Accuracy of serology for the diagnosis of Helicobacter pylori infection--a comparison of eight kits

A Malaysian consensus report on the diagnosis and treatment of Helicobacter pylori infection

Helicobacter pylori is one of the most common chronic bacterial infections in humans and responsible for 90% of duodenal ulcers and 70-90% of gastric ulcers. Despite this, many misconceptions regarding the appropriate diagnostic method and treatment strategies still exist in the Malaysian clinical practice. Under the initiative of the steering committee, an expert panel consisting of nine key opinion leaders in the field of gastroenterology convened to develop a set of consensus statements that are relevant to the Malaysian healthcare practice. The panel members reviewed the current evidence on the management of H. pylori infection, focusing on the best practices that are relevant to the Malaysian population based on clinical experience and published clinical evidence. Using the modified Delphi method, the panel achieved consensus in three areas of H. pylori infection management: indications for testing, diagnosis, and treatment. The panel proposed a set of 19 consensus statements, which were synthesized via two rounds of blinded voting and group discussions. The recommendations provided are relevant to the Malaysian population and can be used as a guide by physicians across various healthcare settings to facilitate appropriate diagnostic testing and treatment of H. pylori infection.

Histologic detection of Helicobacter pylori by the immunohistochemical method using anti-Helicobacter pylori polyclonal antibody: A cross-sectional study of patients with gastric pathologies at the Muhimbili National Hospital in Dar-es-salaam, Tanzania

BACKGROUND AND STUDY AIM

Immunohistochemistry is one of the superior methods and is regarded as the gold standard for the detection of Helicobacter pylori. We aimed to detect the presence of Helicobacter pylori in gastric biopsies among patients at the Muhimbili National Hospital from January 2012 to December 2016. Also, we determined the predictors of Helicobacter pylori infection.

PATIENTS AND METHODS

Retrospectively, we retrieved the tissue blocks of gastric biopsies at the Central Pathology Laboratory of the patients with different gastric pathologies at the Muhimbili National Hospital from January 2012 to December 2016. Helicobacter pylori were detected using anti-Helicobacter pylori polyclonal antibodies. Binary logistic regression analysis was done to determine the predictors of Helicobacter pylori infection. A two-tailed p < 0.05 was considered significant.

RESULTS

The prevalence of detection of Helicobacter pylori was 37.1% (63/170) using immunohistochemistry compared to 32.4% (55/170) using histology. Peptic ulcer disease, the absence of gastric cancer, and chronic gastritis were the predictors of Helicobacter pylori infection in our study (AOR = 0.2, 95% CI = 0.06-0.70, p = 0.011, AOR = 3.23, 95% CI = 1.02-10.29, p = 0.047, AOR = 0.32, 95% CI = 0.12-0.87, p = 0.025, respectively).

CONCLUSION

In this study, Helicobacter pylori infection was associated with the presence of peptic ulcer disease, chronic gastritis, and the absence of gastric cancer. The rate of detection of Helicobacter pylori infection was higher in tissue blocks of elderly patients than in those of young patients. Also, gastric cancer was more prevalent in old female patients.

Are Patients with Perforated Peptic Ulcers Who are Negative for Helicobacter pylori at a Greater Risk?

Background: The link between Helicobacter pylori infection and peptic ulceration is well established. Recent studies have reported a decrease of H. pylori-related peptic ulcer disease; Helicobacter pylori eradication is likely the cause of this decrease. We hypothesized that patients with H. pylori-positive perforated peptic ulcer disease (PPUD) requiring surgical intervention had worse outcomes than patients with H. pylori-negative PPUD. Patients and Methods: A prospectively collected Acute and Critical Care Surgery registry spanning the years 2008 to 2015 was searched for patients with PPUD and tested for H. pylori serum immunoglobulin G (IgG) test. Patients were divided into two cohorts: H. pylori positive (HPP) and H. pylori negative (HPN). Demographics, laboratory values, medication history, social history, and esophagogastroduodenoscopy were collected. Student t-test was used for continuous variables and χ² test was used for categorical variables. Linear regression was applied as appropriate. Results: We identified 107 patients diagnosed with PPUD, of whom 79 (74%) patients had H. pylori serum IgG testing. Forty-two (53.2%) tested positive and 37 (46.8%) tested negative. Helicobacter pylori-negative PPUD was more frequent in females (70.27%, p = 0.004), whites (83.78%, p = 0.001) and patients with higher body mass index (BMI) 28.81 ± 8.8 (p = 0.033). The HPN group had a lower serum albumin level (2.97 ± 0.96 vs. 3.86 ± 0.91 p = 0.0001), higher American Society of Anesthesiologists (ASA; 3.11 ± 0.85 vs. 2.60 ± 0.73; p = 0.005), and Charlson comorbidity index (4.81 ± 2.74 vs. 2.98 ± 2.71; p = 0.004). On unadjusted analysis the HPN cohort had a longer hospital length of stay (LOS; 20.20 ± 13.82 vs. 8.48 ± 7.24; p = 0.0001), intensive care unit (ICU) LOS (10.97 ± 11.60 vs. 1.95 ± 4.59; p = 0.0001), increased ventilator days (4.54 ± 6.74 vs. 0.98 ± 2.85; p = 0.004), and higher rates of 30-day re-admission (11; 29.73% vs. 5; 11.91%; p = 0.049). Regression models showed that HPN PPUD patients had longer hospital and ICU LOS by 11 days (p = 0.002) and 8 days (p = 0.002), respectively, compared with HPP PPUD. Conclusion: In contrast to our hypothesis, HPN patients had clinically worse outcomes than HPP patients. These findings may represent a difference in the baseline pathophysiology of the peptic ulcer disease process. Further investigation is warranted.

Non-invasive diagnostic tests for Helicobacter pylori infection

BACKGROUND

Helicobacter pylori (H pylori) infection has been implicated in a number of malignancies and non-malignant conditions including peptic ulcers, non-ulcer dyspepsia, recurrent peptic ulcer bleeding, unexplained iron deficiency anaemia, idiopathic thrombocytopaenia purpura, and colorectal adenomas. The confirmatory diagnosis of H pylori is by endoscopic biopsy, followed by histopathological examination using haemotoxylin and eosin (H & E) stain or special stains such as Giemsa stain and Warthin-Starry stain. Special stains are more accurate than H & E stain. There is significant uncertainty about the diagnostic accuracy of non-invasive tests for diagnosis of H pylori.

OBJECTIVES

To compare the diagnostic accuracy of urea breath test, serology, and stool antigen test, used alone or in combination, for diagnosis of H pylori infection in symptomatic and asymptomatic people, so that eradication therapy for H pylori can be started.

SEARCH METHODS

We searched MEDLINE, Embase, the Science Citation Index and the National Institute for Health Research Health Technology Assessment Database on 4 March 2016. We screened references in the included studies to identify additional studies. We also conducted citation searches of relevant studies, most recently on 4 December 2016. We did not restrict studies by language or publication status, or whether data were collected prospectively or retrospectively.

SELECTION CRITERIA

We included diagnostic accuracy studies that evaluated at least one of the index tests (urea breath test using isotopes such as 13C or 14C, serology and stool antigen test) against the reference standard (histopathological examination using H & E stain, special stains or immunohistochemical stain) in people suspected of having H pylori infection.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the references to identify relevant studies and independently extracted data. We assessed the methodological quality of studies using the QUADAS-2 tool. We performed meta-analysis by using the hierarchical summary receiver operating characteristic (HSROC) model to estimate and compare SROC curves. Where appropriate, we used bivariate or univariate logistic regression models to estimate summary sensitivities and specificities.

