Accurate diagnosis of Helicobacter pylori. Culture, including transport

Helicobacter pylori intragastric colonization and migration: Endoscopic manifestations and potential mechanisms

After being ingested and entering the human stomach, Helicobacter pylori (H. pylori) adopts several effective strategies to adhere to and colonize the gastric mucosa and move to different regions of the stomach to obtain more nutrients and escape from the harsher environments of the stomach, leading to acute infection and chronic gastritis, which is the basis of malignant gastric tumors. The endoscopic manifestations and pathological features of H. pylori infection are diverse and vary with the duration of infection. In this review, we describe the endoscopic manifestations of each stage of H. pylori gastritis and then reveal the potential mechanisms of bacterial intragastric colonization and migration from the perspective of endoscopists to provide direction for future research on the effective therapy and management of H. pylori infection.

Impact of Helicobacter pylori virulence markers on clinical outcomes in adult populations

BACKGROUND

In recent years, associations between specific virulence markers of Helicobacter pylori (H. pylori) and gastrointestinal disorders have been suggested.

AIM

To investigate the presence of virulence factors including vacuolating cytotoxin A genotypes (s1m1, s1m2, s2m1, and s2m2), cytotoxin-associated gene A (CagA), and urease activity in H. pylori strains isolated from Arab and Jewish populations in northern Israel and to assess associations between these factors and patients’ demographics and clinical outcomes.

METHODS

Patients (n = 108) who underwent gastroscopy at the Baruch Padeh Medical Center, Poriya due to symptomatic gastroduodenal pathologies as part of H. pylori diagnosis were enrolled in the study. Gastric biopsy specimens were collected from the antrum of the stomach. Clinical condition was assessed by clinical pathology tests. Bacteria were isolated on modified BD Helicobacter Agar (BD Diagnostics, Sparks, MD, United States). Bacterial DNA was extracted, and PCR was performed to detect CagA and vacuolating cytotoxin A genes. Urease activity was assessed using a rapid urease test.

RESULTS

A significant correlation was found between disease severity and patient ethnicity (P = 0.002). A significant correlation was found between CagA presence and the s1m1 genotype (P = 0.02), which is considered the most virulent genotype. Further, a higher level of urease activity was associated with isolates originating from the Jewish population. Moreover, higher urease activity levels were measured among CagA-/s1m1 and CagA-/s2m2 isolates.

CONCLUSION

Our study highlights the importance of incorporating molecular methods for detection of virulence markers of H. pylori in order to tailor optimal treatments for each patient. Further investigation should be performed regarding associations between H. pylori virulence factors and ethnicity.

Helicobacter pylori Infection, Its Laboratory Diagnosis, and Antimicrobial Resistance: a Perspective of Clinical Relevance

Despite the recent decrease in overall prevalence of Helicobacter pylori infection, morbidity and mortality rates associated with gastric cancer remain high. The antimicrobial resistance developments and treatment failure are fueling the global burden of H. pylori-associated gastric complications. Accurate diagnosis remains the opening move for treatment and eradication of infections caused by microorganisms. Although several reports have been published on diagnostic approaches for H. pylori infection, most lack the data regarding diagnosis from a clinical perspective. Therefore, we provide an intensive, comprehensive, and updated description of the currently available diagnostic methods that can help clinicians, infection diagnosis professionals, and H. pylori researchers working on infection epidemiology to broaden their understanding and to select appropriate diagnostic methods. We also emphasize appropriate diagnostic approaches based on clinical settings (either clinical diagnosis or mass screening), patient factors (either age or other predisposing factors), and clinical factors (either upper gastrointestinal bleeding or partial gastrectomy) and appropriate methods to be considered for evaluating eradication efficacy. Furthermore, to cope with the increasing trend of antimicrobial resistance, a better understanding of its emergence and current diagnostic approaches for resistance detection remain inevitable.

Isolation of Helicobacter pylori using leftover tissue in the rapid urease test kit

BACKGROUND AND AIMS

Isolation of Helicobacter pylori is considered difficult because of the requirement of the additional biopsy tissue and the effort involved in the isolation of the bacterium. We investigated whether H pylori can be cultured from tissue samples used for the rapid urease test (RUT).

