Determination of Helicobacter pylori Virulence Genes in Gastric Biopsies by PCR. ISRN Gastroenterol. 2013;2013:606258. [PMID: 23691338 PMCID: PMC3649278 DOI: 10.1155/2013/606258]

Molecular characterization of Helicobacter pylori isolated from Nile Tilapia (Oreochromis niloticus) and fish handlers

BACKGROUND

Helicobacter pylori is a worldwide pathogen that affects both animals and humans with a wide environmental distribution, causing serious health problems in humans. This research has timely addressed the topic of new sources of H. pylori infection, which is currently a global issue, especially in developing countries. For this purpose, 115 Tilapia fish, 50 freshwater samples, and 88 fish-handlers' stool samples were investigated for the presence of H. pylori in Qena Governorate, Egypt. The applied techniques were antigen screening tests, culturing, and molecular methods through ureC gene amplification, and 16 S rRNA characterization.

RESULTS

Helicobacter pylori was detected in 7.83%, 14%, 4.35%, and 12% of the investigated fish and water samples by culture and PCR methods, respectively. Out of the total studied participants, 40 tested positive for H. pylori when screened by stool antigen test, of which 35 (39.77%), and 31 (35.23%) were confirmed by conventional and molecular techniques, respectively. The Fisher's exact test has shown a statistically significant correlation between H. pylori infection, sex, and age as risk factors, while the association was insignificant concerning the residence. Males contracted the infection at a higher rate than females (48.08% and 16.67%, respectively). Also, H. pylori infection rate was the highest among fish-handlers aged 36-45 years old (46.67%), followed by the 26-35 years old age group (39.53%). With regard to the residence, a higher occurrence rate was recorded in the rural (36.07%) than the urban population (33.33%). Helicobacter pylori isolates harbored the highest antimicrobial resistance against ampicillin (100%), metronidazole (95.24%), while the least antimicrobial resistance was recorded against levofloxacin (21.43%), and clarithromycin (26.20%). The phylogenetic analysis revealed a high degree of homology between the isolates selected from Tilapia fish, freshwater, and fish-handlers.

CONCLUSIONS

Our data emphasized the role that fish and freshwater play in disseminating H. pylori infection as one of the diseases that has a significant public health issue.

Detection of Helicobacter Pylori’s Virulence Gene (UreA) and its Influence on the Result of Rapid Urease Test (RUT)

UreA is an important virulence factor of Helicobacter pylori that, along with UreB and UreC, produces urease. Urease enzyme helps the bacterium to colonize the human stomach through metabolizing urea in order to neutralize the gastric environment. The current study aimed to detect the prevalence of the H. pylori’s ureA virulence factor gene, and to investigate the influence of this gene on the result of the rapid urease test (RUT). Eighty stomach biopsy samples were isolated from participants who were suspected to be infected with H. pylori in Erbil city. Participants were 36 males and 44 females, aged between 18 and 67 years. The results showed that 42 (52.5%) of the participants were positive for H. pylori when tested by RUT, while 59 (73.8%) of the patients showed positive H. pylori infection when tested by polymerase chain reaction (PCR) targeting the 16S rRNA gene. The results of the PCR test based on the ureA gene revealed that 42 (52.5%) of the samples were positive. The important finding of this research is the presence of 100% compatibility between positive samples of RUT and ureA genes. It can be concluded from this study that a person may be infected with H. pylori, but the RUT test fails to detect the infection if the bacteria lack the ureA gene, indicating a direct impact of this gene on the result of RUT, which is a defect of RUT.

Genetic Diversity of Helicobacter pylori Isolates from Patients with Gastric Diseases in Isfahan

Background

Helicobacter pylori (H. pylori), a spiral-shaped bacterium colonizing the human stomach, is generally acquired in childhood. This pathogen is highly diverse and can be used as genetic markers for predict the history of human migrations. This study aimed to determine the genetic diversity of H. pylori isolates from patients with dyspepsia by the multi-locus sequence typing (MLST) and update data on the prevalence of H. pylori among Iranian dyspeptic patients.