MAIN RESULTS

We included 101 studies involving 11,003 participants, of which 5839 participants (53.1%) had H pylori infection. The prevalence of H pylori infection in the studies ranged from 15.2% to 94.7%, with a median prevalence of 53.7% (interquartile range 42.0% to 66.5%). Most of the studies (57%) included participants with dyspepsia and 53 studies excluded participants who recently had proton pump inhibitors or antibiotics.There was at least an unclear risk of bias or unclear applicability concern for each study.Of the 101 studies, 15 compared the accuracy of two index tests and two studies compared the accuracy of three index tests. Thirty-four studies (4242 participants) evaluated serology; 29 studies (2988 participants) evaluated stool antigen test; 34 studies (3139 participants) evaluated urea breath test-13C; 21 studies (1810 participants) evaluated urea breath test-14C; and two studies (127 participants) evaluated urea breath test but did not report the isotope used. The thresholds used to define test positivity and the staining techniques used for histopathological examination (reference standard) varied between studies. Due to sparse data for each threshold reported, it was not possible to identify the best threshold for each test.Using data from 99 studies in an indirect test comparison, there was statistical evidence of a difference in diagnostic accuracy between urea breath test-13C, urea breath test-14C, serology and stool antigen test (P = 0.024). The diagnostic odds ratios for urea breath test-13C, urea breath test-14C, serology, and stool antigen test were 153 (95% confidence interval (CI) 73.7 to 316), 105 (95% CI 74.0 to 150), 47.4 (95% CI 25.5 to 88.1) and 45.1 (95% CI 24.2 to 84.1). The sensitivity (95% CI) estimated at a fixed specificity of 0.90 (median from studies across the four tests), was 0.94 (95% CI 0.89 to 0.97) for urea breath test-13C, 0.92 (95% CI 0.89 to 0.94) for urea breath test-14C, 0.84 (95% CI 0.74 to 0.91) for serology, and 0.83 (95% CI 0.73 to 0.90) for stool antigen test. This implies that on average, given a specificity of 0.90 and prevalence of 53.7% (median specificity and prevalence in the studies), out of 1000 people tested for H pylori infection, there will be 46 false positives (people without H pylori infection who will be diagnosed as having H pylori infection). In this hypothetical cohort, urea breath test-13C, urea breath test-14C, serology, and stool antigen test will give 30 (95% CI 15 to 58), 42 (95% CI 30 to 58), 86 (95% CI 50 to 140), and 89 (95% CI 52 to 146) false negatives respectively (people with H pylori infection for whom the diagnosis of H pylori will be missed).Direct comparisons were based on few head-to-head studies. The ratios of diagnostic odds ratios (DORs) were 0.68 (95% CI 0.12 to 3.70; P = 0.56) for urea breath test-13C versus serology (seven studies), and 0.88 (95% CI 0.14 to 5.56; P = 0.84) for urea breath test-13C versus stool antigen test (seven studies). The 95% CIs of these estimates overlap with those of the ratios of DORs from the indirect comparison. Data were limited or unavailable for meta-analysis of other direct comparisons.

AUTHORS' CONCLUSIONS

In people without a history of gastrectomy and those who have not recently had antibiotics or proton ,pump inhibitors, urea breath tests had high diagnostic accuracy while serology and stool antigen tests were less accurate for diagnosis of Helicobacter pylori infection.This is based on an indirect test comparison (with potential for bias due to confounding), as evidence from direct comparisons was limited or unavailable. The thresholds used for these tests were highly variable and we were unable to identify specific thresholds that might be useful in clinical practice.We need further comparative studies of high methodological quality to obtain more reliable evidence of relative accuracy between the tests. Such studies should be conducted prospectively in a representative spectrum of participants and clearly reported to ensure low risk of bias. Most importantly, studies should prespecify and clearly report thresholds used, and should avoid inappropriate exclusions.

Designing a novel ELISA method based on CagA, NapA recombinant antigens to increase sensitivity and specificity of Helicobacter pylori whole cell antigen detection

AIM

In this research, we designed a direct Enzyme Linked Immunoassay method to detect Helicobacter pylori antigens in stool specimens.

BACKGROUND

Helicobacter pylori infection as the worldwide problem is related to many gastrointestinal disorders such as gastritis, gastric cancer, non-ulcer disease, peptic ulcer disease and duodenal ulcer.

METHODS

We produced and purified recombinant CagA and NapA antigens in Escherichia coli and extracted their antibodies from a panel of positive sera specimens. We designed a novel enzyme linked immunoassay direct method in combination with the whole cell for the qualitative and quantitative detection of Helicobacter pylori antigens in human stool. Assay performance was evaluated by histopathology staining and urease activity.

RESULTS

The sensitivity and specificity of assay was determined as 91.7 [95% confidence interval: 89.3-95.6%] and 93.1% [95% CI: 91.2-96.4%], respectively. Novel ELISA exhibits enhanced sensitivity and specificity of Helicobacter pylori detection in comparison with another commercially available kit.

CONCLUSION

Combination of the recombinant antigens and whole cell of Helicobacter pylori in immunoassay designing is a new approach about early diagnosis, treatment and fallowing up of the Helicobacter pylori infected patients, especially in peptic cancer cases.

Natural Course of Helicobacter pylori Infection in Japanese Hemodialysis Patients

INTRODUCTION

Helicobacter pylori (H. pylori) infection is one of the major risk factors for gastrointestinal morbidity in hemodialysis patients. Primary end point is to investigate H. pylori infection rate in hemodialysis patients. As secondary end point, we clarified whether pepsinogen (PG) level was related with H. pylori infection status in hemodialysis patients.

METHODS

Serum levels of PG I, II, and anti-H. pylori IgG antibody were assessed in 500 Japanese hemodialysis patients.

RESULTS

H. pylori infection rate was 15.0% (75/500; 95% CI 12.0-18.4). The duration of hemodialysis in H. pylori-positives was 4.6 ± 3.8 years, which was significantly shorter than in H. pylori-negatives (7.3 ± 6.9, p = 0.001). PG I levels positively correlated with the PG II level and PG I/II ratio (|R| = 0.661, p < 0.001, and |R| = 0.544, p <0.001, respectively). Using a cutoff value of 7.75, the sensitivity and specificity of PG I/II ratio for predicting H. pylori-negatives were 86.3 and 87.8%, respectively (area under the curve 0.930).

CONCLUSIONS

In hemodialysis patients, infection rate with H. pylori was <20%, with lower rates in patients receiving hemodialysis for longer terms. A PG I/II ratio with a cutoff value of 7.75 may be useful for screening for H. pylori status.

Status of Epstein-Barr Virus Coinfection with Helicobacter pylori in Gastric Cancer

Epstein-Barr virus is a ubiquitous human herpesvirus whose primary infection causes mononucleosis, Burkett's lymphoma, nasopharyngeal carcinoma, autoimmune diseases, and gastric cancer (GC). The persistent infection causes malignancies in lymph and epithelial cells. Helicobacter pylori causes gastritis in human with chronic inflammation. This chronic inflammation is thought to be the cause of genomic instability. About 45%-word population have a probability of having both pathogens, namely, H. pylori and EBV. Approximately 180 per hundred thousand population is developing GC along with many gastric abnormalities. This makes GC the third leading cause of cancer-related death worldwide. Although lots of research are carried out individually for EBV and H. pylori, still there are very few reports available on coinfection of both pathogens. Recent studies suggested that EBV and H. pylori coinfection increases the occurrence of GC as well as the early age of GC detection comparing to individual infection. The aim of this review is to present status on coinfection of both pathogens and their association with GC.

Performances of Four Helicobacter pylori Serological Detection Kits Using Stool Antigen Test as Gold Standard

The aim was to determine the performances of four Helicobacter pylori serological detection kits in different target groups, using Amplified IDEIA™ Hp StAR™ as gold standard. Kits studied were Rapid Immunochromatoghraphic Hexagon, Helicoblot 2.1, an EIA IgG kit and EIA IgA kit.

METHODS

Stool and blood samples were collected from 162 apparently healthy participants (control) and 60 Type 2 diabetes mellitus (T2DM) patients.

RESULTS

The performances of the four serological detection kits were found to be affected by gender, age, health status and ethnicity of the participants. In the control group, the Helicoblot 2.1 kit had the best performance (AUC = 0.85; p<0.05, accuracy = 86.4%), followed by EIA IgG (AUC = 0.75; p<0.05, accuracy = 75.2%). The Rapid Hexagon and EIA IgA kits had relatively poor performances. In the T2DM subgroup, the kits H2.1 and EIA IgG had best performances, with accuracies of 96.5% and 93.1% respectively. The performance of EIA IgG improved with adjustment of its cut-off value.

CONCLUSION

The performances of the detection kits were affected by various factors which should be taken into consideration.