METHODS

Totally, 174 specimens from 87 patients referred for endoscopy were prospectively included. During endoscopy, two biopsy specimens were obtained, one each from the gastric antrum and the corpus, and were placed into a commercially available RUT kit. After detection of urease activity, H pylori was cultured using tissue leftover in the RUT, regardless of the result.

RESULTS

H pylori was successfully isolated using leftover tissue in 72.4% (63/87) of the patients. In 32 patients, H pylori was isolated from both specimens, while in 31 patients, it was isolated from either antrum or corpus. Eighty-one H pylori strains were isolated from 141 specimens with positive RUT results (57.4%), whereas 14 strains were isolated from 33 specimens with negative RUT results (42.4%). The median interval between tissue acquisition and inoculation onto the isolation media was 3.6 hours (range: 0.5-27.5 hours) in cases with successful cultures, compared to 23.5 hours (range: 0.5-76.0 hours) in cases with failed cultures. Among the positive RUT tissues, 80.4% (45/56) were cultured successfully when the tissue was inoculated within 4 hours of the biopsy.

CONCLUSIONS

RUT kits can be used as transport media for H pylori, and this media is most efficient when used within 4 hours of the test.

Phenotype and Molecular Detection of Clarithromycin and Levofloxacin Resistance in Helicobacter pylori Clinical Isolates in Beijing

Introduction

Understanding drug resistance is important in drug selection for Helicobacter pylori (H. pylori) eradication, and drug resistance data are lacking in Beijing.

Purpose

This cross-sectional study aimed to isolate H. pylori from patients with gastroduodenal diseases and to analyze drug resistance to clarithromycin (CLA) and levofloxacin (LEV), which are used frequently in China.

Patients and Methods

One hundred and seventy-six patients with gastroduodenal diseases undergoing gastroduodenoscopy were selected by convenient sampling. Gastric mucosa samples were cultured and sub-cultured using a new medium broth. Active H. pylori strains were confirmed by microscopy observation as Gram-negative curved bacilli with positive test results for urease, oxidase, and catalase, and H. pylori 16S rRNA amplification by polymerase chain reaction (PCR). CLA and LEV resistance was identified by minimum inhibitory concentration (MIC) tests and sequencing of 23S rRNA, gyrA, and gyrB genes.

Results

From the 176 clinical samples, 112 (112/176, 63.6%) were confirmed with H. pylori infection and 65 (65/176, 36.9%) active H. pylori strains were obtained and further confirmed by MIC assay. Overall, the rates of CLA-resistant and LEV-resistant mutations in the 112 samples were 50.9% and 33.0%, respectively. Mutation related to CLA resistance was A2143G in the 23S rRNA gene and mutations associated with LEV resistance were N87K, D91G, and D91Y in the gyrA gene. Of 112 samples, 22 (19.6%) presented dual resistance to CLA and LEV. Resistance of the H. pylori strains to CLA (r=0.846, P<0.001) and LEV (r=0.936, P<0.001) had a strong correlation in phenotypic and genotypic level.

Conclusion

The results indicated that resistance of CLA and LEV is severe among patients with gastroduodenitis. A good consistency could be found as to drug resistance between genotypic or phenotypic assay, suggested extending the detection of H. pylori drug resistance from the MIC method to a genotypic assay.

Detection of Helicobacter pylori in Nasal Polyps

To detect the presence of Helicobacter pylori in nasal polyps. A case-control study was conducted enrolling 35 patients with nasal polyps (cases) and patients undergoing septoplasty (controls). Fresh tissue samples were used for urea broth test and imprint cytology, while formalin fixed tissue sections were used for morphology, special stains and immunohistochemistry for H. pylori. Fresh stool samples from both groups were tested to correlate the gastrointestinal status. H. pylori was detected in 40.0 % (14/35) of cases and 8.5 % of controls (3/35) (p = 0.004) by immunohistochemistry. Amongst cases, eight were positive with urea broth test, six with imprint cytology (Giemsa stain), three with H & E, and nine with modified McMullen's stain. Hyperplasia of the lining epithelium and lymphoid aggregates were significantly noticed in nasal polyps positive for H. pylori. Stool antigen test was positive in subjects who were positive for H. pylori in the nasal mucosa. There appears to be an association between H. pylori and nasal polyps. Immunohistochemistry is more sensitive and specific method to detect H. pylori. H. pylori induced inflammatory tissue reaction pattern indicates a possible causal association. Further studies are needed to prove the causal relationship between H. pylori and nasal polyps.

