High frequency variations of Helicobacter pylori isolates in individual hosts in a Chinese population

High prevalence of Helicobacter pylori mixed infections identified by multilocus sequence typing in Ningbo, China

This study used multilocus sequence typing (MLST) to investigate the prevalence of Helicobacter pylori (H. pylori) mixed infections and H. pylori mixed infections involving unrelated strains; and determined the phylogeographic groups of H. pylori recovered from patients in Ningbo, China. A total of 156 H. pylori isolates were obtained from a convenience sample of 33 patients with culture-positive H. pylori infection. MLST was used to classify 150 H. pylori clinical isolates and 12 methodological control strains (6 clinical isolates and 6 strains of American Type Culture Collection H. pylori) into 43 and 12 sequence types (STs), respectively. In this study, 246 new alleles and 53 new STs were identified by MLST. The prevalence of mixed infections was 41% (11/27). The prevalence of H. pylori mixed infections involving unrelated strains was 46% (5/11) and the prevalence of H. pylori mixed infections involving completely unrelated strains (strains with all 7 housekeeping genes different) was 36% (4/11). A phylogenetic tree was created to determine the evolutionary relationships between different strains. The STs in this study were clustered within the hspEAsia subgroup (98%) and hpEurope group (2%). H. pylori mixed infections were common in Ningbo, China. The H. pylori isolates belonging to the hpEurope group were recovered from three different biopsy samples in a native Chinese patient. Most of H. pylori strains colonizing the antrum, corpus, and duodenum bulb were homologous.

Helicobacter pylori Infection and Peptic Ulcer Disease in Symptomatic Children in Southern Vietnam: A Prospective Multicenter Study

BACKGROUND

Helicobacter pylori (H. pylori) remains a major cause of gastroduodenal diseases. We aimed to evaluate the burden of this infection, particularly peptic ulcer disease in Vietnamese children.

METHODS

We enrolled consecutive children referred for esophagogastroduodenoscopy at two tertiary children's hospitals in Ho Chi Minh City, from October 2019 to May 2021. Children treated with proton pump inhibitors during the last two weeks or antibiotics for four weeks, and those having a previous or interventional endoscopy were excluded. H. pylori infection was diagnosed with either a positive culture or positive histopathology combined with a rapid urease test, or with a polymerase chain reaction of the urease gene. The study was approved by the Ethics Committee and written informed consent/assent was obtained.

RESULTS

Among 336 enrolled children aged 4-16 (mean: 9.1 ± 2.4 years; 55.4% girls), H. pylori infection was positive in 80%. Peptic ulcers were detected in 65 (19%), increasing with age, and 25% with anemia. cagA+ strains were detected at a higher rate in children with ulcers.

CONCLUSIONS

Prevalence of H. pylori and peptic ulcers is high among symptomatic Vietnamese children. It is crucial to have a program for early detection of H. pylori to reduce ulcer risk and gastric cancer later.

Heterogeneity of Helicobacter pylori Strains Isolated from Patients with Gastric Disorders in Guiyang, China

Purpose

Chronic Helicobacter pylori infection causes peptic ulcers in a subpopulation of individuals and is a risk factor for the development of gastric cancer. Multiple infections and heteroresistant H. pylori contribute to poor treatment efficacy. Here, we investigated the extent of genetic diversity among H. pylori strains within a given host and its influence on the results of antibiotic (metronidazole, levofloxacin, clarithromycin, amoxicillin, and tetracycline) susceptibility testing.

Materials and Methods

Gastric mucosa biopsy samples were obtained from patients with gastric disorders, including 48 H. pylori positive patients, who were never previously treated for H. pylori infection. Five potential H. pylori colonies isolated from each sample were subcultured for enrichment. Enriched H. pylori colonies were identified through Gram staining and assays for urease, oxidase, and catalase. For each H. pylori monoclonal colony, the antibiotic susceptibility was assessed, genomic DNA was sequenced, and the cytotoxin-associated gene A (cagA) genotype was verified. Co-infection with multiple H. pylori strains was determined using random amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR).

Results

Thirteen gastric mucosa biopsy samples were positive for H. pylori. Five monoclonal strains isolated from each of these 13 patients were identified as H. pylori. RAPD-PCR indicated that intra-patient monoclonal strains of H. pylori in 10 of the 13 samples exhibited heterogeneity. Among the 13 patients, intra-patient monoclonal strains isolated from 4 patients had identical cagA genotype, whereas intra-patient monoclonal strains isolated from the other 9 patients harbored more than one cagA genotype. The antibiotic susceptibility of five intra-patient monoclonal strains from seven patients was inconsistent.

Conclusion

The existence of heterogeneous H. pylori strains with resistance to different drugs and virulence were common within the gastric mucosa of an individual patient.