Helicobacter pylori infection in patients with liver cirrhosis: prevalence and association with portal hypertensive gastropathy

BACKGROUND

The role of Helicobacter pylori (H. pylori) in the pathogenesis of portal hypertensive gastropathy (PHG) in cirrhotic patients is poorly defined. The aim of this study was toinvestigate the prevalence of H. pylori infection and its association with PHG in patients with liver cirrhosis.

METHODS

Seroprevalence of H. pylori was tested in 70 cirrhotic patients with PHG (cases) and 70 cirrhotic patients without PHG (controls) using an anti-H. pylori IgG ELISA. All patients underwent upper gastrointestinal endoscopy to assess the severity of PHG and grade of varices.

RESULTS

The presence of H. pylori was observed in 31 (44.3%) cirrhotic patients with PHG (cases) compared to 19 (27.1%) cirrhotic patients without PHG (controls). The risk estimate showed a significant association between H. pylori and PHG in cirrhotic patients (P=0.034, OR 2.134, 95% CI 1.052-4.327). Out of the 31 patients with PHG and H. pylori infection, 19 had severe PHG and 12 had mild PHG while 5 patients had severe PHG and 34 had mild PHG in the group of H. pylori negative patients. The difference was statistically significant (P<0.001, OR 10.767, 95% CI 3.293-35.205). Of the 70 patients with PHG, 24 had severe PHG and of these 18 (75%) were in Child C compared to 6 (25%) in Child B.

CONCLUSION

There is significant association between H. pylori infection and PHG in cirrhotic patients which is also related to severity of PHG. Thus, H. pylori needs to be eradicated in cirrhotic patients with PHG.

Effect of gastric acidification on the (14)C-UBT HELIPROBE(®) accuracy during Pantoprazole treatment in Helicobacter pylori positive patients

The aim of this study was to evaluate the influence of using Citric Acid on false negative rates induced by PPIs during (14)C-UBT in dyspeptic patients with H. pylori infection. In a crossover randomized controlled clinical trial, one hundred dyspeptic patients (46 females and 54 males) with determined H. pylori infection who referred to gastrointestinal Outpatient Clinic of Razi Hospital-Rasht, Iran. All the patients underwent a (14)C-UBT HELIPROBE(®) baseline test and the positive ones entered the second phase. They were divided randomly to two groups and started PPIs treatment by Pantoprazole (20 mg/daily Pantozol(®) Nycomed Company) and underwent two other UBTs in days 12-13 and 14-15 with and without 4 grams Citric Acid. In group I who underwent UBT with Citric Acid in days 12-13 (UBT2) and UBT without Citric Acid in days 14-15 (UBT3), there was no significant difference between the UBT results with and without Citric Acid (P≥0.05). In group II who underwent UBT without Citric Acid in days 12-13 and UBT with Citric Acid in days 14-15, the false negative rates were not significantly different between UBT with and without Citric Acid (P≥0.05). In both groups the results of UBT without Citric Acid after Pantoprazole consumption didn't change significantly compared to the baseline UBT. Also the difference between the false negative rates of baseline UBT and UBT without citric acid was not significant (P>0.05). These results suggest that acidification of gastric environment during (14)C-UBT cannot prevent false negative results and do not increase the accuracy of the test in patients taking PPIs.

Reliability of Diagnostic Tests for Helicobacter pylori Infection

Introduction. Helicobacter pylori (H. pylori) infection is very common worldwide. A reliable diagnosis is crucial for patients with H. pylori-related diseases. At followup, it is important to confirm that eradication therapy has been successful. There is no established gold standard for the diagnosis of H. pylori infection. Material and Methods. A sample of 304 volunteers from the general population was screened for H. pylori infection with serology, ¹³C-urea breath test (UBT), rapid urease test (RUT) on fresh biopsy, culture from biopsy, and histological examination. Culture was used as gold standard. Results. The sensitivity was 0.99 for serology, 0.90 for UBT, 0.90 for RUT, and 0.90 for histological examination. Corresponding specificities were 0.82, 0.99, 0.98, and 0.97, respectively. The accuracy was 0.86 for serology, 0.96 for UBT, 0.95 for RUT, 0.93 for culture, and 0.95 for histology. There was a strong correlation between the results of UBT and the histological scores of H. pylori colonisation as well as between the results of UBT and the scores of RUT. Conclusion. There were only minor differences in accuracy between the three invasive tests for H. pylori infection in this population. RUT may be recommended as the first choice since a result is obtained within hours. The accuracy of UBT was comparable to the invasive tests, and it is recommended for situations when endoscopy is not needed.

Gastric acid secretion level modulates the association between Helicobacter pylori infection and low-dose aspirin-induced gastropathy

BACKGROUND

The relative contribution of gastric acid secretion and Helicobacter pylori infection to low-dose aspirin-induced gastropathy remains to be clarified. This is partly because the capability of the infection to modify gastric acid secretion complicates the interaction. The aim of this study was to estimate the association of aspirin-induced mucosal injury, as well as H. pylori infection, with gastric acid output.

METHODS

A total of 186 male outpatients, comprising 60 aspirin takers, on 100 mg of enteric-coated aspirin daily and 126 non-aspirin takers were prospectively enrolled in this study. Gastrin-stimulated acid output was estimated by the endoscopic gastrin test. The grade of gastric mucosal injury was assessed endoscopically according to the modified Lanza score. Multiple logistic regression analyses were used to adjust for potential confounders.

RESULTS

The gastric acid secretion level, with an odds ratio (OR) (95% confidence interval [CI]) of 10.5 (3.0-36.9) and aspirin administration, with an OR (95% CI) of 7.4 (3.0-18.3) were independently associated with gastric mucosal injury, and the co-existence of both factors greatly elevated the risk of mucosal injury, with an OR (95% CI) of 77.0 (13.5-440.0). H. pylori infection, itself, did not show any significant effect on the aspirin-induced mucosal injury after adjusting for gastric acid secretion.

CONCLUSIONS

This study has demonstrated that aspirin-induced gastropathy is directly associated with gastric acid secretion. In addition, it also suggested that the gastric acid secretion level modulates the association between H. pylori infection and aspirin-induced gastropathy.

Non-invasive testing for Helicobacter pylori in patients hospitalized with peptic ulcer hemorrhage: a cost-effectiveness analysis

PURPOSE

Guidelines recommend routine invasive screening for Helicobacter pylori in patients with peptic ulcer hemorrhage (PUH). However, compliance with screening remains suboptimal. The aim of this study was to determine if a simplified approach based on noninvasive screening is cost effective in PUH.

RESULTS

In the base case, post-endoscopy urea breath test (UBT) dominated the invasive testing with 34 fewer hemorrhages and cost savings of $406,600 in a cohort of 10,000 patients. When compliance with invasive testing decreases to 60%, post-endoscopy UBT leads to 109 fewer hemorrhages and cost savings of $1,089,600. The invasive strategy becomes the preferred choice if the sensitivity of UBT reduces to <75%, such as in patients taking proton-pump inhibitors (PPI) before hospitalization.

CONCLUSIONS

Post-endoscopy UBT is cost effective in PPI-naïve patients presenting with PUH. This strategy, once prospectively validated, can prove to be a preferred approach in institutions where compliance with invasive testing is suboptimal.

Investigation of Helicobacter pylori in tonsillary tissue with Pronto Dry test and pathologic examination

OBJECTIVE

The objectives of this clinical study were to identify, by means of the Pronto Dry test and pathologic examination, Helicobacter pylori (HP) in tonsillary tissue and to establish the role of HP in tonsillary microbiology by identifying that bacterium in the tonsillary mucosa or within the tonsil core.

METHODS

The subjects consisted of 52 patients (25 men and 27 women; age range, 3-65 years; mean age, 15.1+/-14.5 years) who were scheduled to undergo tonsillectomy for the treatment of chronic tonsillitis and who had not been treated with an antibiotic or a bismuth-containing compound for 6 months before the initiation of the study. In each patient, two specimens (one 4 mm x 4 mm tissue sample from the nonmucosal tonsil core and one 4 mm x 4 mm sample of mucosal tissue) were excised from both tonsils immediately after tonsillectomy. The specimens were placed in the Pronto Dry test kit, and the test results were obtained 1 h later. The remaining tonsillary tissues were submitted for pathologic analysis via hematoxylin-eosin stain, Giemsa stain, Warthin-Starry silver stain, and staining for inducible nitric oxide synthase (iNOS).