Materials and Methods

In this descriptive cross-sectional study, 165 gastric biopsy specimens were obtained from patients with dyspepsia referred to Dr. Shariati Hospital of Isfahan, Iran, from April to July 2018. The status of H. pylori infection was determined by FISH in paraffin-embedded biopsy specimens. MLST of seven housekeeping genes was performed for 20 H. pylori isolates. The phylogenetic tree was plotted using CLC v8 and iTol software.

Results

The overall prevalence of H. pylori infection was 53.3%. In the results of the analysis of MLST, a total of 14 new STs were recorded. The results of the global analysis showed that all the isolates, with a wide diversity, have a genetic affinity with members of the European population, such as Italy and Russia, and are in the hpEurope haplotype.

Conclusion

Given the high prevalence of H. pylori infection in this region, early and accurate identification of patients seems necessary. Sequence analysis and determination of the origin of the phylogeny of strains can be effective in clinical management and monitoring of risk factors for chronic and recurrence of infection.

A Review on Secondary Immune Thrombocytopenia in Malaysia

Immune thrombocytopenia (ITP) is an acquired autoimmune disease that occurs in adults and children. In Malaysia, the clinical practice guideline (CPG) for the management of ITP was issued in 2006, which focused almost exclusively on primary ITP (pITP), and only a few secondary ITP (sITP) forms were addressed. All published (twenty-three) sITP articles among children and adults in Malaysia, identified on the academic databases were retrieved. The articles were published between 1981 and 2019, at a rate of 0.62 publications per year. The publications were considered low and mainly focused on rare presentation and followed-up of secondary diseases. This review revealed that sITP in Malaysia is commonly associated with autoimmune diseases (Evan’s syndrome, SLE and WAS), malignancy (Kaposi’s sarcoma and breast cancer) and infection (dengue haemorrhagic fever, Helicobacter pylori and hepatitis C virus). The relationship between ITP and autoimmune diseases, malignancy and infections raise the question concerning the mechanism involved in these associations. Further studies should be conducted to bridge the current knowledge gap, and the further information is required to update the existing CPG of management of ITP in Malaysia.

Precancerous Gastric Lesions with Helicobacter pylori vacA +/babA2+/oipA + Genotype Increase the Risk of Gastric Cancer

Objective

The clinical outcomes of gastric diseases such as chronic gastritis, peptic ulcer, and gastric cancer have been attributed to the interplay of virulence factors of Helicobacter pylori (H. pylori), host genetic susceptibility, and host immune responses. This study investigated the presence of cagA, vacA, iceA2, babA2, and oipA genes and their association with clinical outcomes.

Methods

Chronic gastritis, atrophic gastritis, and intestinal metaplasia specimens were obtained from patients who underwent endoscopy and surgical resection between January 2017 and December 2018; specimens from gastric cancer patients treated between January 2014 and December 2018 were also added. H. pylori), host genetic susceptibility, and host immune responses. This study investigated the presence of cagA, vacA, iceA2, babA2, and oipA genes and their association with clinical outcomes. H. pylori), host genetic susceptibility, and host immune responses. This study investigated the presence of

Results

H. pylori), host genetic susceptibility, and host immune responses. This study investigated the presence of vacA, babA2, and oipA genes and their association with clinical outcomes. vacA, babA2, and oipA genes and their association with clinical outcomes. P=0.033, OR = 2.64; 95% CI = 1.44–4.82, P=0.033, OR = 2.64; 95% CI = 1.44–4.82, P=0.033, OR = 2.64; 95% CI = 1.44–4.82, H. pylori vacA⁺/babA2, and oipA genes and their association with clinical outcomes. P=0.033, OR = 2.64; 95% CI = 1.44–4.82,

Conclusion

In this present study, we reported on the virulence genes of H. pylori infection to reveal their association with increased risk of chronic gastritis, precancerous gastric lesions, and gastric cancer. Precancerous gastric lesions with H. pylori vacA+/babA2+/oipA+ genotype increased the risk of gastric cancer.H. pylori), host genetic susceptibility, and host immune responses. This study investigated the presence of H. pylori vacA⁺/babA2, and oipA genes and their association with clinical outcomes.