Antimicrobial susceptibility and clarithromycin resistance patterns of Helicobacter pylori clinical isolates in Vietnam

Helicobacter pylori is a gastric pathogen that causes several gastroduodenal disorders such as peptic ulcer disease and gastric cancer.  Eradication efforts of H. pylori are often hampered by antimicrobial resistance in many countries, including Vietnam.  Here, the study aimed to investigate the occurrence of antimicrobial resistance among H. pylori clinical isolates across 13 hospitals in Vietnam.  The study further evaluated the clarithromycin resistance patterns of H. pylori strains.  In order to address the study interests, antimicrobial susceptibility testing, epsilometer test and PCR-based sequencing were performed on a total of 193 strains isolated from patients, including 136 children (3–15 years of age) and 57 adults (19–69 years of age).  Antimicrobial susceptibility testing showed that the overall resistance to amoxicillin, clarithromycin, levofloxacin, metronidazole, and tetracycline was 10.4%, 85.5%, 24.4%, 37.8%, and 23.8% respectively.  The distribution of minimum inhibitory concentrations (MICs) of clarithromycin-resistant strains was 85.5% with MIC >0.5 μg/mL.  The majority of the clarithromycin resistant isolates (135 of 165 subjects) have MICs ranging from 2 μg/mL to 16 μg/mL.  Furthermore, sequencing detection of mutations in 23S rRNA gene revealed that strains resistant and susceptible to clarithromycin contained both A2143G and T2182C mutations.  Of all isolates, eight clarithromycin-resistant isolates (MIC >0.5 μg/mL) had no mutations in the 23S rRNA gene.  Collectively, these results demonstrated that a proportion of clarithromycin-resistant H. pylori strains, which are not related to the 23S rRNA gene mutations, could be potentially related to other mechanisms such as the presence of an efflux pump or polymorphisms in the CYP2C19 gene.  Therefore, the present study suggests that providing susceptibility testing prior to treatment or alternative screening strategies for antimicrobial resistance is important for future clinical practice.  Further studies on clinical guidelines and treatment efficacy are pivotal for successful eradication of H. pylori infection.

New transport medium for cultural recovery of Helicobacter pylori

We developed a new transport medium (GESA--Helicobacter pylori transport medium [publication no. WO/2014/019696, patent pending no. PCT/EP2013/002292; Liofilchem s.r.l., Roseto degli Abruzzi, Teramo, Italy]) for recovery of Helicobacter pylori from gastric biopsy samples. GESA transport medium, in a semisolid state, provides the optimal conditions for maintaining the viability of the microorganism over time. The efficacy of the transport medium was assessed through in vitro and ex vivo experiments. We were able to recover different suspensions of H. pylori ATCC 43629 and H. pylori 13 A in GESA transport medium stored at 4 °C for up to 10 days. In particular, with a starting inoculum of ∼ 10(5) CFU, after 7 days of storage, 150 ± 25 CFU and 40 ± 7 CFU of the reference and clinical strains were detected, respectively. H. pylori colonies were isolated from gastric specimens taken from both the antrum and the fundus in 68 (90.66%) of 75 urea breath test (UBT)-positive patients. Moreover, GESA transport medium allowed the recovery and isolation of H. pylori colonies from additional biopsy samples from 13 of the 75 detected subjects at up to 10 days of biopsy sample storage at 4 °C. Finally, GESA transport medium preserved its characteristics when stored at 4°C for 1 year from its preparation, thus allowing good recovery of H. pylori. GESA transport medium can be considered a standardized transport medium with high performance that optimizes the recovery rate of H. pylori grown by culture.

