Toshihiro Nishizawa

Extragastric manifestations of Helicobacter pylori infection.

In the previous year, some extragastric diseases, possibly linked to Helicobacter pylori infection, have been largely investigated. There are, in fact, several studies concerning cardiovascular diseases, lung diseases, hematologic diseases, eye and skin diseases, hepatobiliary diseases, diabetes mellitus, and neurological disorders. Among them, the relationship between bacterial CagA positivity and coronary heart disease is reportedly emphasized. Concerning normal tension glaucoma, new interesting data are playing in favor of the association with H. pylori infection. For other diseases, there are many interesting results, although more studies are needed to clarify the reality of the proposed association.

Helicobacter pylori eradication therapy

Helicobacter pylori infection is the main cause of gastritis, gastroduodenal ulcers and gastric cancer. H. pylori eradication has been shown to have a prophylactic effect against gastric cancer. According to several international guidelines, the first-line therapy for treating H. pylori infection consists of a proton pump inhibitor (PPI) or ranitidine bismuth citrate, with any two antibiotics among amoxicillin, clarithromycin and metronidazole, given for 7-14 days. However, even with these recommended regimens, H. pylori eradication failure is still seen in more than 20% of patients. The failure rate for first-line therapy may be higher in actual clinical practice, owing to the indiscriminate use of antibiotics. The recommended second-line therapy is a quadruple regimen composed of tetracycline, metronidazole, a bismuth salt and a PPI. The combination of PPI-amoxicillin-levofloxacin is a good option as second-line therapy. In the case of failure of second-line therapy, the patients should be evaluated using a case-by-case approach. European guidelines recommend culture before the selection of a third-line treatment based on the microbial antibiotic sensitivity. H. pylori isolates after two eradication failures are often resistant to both metronidazole and clarithromycin. The alternative candidates for third-line therapy are quinolones, tetracycline, rifabutin and furazolidone; high-dose PPI/amoxicillin therapy might also be promising.

Roles of oxidative stress in stomach disorders

The stomach is a sensitive digestive organ that is susceptible and exposed to exogenous pathogens from the diet. In response to such pathogens, the stomach induces oxidative stress, which might be related to the development of gastric organic disorders such as gastritis, gastric ulcers, and gastric cancer, as well as functional disorders such as functional dyspepsia. In particular, the bacterium Helicobacter pylori plays a major role in eliciting and confronting oxidative stress in the stomach. The present paper summarizes the pathogenesis of oxidative stress in the stomach during the development of various stomach diseases.

Therapeutic strategies for functional dyspepsia and the introduction of the Rome III classification

Although placebo response rates in clinical trials for functional dyspepsia (FD) are more than 30%, a recent meta-analysis based on randomized controlled trials (RCTs) showed that antisecretory drugs were more or less superior to placebos. On the other hand, large-scale RCTs on the efficacy of treatment with prokinetics on FD are still needed. Indications for antibiotic eradication therapy for Helicobacter pylori-positive FD are still controversial, but there seems to be a small but significant therapeutic gain achieved with H. pylori eradication. Since preprandial and postprandial symptomatic disturbances are very important targets for FD treatment, ghrelin, a novel appetite-promoting gastrointestinal peptide that also promotes gastric motility or basal acid secretion can be expected to be a therapeutic target. In the recently published Rome III classification, FD is redefined for patients with symptoms thought to originate from the gastroduodenal region, specifically epigastric pain or burning, postprandial fullness, or early satiation, and it is divided into the subcategories postprandial distress syndrome and epigastric pain syndrome. These new criteria are of value in clinical practice, for epidemiological, pathophysiological, and clinical research, and for the development of new therapeutic strategies.

Contribution of efflux pumps to clarithromycin resistance in Helicobacter pylori

Background and Aims:  Although clarithromycin (CLR) is one of the most commonly recommended component drugs of Helicobacter pylori eradication regimens, the prevalence of CLR‐resistant H. pylori has been increasing. It is well known that CLR resistance is associated with point mutations in 23S rRNA, but an active multidrug efflux mechanism of H. pylori may also play a role in its drug resistance. At least four gene clusters have been identified as efflux pump systems in H. pylori and the present study was designed to investigate their role in the CLR resistance of clinical isolates of H. pylori.