Genetic diversity and virulence characteristics of Helicobacter pylori isolates in different human ethnic groups

Helicobacter pylori is the most predominant bacterium in almost 50% of the world's population and colonization causes a persistent inflammatory response leading to chronic gastritis. It shows high genetic diversity and individuals generally harbour a distinct bacterial population. With the advancement of whole-genome sequencing technology, new H. pylori subpopulations have been identified that show admixture between various H. pylori strains. Genotypic variation of H. pylori may be related to the presence of virulence factors among strains and is associated with different outcomes of infection in different individuals. This review summarizes the genetic diversity in H. pylori strain populations and its virulence characteristics responsible for variable outcomes in different ethnic groups.

Multiple cag genotypes of Helicobacter pylori isolates colonize the oesophagus in individual hosts in a Venezuelan population

PURPOSE

Multiple Helicobacter pylori strains colonize and coexist in the stomach of one single patient, carrying heterogeneous distributions of cag genotypes. The oesophagus provides a niche for H. pylori colonization; however, little is known about its adaptive role.

METHODOLOGY

Using PCR for cagA, cagE and virB11 genes from cag-pathogenicity island (PAI) and Etest for antimicrobial susceptibility test, we determined cag-PAI genotypes associated with H. pylori virulence, when positive cultures were matching in both the stomach and the oesophagus (96 isolates; 8 out of 80 dyspeptic patients).

RESULTS

The stomach showed complete cag-PAI islands in 77 % of the isolates, whereas the oesophagus showed complete cag-PAI islands only in 44 % of the isolates. Expression of CagA and interleukin 8 correlated with inflammatory processes and histopathological changes in the stomach, but not in the oesophagus. Different cag-PAI profiles were found in both mucosae of an individual host, and at least one oesophagus profile corresponded to one profile identified in stomach. The antibiotic resistance profiles showed variability in the colonization by single or mixed H. pylori isolates in the gastric and oesophageal mucosa both intra- and inter-individuals.

CONCLUSION

These results demonstrate colonization with multiple H. pylori isolates in the oesophageal mucosa, like those found in the stomach of individual hosts. H. pylori was characterized by a dominant partial island, low interleukin 8 induction with lower histopathological damage and lower antibiotic resistance, suggesting that the microenvironmental changes in individual hosts select less virulent isolates in the oesophagus than in the stomach. New approaches to ensure effective eradication therapy in multi-resistant H. pylori strains must be developed.

Natural variant of the Helicobacter pylori CagA oncoprotein that lost the ability to interact with PAR1

Helicobacter pylori strains carrying the cagA gene are associated with severe disease outcomes, most notably gastric cancer. CagA protein is delivered into gastric epithelial cells by a type IV secretion system. The translocated CagA undergoes tyrosine phosphorylation at the C-terminal EPIYA motifs by host cell kinases. Tyrosine-phosphorylated CagA acquires the ability to interact with and activate SHP2, thereby activating mitogenic signaling and inducing cell morphological transformation (hummingbird phenotype). CagA also interacts with PAR1b via the CM sequence, resulting in induction of junctional and polarity defects. Furthermore, CagA-PAR1b interaction stabilizes the CagA-SHP2 complex. Because transgenic mice systemically expressing CagA develop gastrointestinal and hematological malignancies, CagA is recognized as a bacterium-derived oncoprotein. Interestingly, the C-terminal region of CagA displays a large diversity among H. pylori strains, which influences the ability of CagA to bind to SHP2 and PAR1b. In the present study, we investigated the biological activity of v225d CagA, an Amerindian CagA of H. pylori isolated from a Venezuelan Piaroa Amerindian subject, because the variant CagA does not possess a canonical CM sequence. We found that v225d CagA interacts with SHP2 but not PAR1b. Furthermore, SHP2-binding activity of v225d CagA was much lower than that of CagA of H. pylori isolated from Western countries (Western CagA). v225d CagA also displayed a reduced ability to induce the hummingbird phenotype than that of Western CagA. Given that perturbation of PAR1b and SHP2 by CagA underlies the oncogenic potential of CagA, the v225d strain is considered to be less oncogenic than other well-studied cagA-positive H. pylori strains.

Epidemiology and diagnosis of Helicobacter pylori infection

Medline, PubMed and the Cochrane databases were searched on epidemiology and diagnosis of Helicobacter pylori for the period of April 2011-March 2012. Several studies have shown that the prevalence of H. pylori infection is decreasing in adults and children in many countries. Various diagnostic tests are available, and most of them have high sensitivity and specificity. The Maastricht IV/Florence consensus report states that the urea breath test using (13)C urea remains the best test to diagnose H. pylori infection. Among the stool antigen tests, the ELISA monoclonal antibody test is recommended. All these tests were used, either as a single diagnostic test or in combination, to investigate H. pylori infection among different populations throughout the world. Of particular interest, current improvements in high-resolution endoscopic technologies enable increased diagnostic accuracy for the detection of H. pylori infection, but none of these techniques, at present, are specific enough for obtaining a real-time diagnosis of H. pylori infection.