PCR detection of clarithromycin-susceptible and -resistant Helicobacter pylori from formalin-fixed, paraffin-embedded gastric biopsies

Antimicrobial resistance to clarithromycin is a growing concern in the treatment of Helicobacter pylori and is associated with three major point mutations of the 23S rRNA, A2142C, A2142G, and A2143G. The use of traditional culture-based methods for determination of clarithromycin resistance in H. pylori are time consuming and lack sensitivity. We implemented a real-time PCR with melt curve analysis to detect and characterize H. pylori in formalin-fixed, paraffin-embedded gastric biopsy specimens to assess the frequency of clarithromycin resistance mutations in our study population. One hundred and fifty-three formalin-fixed, paraffin-embedded gastric biopsies were chosen on the basis of positive immunohistochemical staining for H. pylori and an accompanying histopathological diagnosis of Helicobacter-associated gastritis. New adjacent sections were taken for immunohistochemical staining and DNA extraction with subsequent testing by PCR assay and melt curve analysis using a primer and probe combination first described by Oleastro et al.(12) One hundred and forty-six samples demonstrated adequate amplification of a human DNA control target. Of these, there were 122 H. pylori immunohistochemistry-positive samples. In all, 103 out of 122 (84%) immunohistochemistry-positive samples demonstrated amplifiable H. pylori 23S rRNA gene target and 19 (16%) demonstrated no amplification of H. pylori. Twenty-two samples were negative for H. pylori by immunohistochemistry and PCR. Two were negative for H. pylori by immunohistochemistry, but were positive for H. pylori by PCR. In all, 52 out of 105 (50%) PCR-positive samples demonstrated resistance mutations, and it was determined that a heterogeneous population of mutated and unmutated organisms was present in 11 out of 52 samples. The use of PCR assays allows for a timely assessment of clarithromycin resistance status without the disadvantages of culture-based methods, and may lead to a decrease in treatment failure rates.

Incidence of Helicobacter pylori infection and their clarithromycin-resistant strains in otitis media with effusion regarding phenotypic and genotypic studies

Helicobacter pylori (H. pylori) are pathogenic bacteria that infect a half of the human population, colonize gastric mucosa and can be found in gastric juice. Reflux of gastric juice has been suggested to be associated with glue ear in children. It has been suggested that tonsil and adenoid tissues are potential reservoirs of H. pylori infection. These observations raise the question as to whether H. pylori infection might have a role in otitis media with effusion (OME) in children. The objectives of this research were to evaluate the incidence and possible role of H. pylori in the pathogenesis of OME in children and to evaluate the clarithromycin-resistant strains. Molecular assessment was done to evaluate the culture results vs. molecular study. A total of 60 children, who were prone to ventilation tube insertion, adenoidectomy and/or tonsillectomy were included in the study. The control group consisted of 40 children who underwent adenoidectomy and/or tonsillectomy without the history of OME. Samples of the middle ear fluid and mucosa, adenoid tissue, tonsillar tissue and gastric lavage were cultured and underwent polymerase chain reaction (PCR) analysis then were assembled by using QIAxcel System as capillary electrophoresis for H. pylori detection. There was significant difference between the results of cultures and PCR (P < 0.05). Middle ear fluid culture was positive for H. pylori in 40% of the patients vs. 56.7% PCR results while middle ear mucosa culture was positive in 20% vs. 26.7% PCR results. Gastric lavage culture was positive in 46.6% of the patients and PCR was positive in 63.3% of the patients. Adenoid culture and PCR were positive in 56.3% for each, while tonsil culture was positive in 70% and PCR was positive in 90%. H. pylori presence in the gastric lavage, the tonsillar and adenoid tissues by culture and PCR was significantly more frequent in the study group compared to the control group. The minimum inhibitory concentration (MIC) values of clarithromycin-resistant isolates ranged from 1.5 to 8 μg/ml. This study showed the presence of H. pylori in around 50% of the patients with OME. PCR revealed its sensitivity than culture techniques. The incidence of clarithromycin resistance was found to be high among the isolates (39.6%).

In vivo measurement of Helicobacter pylori infection

Helicobacter pylori is a well-recognized gastroduodenal pathogen (National Institute of Health Consensus Conference, JAMA 272:65-9, 1994) and a class I carcinogen (International Agency for Research on Cancer, IARC Monograph on the Evaluation of Carcinogenic Risk to Humans 61:177-240, 1994) which successfully colonizes the harsh acidic environment of the stomach. H. pylori is the causative factor for peptic ulcer disease (PUD) and an independent risk factor for gastric adenocarcinoma development. Therefore, accurate detection of infection is crucial for devising proper eradication regimens and preventing the more severe GI complications.Detection of H. pylori in the gastric mucosa can be performed via (1) direct detection of the bacterium; culture, histology and polymerase chain reaction (PCR) or (2) indirect detection of its enzymatic products particularly urease as well as serum H. pylori-specific antibody responses, which can be detected by rapid urease test (RUT) and serology, respectively.The accuracy of these diagnostic tests is reported as follows: 98.1% for bacterial culture, 98.1% for histology, 94.3% for PCR, 96.2% for RUT, and 84.9% for serology (Ni et al, J Pediatr 136(6):823-7, 2000).