RESULTS

The results of the Pronto Dry test were positive for HP in 42% (n=22) of the excised mucosal tissue and in 47% (n=24) of the excised core tissue. In 27% (n=14) of the patients, both the core and the mucosal tissues tested positive for HP. There was no significant difference between the positive Pronto Dry test ratios of the biopsies obtained from the mucosa and those obtained from the core (P=0.693). iNOS staining showed that macrophage iNOS activity was significantly higher (P=0.025) in biopsied mucosal tissues with a positive Pronto Dry test result than in those with a negative result. Light microscopy revealed no HP in samples stained with hematoxylin-eosin stain, Giemsa stain, or Warthin-Starry silver stain.

CONCLUSION

Positive Pronto Dry test results and the results of iNOS staining showed that HP contributes to chronic tonsillitis, especially at the mucosal layer. Although HP does not colonize, it contributes to the chronic tonsillary inflammatory process as a triggering agent by affecting macrophages in the tonsil and thus increasing iNOS expression.

Association of Helicobacter pylori infection and giardiasis: Results from a study of surrogate markers for fecal exposure among children

AIM: To investigate whether Helicobacter pylori (H pylori) infection is associated with hepatitis A virus (HAV) infection, presence of enteroparasites, and other surrogates of fecal exposure.

METHODS: We conducted a cross-sectional study in 121 children consecutively admitted at a pediatric hospital in Salvador, Brazil. H pylori and HAV infection were identified by the presence of serum antibodies. Stool specimens were examined for the presence of ova and parasites. A structured questionnaire inquiring about sanitary conditions and life style was applied to each subject.

RESULTS: Fifty-one of the 121 children (42.1%) were found to be seropositive for H pylori, and 45 (37.2%) for HAV. The seroprevalence of H pylori and HAV both increased significantly with age. Cross-tabulation of data showed that 26 (21.5%) were seropositive and 51 (42.1%) were negative for both H pylori and HAV antibodies (χ² = 7.18, OR = 2.8, CI 1.30-5.97). The age adjusted OR for an HAV-infected child being H pylori positive was 2.3 (CI 1.02-5.03). The agreement between H pylori and HAV seropositivity was fair (κ = 0.24). After controlling for possible confounding, the variables remaining independently associated with seropositivity to H pylori were age, presence of Giardia lamblia in feces (OR = 3.2, 95%CI, 1.1-9.5) and poor garbage disposal quality (OR = 2.4, 95%CI, 1.1-5.1).

CONCLUSION: Our data suggest that H pylori infection is associated with surrogate markers of fecal exposure. Thus, we conclude that the fecal-oral route is relevant in the transmission of HP among children in an urban setting of a developing country. The association observed between G. lamblia and H pylori infection may have several explanations. Further studies to investigate this relationship are warranted.

Cost-effectiveness of population screening for Helicobacter pylori in preventing gastric cancer and peptic ulcer disease, using simulation

OBJECTIVES

To evaluate the cost-effectiveness of population screening for Helicobacter pylori in preventing gastric cancer and peptic ulcer disease in England and Wales.

METHODS

A discrete event simulation model used parameter estimates, derived from peer-reviewed literature, routine data and statistical modelling. Population screening was compared with no screening but with opportunistic eradication in patients presenting with dyspepsia. Costs included screening, eradication and costs averted to provide costs per life years saved (cost/LYS) for preventing gastric cancer and peptic ulcer disease. Sensitivity analyses were undertaken.

RESULTS

The cost/LYS from screening at age 40 years was Uk pounds 5860 at discount rates of 6%. The outcomes were sensitive to H. pylori prevalence, the degree of opportunistic eradication, the discount rate, the efficacy of eradication on gastric cancer risk, the risk of complicated peptic ulcer disease and gastric cancer associated with H. pylori infection, and the duration of follow-up. In sensitivity analyses, the cost/LYS rarely exceeded UK pounds 20000 over an 80-year follow-up, but did for shorter periods.

CONCLUSIONS

H. pylori screening may be cost-effective in the long term. However, before screening can be recommended further evidence is needed to resolve some of the uncertainties, particularly over the efficacy of eradication on risk of gastric cancer, the risk associated with complicated peptic ulcers, and the effect of more widespread opportunistic testing of patients with dyspepsia.

Diagnostic accuracy of serological kits for Helicobacter pylori infection with the same assay system but different antigens in a Japanese patient population

Helicobacter pylori infection is thought to be a causal risk factor for gastric carcinoma. Recently, diagnostic accuracy of serological kits for H. pylori infection that were made in Western countries has been reported to be lower when used among Oriental populations. Diagnostic accuracy of two serological kits [HM-CAP and HM-CAP with antigens extracted from clinically isolated Japanese H. pylori strains (J-HM-CAP)] was investigated in 440 samples from a Japanese patient population by using the (13)C-urea breath test as gold standard. According to the original optimal cut-off value, HM-CAP provided 87.5 % sensitivity and 84.8 % specificity with 86.8 % accuracy and J-HM-CAP provided 95.5 % sensitivity and 81.9 % specificity with 92.3 % accuracy. This study suggests that antigens from HM-CAP are satisfactory for examining a Japanese patient population, but that using local antigens improves accuracy.

Helicobacter pylori strains expressing the vacuolating cytotoxin interrupt phagosome maturation in macrophages by recruiting and retaining TACO (coronin 1) protein

Recent evidence suggests that persistence of Helicobacter pylori can be explained, at least in part, by the failure of macrophages to kill bacteria. The fate of type 1 H. pylori strain LC11, which expresses the cag pathogenicity island (PAI) and the vacuolating cytotoxin, and type 2 strain LC20, which lacks both these virulence factors, was determined following infection of the murine macrophage cell line RAW 264.7 or the human macrophage-like cell line THP-1. Helicobacter pylori strain LC11 displayed enhanced survival in macrophages in comparison with strain LC20 (4.0 +/- 0.2 versus 2.1 +/- 0.6 log CFU ml-1, P < 0.01) at 24 h. Phagosomes containing strain LC11 showed reduced co-localization with LysoTracker Red, higher levels of expression of the early endosome marker EEA1 expression and lower expression of the late endosome/lysosome marker LAMP1 relative to internalized strain LC20, both at 2 h and 24 h. These findings indicate that, in contrast to strain LC20, strain LC11 resides in a compartment with early endosome properties and does not fuse with lysosomes. In addition, phagosomes containing LC11 recruited and retained a higher percentage of TACO (coronin 1) protein in comparison with phagosomes containing strain LC20. Furthermore, IFN-gamma stimulation facilitated maturation of phagosomes containing strain LC11 in association with the release of TACO and a reduction in bacterial survival. We have demonstrated through the use of isogenic cagA-, cagE-/picB- and vacA- mutant strains, that VacA plays a significant role in the interruption of the phagosome maturation. Taken together, these results indicate that, following phagocytosis, H. pylori strains expressing the vacuolating cytotoxin arrest phagosome maturation in association with the retention of TACO.

The cost-effectiveness of competing strategies for the prevention of recurrent peptic ulcer hemorrhage

OBJECTIVE

Several strategies exist for the prevention of recurrent ulcer-related hemorrhage, yet the cost-effectiveness has not been evaluated and remains uncertain. The aim of this study was to compare the cost-effectiveness of competing management strategies considering both nonsteroidal anti-inflammatory drugs status and the accuracy of Helicobacter pylori (H. pylori) testing.

METHODS

Decision analysis was used to compare the cost-per-recurrent hemorrhage prevented for 11 strategies over 1 yr. Clinical and costs estimates were derived from a systematic review of the medical literature and the Medicare Fee Schedule and Drug Topics Redbook. Sensitivity analyses were performed for important variables.

RESULTS

The test/retest eradication strategy with maintenance proton pump inhibitor therapy for H. pylori-negative patients was most effective (prevention of recurrence in 96.0%). The test/retest eradication strategy with maintenance histamine-2 receptor antagonist therapy for H. pylori-negative patients was least costly ($1070). The test/retest strategies were dominant with average cost-effectiveness ratios of $1118-1310/recurrent hemorrhage prevented with maintenance antisecretory therapy. The average cost-effectiveness ratios for "selective" H. pylori eradication strategies with maintenance antisecretory therapy were $1263-1673. The model was robust to varying estimates over prespecified ranges.

