Accurate diagnosis of Helicobacter pylori. Polymerase chain reaction tests

Relationship between Helicobacter pylori infection and nonalcoholic fatty liver disease: What should we expect from a meta-analysis?

BACKGROUND

The relationship between Helicobacter pylori (H. pylori) infection and nonalcoholic fatty liver disease (NAFLD) is a matter of debate. Although it has been studied in many observational studies, the results remain controversial. Therefore, we performed a meta-analysis to assess the association between H pylori infection and risk of NAFLD.

METHODS

We searched Pubmed, EMBASE, and Web of Science databases, from inception to September 10, 2020. Odds ratio (OR) and 95% confidence interval (CI) were pooled by random-effects model. The statistical heterogeneity among studies (I2-index), subgroup analyses, regression analyses, sensitivity analysis and the possibility of publication bias were assessed.

RESULTS

A total of seventeen studies involving 91,958 individuals were included in our meta-analysis. Meta-analysis of data from cross-sectional and case-control studies showed that H pylori infection was associated with increased risk of prevalent NAFLD (n = 15; involving 74,561 middle-aged individuals; OR1.38, 95% CI 1.23-1.55, I2 = 86.8%, P < .001). The results of meta-regression implicated that the study type and the case-control ratio impacted the total effect size. Funnel plot did not show significant publication bias. Meta-analysis of data from longitudinal studies showed that H pylori infection was also associated with increased NAFLD incidence (n = 2; involving 17397 individuals; OR 1.21, 95% CI 1.01-1.44, I2 = 6.5%, P = .301).

CONCLUSIONS

The results indicated that a positive association between H pylori infection and the risk of NAFLD. Further studies are required to strengthen the association and clarify the mechanism.

Profile of Helicobacter pylori cagA &vacA genotypes and its association with the spectrum of gastroduodenal disease

PURPOSE

Globally, H. pylori virulence factors cagA and vacA genotypes and its variation is leading to the austere form of the gastroduodenal disease. Our objectives were to detect H. pylori in dyspeptic patients from biopsy samples with the validation of the various existing diagnostic tools and to screen the cagA, vacA genotypes profile from biopsy specimens and how it impacts in progression of gastroduodenal disease in southern India.

METHODS

374 patients who attended endoscopy unit at Kasturba Hospital, Manipal with their consent obtained their biopsies. H. pylori were detected by HPE, Culture, RUT and PCR and its virulence gene were patterned with PCR.

RESULTS

The positive rate of H. pylori by HPE, RUT, Culture and PCR were 51.33%, 47.1%, 32.4% and 50.3% respectively and comparison by Bayesian LCMs analysis showed PCR is superior among them. The frequency of H. pylori virulence gene viz cagPAI (cagA) were 80.9%, and vacA alleles-s1m1 (42%), s1m2 (33%) and s2m2 (25%) genotypes by PCR respectively. Four combinations of cagA/vacA genotypes were noted, majority of strains harboured cagA⁺/vacA s1m1 genotypes (42.6%), interestingly this hyper-virulent strain more frequently seen in severe gastroduodenal disease whereas cagPAI negative strains as well as cagA^-/vacA s2m2 combinations (19.1%) are seen most commonly in functional dyspepsia cases and depicted significant association by Chi-square test.

CONCLUSIONS

This study validates and compares the existing diagnostic methods for detecting H. pylori in biopsies. Also, it reveals some pattern of virulence gene combination will play a vital role in disease progression.

Primary antibiotic resistance and its relationship with cagA and vacA genes in Helicobacter pylori isolates from Algerian patients