mRNA levels of TLR4 and TLR5 are independent of H pylori

AIM: To determine if the presence H pylori or its virulence affect toll-like receptor 4 (TLR4) and TLR5 mRNA expression levels.

METHODS: For the in vivo assays, gastric biopsies were obtained from 40 patients and H pylori status was determined. For the in vitro assays, human gastric adenocarcinoma mucosal cells (AGS) were cultured in the presence or absence of twelve selected H pylori strains. H pylori strains isolated from culture-positive patients and selected strains were genotyped for cagA and vacA. The cDNA was obtained from mRNA extracted from biopsies and from infected AGS cells. TLR4 and TLR5 mRNA levels were examined by real-time PCR.

RESULTS: The presence of H pylori did not affect the mRNA levels of TLR4 or TLR5 in gastric biopsies. The mRNA levels of both receptors were not influenced by the vacA status (P > 0.05 for both receptors) and there were no differences in TLR4 or TLR5 mRNA levels among the different clinical presentations/histological findings (P > 0.05). In the in vitro assay, the mRNA levels of TLR4 or TLR5 in AGS cells were not influenced by the vacAs1 status or the clinical condition associated with the strains (P > 0.05 for both TLR4 and TLR5).

CONCLUSION: The results of this study show that the mRNA levels of TLR4 and TLR5 in gastric cells, both in vivo and in vitro, are independent of H pylori colonization and suggest that vacA may not be a significant player in the first step of innate immune recognition mediated by TLR4 or TLR5.

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.

Prevalence of Helicobacter pylori in Georgian patients with dyspepsia

BACKGROUND

Georgia has showed a high prevalence of peptic ulcer disease (PUD), but the prevalence of Helicobacter pylori in this country is practically unknown. The purpose of this study was to determine the prevalence of H. pylori and specific genotypes in different populations in Georgia.

MATERIALS AND METHODS

We studied 62 patients from several hospitals in Tbilisi, Georgia. More than 55% of patients had PUD. We determined H. pylori presence as well as specific genotypes cagA and vacA by polymerase chain reaction. In addition, we studied serum samples from 94 healthy persons to determine H. pylori and CagA prevalence by ELISA.

RESULTS

We found a high prevalence of H. pylori and CagA in the healthy population (70.2 and 57.4%, respectively) and a high prevalence of CagA among the H. pylori-positive persons (71.2%). Prevalence increased with age as reported in other countries (p = .05). Among symptomatic persons, we found nearly the same high prevalence of H. pylori (64.5%) as in the asymptomatic population. Furthermore, in symptomatic H. pylori patients, we found 65.0 and 67.5% prevalence of cagA and vacA, respectively. For 33 patients with PUD, 24 patients (72.7%) were H. pylori positive and 66.7% of them were cagA positive. In contrast, among the patients with non-ulcer dyspepsia (NUD), 16 (55.2%) were H. pylori positive and 62.5% of them were colonized with cagA-positive strains. H. pylori and cagA prevalence were not significantly different between PUD and patients with NUD.

CONCLUSIONS

We confirmed that among individuals in Georgia, the prevalence of H. pylori is high and cagA-positive strains were equally present among H. pylori-positive patients with PUD and NUD and asymptomatic persons.

Diagnostic Utility of Invasive Tests and Serology for the Diagnosis of Helicobacter pylori Infection in Different Clinical Presentations

BACKGROUND

Invasive and noninvasive tests are used for the diagnosis of Helicobacter pylori infection. The aim of this study was to determine the diagnostic utility of rapid urease test (RUT), culture, histology and serology for the diagnosis of H. pylori in patients with different clinical presentations.