Prevalence and factors associated with H. pylori infection in Saudi patients with dyspepsia

Background

Helicobacter pylori (H. pylori) is a major cause of peptic ulcer disease (PUD) and chronic active gastritis that may progress to gastric cancer. Globally, it has been estimated that 50% or more of the world’s population is infected by H. pylori, making it the most widespread infection across the globe.

Objectives

To determine the prevalence of H. pylori infection and to identify factors associated with H. pylori infection in Saudi patients presenting with dyspepsia.

Methods

In this prospective cross-sectional study, a total of 404 gastric biopsies were endoscopically obtained from 404 patients with dyspepsia from September 2014 to April 2016 (Jazan Province, Saudi Arabia). The specimens were analyzed using the real-time polymerase chain reaction (PCR). The data was examined using descriptive statistics as well as determining the prevalence, and employing Chi square and Fisher exact test. A p-value of ≤0.05 was considered statistically significant in examining the research hypotheses.

Results

The overall prevalence of H. pylori in Jazan Province was 46.5% (95% CI: 41.7–51.4) and the prevalence was lower among those > 55 years old. Prevalence was higher among urban (50.0%; 95% CI: 43.1–56.8) versus rural (42.1%; 95% CI: 35.1–49.3), but with no significant difference. Prevalence did not show significant difference among different Body Mass Index (BMI) categories, ranging from 40.2% to 47.7%. The prevalence of H. pylori in females was 47.1% (95% CI: 40.4–53.9) versus 45.6% (95% CI: 38.7–52.6) in males. Histopathology findings were associated with H. pylori infection with prevalence of 58.1% among patients with chronic active gastritis, compared to 24.1% and 34.8% among mild and chronic gastritis, respectively.

Conclusion

Our results indicate that there is a high prevalence of H. pylori among Saudi patients with dyspepsia. Prevalence of H. pylori was high in ages below 55 years. Chronic active gastritis was significantly associated with H. pylori infection. In depth studies are needed to determine associated factors with of H pylori infection in the region

The Prevalence of Helicobacter pylori in Estonian Bariatric Surgery Patients

Helicobacter pylori (Hp) is one of the most important human pathogens that can cause duodenal and gastric ulcers, gastritis and stomach cancer. Hp infection is considered to be a cause of limiting access to bariatric surgery. The aim of this study was to determine the prevalence of Hp in patients with obesity going into bariatric surgery and to reveal the relationship between Hp and clinical data. The study group was formed of 68 preoperative bariatric surgery patients (body mass index (BMI) 44.7 ± 4.8). Gastric biopsies (antrum and corpus) were used for histological and molecular (caqA and glmM genes) examinations. The PCR method revealed Hp infection in 64.7% of obese patients that is higher in comparison with histological analysis (55.9%). The prevalence of cagA and glmM genes in antrum mucosa was 45.6% and 47.0% while in the corpus it was 41.2% and 38.3%, respectively. The coincidence of both cagA and glmM virulence genes in the antrum and corpus mucosa was 33.8% and 22.1%, respectively. Either of the genes was found in 58.8% of antrum and 57.3% of corpus mucosa. Presence of caqA and glmM genes was in association with active and atrophic chronic gastritis. In conclusion, our study demonstrated that two thirds of morbidly obese patients undergoing bariatric surgery are infected with Hp and have a high prevalence of cagA and glmM virulence genes that points out the necessity for diagnostics and treatment of this infection before surgery.

Determination of Helicobacter pylori virulence-associated genes in duodenal ulcer and gastric biopsies

Background:Helicobacter pylori (H. pylori or Hp) has been strongly associated with the peptic ulcer diseases, chronic gastritis, ulcers, and gastric cancer. Genes associated with pathogenicity have been designated for H. pylori, and some of them appear to be related to more severe clinical consequences of the infection. The present study was conducted to determine cagA, vacA, cagE, iceA1, oipA, and iceA2 genes in H. pylori strains isolated from gastroduodenal patients, who referred to Shariati hospital in Tehran, Iran. Methods: Gastric biopsy specimens were collected during endoscopy from patients, who referred to the Shariati hospital in Tehran, Iran during January and November 2015. After isolation of H. pylori from the biopsy culture, genomic DNA was extracted and subsequently used to identify H. pylori and virulence genes using specific primers. Results: The isolation rate of H. pylori strains was 65.7% (169/257). The frequency of cagA, vacA, cagE, iceA1, oipA, and iceA2 was 143 (% 84.6), 169 (100%), 131 (77.5%), 97 (57.3%), 89 (52.6%), and 72 (42.6%), respectively. Conclusion: In this study, a significant difference was observed between investigated genes and strains isolated from PUD and GC patients (p<0.05).