CONCLUSIONS

Test/retest strategies for H. pylori are cost-effective for the prevention of recurrent ulcer-related hemorrhage because they maximize H. pylori detection and eradication, resulting in fewer recurrent hemorrhages and fewer patients requiring antisecretory therapy.

Helicobacter pylori is a risk factor for peptic ulcer disease in cirrhotic patients. A meta-analysis

BACKGROUND

Peptic ulcer disease is highly prevalent in cirrhosis, and ulcer complications are a major cause of morbidity in these patients. Helicobacter pylori infection is considered the chief aetiological factor of ulcer disease. However, in cirrhotic patients the role of H. pylori in the pathogenesis of peptic ulcer remains uncertain.

AIM

To evaluate the evidence of the pathogenic role of H. pylori infection in peptic ulcer disease in patients with cirrhosis.

MATERIALS AND METHODS

An extensive MEDLINE search of the literature was performed. Studies reporting the prevalence of H. pylori infection in cirrhotic patients with and without ulcers were selected. Meta-analysis was conducted using RevMan 4.0.3. Pooled odds ratios were calculated for each comparison, using a fixed model analysis.

RESULTS

The search identified seven studies with a total of 976 patients with cirrhosis (275 cases with ulcer disease and 701 controls). The prevalence of H. pylori infection in patients with peptic ulcer disease was higher than in those without. The pooled odds ratio was 2.70 (95% CI, 1.91-3.82). H. pylori infection was associated more or less equally with duodenal and gastric ulcers.

CONCLUSION

H. pylori infection increases the risk of peptic ulcer disease in patients with cirrhosis.

The cost-effectiveness of population Helicobacter pylori screening and treatment: a Markov model using economic data from a randomized controlled trial

BACKGROUND

Economic models have suggested that population Helicobacter pylori screening and treatment may be a cost-effective method of reducing mortality from gastric cancer. These models are conservative as they do not consider that the programme may reduce health service peptic ulcer and other dyspepsia costs. We have evaluated the economic impact of population H. pylori screening and treatment over 2 years in a randomized controlled trial and have incorporated the results into an economic model exploring the impact of H. pylori eradication on peptic ulcer disease and gastric cancer.

METHODS

Subjects between the ages of 40 and 49 years were randomly invited to attend their local primary care centre. H. pylori status was evaluated by (13)C-urea breath test and infected individuals were randomized to receive omeprazole, 20 mg b.d., clarithromycin, 250 mg b.d., and tinidazole, 500 mg b.d., for 7 days or identical placebos. Economic data on health service costs for dyspepsia were obtained from a primary care note review for the 2 years following randomization. These data were incorporated into a Markov model comparing population H. pylori screening and treatment with no intervention.

RESULTS

A total of 2329 of 8407 subjects were H. pylori positive: 1161 were randomized to receive eradication therapy and 1163 to receive placebo. The cost difference favoured the intervention group 2 years after randomization, but this did not reach statistical significance (11.42 ponds sterling per subject cost saving; 95% confidence interval, 30.04 ponds sterling to -7.19 pounds sterling; P=0.23). Analysis by gender suggested a statistically significant dyspepsia cost saving in men (27.17 ponds sterling per subject; 95% confidence interval, 50.01 pounds sterling to 4.32 pounds sterling; P=0.02), with no benefit in women (-4.46 per subject; 95% confidence interval, -33.85 pounds sterling to 24.93 pounds sterling). Modelling of these data suggested that population H. pylori screening and treatment for 1,000,000 45-year-olds would save over 6,000,000 pounds sterling and 1300 years of life. The programme would cost 14, 200 pounds sterling per life year saved if the health service dyspepsia cost savings were the lower limit of the 95% confidence intervals and H. pylori eradication had only a 10% efficacy in reducing mortality from distal gastric cancer and peptic ulcer disease.

CONCLUSIONS

Modelling suggests that population H. pylori screening and treatment are likely to be cost-effective and could be the first cost-neutral screening programme. This provides a further mandate for clinical trials to evaluate the efficacy of population H. pylori screening and treatment in preventing mortality from gastric cancer and peptic ulcer disease.

Interactions between Helicobacter pylori and other risk factors for peptic ulcer bleeding

AIM

To investigate the role of Helicobacter pylori, expressing the virulence marker CAGA (cytotoxin associated gene product A) in ulcer complications and its interaction with nonsteroidal anti-inflammatory drugs (NSAIDs) and other risk factors.

DESIGN

Case control study using conditional logistic regression analysis.

SETTING

University and City Hospitals, Nottingham.

SUBJECTS

203 consecutive patients with ulcer bleeding and 203 age- and sex-matched controls.

RESULTS

Ulcer bleeding was more likely with positive H. pylori serology (odds ratio = 3.3, 95% CI: 1.7--6.6 for CagA positive, but only OR = 1.6, 95% CI: 0.7-3.7 for CagA negative serology), current smoking (OR 2.2, 95% CI: 1.04-4.7), aspirin < or = 300 mg daily (OR 7.7, 95% CI: 2.8-20.6), all other nonsteroidal anti-inflammatory drugs (NSAIDs: OR 10.6, 95% CI: 3.1-35.7 for < or = 1 defined daily dose lower and OR 22.6, 95% CI: 6.2-82.0 for higher doses) and past ulcer history (OR 5.6, 95% CI: 2.3-14.1). Aspirin < or = 300 mg daily was used by 25.1% of patients vs. 7.4% of controls. Smoking only enhanced risk in the presence of H. pylori, with a synergistic interaction (interaction odds ratio = 4.9, 2.4-9.9, P=0.002). Conversely, risks with non-aspirin NSAIDs were reduced in the presence of H. pylori, particularly if CagA-positive (interaction odds ratio=0.21, 0.05-0.9, P=0.03).

CONCLUSIONS

CagA positive H. pylori infection is associated with an increased risk of ulcer bleeding. The risk from non-aspirin NSAIDs is even higher, but is less in H. pylori infected people. Low-dose aspirin is now commonly associated with ulcer bleeding.

Helicobacter pylori and tonsillectomy

Tonsillar tissue is a component of mucosa-associated lymphoid tissue (MALT), which has evolved to protect vulnerable mucosal surfaces. Helicobacter pylori, implicated as an aetiological factor in duodenal ulcers and gastritis, induces the appearance of lymphoid aggregates (MALT) in the stomach. This organism is cytotoxic via a nitric oxide synthase cascade. The possibility that tonsillar tissue processes Helicobacter pylori or that Helicobacter pylori can colonize the palatine tonsils is explored. The study design was that of a prospective study. We determined if Helicobacter pylori (i) forms part of the normal microenvironment of the tonsil, (ii) plays a role in the pathogenesis of tonsillitis and (iii) is associated with increased expression of inducible nitric oxide synthase (iNOS) in macrophages of the tonsil. Serology for Helicobacter pylori was performed on 50 patients undergoing tonsillectomy. Tonsillar specimens were monitored for urease activity by CLO test (a sealed plastic slide holding an agar gel, which contains urea and detects the urease enzyme of Helicobacter pylori), and immunocytochemically probed for Helicobacter pylori and iNOS expression. The mean age of this patient group was 17.2 years (3-36 years). Fourteen (28%) were sero-positive for Helicobacter pylori but no evidence of this pathogen was found in any tonsillar specimen. The number of macrophages staining for iNOS, per field, under a magnification of x40, was increased in sero-positive patients (13.3 +/- 1.3 versus 9.9 +/- 0.7; P = 0.01). Helicobacter pylori does not appear to colonize the tonsil. We believe that Helicobacter pylori primes the tonsils by inducing macrophage iNOS expression. The higher expression in sero-positive patients is a reflection of a pro-inflammatory reaction to Helicobacter pylori that is both local and systemic.