METHODS

We studied 527 consecutive patients (mean age, 52.5 years; F:M, 1.3; age range 15-89 years) enrolled at the Hospital Universitario, Universidad Autónoma de Nuevo León. Patients had gastric cancer (GC, 9.1%), non-ulcer dyspepsia (NUD, 81.4%), or peptic ulcer disease (PUD, 9.1%). The infection by H. pylori was determined by histology, rapid urease test, culture, and serology. Patients were determined as infected with H. pylori if at least a) two invasive tests were positive and b) two tests were positive (invasive or non-invasive). Diagnostic utility was calculated for each assay.

RESULTS

Prevalence of infection in the whole studied population was 50.9%. In NUD patients the prevalence was 51.3%, in PUD patients 58.3%, and in GC patients 39.6%. When we used the first diagnostic criteria, for the whole studied population, the RUT was the most reliable test, followed by the culture. Histology had the best sensitivity for the whole studied population and NUD patients and RUT had the best sensitivity value for the GC patients. In the whole studied population, NUD and GC patients, RUT and culture had the best specificity, accuracy and PPV. For PUD patients, serology had the best performance. When we used the second diagnostic criteria, histology and serology had a better performance compared with the results obtained with the first diagnostic criteria.

CONCLUSIONS

Diagnostic utility of the tests varies according to the clinical presentations, which should be considered in the selection of the diagnostic test for the detection of H. pylori.

Stool antigen testing for the diagnosis and confirmation of eradication of Helicobacter pylori infection: a prospective blinded trial

BACKGROUND AND AIMS

Helicobacter pylori is an established pathogen for a wide spectrum of gastroduodenal diseases. We investigated the usefulness of H. pylori stool antigen test (HpSA) before and after eradication therapy on patients referred for gastroscopy.

METHODS

Over a 12-month period, 127 adult patients (47% males) underwent HpSA and gastroscopy with dual biopsies from the antrum and proximal body of the stomach for urease and histology. The positive patients (histology, urease or combined positive) received triple therapy consisting of clarithromycin 500 mg, amoxycillin 1 g and omeprazole 20 mg, each given twice daily for 7 days. Six weeks post-therapy, eradication was verified with the 13C-urea breath test (UBT) and the HpSA results compared on a second stool sample.

RESULTS

Pre-therapy, 23/113 patients were positive by urease test, 22/112 by histology and 22/112 were combined positive. For the HpSA, compared to combined urease and histology as the reference standards, the sensitivity and specificity were 79 and 92% while the positive and negative predictive values (PPV and NPV) were 68 and 96%, respectively. Post-therapy, UBT was adopted as the reference standard and 18 paired samples were available for analysis: three were positive and 15 were negative. Sensitivity and specificity were 67 and 100% while the PPV and NPV were 100 and 94%, respectively.

CONCLUSIONS

In this prospective study, HpSA was found to be a reasonably useful diagnostic test for H. pylori infection. Post-eradication, it was highly specific and similar to UBT in terms of PPV and NPV. The test is non-invasive and cheaper than the urease test or the UBT, making it a candidate in the investigation of dyspepsia.

Role of the polymorphic IL-1B, IL-1RN and TNF-A genes in distal gastric cancer in Mexico

Several cytokine gene polymorphisms have been associated with increased risk of distal gastric cancer (GC) and its precursor histological markers in Caucasian, Asian and Portuguese populations although little is known about their role in other ethnic groups. Our study investigates the role of the IL-1B-31, IL-1RN and TNF-A-308 gene polymorphisms as risk factors for the development of GC in a Mexican population. We studied 278 patients who were enrolled at the Hospital Universitario Dr. Jose Eleuterio Gonzalez, Universidad Autonoma de Nuevo Leon. The subjects were divided into 2 groups. Sixty-three patients with histologically confirmed distal GC (mean age = 58.8 years, range = 22-84, F:M = 0.56), and 215 patients with no evidence of distal or proximal GC (mean age = 56.1 years, range = 18-92, F:M = 1.17). The IL-1B-31 and the TNF-A-308 polymorphisms were determined by PCR-RFLP and pyrosequencing, respectively, in all cases and controls. The VNTR polymorphism in intron 2 of the 1L-1RN gene was typed by PCR in 25 cases and 201 controls. The H. pylori status was determined by histology, rapid urease test, culture and serology for non-cancer controls and by histology for the GC cases. The carriage of the proinflammatory IL-1B-31*C allele was associated with increased risk of distal GC (odds ratio [OR] = 7.63, 95% confidence interval [CI] = 1.73-46.94, p = 0.003). When cases and controls were matched by age and gender, the OR value was higher (OR = 8.05, 95% CI = 1.8-50.22, p = 0.001). When only H. pylori GC cases and controls were compared, the OR value was 7.8 (95% CI = 1.05-161.8, p = 0.04). No association was found between any of the other polymorphisms studied and distal GC. In this Mexican population, the IL-1B proinflammatory genotype increases the risk of distal GC. These findings are similar to previous reports in Caucasian populations and underscore the importance of cytokine gene polymorphisms in the development of distal GC.