The epidemiology of Helicobacter pylori resistance to antibiotics is poorly documented in Africa and especially in Algeria. The aim of our study was to determine the antibiotic resistance rates, as well as its possible relationship with VacA and CagA virulence markers of isolates from Algerian patients. One hundred and fifty one H. pylori isolate were obtained between 2012 and 2015 from 200 patients with upper abdominal pain. Antimicrobial susceptibility testing was performed for amoxicillin, clarithromycin, metronidazole, ciprofloxacin, rifampicin and tetracycline. Molecular identification of H. pylori and the detection of vacA and cagA genes were performed using specific primers. We found that H. pylori was present in 83.5% of collected biopsies, 54.9% of the samples were cagA positive, 49.67% were vacA s1m1, 18.30% were vacA s1m2 and 25.49% were vacA s2m2. Isolates were characterized by no resistance to amoxicillin (0%), tetracycline (0%), rifampicin (0%), a high rate of resistance to metronidazole (61.1%) and a lower rate of resistance to clarithromycin (22.8%) and ciprofloxacin (16.8%). No statically significant relationship was found between vagA and cagA genotypes and antibiotic resistance results (p > 0.5) except for the metronidazole, which had relation with the presence of cagA genotype (p = 0.001).

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 Genes in Gastric Biopsies by PCR

Aim. The aim of this study was to identify the presence of H. pylori in biopsy specimens from symptomatic patients by PCR. In addition, the rate of cagA, vacA, iceA1, and iceA2 virulence genes was determined. Materials and Methods. One hundred antral gastric biopsy specimens were collected during endoscopy from patients suffering from gastroduodenal symptoms. The samples were collected by the gastroenterologists in their own clinics in Ramallah, Palestine. DNA was extracted from the biopsies and subsequently used for PCR identification of H. pylori and the virulence genes using specific primers. Results. The rate of positive H. pylori in the collected biopsies was 44%. The rates of the virulence genes in this sample: cagA, vacA, iceA1, and iceA2 were 65.9%, 40.9%, 63.6%, and 84.1%, respectively. Conclusion. The iceA2 gene was the most frequent in this study. Much research is necessary to determine the presence of an association of this gene with gastric pathology. Variation in the rates of the iceA gene in different countries is a strong indication of its geographical distribution. This study would provide important information regarding the prevalence of virulence genes (vacA, cagA, iceA1, and iceA2) in H. pylori strains in the sample tested in this country.

Detection of Helicobacter pylori in adenotonsillar tissue of children with chronic adenotonsillitis using rapid urease test, PCR and blood serology: a prospective study

OBJECTIVE

Contradictory results have been reported regarding Helicobacter pylori (H. pylori) detection in adenotonsillar tissue. The aims of this study were to investigate whether adenotonsillar tissue of symptomatic children with chronic adenotonsillitis harbors the H. pylori organism, using two biopsy-based invasive methods namely; rapid urease test (RUT) and polymerase chain reaction (PCR) as well as blood serology and to compare the results obtained from each of these methods to the "gold standard".

METHODS

This prospective clinical study was carried out on 20 children aged between 2 and 10 years scheduled for tonsillectomy +/- adenoidectomy in a tertiary referral center. Exclusion criteria included: use of antacids, H(2) blockers or antibiotics during the previous month before surgery and adenotonsillectomy for obstructive sleep apnea. Core biopsy samples from resected adenotonsillar tissue was tested for H. pylori detection using both RUT and PCR assay for the ureC gene. Preoperative patient venous blood samples were also tested for H. pylori IgG antibodies. As a "gold standard", examined tissue was considered to be H. pylori infected if the two biopsy specimen-based methods (RUT and PCR) yielded positive results.

RESULTS

Thirty adenotonsillectomy specimens were tested (20 tonsils and 10 adenoids). RUT was positive in 16 (53.3%) specimens (12 tonsils and 4 adenoids). According to the "gold standard", 11/16 were considered false-positive, yielding this test sensitivity 100% and specificity 56%. The ureC gene sequence was detected by PCR in 5 (16.6%) specimens (3 tonsils and 2 adenoids), all of which were also positive by RUT, thus were considered H. pylori infected. Accordingly, PCR had a 100% sensitivity and specificity. Serology testing was positive for H. pylori IgG antibodies in 4/20 patients (20%), only two of them were found to have H. pylori infected adenotonsillar tissue.

CONCLUSIONS

Based on our findings it seems that adenotonsillar tissue may constitute an extra-gastric reservoir for H. pylori in symptomatic children with chronic adenotonsillitis. RUT was found to be of less accuracy than PCR in H. pylori detection in an extra-gastric location, thus results of previous studies using this test alone for detection of oral H. pylori should be treated with caution.