New immunoassay for the detection of Helicobacter pylori infection compared with urease test, 13C breath test and histology: validation in the primary care setting

Helicobacter pylori plays a major role in peptic ulcer disease and, as a result, testing for H. pylori infection among patients with dyspepsia has often been advocated. The aim of the study was to determine the diagnostic accuracy, the analytical performance, and optimal cut-off point of a new serological assay, the Pyloriset EIA-G III for the detection of H. pylori infection in the primary care setting. For 113 primary care patients with dyspepsia urea breath test, CLO test, histology and serology tests were performed. Diagnostic accuracy of the Pyloriset EIA-G III was evaluated against a reference standard of a carbon urea breath test (CUBT), CLO test and histology (from gastric biopsies). Precision, linearity and correlation of the serological assay with the CUBT and former Pyloriset were also determined. At the optimal cut-off level of 40 U/ml, the positive predictive value was 92.1%, negative predictive value 96.3%, sensitivity 87.5%, and specificity 93.9%. The within-run precision was high. The recovery data were good. The correlation of both CUBT and the former Pyloriset EIA-G and the Pyloriset EIA-G III was high. At the cut-off level of 40 U/ml, the new Pyloriset EIA-G III is a reliable method to detect H. pylori infection in the primary care setting.

Evaluation of five commercial serological tests for the detection of Helicobacter pylori infection in Chinese

BACKGROUND

Commercial serological tests for the detection of Helicobacter pylori infection must be locally validated. We evaluated the accuracy of five commercial tests in the Chinese population.

METHODS

Serum samples were collected from patients referred for upper endoscopy. Antral biopsies were taken for histological examination and culture of H. pylori. The gold standard for diagnosing H. pylori infection was positive histological staining and/or positive H. pylori culture. The serum samples were tested for H. pylori antibodies using the following tests: (i) Cobas Core Anti-H. pylori EIA; (ii) GAP IgG; (iii) GAP IgM; (iv) H. pylori microwell EIA (Quidel); and (v) Premier H. pylori. The sensitivity, specificity and accuracy of each test was calculated according to the manufacturers' instructions or according to a new cut-off value.

RESULTS

A total of 158 patients were recruited amongst whom 114 (72%) were H. pylori-positive. Indeterminate results varied from 7% to 19%. The accuracy of the tests varied from 57% to 85%. By using new cut-off values, the accuracy was much improved, ranging from 73.4% to 86.7%.

CONCLUSIONS

By defining new cut-off values for the Chinese population, we were able to improve the performance of some of the serology tests. This illustrates the importance of local validation.

Validation of serological tests forHelicobacter pylori infection in an Irish population

BACKGROUND

Serological tests for Helicobacter pylori using laboratory and 'office' formats are commonly used, easy to perform, inexpensive and widely available. Local validation of test performance is required.

AIMS

This study examined the performance of a laboratory and 'office' ELISA in a population of Irish dyspeptics presenting for endoscopy.

METHODS

Consecutive patients presenting for endoscopy had blood drawn at sedation. Samples were analysed using two ELISA formats; a standard laboratory format and an 'office' ELISA test card. H. pylori infection was diagnosed by analysis of antral and corpus biopsies using the rapid urease test, culture and histology. A combination of two positive invasive tests was considered indicative of infection.

RESULTS

The sensitivity and specificity of laboratory ELISA was 82.4% and 85% respectively while the values for the 'office' ELISA were 87.7% and 85.7% respectively. In patients under 45 years sensitivities and specificities of the 'office' test exceeded 90%. The two serological tests agreed in 87.5% of subjects.

CONCLUSIONS

Both tests performed satisfactorily. However, indeterminate results impaired the usefulness of the laboratory ELISA particularly when using a new cut-off. The 'office' ELISA performed particularly well in young patients. A simpler test using antigens from locally prevalent strains to optimise accuracy is awaited.

The cost-effectiveness of diagnostic testing strategies for Helicobacter pylori

OBJECTIVE

Several noninvasive methods are now available for diagnosing Helicobacter pylori infection. Because the prevalence of H. pylori infection is variable in patients requiring testing, the optimal testing strategies may vary under different conditions. The aim of this study was to evaluate the cost-effectiveness of competing diagnostic strategies for H. pylori in patients with varying H. pylori prevalence.

METHODS

A decision analysis was performed comparing the costs per number of correct diagnoses achieved by alternative sequential testing strategies. Estimates of H. pylori prevalence and test characteristics were derived from a systematic review of the MEDLINE bibliographic database. Cost estimates were derived from the 2000 Medicare Fee Schedule.

RESULTS

The enzyme-linked immunosorbent assay (ELISA) test had the lowest cost per correct diagnosis at low (30%), intermediate (60%), and high (90%) prevalence ($90-$95/correct diagnosis), but its diagnostic accuracy was low (80-84%). At low and intermediate prevalence the stool test was more accurate (93%), with an average cost of $126-$127 per correct diagnosis. Additional confirmatory testing of positive or negative tests increased the diagnostic accuracy of the stool test, but had high incremental costs. ELISA testing was preferable when prevalence rates were very high (90%), and using a confirmatory urea breath test for negative ELISA tests increased the diagnostic accuracy to 96%, with modest incremental costs. If the cost of the breath test was <$50 or if the cost of the stool test is >$82, breath testing became preferable to stool testing. If the cost of the stool test fell to <$20, it became preferable to ELISA. Similarly, if the cost of the ELISA serology was >$39 then stool testing became preferable at all prevalence rates. Fingerstick whole blood tests were not cost-effective.

CONCLUSIONS

The choice of an initial test for H. pylori detection depends on the prevalence of H. pylori infection and the value placed on increased diagnostic accuracy. Although ELISA results in the lowest cost-effectiveness ratios, in patients at low-intermediate pretest probability of infection, the stool test provides increased accuracy, with modest incremental costs.

Modified rapid urease test for Helicobacter pylori detection in relation to an immunohistochemical stain

BACKGROUND

The rapid urease test and touch cytology have been used for the rapid detection of Helicobacter pylori infection. Recently, a modified rapid urease (MRU) test, which provides results in 20 min has been available on a commercial basis. To date, few reports have evaluated the accuracy of this test. This study evaluated the sensitivity, specificity, and accuracy of the MRU test and touch cytology to detect H. pylori in relation to the density of H. pylori infection determined semi-quantitatively by using immunohistochemical stains.

METHODS

Biopsy specimens obtained from a total of 60 patients who underwent endoscopy for evaluation of gastroduodenal diseases were studied by using the MRU test, Giemsa stain for touch smear tissue and histological methods. An immunohistochemical stain was used as a standard, and the density of H. pylori infection was graded according to the number of individual bacteria seen as follows: grade 0 = 0; grade 1+ = 1-9; grade 2+ = 10-29; grade 3+ = 30-99; grade 4+ > or = 100. The severity of gastritis was evaluated histologically in each specimen and compared with the density of H. pylori infection.

RESULTS

The MRU test had an overall sensitivity of 73%, specificity of 100% and accuracy of 85%. The Giemsa stain had a sensitivity of 91%, specificity of 100% and accuracy of 95%.The sensitivities of the MRU test and Giemsa stain decreased in mild H. pylori infection. In the MRU test, the sensitivity was 47% when the density of H. pylori infection was 1+, while 80-100% sensitivities were obtained when the densities of infection were > or = 2+. With the Giemsa stain, the sensitivity was 80% when the density was 1+, while the sensitivity increased to 100% when the densities were > or = 2+. The severity of gastritis determined by the Rauws scores showed a positive correlation with the density of H. pylori infection as evaluated by immunohistochemical staining.

CONCLUSIONS

The MRU test had high sensitivity and specificity for moderate to severe H. pylori infection, but it may result in false-negative results in tests for mild infection. As the MRU test has the advantages of shorter incubation times and low cost, a combination of the MRU test and the Giemsa stain for touch cytology may be the most time- and cost-efficient tests in a clinical setting for the diagnosis of H. pylori infection.

Western blotting is useful in the salivary diagnosis of Helicobacter pylori infection

BACKGROUND

The salivary diagnosis of Helicobacter pylori infection offers attractive possibilities for the epidemiological study of infection in children. Salivary enzyme linked immunosorbent assay (ELISA) is less reliable then serum ELISA, owing to variable transudation of immunoglobulin. In addition, children are more difficult to study because of lower specific serum antibody concentrations to H pylori. The performance of salivary western blotting in comparison with serum western blotting and serum ELISA was investigated in school children.

SUBJECTS AND METHODS

Paired serum and saliva specimens were obtained from 669 [corrected] school children aged 9-11 in 10 British towns. All saliva and serum specimens were first analysed by ELISA; subsequently, western blotting of both specimens was performed on 31 and 34 specimens, respectively, to establish the criteria for positivity for western blotting. The remaining 121 specimens were then tested blindly and saliva was compared with the serum.

