testing method, was adopted in all the centers. The pattern of single and multiple resistance at the respective centers and at the national level were analyzed.

RESULTS

Overall H. pylori resistance rate was 77.9% to metronidazole, 44.7% to clarithromycin and 32.8% to amoxycillin. Multiple resistance was seen in 112/259 isolates (43.2%) and these were two/three and four drug resistance pattern to metronidazole, clarithromycin, amoxycillin observed (13.2, 32 and 2.56%, respectively). Metronidazole resistance was high in Lucknow, Chennai and Hyderabad (68, 88.2 and 100%, respectively) and moderate in Delhi (37.5%) and Chandigarh (38.2%). Ciprofloxacin and tetracycline resistance was the least, ranging from 1.0 to 4%.

CONCLUSION

In the Indian population, the prevalence of resistance of H. pylori is very high to metronidazole, moderate to clarithromycin and amoxycillin and low to ciprofloxacin and tetracycline. The rate of resistance was higher in southern India than in northern India. The E-test emerges as a reliable quantitative antibiotic susceptibility test. A change in antibiotic policy to provide scope for rotation of antibiotics in the treatment of H. pylori in India is a public health emergency.

Molecular mechanism of the resistance of Helicobacter pylori to clarithromycin

AIM

To investigate the resistance mechanism of Hp to clarithromycin.

METHODS

With E-test method, we examined the minimal inhibitory concentration (MIC) to clarithromycin of 35 Hp clinical isolates. Resistance strains were defined when MIC≥8 mg/L. Extract the DNA from the bacteria with the phenol-chloroform extraction method. Then amplify the fragments from 2 047 to 2 347 of 23 S rRNA gene. Gene sequence of the PCR products was analyzed to observe the mutation in the resistant Hp strains.

RESULTS

Compared with susceptible strains, No13 strain contained one point mutation (T2289C), No17 had two point mutations (G2224A, T2289C) and No22 strain had 3 point mutations (G2224A, C2245T, T2289C).The MICs of the 3 resistant Hp isolates were as follows: No13 of 8.0 mg/L, No17 of 64 mg/L, No22 of >256 mg/L. With increase of the resistance of Hp strains, the number of point mutations increased.

CONCLUSION

The point-mutations at 23 S rRNA gene responsible for Hp resistance to clarithromycin have not been reported in literature either at home or abroad, demonstrating that different mechanism of Hp resistance to clarithromycin exists in different regions.

Cloning, expression and antigenic analysis of heat shock protein A gene of human Helicobacter pylori

AIM

To construct a recombinant vector containing gene encoding heat shock protein A with a Mr of 13 000 from human Helicobacter pylori (H pylori) and express it in E. coli BL21, and to explore the antigenicity.

METHODS

The target gene was amplified from H pylori chromosome by PCR, and then inserted into the prokaryotic expression vector pET32a (+) digested by restrictive endonuclease enzymes of kpn I, BamH I simultaneously. The recombinant vector was transformed and expressed in E.coli BL21.The antigenicity of recombinant fusion protein was analysed by Western blot.

RESULTS

Enzyme digestion and sequencing analysis showed that the target gene has been inserted into the recombinant vector, but as compared with the gene reported by GenBank, 1.6% of gene mutation and 1.6% of amino acid residues change in H pylori occurred, respectively. SDS-PAGE analysis showed that the recombinant vector could be expressed in E.coli BL21, the relative molecular mass (Mr) of expressed product was 33×10³, while Mr of protein expressed by pET32a (+) was about 20×10³, and soluble fusion expression product accounted for 18.96% of total bacterial protein. After purification with Ni+-NTA agarose resin, the purity of recombinant fusion protein was about 95%. Western blot result showed that recombinant fusion protein could be recognized by anti-H pylori positive serum, suggesting that the protein had good antigenicity.

CONCLUSION

The gene encoding H pylori heat shock protein A has been cloned and expressed successfully. The results lay the foundation for development of H pylori protein vaccine and a quick diagnostic kit for detection of H pylori infection.

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Construction and characterization of bivalent vaccine candidate expressing HspA and Mr18000 OMP from Helicobacter pylori

AIM: To construct a recombinant vector which can express outer membrane protein (OMP) with M_r18000 and heat shock protein A (HspA) from Helicobacter pylori (H. pylori) in E. coli BL21, and to exploit the possibility for obtaining the vaccine conferring protection from H. pylori infection.