Detection of Helicobacter pylori by enzyme-linked immunosorbent assay of thermophilic helicase-dependent isothermal DNA amplification

An enzyme-linked immunosorbent assay (ELISA) of thermophilic helicase-dependent isothermal DNA amplification (tHDA) was developed for detection of Helicobacter pylori. The primers targeting ureC were used for the amplification of bacterial DNA by the isothermal digoxigenin (DIG)-labeling tHDA process, resulting in the accumulation of DIG-labeled DNA amplicons. The amplicons were denatured using heat and then hybridized with a specific biotinylated DNA probe, which was noncovalently immobilized on streptavidin-coated microtiter plate. The hybrids were colorimetrically detected by the addition of an anti-DIG antibody HRP conjugate and 2,2-azino-di-(3-ethylbenzthiazolinsulfonate) substrate solution. Results obtained from the gastric biopsy samples showed 90% and 95.7% of sensitivity and specificity, respectively, in comparison with culture results, and 96.6% and 96.8% of sensitivity and specificity, respectively, in comparison with those of the histologic studies. This assay significantly reduces the time needed for the identification of H. pylori and has the potential to facilitate early detection of this gastrointestinal pathogen.

American College of Gastroenterology guideline on the management of Helicobacter pylori infection

Helicobacter pylori (H. pylori) remains a prevalent, worldwide, chronic infection. Though the prevalence of this infection appears to be decreasing in many parts of the world, H. pylori remains an important factor linked to the development of peptic ulcer disease, gastric malignanc and dyspeptic symptoms. Whether to test for H. pylori in patients with functional dyspepsia, gastroesophageal reflux disease (GERD), patients taking nonsteroidal antiinflammatory drugs, with iron deficiency anemia, or who are at greater risk of developing gastric cancer remains controversial. H. pylori can be diagnosed by endoscopic or nonendoscopic methods. A variety of factors including the need for endoscopy, pretest probability of infection, local availability, and an understanding of the performance characteristics and cost of the individual tests influences choice of evaluation in a given patient. Testing to prove eradication should be performed in patients who receive treatment of H. pylori for peptic ulcer disease, individuals with persistent dyspeptic symptoms despite the test-and-treat strategy, those with H. pylori-associated MALT lymphoma, and individuals who have undergone resection of early gastric cancer. Recent studies suggest that eradication rates achieved by first-line treatment with a proton pump inhibitor (PPI), clarithromycin, and amoxicillin have decreased to 70-85%, in part due to increasing clarithromycin resistance. Eradication rates may also be lower with 7 versus 14-day regimens. Bismuth-containing quadruple regimens for 7-14 days are another first-line treatment option. Sequential therapy for 10 days has shown promise in Europe but requires validation in North America. The most commonly used salvage regimen in patients with persistent H. pylori is bismuth quadruple therapy. Recent data suggest that a PPI, levofloxacin, and amoxicillin for 10 days is more effective and better tolerated than bismuth quadruple therapy for persistent H. pylori infection, though this needs to be validated in the United States.

Is Helicobacter pylori a pathogenic agent of the cervix uteri?

BACKGROUND

Helicobacter pylori is a gram-negative, microaerophilic rod-shaped bacterium that lives beneath the gastric mucosal layers, on the surface of epithelial cells. Gastric infection with this organism causes inflammation of the gastric mucosa, which can lead to gastritis, duodenal or gastric ulcers and even in rare cases to gastric carcinoma or MALT lymphoma. Approximately 50% of the population of the entire world is believed to be infected with H. pylori, but the exact route of transmission is still uncertain. It has been speculated that the cervix, with its endocervical columnar epithelium and acidic mucous layer, might provide a suitable environment for H. pylori. H. pylori might be a pathogenic agent for cervical infection. In order to address this issue we studied H. pylori in the endocervical tissue.

METHODS

To investigate our hypothesis, we examined cervical tissue using PCR, culture, and Gram-stain. Thirty-three cervices from women who underwent total hysterectomy for noninvasive non-cervical benign uterine diseases were analyzed in this study. Twenty-one patients had cervicitis and 12 patients were included as controls.