RESULTS

The sensitivity and specificity of salivary ELISA in the 669 [corrected] specimens was 32 of 50 (64%) and 530 of 619 (86%) [corrected], respectively, when compared with serum ELISA. The western blotting validation was performed on 28 subjects with positive serum and positive salivary ELISA, 28 saliva positives with negative serum, 16 saliva negatives with positive serum, and 50 doubly negative subjects. Compared with serum western blots, the sensitivity and specificity of salivary western blots was 38 of 47 (81%) and 68 of 75 (91%), respectively. Using serum ELISA as the gold standard, the sensitivity and specificity were 32 of 44 (73%) and 72 of 78 (92%), respectively, the specificity being significantly higher than salivary ELISA (p < 0.001).

CONCLUSION

Salivary western blotting for IgG is useful in the diagnosis of H pylori infection and is superior to ELISA. It also permits the identification of pathogenic strains.

Insufficient diagnostic accuracy of imported serological kits for Helicobacter pylori infection in Japanese population

Although there are many reports of the high diagnostic accuracy of commercially available serologic kits for Helicobacter pylori infection in Western countries, they rarely has been investigated in oriental population. Accordingly we examined their usefulness in 492 Japanese patients with dyspeptic symptoms. Diagnostic accuracy of 4 imported serologic kits (HEL-p TEST, HM CAP, G.A.P IgG, Helico G2) was investigated using the (13)C-urea breath test as the gold standard. When intermediate results were excluded, the sensitivity, specificity and accuracy of these serologic tests ranged from 88.6% to 97.8%, 67.9% to 85.9%, and 87.9% to 91.4%, respectively, which were comparable with reported median accuracy in the Western population. However, there were many intermediate results in these tests, ranging from 5.3% to 23.0%. Their usefulness seemed to be limited in our patient population because of the large number of intermediate results.

Treatment of Helicobacter pylori infection in clinical practice in the United States: results from 224 patients

Our objectives were to define treatment success, compliance, and side effects for treatment of Helicobacter pylori in clinical practice. In all, 224 consecutive patients received Helicobacter pylori treatment: 97 received two weeks of bismuth subsalicylate, metronidazole, tetracycline four times a day with a H2-receptor antagonist twice a day (BMT); 89 received one week of metronidazole, lansoprazole, and clarithromycin twice a day (MLC); and 38 received one week of BMT with lansoprazole twice a day (BMT-PPI). Cure rates were: BMT 81% (95% CI 74-89%), MLC 90% (95% CI 84-96%) BMT-PPI 87% (95% CI 81-92%). More patients prescribed a bismuth-based regimen discontinued medications due to side effects compared to MLC (P = 0.049). Nausea was more common for BMT compared to MLC (P = 0.04). In conclusion, treatment of Helicobacter pylori infection with a one-week course of MLC achieves a high rate of cure in clinical practice. Significantly fewer patients prescribed PPI-based therapy discontinue medications due to side effects as compared to bismuth-based triple therapy.

Nitric oxide synthetase and Helicobacter pylori in patients undergoing appendicectomy

BACKGROUND: This study was designed to determine whether Helicobacter pylori forms part of the normal microenvironment of the appendix, whether it plays a role in the pathogenesis of acute appendicitis, and whether it is associated with increased expression of inducible nitric oxide synthetase (iNOS) in appendicular macrophages. METHODS: Serology for H. pylori was performed on 51 consecutive patients undergoing emergency appendicectomy. Appendix samples were tested for urease activity, cultured and stained for H. pylori, graded according to the degree of inflammatory infiltrate, and probed immunohistochemically for iNOS expression. RESULTS: The mean age of the patients was 21 (range 7-51) years. Seventeen patients (33 per cent) were seropositive for H. pylori but no evidence of H. pylori was found in any appendix specimen. However, an enhanced inflammatory cell infiltration was observed in seropositive patients (P < 0.04) and the expression of macrophage iNOS in the mucosa of normal and inflamed appendix specimens was increased (P < 0.01). CONCLUSION: H. pylori does not colonize the appendix and is unlikely to be a pathogenic stimulus for appendicitis. Priming effects on mucosal immunology downstream from the foregut may occur after infection with H. pylori.

How useful is the detection kit for antibody to Helicobacter pylori in urine (URINELISA) in clinical practice?

OBJECTIVE

Increased knowledge of the significance of Helicobacter pylori (H. pylori) infection in gastric disorders has accelerated the trend of screening patients with dyspepsia for its infection. Serological examination of antibody for H. pylori has been widely performed. Recently, a urine-based enzyme-linked immunosorbent assay (URINELISA) kit for detection of antibody for H. pylori has been developed. Accordingly, we evaluated its diagnostic accuracy in clinical practice.

METHODS

Subjects of this study were 132 patients who presented at our university hospital because of dyspeptic symptoms (81 men, 51 women; age, 41.5+/-1.4 yr). 13C urea breath test, blood drawing for serological antibody for H. pylori infection by four different kits, and urine collection for the URINELISA test for detection of the antibody were performed. Diagnostic accuracy of the commercially available antibodies in serum and in urine were investigated using the results of the 13C urea breath test as the gold standard.

RESULTS

Sensitivity, specificity, and accuracy of URINELISA were 86.3% (95% confidence intervals [CI], 76-93%), 91.5% (95% CI, 81-97%), and 88.6% (95% CI, 82-93%), respectively, which were comparable to those of imported serological kits.

CONCLUSIONS

The URINELISA kit for detecting anti-H. pylori antibody in urine provides diagnostic accuracy comparable to that of imported kits for detecting antibodies in serum and is considered to be clinically useful for the diagnosis of H. pylori infection.

Use of a dried plasma collection card for simplified diagnosis of Helicobacter pylori infection

OBJECTIVES

To compare testing for Helicobacter pylori IgG antibodies using a dried plasma collection card device with specimens obtained by venepuncture.

METHODS

Eighty-four patients underwent testing for H. pylori IgG antibodies by venepuncture and by fingerstick using a single drop of blood placed on each of two dried plasma collection card devices. The correlation of venepuncture results to dried plasma card results was assessed.

RESULTS

There was a high degree of correlation of EIA results between venepuncture and dried plasma card specimens (r=0.98). The qualitative result of the first dried plasma card and venepuncture specimen testing differed in 7 of 84 patients and for the second dried plasma card differed in 7 of 82 patients. The first dried plasma card was 93% sensitive and 100% specific and the second was 93% sensitive and 98% specific as compared to the venepuncture result. There was a high degree of correlation between the first and second dried plasma cards (r=0.996).

CONCLUSIONS

The dried plasma collection card has adequate sensitivity and excellent specificity as compared to venepuncture specimens and is a feasible alternative for H. pylori IgG antibody testing.

Serologic screening before endoscopy: the value of Helicobacter pylori serology, serum recognition of the CagA and VacA proteins, and serum pepsinogen I

BACKGROUND

We wanted to assess the diagnostic value of pre-endoscopy screening by Helicobacter pylori serology, serum recognition of the CagA and VacA proteins, and serum pepsinogen I levels (sPGI) in patients up to 55 years of age with uncomplicated simple dyspepsia.

METHODS

Consecutive dyspeptic patients referred for open-access endoscopy, excluding patients with alarm symptoms, recent intake of acid suppressants, or ingestion of non-steroidal anti-inflammatory drugs. H. pylori status was determined by histology and urease testing. H. pylori serologic status was determined with the enzyme-linked immunosorbent assay (ELISA) and Western blotting, serum recognition of CagA and VacA with Western blot, and sPGI levels by radioimmunoassay.

RESULTS

One hundred and fifteen patients were studied (mean age, 40 years: range, 20-55 years), of whom 58 were H. pylori-positive in biopsy-based tests. Twenty-one patients (18%) had significant gastroduodenal lesions (erosions, ulcers, or cancer). The sensitivity (specificity) of the ELISA (optimized) and Western blot in determining H. pylori status was 94.8% (89.5%) and 100% (96.4%), respectively. Screening strategies based on the ELISA or Western blot for determining H. pylori serologic status would have detected 95% or 100% of significant lesions, respectively, and each 'saved' 47% of endoscopies for simple dyspepsia. Serum recognition of the CagA protein would have detected 95% of significant lesions and 'saved' 55% of endoscopies, whereas recognition of the VacA protein would have detected only 81% of the lesions. Screening by H. pylori serology plus a 'low' (<55 ng/ml) or 'high' sPGI (>125 ng/ml) would detect only 57% of significant lesions, although the only case of cancer was included in the hypopepsinogenaemic subgroup of just 11 patients.