Vacuolating cytotoxin A (VacA) - A multi-talented pore-forming toxin from Helicobacter pylori

Helicobacter pylori is associated with severe and chronic diseases of the stomach and duodenum such as peptic ulcer, non-cardial adenocarcinoma and gastric lymphoma, making Helicobacter pylori the only bacterial pathogen which is known to cause cancer. The worldwide rate of incidence for these diseases is extremely high and it is estimated that about half of the world's population is infected with H. pylori. Among the bacterial virulence factors is the vacuolating cytotoxin A (VacA), which represents an important determinant of pathogenicity. Intensive characterization of VacA over the past years has provided insight into an ample variety of mechanisms contributing to host-pathogen interactions. The toxin is considered as an important target for ongoing research for several reasons: i) VacA displays unique features and structural properties and its mechanism of action is unrelated to any other known bacterial toxin; ii) the toxin is involved in disease progress and colonization by H. pylori of the stomach; iii) VacA is a potential and promising candidate for the inclusion as antigen in a vaccine directed against H. pylori and iv) the vacA gene is characterized by a high allelic diversity, and allelic variants contribute differently to the pathogenicity of H. pylori. Despite the accumulation of substantial data related to VacA over the past years, several aspects of VacA-related activity have been characterized only to a limited extent. The biologically most significant effect of VacA activity on host cells is the formation of membrane pores and the induction of vacuole formation. This review discusses recent findings and advances on structure-function relations of the H. pylori VacA toxin, in particular with a view to membrane channel formation, oligomerization, receptor binding and apoptosis.

Expression of cagA, virB/D Complex and/or vacA Genes in Helicobacter pylori Strains Originating from Patients with Gastric Diseases

In order to better understand pathogenicity of Helicobacter pylori, particularly in the context of its carcinogenic activity, we analysed expression of virulence genes: cagA, virB/D complex (virB4, virB7, virB8, virB9, virB10, virB11, virD4) and vacA in strains of the pathogen originating from persons with gastric diseases. The studies were conducted on 42 strains of H. pylori isolated from patients with histological diagnosis of non-atrophic gastritis—NAG (group 1, including subgroup 1 containing cagA⁺ isolates and subgroup 2 containing cagA^- strains), multifocal atrophic gastritis—MAG (group 2) and gastric adenocarcinoma—GC (group 3). Expression of H. pylori genes was studied using microarray technology. In group 1, in all strains of H. pylori cagA⁺ (subgroup 1) high expression of the gene as well as of virB/D was disclosed, accompanied by moderate expression of vacA. In strains of subgroup 2 a moderate expression of vacA was detected. All strains in groups 2 and 3 carried cagA gene but they differed in its expression: a high expression was detected in isolates of group 2 and its hyperexpression in strains of group 3 (hypervirulent strains). In both groups high expression of virB/D and vacA was disclosed. Our results indicate that chronic active gastritis may be induced by both cagA⁺ strains of H. pylori, manifesting high expression of virB/D complex but moderate activity of vacA, and cagA^- strains with moderate expression of vacA gene. On the other hand, in progression of gastric pathology and carcinogenesis linked to H. pylori a significant role was played by hypervirulent strains, manifesting a very high expression of cagA and high activity of virB/D and vacA genes.

Virulence factors and antibiotic resistance of Helicobacter pylori isolated from raw milk and unpasteurized dairy products in Iran

BACKGROUND

Despite the high importance of Helicobacter pylori, the origin and transmission of this bacterium has not been clearly determined. According to controversial theories and results of previous studies, animal source foods - especially milk - play an important role in the transmission of H. pylori to humans. The aim of the present study was to determine the distribution of vacA, cagA, iceA and oipA virulence factors in H. pylori strains isolated from milk and dairy products and study their antimicrobial resistance properties.

