Abstract
Helicobacter pylori is a Gram-negative microaerophilic bacterium which colonizes the gastric mucosa of the human stomach. Infection with H. pylori is associated with gastritis, gastric ulcer, duodenal ulcer. The common treatment of H. pylori infection includes antibiotics and a combination of a proton pump inhibitor. Because of an increased use of antibiotic agents, resistance to antibiotics is the major cause of the therapy failure. The aim of this study is to investigate the efficacy of the triple therapy and the prevalence of the resistance of the three antibiotics used in eradication therapy, which are metronidazole, clarithromycin, and amoxicillin. 151 patients who took the triple therapies containing lansoprazole, clarithromycin, and metronidazole/amoxicillin in Taichung Veterans General Hospital were enrolled in this study and 137 patients completed the course of treatment. The resistance of fifty-one strains collected from patients in 2000 were determined by its minimal inhibitory concentration (MIC) values of the three antibiotics, which were determined by E-test. Two regimens were used in this study: the eradication rate of the LAC regimen total is 88.41% and it is 85.29% in LMC regimen. In LAC regimen, the prevalence of resistance of metronidazole and clarithromycin is 39.29% and 7.14% respectively. In LMC regimen, the prevalence of these two antibiotics are 43.48% and 4.35%. No amoxicillin-resistant strains are found in this study. Eighteen different strains from fifteen patients were analyzed for the reason of therapy failure. The strains were examined by polymerase chain reaction (PCR) and PCR-based restriction fragment length polymorphism (RFLP) of the vacA and ureA-ureB genes to examine whether the strains obtained before and after treatment are the same. Their MIC values were also determined by E-test. The rdxA and 23s rRNA genes from both antibiotic resistant and sensitive strains were sequenced to investigate the difference between those strains. We find that there are two re-infection cases in LAC regimen and six different strains six patients are resistant to metronidazole or clarithromycin and four different strains from four patients are resistant to both metronidazole and clarithromycin. In the gene analysis, most our data correspond with published data. We also find one interesting strain has the three amino acids deletion in its rdxA gene, which is not seen in other data.