METHODS: The target gene of HspA was amplified from H. pylori chromosome by PCR, and then inserted into the prokaryotic expression vector pET32a (+) by restrictive endonuclease enzyme kpn I, BamH I simultaneously. The recombinant vector was used to sequence, and then together with pET32a (+)/Omp₁₈, digested by restrictive endonuclease enzyme Hind III and BamH I simultaneously. pET32a(+)/ HspA and Omp₁₈ were recovered from 1% agarose gel by gel kit, and ligated with T₄ ligase by BamH I digested viscidity end. The recombinant plasmid of pET32a(+)/HspA/Omp₁₈ was transformed and expressed in E. coli BL21 (DE3) under induction of IPTG. After purification, its antigenicity of the fusion protein was detected by Western blot.

RESULTS: Enzyme digestion analysis and sequencing showed that the target genes were inserted into the recombinant vector, composed of 891 base pairs, encoded objective polypeptides of 297 amino acid residues. Compared with GenBank reported by Tomb et al there were 1.3% and 1.4% differences in obtained H. pylori nucleotide sequence and amino acid residues, respectively. SDS-PAGE analysis showed that relative molecule mass (M_r) of the expressed product was M_r 51000, M_r of protein expressed by pET32a (+) was about M_r 20000, and soluble expression product accounted for 18.96% of total bacterial protein. After purification with Ni⁺²-NTA agarose resins, the purification of recombinant fusion protein was about 95%. Western blot showed that recombinant fusion protein could be recognized by the patients’ serum infected with H. pylori and anti-Omp₁₈ monoclone, suggesting that this protein had good antigenicity.

CONCLUSION: The gene coding for H. pylori M_r18000 OMP and HspA was cloned and expressed successfully. The results obtained lay the foundation for development of H. pylori protein vaccine and a quick diagnostic kit.

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Recombinant Helicobacter pylori catalase

AIM: To construct a recombinant strain which highly expresses catalase of Helicobacter pylori (H. pylori) and assay the activity of H. pylori catalase.

METHODS: The catalase DNA was amplified from H. pylori chromosomal DNA with PCR techniques and inserted into the prokaryotie expression vector pET-22b (+), and then was transformed into the BL21 (DE3) E. coli strain which expressed catalase recombinant protein. The activity of H. pylori catalase was assayed by the Beers&Sizers.

RESULTS: DNA sequence analysis showed that the sequence of catalase DNA was the same as GenBank’s research. The catalase recombinant protein amounted to 24.4% of the total bacterial protein after induced with IPTG for 3 hours at 37 °C and the activity of H. pylori catalase was high in the BL21 (DE3) E. coli strain.

CONCLUSION: A clone expressing high activity H. pylori catalase is obtained, laying a good foundation for further studies.

Construction of clone expressing adhesin Hsp60 of Helicobacter pylori

AIM

To construct a recombinant vector containing gene encoding Hsp60 gene of Helicobacter pylori and to express the vector in E.coli BL21.

METHODS

The Hsp60 gene was amplified from H.pylori chromosome by PCR and inserted into the prokaryotie expression vector pET-22b (+). The recombinant vector was transformed and expressed in E.coli BL21 (DE3). Recombinant Hsp60 protein immunogenicity was studied by Western blot.

RESULTS

The 1.6 kb Hsp60 gene was successfully isolated. Recombinant E.coli strains expressed Hsp60 were obtained, the expression protein amounted to 27.2% of the total bacterial protein after induced with IPTG for 3 h at 37 ℃, which included inclusion body and soluble protein. Inclusion body was the major pattern of the expression that amounted to 76.6% of the insoluble protein. Western blot analysis of rHsp60 confirmed that it could be specially recognized by serum from Hp infected patients.

CONCLUSION

The gene coding for Hp Hsp60 is cloned and expressed successfully. The results obtained lay the foundation for constructing the H.pylori vaccine.

Prospective cohort study of comprehensive prevention to gastric cancer

AIM: To evaluate the preliminary effects of comprehensive prevention of gastric cancer in Zhuanghe County epidemiologically.

