Background Recently, problems associated with proton pump inhibitor (PPI) use have begun to surface. PPIs influence the gut microbiota; therefore, PPI use may increase the risk of enteric infections and cause bacterial translocation. In this study, we investigated fecal microbiota composition, fecal organic acid concentrations and pH, and gut bacteria in the blood of the same patients before and after PPI use. Methods Twenty patients with reflux esophagitis based on endoscopic examination received 8 weeks of treatment with PPIs. To analyze fecal microbiota composition and gut bacteria in blood and organic acid concentrations, 16S and 23S rRNA-targeted quantitative RT-PCR and high-performance liquid chromatography were conducted. Results Lactobacillus species were significantly increased at both 4 and 8 weeks after PPI treatment compared with bacterial counts before treatment (P = 0.011 and P = 0.002, respectively). Among Lactobacillus spp., counts of the L. gasseri subgroup, L. fermentum, the L. reuteri subgroup, and the L. ruminis subgroup were significantly increased at 4 and 8 weeks after treatment compared with counts before treatment. Streptococcus species were also significantly increased at 4 and 8 weeks after PPI treatment compared with counts before treatment (P < 0.01 and P < 0.001, respectively). There was no significant difference in the total organic acid concentrations before and after PPI treatment. Detection rates of bacteria in blood before and after PPI treatment were 22 and 28%, respectively, with no significant differences. Conclusions Our quantitative RT-PCR results showed that gut dysbiosis was caused by PPI use, corroborating previous results obtained by metagenomic analysis.

Mucosa-associated lymphoid tissue (MALT) lymphoma, which was first reported in 1984, shows an indolent clinical course. However, the detailed clinicopathological characteristics of gastric MALT lymphoma have not been fully elucidated. We performed a literature search concerning the clinical features and treatment for gastric MALT lymphoma using PubMED. MALT lymphomas develop in single or multiple extranodal organs, of which the stomach is one of the most frequent sites; gastric MALT lymphoma accounts for 7% to 9% of all B-cell lymphomas, and 40% to 50% of primary gastric lymphomas. The eradication of Helicobacter pylori (H. pylori) is the first-line treatment for patients with gastric MALT lymphoma, regardless of the clinical stage. Approximately 60–90% of cases with stage I/II₁ disease only achieve a complete histological response via H. pylori eradication. In patients who do not respond to H. pylori eradication therapy, second-line treatments such as watch-and-wait, radiotherapy, chemotherapy, rituximab immunotherapy, and/or a combination of these are recommended. Thus, H. pylori plays a causative role in the pathogenesis of gastric MALT lymphoma, and H. pylori eradication leads to complete histological remission in the majority of cases.

An HLA‐B null allele was identified in a Japanese family during histocompatibility testing for bone marrow transplantation. The propositus was a healthy Japanese woman with three children, and her parents were cousins. Serological HLA typing of the family members indicated that the propositus was homozygous for the A24‐Cw4‐B blank (B null)‐DR4.2‐DQ3 haplotype. Total RNA was extracted from peripheral blood of the propositus was converted to first‐strand cDNA using reverse transcriptase. The cDNA was amplified by the polymerasee chain reaction (PCR) using HLA‐B locus‐specific primers. The PCR product showed no change in size upon polyacrylamide gel electrophoresis (PAGE) compared to that of normal controls, suggesting that HLA‐B gene mRNA was normally expressed. The nucleotide sequence of the cDNA was the same as that of B*1501 except at nucleotide 369 or codon 123, where C was replaced with A; TAC encodes Tyr whereas TAA is a stop codon. This point mutation may have truncated the HLA‐B molecule of the propositus, resulting in the negative results we obtained with anti‐HLA‐B sera.

Background and Aim: Inhibition of gastric acid secretion is important for eradicating Helicobacter pylori. Vonoprazan (VPZ) is a strong, long-lasting inhibitor of gastric acid secretion. Studies that examined the effectiveness of VPZ-based triple therapy in second-line treatment have been performed. However, there have been no randomized controlled studies to compare the effect between VPZ-based triple therapy and proton pump inhibitor (PPI)-based triple therapy in second-line treatment, and it is not known which is more effective between VPZ-based and PPI-based therapies. This study aimed to compare the effectiveness of second-line triple therapies including VPZ or rabeprazole (RPZ) as the PPI. Methods: Eligible patients with H. pylori infection who failed first-line triple therapy were assigned randomly to the VPZ [VPZ40 mg/day, amoxicillin (AMPC) 1500 mg/day, metronidazole (MNZ) 500 mg/day] or RPZ (RPZ20 mg/day, AMPC1500 mg/day, MNZ500 mg/day) group. A ¹³C-urea breath test result of less than 2.5% was considered as successful eradication. Results: In total, 46 and 41 patients were analyzed as intention to treat (ITT) and per protocol (PP), respectively. Eradication rates in the VPZ and RPZ groups were 73.9% [95% confidence interval (CI) 51.6–89.8%] and 82.6% (95% CI 61.2–95.0%) based on ITT analysis, respectively ( p = 0.72). Based on PP analysis, the eradication rates in the VPZ and RPZ groups were 89.5% (95% CI 66.9–98.7%) and 86.4% (95% CI 65.1–97.1%), respectively ( p = 1.00). Two patients in the VPZ group and one in the RPZ group discontinued treatment due to side effects ( p = 1.00). Conclusion: There were no significant differences in efficacy and safety between second-line therapies including VPZ or RPZ.

Background and Aim: We aimed to evaluate endoscopic findings of Helicobacter pylori (H. pylori)-positive children and young adults based on the Kyoto classification, and to examine if there are age-associated changes in H. pylori-positive gastritis. Methods: H. pylori-positive patients under 40 years old who underwent upper gastrointestinal endoscopy from 1 April 2009 to 15 February 2017 were included. Subjects were classified into the Pediatric (<20 years) and Young adult groups (20-39 years). The patients' endoscopic photographs were retrospectively re-evaluated based on the Kyoto classification. We compared endoscopic findings between the two groups and examined alterations in the findings of H. pylori-associated gastritis in 5-year age groups. Results: Forty-three and 163 subjects were classified into the Pediatric and Young adult groups, respectively. In the Pediatric group, nodularity was seen in the majority (93.0%); other endoscopic findings in order of decreasing frequency included mucosal swelling (32.6%), spotty redness (25.6%), diffuse redness (18.6%), and atrophy (9.3%). In the Young adult group, endoscopic findings included atrophy (66.9%), mucosal swelling (49.7%), spotty redness (39.3%), nodularity (31.9%), and diffuse redness (30.3%). The difference in prevalence of nodularity or atrophy between the two groups reached statistical significance (P < 0.0001 each). The rate of nodularity decreased with increasing age in the Young adult group. The rate of atrophy was 33% in young adult patients aged 20-24, and the rate increased to >65% in patients over age 25. Conclusion: H. pylori-positive children had endoscopic findings besides nodularity based on the Kyoto classification. The prevalence of atrophy increased in patients over age 20.