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Fast and accurate quantitative detection of Helicobacter pylori and identification of clarithromycin resistance mutations in H. pylori isolates from gastric biopsy specimens by real-time PCR

Rapid identification of patients infected with clarithromycin-resistant Helicobacter pylori without the need for culture can help to avoid useless prescriptions of clarithromycin. We developed and tested a routine real-time quantitative PCR assay dedicated to that purpose. One hundred ninety-six consecutive gastric biopsy specimens were examined by culture, histology performed by a trained physician, and rapid PCR with the LightCycler apparatus. Infection was defined as (i) positivity of culture, (ii) positivity of histology, or (iii) positivity of PCR if confirmed by positivity of a concomitant indirect test (serology or urea breath test). Susceptibility to clarithromycin was tested by E-test and PCR. The prevalence of infection was 33.7% (66 of 196 samples). The sensitivities of culture, histology, and PCR were 90.9% (60 of 66 samples), 87.9% (58 of 66 samples), and 97.0% (64 of 66 samples), respectively. The specificity of PCR was 94.6% (123 of 130 samples). The linearity of the PCR results was achieved over a 6-log range of input DNA, and we were able to accurately quantify as few as 300 bacteria and to qualitatively detect as few as 30 bacteria per DNA sample. For clarithromycin susceptibility testing, there was 98.2% (55 of 56 samples) concordance between E-test and PCR. Forty-eight strains were clarithromycin susceptible, and 9 strains were clarithromycin resistant. The single discrepancy concerned a culture which was a mixture of mutant and wild type, with a susceptible-to-resistant ratio of 11.5: the resistant population was detected by E-test but not by PCR. Our PCR assay is accurate for fast detection of H. pylori as well as of clarithromycin resistance and is also able to objectively determine bacterial density.

Comparison of Helicobacter pylori prevalence in symptomatic patients in northeastern Mexico with the rest of the country: its association with gastrointestinal disease

BACKGROUND

Prevalence of Helicobacter pylori varies among different geographic regions. The aim of this study was to assess H. pylori prevalence in symptomatic patients in northeastern Mexico and its possible association of H. pylori with disease.

METHODS

We studied 261 symptomatic patients (female/male 1.44, mean age 53 years) who underwent gastrointestinal endoscopy at Hospital Universitario Dr. José Eleuterio González in Monterrey, Nuevo León, Mexico. Among patients included in this study, 209 (80.1%) had nonulcer dyspepsia (NUD), 30 (11.5%) peptic ulcer disease (PUD), and 22 (8.4%) high-grade dysplasia or gastric cancer. H. pylori status was determined by histology, positive rapid urease test, culture, or IgG whole-cell anti-H. pylori. Specific IgG antibodies for CagA status were determined by ELISA as previously described. Patients were defined as infected with H. pylori by positive results of two or more diagnostic tests used.

RESULTS

Overall prevalence of H. pylori was 67.8%. According to clinical presentation, gender (male) was related with gastric cancer (p <0.01) and with PUD (p <0.05). Of 177 patients infected with H. pylori, 90 (50.8%) were seropositive for CagA antigen; in addition, H. pylori CagA+ was more common in patients with PUD (77.8%) than with NUD (43.2%) (p <0.05). However, no association was found between gastric cancer patients and presence of CagA+ H. pylori strains.

CONCLUSIONS

H. pylori prevalence in symptomatic patients in northeastern Mexico is as high as the prevalence reported for the entire country. We confirmed that patients with gastric cancer and PUD are more likely to be male. CagA+ strains were associated with patients who presented PUD but not gastric cancer.