Molecular Detection of H. pylori Using Adherent Gastric Mucous to Biopsy Forceps

What Is New in Helicobacter pylori Diagnosis. An Overview

Helicobacter pylori infection remains one of the most prevalent infections worldwide, especially in low-resource countries, and the major risk factor for peptic ulcer and gastric cancer. The “test-and-treat” strategy is recommended by several guidelines and consensus. The choice of testing method is based on patient age, presence of alarm signs and/or symptoms, use of non-steroidal anti-inflammatory drugs, as well as local availability, test reliability, and cost. Culture is the gold standard to detect H. pylori and, possibly, to perform susceptibility testing, however, it requires upper endoscopy and dedicated labs. Recent advances in molecular biology have provided new strategies in detecting infection and antimicrobial resistance without invasive tests. In this review we attempt to offer a comprehensive panorama on the new diagnostic tools and their potential use in clinical settings, in order to accomplish specific recommendations.

Helicobacter pylori eradication therapy outcome according to clarithromycin susceptibility testing in Japan

BACKGROUND

Helicobacter pylori (Hp) infection increases the risk of gastric cancer. Therefore, eradication is a global goal, which requires continuous monitoring of therapeutic regimens and effectiveness. Clarithromycin resistance is an important contributor to eradication failure, and metronidazole is recommended as second-line treatment in such cases. Here, we retrospectively evaluated the clarithromycin and metronidazole resistance rates and treatment effectiveness in patients with Hp using tailored therapies according to clarithromycin susceptibility testing.

METHODS

Data on drug susceptibility were obtained for 5249 Japanese Hp patients between July 2005 and August 2018. Clarithromycin/metronidazole resistance rates were analyzed according to year, gender, and age with Fisher's exact test. The relationship between clarithromycin resistance and Hp therapy outcomes was assessed for 1300 patients. Treatment regimens included a clarithromycin- or metronidazole-containing 7-day triple therapy with one of several proton pump inhibitors and vonoprazan.

RESULTS

Clarithromycin resistance increased annually and was higher in women and younger patients (<30 years). Rates of metronidazole resistance were stable but decreased with age. Hp treatment regimens using PPIs had eradication rates of 88% and 45% among clarithromycin-sensitive and clarithromycin-resistant cases, respectively, while regimens including vonoprazan had eradication rates of around 90% regardless of clarithromycin susceptibility. In particular, triple therapy with vonoprazan, amoxicillin, and metronidazole achieved 98% eradication.

CONCLUSION

Clarithromycin-containing triple therapy even using vonoprazan did not achieve satisfactory eradication rates even in the clarithromycin-sensitive group. To avoid antibiotic misuse in population with low metronidazole resistance, 7-day vonoprazan, amoxicillin, and metronidazole triple therapy might be a strong candidate as a first-line eradication therapy.

Analysis of the colonic mucosa associated microbiota (MAM) using brushing samples during colonic endoscopic procedures

The mucosa-associated microbiota is an important component in human microbiota. The aim was to investigate mucosa-associated microbiota using brush samples during endoscopic procedures and compare with fecal microbiota. Seven patients who were planning to undergo a routine colonoscopy were recruited. Mucosal brushing samples were taken from 3 sites (terminal ileum, ascending and sigmoid colon), and a fecal sample was taken on the morning of colonoscopy. The samples were immediately placed in microcentrifuge tubes containing DNA stabilization reagent and analyzed using the next generation sequencer. The individual differences in microbiota were more evident than the differences of the sampling sites. Actinobacteria was more abundant and Bacteroidetes was less in the brush samples than those in the fecal samples. Taxonomic composition at the genus level and the proportion of genes responsible for some functions in the brushing samples tended to be different from those in the fecal samples. Bulleidia and Oribacteriumi were significantly more abundant and the proportions of genes responsible for transcription factors and phosphotransferase system were higher in ileal mucous than those in fecal samples. Brushing during colonoscopic procedure instead of using feces samples might be useful to analyze mucosa-associated microbiota.

Helicobacter pylori Eradication with Proton Pump Inhibitors or Potassium-Competitive Acid Blockers: The Effect of Clarithromycin Resistance

BACKGROUND

Vonoprazan is a novel potassium-competitive acid blocker (P-CAB) recently approved for Helicobacter pylori eradication therapy in Japan.

AIMS

To compare PPI- and P-CAP-containing triple therapy and vonoprazan-based triple therapy.

METHODS

Two hundred ninety-five initial subjects received a PPI-containing triple therapy; the next 125 subjects received vonoprazan-containing triple therapy. Two sequential groups received 7-day eradication regimens consisting of amoxicillin 750 mg, clarithromycin 200 mg both twice a day with standard dose PPI or vonoprazan (20 mg) each twice daily. H. pylori eradication was confirmed by a 13C-UBT. Clarithromycin susceptibility was evaluated by 23S rRNA PCR.

RESULTS

Population cure rates with clarithromycin susceptible strains were 89.6 versus 100 % for PPI and vonoprazan therapies, respectively. Cure rates with resistant strains were 40.2 % with PPI therapy versus 76.1 % with vonoprazan triple therapy. There was no difference in side effects.

CONCLUSIONS

Although 7-day P-CAB triple therapy was superior to 7-day PPI triple therapy, neither was highly effective, or can be recommended, in the presence of clarithromycin-resistant infections.

Diagnostic of Helicobacter pylori infection

There is progress in endoscopy techniques. While it is not yet possible to detect Helicobacter pylori directly in the stomach, it becomes easier to detect the mucosal changes induced by the bacteria. Some small changes can also increase the sensitivity of the invasive tests, for example culture or histology, but the wide use of proton-pump inhibitors has a negative impact on these tests. Only molecular methods are able to detect a limited load of bacteria, especially by using real-time PCR but also with new methods, for example dual-priming oligonucleotide-based PCR, loop-medicated isothermal amplification, droplet-digital PCR or a multiple genetic analysis system. Among the noninvasive tests, urea breath test remains a test of major interest, while there are attempts to develop an ammonia breath test and other nanosensor devices. A new antigen stool test, a chemoluminescence immunoassay using the LIAISON apparatus has also been tested for the first time with success. Despite its limitations, serology remains the most popular test to detect H. pylori antibodies. It also allows pepsinogen dosage which is of interest for detecting atrophy.