RESULTS

Of the 29 patients studied, none showed evidence of H. pylori infection. H. pylori was not detected by PCR, histology, or culture.

CONCLUSIONS

We could not detect H. pylori in the cervix of patients with cervicitis. H. pylori-infected patients' cervices remain to be investigated, and a larger study is needed to draw firm conclusions.

Polymerase chain reaction: A sensitive method for detecting Helicobacter pylori infection in bleeding peptic ulcers

AIM: To assess the sensitivity and specificity of polymerase chain reaction (PCR) in detecting Helicobacter pylori (H pylori) infection in patients with bleeding peptic ulcers, and to compare its diagnostic efficacy with other invasive and non-invasive tests.

METHODS: From April to September 2002, H pylori status in 60 patients who consecutively presented with gastroduodenal ulcer bleeding was examined by rapid urease tests (RUT), histology, culture, PCR, serology and urea breath tests (UBT).

RESULTS: The sensitivity of PCR was significantly higher than that of RUT, histology and culture (91% vs 66%, 43% and 37%, respectively; P = 0.01, < 0.001, < 0.001, respectively), but similar to that of serology (94%) and UBT (94%). Additionally, PCR exhibited a greater specificity than serology (100% vs 65%, P < 0.01). However, the specificity of PCR did not differ from that of other tests. Further analysis revealed significant differences in the sensitivities of RUT, culture, histology and PCR between the patients with and those without blood in the stomach (P < 0.01, P = 0.09, P < 0.05, and P < 0.05, respectively).

CONCLUSION: PCR is the most accurate method among the biopsy-based tests to detect H pylori infection in patients with bleeding peptic ulcers. Blood may reduce the sensitivities of all biopsy-based tests.

Diagnosis of helicobacter pylori infection by polymerase chain reaction: is it worth it?

The aim of this study was to determine to what degree polymerase chain reaction (PCR) was superior to histology and culture, and whether a noncommercial urease test was of value, in detecting Helicobacter pylori in gastric biopsy specimens. Gastric biopsy specimens from the antrum and corpus of 134 consenting patients were subjected to PCR, targeting the glmM (ureC) gene, histology, culture, and a rapid urease test. PCR detected H. pylori in the biopsy specimens from 59 patients. All methods showed a high degree of sensitivity and specificity, but histology gave 2 false-negatives, and culture and the urease test gave 1 false-negative compared with PCR. PCR of a glmM gene segment was superior to the other methods for the detection of H. pylori infection and was comparable to histology in terms of cost. Nevertheless, in this study, histology and culture were found to be relatively reliable methods for examining gastric biopsy specimens.

Helicobacter pylori infection in pediatric population: epidemiology, pathophysiology, and therapy

Helicobacter pylori, one of the most commonly encountered human pathogens, has been recognized in more than half of adults and children with chronic nonspecific gastritis, and nearly all children with peptic ulcer disease demonstrate antral infection with H. pylori. A high prevalence and early colonization of H. pylori infection in childhood was described in developing countries in contrast to developed countries. The current diagnostic methods include histology, microbiological culture, urease activity detection, polymerase chain reaction, and stool antigen detection. The infection often presents with nausea, vomiting, and epigastric pain but may remain asymptomatic. The treatment modality options are multiple; however, the association of a proton-pump inhibitor and two antibiotics for 1 or 2 weeks gives the best eradication rates. Drug resistance is a growing problem in this microorganism and new therapeutic options are currently limited.

Helicobacter pylori infection: epidemiology, pathophysiology, and therapy

Helicobacter pylori is one of the most commonly encountered human pathogens. It has been shown to be closely associated with peptic ulcer disease (PUD), gastric adenocarcinoma, and the gastric mucosa-associated lymphoid tissue (MALT) that may lead to gastric lymphoma. The current diagnostic methods include histology, microbiological culture, classic serology, urease activity detection, polymerase chain reaction (PCR) and stool antigen detection. Its treatment modality options are multiple; however, a triple regimen consisting of a proton pump inhibitor (PPI), and two antibiotics for 10 to 14 days is preferred. Drug resistance is a growing problem in this organism and new therapeutic options are currently limited.