The major cause of chemotherapy failure in patients with chronic gastritis and peptic ulcers caused by Helicobacter pylori is clarithromycin (CAM) resistance due to a mutation in the 23S rRNA gene. This study describes a non-invasive and accurate method for the detection of mixed CAM-resistant and -susceptible H. pylori by sequencing of the H. pylori 23S rRNA gene. Faeces were crushed with beads and the 23S rRNA gene was amplified using a nested PCR on the extracted DNA. Mutation analysis of this gene using this method showed that 20.4 % of patients carried mixed CAM-susceptible (wild type) and -resistant (A2142G or A2143G mutant) H. pylori. Furthermore, it was found that 66.6 % of patients who had been treated unsuccessfully carried one of these mutations in the 23S rRNA gene (including the mixed type), whilst standard culture detected CAM-resistant isolates in only 22.2 % of patients with unsuccessful treatment. These data suggest that, for successful therapy, the diagnosis method described here would more accurately detect CAM-resistant H. pylori, including mixed infections. INTRODUCTIONHelicobacter pylori is a Gram-negative, spiral bacterium found in the human stomach. This micro-organism causes chronic gastritis and peptic ulcers (Kuipers, 1997) and is linked to gastric cancer and other non-gastrointestinal diseases (Kusters et al., 2006;Leong & Sung, 2002). To treat H. pylori infections, a triple therapy is used comprising a combination of a proton pump inhibitor and two antimicrobial agents. This is reported to be the most successful method for eradication of infection (Malfertheiner et al., 2002). In Japan, a combination of lansoprazole, amoxicillin and clarithromycin (CAM) (the LAC regimen) is commonly used to eliminate H. pylori (Asaka et al., 2001). Although most patients are treated successfully with this triple therapy, some failure has necessitated the use of additional drugs such as levofloxacin (Asaka et al., 2001;Kato et al., 2000). The major cause of therapy failure in patients is resistance to CAM (Kato et al., 2000; Rimbara et al., 2005a). Therefore, a reliable diagnostic test to detect macrolide resistance would be useful in planning a therapeutic regimen. Standard culture is generally used to determine the susceptibility of H. pylori to antimicrobial agents; however, acquiring a test sample is invasive for the patient, as endoscopy is required to obtain gastric specimens. Faecal culture is not possible, as H. pylori coccoid forms are unculturable; however, there are some reliable non-invasive tests for the diagnosis of H. pylori infections (Graham et al., 1987;Leodolter et al., 2003;Shuber et al., 2002;Vaira et al., 1999).Resistance to CAM in H. pylori is due to a mutation in the 23S rRNA subunit in the 50S ribosome. The two most common mutations are an adenine-to-guanine transition at position 2142 or 2143, the latter leading to an adenineto-cytosine transversion at position 2142 (Alarcon et al., 2003;van Doorn et al., 2001). Resistance due to mutations at other positions has also been rep...

Antibiotic associated diarrhea due to human intestinal microbiota abnormalities is a side effect of H. pylori eradication therapy. We examined intestinal microbiota changes during H. pylori eradication therapy and the preventive effect of CBM588 as a probiotic agent. Nineteen patients with gastro-duodenal ulcer were randomly divided into three groups: group A (without probiotics), group B (with regular doses of CBM588) and group C (with double doses of CBM588). The incidence of diarrhea and soft stools during H. pylori eradication therapy was 43% in group A and 14% in group B, while none of the patients in group C reported diarrhea or soft stools. Both bacterial counts and detection rates of bifidobacteria and/or obligate anaerobe were decreased by eradication therapy. However, bacterial counts of obligate anaerobes in group C were significantly higher than in group A (P < 0.05). Additionally, during eradication therapy C. difficile toxin A was detected in both group A and group B but not in group C. In conclusion, these results indicate that H. pylori eradication therapy induces antibiotic associated diarrhea due to abnormalities in intestinal microbiota and/or C. difficile. However, these side effects might be prevented by probiotics.

The HpSA test is a useful method for the diagnosis of H. pylori infection before and after eradication therapy.

H. pylori resistance to AMPC is still rare in Japan, although the percentage of AMPC-I strains has increased over the last 4 years. The frequency of isolation of strains showing true resistance to AMPC may increase in the future, along with an increase in the frequency of isolation of AMPC-I strains.

Administration of L. reuteri Tablets [Reuterina (ERINA Co.,Inc.)] significantly decreased UBT in H. pylori-positive subjects, demonstrating that L. reuteri suppresses H. pylori urease activity and H. pylori density.