CONCLUSIONS

In patients with uncomplicated, simple dyspepsia up to 55 years of age, screening by H. pylori serology identified 95%-100% of patients with significant gastroduodenal lesions while potentially saving 46.9% of endoscopies. Serum recognition of the CagA protein identified 95% of lesions and would have saved an additional number of endoscopies (7.9%) compared with basic serology. Measurement of sPGI was of limited diagnostic value.

New immunological assays for the diagnosis of Helicobacter pylori infection

There are several types of immunological tests available for the diagnosis and management of Helicobacter pylori infection. Most commercially available serological kits use the enzyme linked immunosorbent assay (ELISA) test format. Originally the kits used crude antigen preparations although many of the newer kits use a more purified antigen preparation, with often increased specificity but lower sensitivity. Near patient test kits are based either on latex agglutination or immunochromatography. Generally they have low sensitivities compared with laboratory tests. Western blotting, ELISA, and recombinant immunoblot assays (RIBA) have also been developed into commercially available kits and can be used to indicate the presence of specific virulence markers. An antigen detection kit has been developed for the detection of Helicobacter pylori in faeces. Immunological reagents have also been combined with other diagnostic modalities to develop immunohistochemical stains and DNA immunoassays. Helicobacter pylori is now recognised as the cause of gastritis and most cases of peptic ulcer disease (PUD); its long term carriage increases the risk of gastric adenocarcinoma sixfold and it is designated as a class I carcinogen. H pylori has also been implicated as a cause of gastric mucosa associated lymphoid tissue lymphomas. Its relation to non-ulcer dyspepsia remains controversial. Additionally, long term carriage of the organism may be associated with short stature in young girls and, in the general population, as a possible risk factor for the development of vasospastic disorders and possibly skin immunopathology such as urticaria. With the recognition of H pylori as an important human pathogen, it has become one of the growing number of organisms to have its complete genome sequence mapped. Serology is an important method of determining colonisation status and can be used for diagnosis, as a screening procedure, or to follow the efficacy of eradication regimens. Most serological assays are in the ELISA format although some are based on the latex agglutination reaction. These latter are used principally as near patient assays. Most assays detect IgG in serum although some detect serum IgA. More recently developed assays detect IgA in saliva and the production of affinity purified antibodies has led to the development of an antigen detection assay for faecal specimens. Serological reagents have also been used in immunocytochemistry and to speed up the detection of amplified products of the polymerase chain reaction (PCR)-DNA immunoassays.

Evaluation of three commercial enzyme-linked immunosorbent assay kits for diagnosis of Helicobacter pylori in Chinese patients

Most of the commercial serological assays for H. pylori are developed and validated in western countries. We evaluated the accuracy of three popular commercial ELISA tests for H. pylori in the Chinese population. Eighty dyspeptic patients were recruited and diagnosis of H. pylori infection was based on biopsy urease test, histology and urea breath test. Thirty-six patients (45%) were positive for H. pylori infection by two or more positive reference tests. Anti-H. pylori IgG antibody was detected by three commercial ELISA tests: GAP IgG (Bio-Rad), HM-CAP (Enteric Products) and Pyloriset EIA-G (Orion). The respective sensitivity, specificity, positive and negative predictive values of the three tests were: GAP IgG (50%, 97.4%, 93.8%, 71.7%), HM-CAP (72.7%, 68.4%, 66.7%, 74.3%) and Pyloriset EIA-G (75%, 86.4%, 81.8%, 80.9%). Despite the high accuracy reported in the West, the performance of these commercial serological tests was unsatisfactory when used in Chinese patients.

Clinical validation of the Helikit: a 13C urea breath test used for the diagnosis of Helicobacter pylori infection

OBJECTIVE

To assess the clinical performance of the Helikit, a 13C urea breath test, in the diagnosis of Helicobacter pylori infection.

METHODS

A total of 205 participants were assessed in Canada and Korea for H. pylori infection status by endoscopy, or a combination of IgG ELISA and CLO test, as well as by the Helikit. The Helikit contains 75 mg of 13C urea as well as citric acid, flavor enhancers and stabilizers in a single plastic cup. The powder is dissolved in 75 mL of water for oral administration. No extra mixing or dilution steps are required.

RESULTS

Using the biopsy-derived data as the gold standard the Helikit displayed a clinical sensitivity of 93.5% (95% confidence interval 88.5 to 98.5%) and a clinical specificity of 97.3% (94.3 to 100%). An overall diagnostic efficiency of 95.6% (92.8 to 98.4%) was obtained. No statistically significant difference in the performance characteristics was found between Korea and Canada. No significant adverse events were noted.

CONCLUSIONS

The Helikit offers an easy, safe and accurate approach to the diagnosis of H. pylori infection.

Non-invasive testing for Helicobacter pylori

Confirmed and potential benefits of eradicating Helicobacter pylori have led to the development of a range of diagnostic tests. As well as techniques using biopsy tissue obtained during endoscopy, a number of non-invasive tests are now available. These may be appropriate for pre-endoscopy screening of younger dyspeptics, for use in research, particularly epidemiological surveys, to confirm successful eradication after treatment, and possibly in the future for screening in asymptomatic populations. Serology requiring laboratory analysis is likely to be the least expensive option, particularly suitable for testing large numbers, while urea breath tests should yield the most accurate results and are appropriate for confirming successful eradication since only current infection is detected. The performance of near-patient tests can lack consistency, but these may be useful for small numbers and where other non-invasive testing is unavailable. Tests should be used with an awareness of their potential limitations in terms of accuracy.

Serology and urea breath test in the diagnosis of H. pylori infection

Helicobacter pylori is a chronic infection that has the potential for causing and initiating serious gastric disease. Specific treatment can be successful in eradication of the infection but is currently complex which hampers essential patient compliance. Therefore, the accurate detection of H. pylori and, importantly, the post-treatment check for cure is vital in the effective management of this infection. This is especially true in cases of asymptomatic individuals. Serology is now a simple ELISA with a high degree of accuracy and has been shown to be useful as a screening tool prior to endoscopy in selected cases. The urea breath test, either using C13 or C14, is a sensitive test easily applied and is the test of choice for post-treatment check for cure. It is also the gold standard for the validation of serology in different populations.

Evaluation of the FlexSure HP whole blood antibody test for diagnosis of Helicobacter pylori infection

OBJECTIVE

Rapid, inexpensive, reliable tests are needed to facilitate the diagnosis of Helicobacter pylori infection. We evaluated the accuracy of the new FlexSure HP whole blood test (SmithKline Diagnostics, Inc.), a rapid, qualitative in-office test for the detection of antibodies to H. pylori utilizing whole blood obtained from a fingerstick.

METHODS

Five North American sites enrolled patients not previously treated for H. pylori who underwent upper endoscopy. Patients had not received antibiotics, bismuth, or proton pump inhibitors within 4 wk before study enrollment. Bacterial infection was established by the presence of H. pylori in gastric biopsies (minimum of two) or positive rapid urease test of antral tissue. The presence of IgG antibodies was determined using FlexSure HP whole blood tests with blood obtained by fingerstick and FlexSure HP serum and ELISA (HM-CAP) tests with serum obtained from venipuncture.

RESULTS

Three hundred ninety-three patients were enrolled (56% male; mean age, 46.8 +/- 16.0 yr). H. pylori infection was present in 187 (48%). Compared with the standard of histology and rapid urease test, sensitivity for FlexSure HP whole blood, FlexSure HP serum, and HM-CAP EIA were, respectively, 84%, 90%, and 95% (p < 0.05 compared with FlexSure HP whole blood). There were no statistical differences in specificity or overall accuracy between the three tests.

CONCLUSIONS

FlexSure HP whole blood demonstrated an accuracy not significantly different from the FlexSure HP serum test but had sensitivity significantly lower than the HM-CAP EIA. FlexSure HP whole blood may be useful for in-office H. pylori diagnosis.