METHODS

A total of 520 raw milk and 400 traditional dairy product samples were cultured and tested. Those that were H. pylori-positive were analyzed for the presence of vacA, cagA, iceA and oipA virulence factors. Antimicrobial susceptibility testing was performed by the disk diffusion method.

RESULTS

One hundred and three out of 520 milk samples (19.8%) and 77 out of 400 dairy products samples (19.2%) were contaminated with H. pylori. The most frequently contaminated samples were ovine milk (35%) and traditional cheese (30%). Total prevalence of vacA, cagA, iceA and oipA factors were 75%, 76.6%, 41.6% and 25%, respectively. H. pylori strains of milk and dairy products harbored high levels of resistance to ampicillin (84.4%), tetracycline (76.6%), erythromycin (70.5%) and metronidazole (70%).

CONCLUSIONS

High presence of antibiotic-resistant strains of H. pylori suggest that milk and dairy samples may be the sources of bacteria that can cause severe infection. Our findings should raise awareness about antibiotic resistance in H. pylori strains in Iran.

Molecular oncology testing in resource-limited settings

Cancer prevalence and mortality are high in developing nations, where resources for cancer control are inadequate. Nearly one-quarter of cancers in resource-limited nations are infection related, and molecular assays can capitalize on this relationship by detecting pertinent pathogen genomes and human gene variants to identify those at highest risk for progression to cancer, to classify lesions, to predict effective therapy, and to monitor tumor burden over time. Prime examples are human papillomavirus in cervical neoplasia, Helicobacter pylori and Epstein-Barr virus in gastric adenocarcinoma and lymphoma, and hepatitis B or C virus in hepatocellular cancer. Research is underway to engineer devices that overcome social, economic, and technical barriers limiting effective laboratory support. Additional challenges include an educated workforce, infrastructure for quality metrics and record keeping, and funds to sustain molecular test services. The combination of well-designed interfaces, novel and robust electrochemical technology, and telemedicine tools will promote adoption by frontline providers. Fast turnaround is crucial for surmounting loss to follow-up, although increased use of cell phones, even in rural areas, enhances options for patient education and engagement. Links to a broadband network facilitate consultation and centralized storage of medical data. Molecular technology shows promise to address gaps in health care through rapid, user-friendly, and cost-effective devices reflecting clinical priorities in resource-poor areas.

Predicting a novel pathogenicity island in Helicobacter pylori by genomic barcoding

AIM: To apply a new, integrated technique for visualizing bacterial genomes to identify novel pathogenicity islands in Helicobacter pylori (H. pylori).

METHODS: A genomic barcode imaging method (converting frequency matrices to grey-scale levels) was designed to visually distinguish origin-specific genomic regions in H. pylori. The complete genome sequences of the six H. pylori strains published in the National Center for Biotechnological Information prokaryotic genome database were scanned, and compared to the genome barcodes of Escherichia coli (E. coli) O157:H7 strain EDL933 and a random nucleotide sequence. The following criteria were applied to identify potential pathogenicity islands (PAIs): (1) barcode distance distinct from that of the general background; (2) length greater than 10000 continuous base pairs; and (3) containing genes with known virulence-related functions (as determined by PfamScan and Blast2GO).

RESULTS: Comparison of the barcode images generated for the 26695, HPAG1, J99, Shi470, G27 and P12 H. pylori genomes with those for the E. coli and random sequence controls revealed that H. pylori genomes contained fewer anomalous regions. Among the H. pylori-specific continuous anomalous regions (longer than 20 kbp in each strain’s genome), two fit the criteria for identifying candidate PAIs. The bioinformatic-based functional analyses revealed that one of the two anomalous regions was the known pathogenicity island cag-PAI, this finding also served as proof-of-principle for the utility of the genomic barcoding approach for identifying PAIs, and characterized the other as a novel PAI, which was designated as tfs3-PAI. Furthermore, the cag-PAI and tfs3-PAI harbored genes encoding type IV secretion system proteins and were predicted to have potential for functional synergy.

CONCLUSION: Genomic barcode imaging represents an effective bioinformatic-based approach for scanning bacterial genomes, such as H. pylori, to identify candidate PAIs.