Clinical And Basic Study Of Amoxicillin On Helicobacter Pylori Eradication

Part?Study on high-dose PPI-amoxicillin dual therapy plus bismuth for Helicobacter pylori eradicationAims:To evaluate the effectiveness and safety of bismuth plus high-dose dual therapy versus high-dose dual therapy alone for Helicobacter pylori treatment.Methods:A total of 160 patients with Helicobacter pylori infection and na?ve to treatment were randomly assigned to receive either esomeprazole 40 mg twice a day and amoxicillin 1 g three times a day with(EAB group)or without(EA group)bismuth 600 mg twice a day for 14 days.Antibiotic resistance of amoxicillin,clarithromycin,metronidazole and levofloxacin were determined by agar dilution method.Six weeks after treatment,eradication was confirmed by the ¹³C-urea breath test.Results:One hundred and sixty subjects were randomized.The per-protocol eradication rates were 96.1%(73/76,95%CI:88.9%-99.2%)in EA group and 93.3%(70/75,95%CI:85.1%-97.8%)in EAB group(P=0.494).The intention-to-treat eradication rates were 92.5%(74/80,95%CI:84.4%-97.2%)in EA group and 88.8%(71/80,95%CI:79.7%-94.7%)in EAB group(P=0.416).The resistance rates of amoxicillin,clarithromycin,metronidazole and levofloxacin were 0%,31.7%,81.4%,and 40.7%.Smoking reduced the treatment effectiveness in those receiving dual therapy without bismuth.In the PP analysis,cure rates in EA group were 70%(7/10)vs.100%(66/66)in smokers vs.non-smokers,P=0.002).In contrast,cure rates were100%(10/10)in smokers vs.92.3%(60/65)in non-smokers in EAB group(P=1.0).Side effects were low in both groups with no significant difference.Conclusions:Fourteen-day of high-dose dual therapy was highly effective and safe as Helicobacter pylori treatment in areas of high prevalence of antibiotic resistance.Adding bismuth may overcome the unfavourable effect of smoking on high-dose dual therapy but offered limited additive effect in general population.Part?Study on susceptibility-guided therapy for Helicobacter pylori infection treatment failuresAims:To evaluated the efficacy and safety of susceptibility-guided therapy for Helicobacter pylori infection following treatment failures.Methods:Consecutive 200 patients with one or more treatment failures were assigned to receive susceptibility-guided therapy.Choice was susceptibility-based using a strategy of using the most effective,best tolerated regimens first and a locally proven reliably effective regimen for multi-drug resistant infections.All received14-day therapies consisting of either clarithromycin,metronidazole,levofloxacin triple therapy(esomeprazole 20 mg b.i.d.and amoxicillin 1 g b.i.d.plus clarithromycin 500 mg b.i.d.,metronidazole 400 mg b.i.d.,levofloxacin 500 mg q.d.).For multi-drug resistant infections,modified bismuth quadruple therapy with esomeprazole,20 mg b.i.d.,bismuth potassium citrate,600 mg b.i.d.,amoxicillin,1 g t.i.d.,and metronidazole,400 mg q.i.d..Antibiotic resistance of clarithromycin,metronidazole and levofloxacin were determined by agar dilution method.Six weeks after treatment,eradication was confirmed by the ¹³C-urea breath test.Results:The eradication rate of susceptibility-guided therapy overall was 94.5%(189/200,95%CI,90.4%-97.2%).Only 28%(56/200)subjects carried strains susceptible to one of the tested antibiotics and were prescribed triple therapy;144multi-drug resistant subjects received bismuth quadruple therapy.In subgroup analysis,the intention-to-treat eradication rates were all>90%(i.e.,91.7%(11/12),92.3%(12/13),and 93.5%(29/31)in those who received clarithromycin,metronidazole,levofloxacin-containing triple therapy and 95.1%(137/144)for the amoxicillin-containing bismuth quadruple therapy).Conclusions:Antimicrobial susceptibility testing guided individual rescue therapy proved highly effective with high eradication rates.However,empirically modified bismuth quadruple therapy is a cheap and efficient treatment for patients with prior treatment failures because of a high proportion of multi-drug resistant infections.Part???Correlation between mutations in penicillin binding protein 1A and amoxicillin resistance in Helicobacter pyloriAims:Amoxicillin is an important antibiotic in the treatment of Helicobacter pylori infections.Resistance to amoxicillin is rare and the mechanism of amoxicillin resistance is is still unclear.The purpose of this study is to explore the mechanism of amoxicillin resistance,and to provide theoretical basis and new ideas for the treatment of Helicobacter pylori.Methods:A total of 48 Helicobacter pylori strains(including 16 amoxicillin resistant strains and 32 amoxicillin susceptible strains)were included and their resistance to amoxicillin was determined by agar dilution method.The bacterial genomic DNA was extracted.The PBP1A gene fragment was amplified by PCR and then were sequenced.Based on standard strain 26695,the sequences of PBP 1A gene between amoxicillin resistant strains and amoxicillin susceptible strains were compared to explore mechanism of amoxicillin resistance.Results:The minimum inhibitory concentrations of amoxicillin-resistant bacteria ranged from 0.5 to 8?g/ml.Sequencing results showed that there were multiple amino acid substitutions in the PBP 1A gene of resistant strains,including A355T,F366L,V374L,S414R,T556S,N562Y and T593A.75%(12/16)of the resistant strains of PBP 1A have amino acid insertion mutations(mainly inserted an amino acid after 464 site and 595 site)and 6.3%(2/16)of the susceptible strains have an amino acid insertion mutation(595 site),and the difference between the two groups is statistically significant(P<0.001).Conclusion:Amino acid substitution and amino acid insertion mutation of PBP 1A gene may be closely related to amoxicillin resistance in Helicobacter pylori,or it may be predicted to be resistant to amoxicillin.