The cause of failure of eradication treatment of Helicobacter pylori

The drug treatment, the combination of lansoprazole + amoxicillin + clarithromycin, for Helicobacter pylori infection with gastroduodenal ulcer was approved for the national heath insurance November 2000 in JAPAN, and has been widely applied. However, failures of eradication have been counted in 10-20% of the cases. The major reason of the failure has been reported as the drug resistance of the H. pylori. Here, we surveyed the antimicrobial resistance of 70 clinical isolates in a Showa University Hospital 2001, 1 to 2002, 1. As a result, the ratio of primary resistance to amoxicillin was about 1.4%, and clarithromycin was about 11.4%. Among 70 H. pylori positive cases, 14 cases were treated with eradication 3 drug combination therapy. In 5 cases, H. pylori were detected after eradication treatment and these five strains acquired the second resistance to neither amoxicillin nor clarithromycin. To distinguish the cause of H. pylori culture-positive after eradication treatment is whether the failure of eradication itself or re-infection, we attempted the analysis of the restriction pattern of H. pylori genome (genome type) using pulsed-field gel electrophoresis. In all 5 cases, genome types of before and after treatment were identical, suggesting the failure of eradication treatment. Three of 5 cases, isolates before and after treatment were susceptible to both of amoxicillin and clarithromycin. Thus, the reason of failure of eradication is considered to ingestion compliance, not antimicrobial agent resistance nor reinfection. The rest of 2 cases, the primary resistance to clarithromycin may result the failure of eradication. Test for drug susceptibility and genome type analysis of H. pylori are significant in certification of an authenticity of an eradication treatment.