METHODS: Stratified sampling and cluster sampling were applied to define the intervention group and the control group. The prospective cohort study was used for evaluating the effect of preventing gastric cancer. The relative risk (RR) and attributable risk percent (AR%) of intervention on gastric cancer death were calculated. Potential years of life lost (PLYY) of the disease was analyzed, and the RR and AR% of PYLL were calculated. Survival analysis was applied among the screened patients.

RESULTS: In the first 4 years after intervening, the relative risk (RR) of intervention on death was 0.5059 (95%CI: 0.3462-0.7392, P < 0.05) with significance statistically. AR% of the intervention on death was 49.41%. The RR of intervention on cumulative PYLL was 0.6778 (95%CI: 0.5604-0.8198, P < 0.05) with statistic significance. AR% of the intervention on cumulative PYLL was 30.32%. The four-year survival rate of the screened patients was 0.6751 (95%CI: 0.5298-0.9047).

CONCLUSION: The initiative intervention results showed that the intervention approach used in the trial was effective, it reduced mortality and increased survival rate, and alleviated the adverse effect of gastric cancer on the health and life of screened population.

Alternative and rescue treatment regimens for Helicobacter pylori eradication

Eradication therapy has been incorporated into clinical practice. The regimens currently recommended for first-line treatment include a 2-week bismuth-based triple therapy (mainly in developing countries), a 1 - 2 week proton pump inhibitor (PPI)-based triple therapy and a 1-week ranitidine bismuth citrate (RBC)-based triple therapy. However, these regimens fail to eradicate Helicobacter pylori in up to 20% of patients due to poor compliance, inadequate treatment duration, smoking, old age and bacterial resistance to nitroimidazoles and/or macrolides in particular. Therefore, alternative regimens that avoid nitroimidazoles and/or macrolides or overcome bacterial resistance to these drugs, improve compliance, minimise side effects and/or reduce costs have been evaluated. One-week quadruple therapy, which adds a PPI or histamine receptor 2-blocker to bismuth-based triple therapy, usually achieves an eradication rate of 90% when used as an alternative first-line therapy but the efficacy decreases when used as a rescue therapy. Several new triple therapies that may be used as alternative and/or rescue therapies have been evaluated. Among these are furazolidone-based (furazolidone plus an antibiotic and a bismuth salt, a PPI or RBC), fluoroquinolone-based (levofloxacin or moxifloxacin plus an antibiotic and a PPI) and ecabet sodium-based (ecabet plus two antibiotics) triple therapies. Recently, rifabutin has been used in combination with a PPI and amoxycillin as a rescue therapy, with satisfactory eradication rates. In addition, a number of new antimicrobial agents are currently under investigation in in vitro studies but the clinical values of these agents needs to be confirmed.

Antibiotic susceptibility of Helicobacter pylori in the Chinese population

AIM

To assess antibiotic susceptibility of Helicobacter pylori (H. pylori) strains to metronidazole, clarithromycin and tetracycline in the Chinese population, and to test the stability of antibiotic resistance in H. pylori 1 year after storage at -80 degrees C.

METHODS

Fifty H. pylori strains isolated from patients with peptic ulcer disease were recovered from storage at -80 degrees C. Susceptibility of these strains to metronidazole, clarithromycin and tetracycline was determined by using validated disk diffusion tests, which was repeated 1 year after storage at -80 degrees C. The DNA profiles of each strain were determined by using the polymerase chain reaction-based-random amplified polymorphic DNA fingerprinting technique (PCR-RAPD). This was repeated if any change in antibiotic susceptibility pattern was noticed.

RESULTS

The resistance rate was 50% to metronidazole and 8% to clarithromycin. None of the strains was resistant to tetracycline. A dual resistance to metronidazole and clarithromycin was demonstrated in three H. pylori strains. The antibiotic susceptibility test reproduced itself in 92% (36 of 39) of the strains 1 year later; the three strains with dual resistance exhibited susceptibility to both antibiotics. Variation in antibiotic susceptibility pattern in the three H. pylori strains was associated with change in the RAPD fingerprint.

CONCLUSION

The prevalence of resistance in H. pylori is high to metronidazole but low to clarithromycin in the Chinese population. The disk diffusion test appears to be a simple and reliable test, while antibiotic resistance in some H. pylori strains may disappear after long-term storage at -80 degrees C.

Helicobacter pylori infection--current treatment practice

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