Randomized clinical trial: rikkunshito in the treatment of functional dyspepsia—a multicenter, double-blind, randomized, placebo-controlled study

Rikkunshito, a standardized Japanese herbal medicine, is thought to accelerate gastric emptying and relieve dyspepsia, although no large‐scale, randomized, placebo‐controlled trials of rikkunshito have been conducted. This study aimed to determine the efficacy and safety of rikkunshito for treating functional dyspepsia (FD).

Quinolone-Based Third-Line Therapy for Helicobacter pylori Eradication

Currently, a standard third-line therapy for Helicobacter pylori (H. pylori) eradication remains to be established. Quinolones show good oral absorption, no major side effects, and marked activity against H. pylori. Several authors have studied quinolone-based third-line therapy and reported encouraging results, with the reported H. pylori cure rates ranging from 60% to 84%. Resistance to quinolones is easily acquired, and the resistance rate is relatively high in countries with a high consumption rate of these drugs. We recently reported a significant difference in the eradication rate obtained between patients infected with gatifloxacin-susceptible and gatifloxacin-resistant H. pylori, suggesting that the selection of quinolones for third-line therapy should be based on the results of drug susceptibility testing. As other alternatives of third-line rescue therapies, rifabutin-based triple therapy, high-dose proton pump inhibitor/amoxicillin therapy and furazolidone-based therapy have been suggested.

Gatifloxacin Resistance and Mutations in gyrA after Unsuccessful Helicobacter pylori Eradication in Japan

ABSTRACT A high resistance rate (47.9%) to gatifloxacin (GAT; 8-methoxy fluoroquinolone) in Helicobacter pylori (H. pylori) strains from 48 Japanese patients is observed after unsuccessful H. pylori eradication. A significant association between MICs for GAT equal to or above 1 μg/ml and mutations of the gyrA gene of H. pylori was demonstrated.

Sitafloxacin and Garenoxacin May Overcome the Antibiotic Resistance of Helicobacter pylori with gyrA Mutation

Resistance of Helicobacter pylori to the standard therapeutic antimicrobials (clarithromycin, metronidazole, amoxicillin [AMX], and tetracycline) ([9][1]) has been demonstrated; therefore, there is an urgent need to introduce other treatment options. Fluoroquinolones, such as levofloxacin (LVX) and

Clarithromycin Versus Metronidazole as First-line Helicobacter pylori Eradication: A Multicenter, Prospective, Randomized Controlled Study in Japan.

Background: Helicobacter pylori eradication rates achieved with a first-line regimen of clarithromycin (CLR) combined with amoxicillin (AMX) and a proton pump inhibitor have recently fallen to ⩽80% because of the increasing incidence of CLR resistance in Japan. This randomized multicenter trial aimed to compare the eradication success of 2 first-line triple therapy regimens: rabeprazole, amoxicillin, and clarithromycin (RAC) versus rabeprazole, amoxicillin, and metronidazole (RAM). Methods: A total of 124 consecutive patients infected with H. pylori were randomized into one of two 7-day therapeutic regimens: RAC (n=60) or RAM (n=64). Eradication was confirmed by the 13C-urea breath test. Adverse effects were also assessed. Results: Intention-to-treat and per protocol H. pylori eradication rates were 73.3%/77.2% in the RAC group and 90.6%/93.5% in the RAM group. The eradication rate of RAM therapy was significantly higher than that of RAC therapy. CLR, metronidazole, and AMX resistance was found in 36.2%, 2.1%, and 0% of patients, respectively. In addition, no relevant differences in adverse effects were observed. Conclusions: Metronidazole-based therapy (RAM) was superior to standard CLR-based therapy (RAC) for first-line H. pylori eradication. This reflects the progressive increase in CLR resistance observed in Japan.