Evaluation of eight commercial kits for Helicobacter pylori IgG antibody detection

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.

Validation of western Helicobacter pylori IgG antibody assays in Korean adults

Helicobacter pylori infection is endemic in Korea, and serology testing is widely performed. The aim of this study was to validate and compare the diagnostic accuracy of Korean and Western serological assays for H. pylori detection in Korean adults. The 114 Korean adults who visited our centre over a 6-month period for the evaluation of H. pylori infection using the urea breath test (UBT) were enrolled in this prospective study. Anti-H. pylori IgG was measured using three commercially available immunoassays: Genedia H. pylori ELISA (Green Cross Medical Science), Chorus helicobacter IgG (DIESSE Diagnostica Senese) and Vidas H. pylori IgG (bioMérieux). Positive UBT findings were obtained in 40.6% of included subjects. The sensitivities and the specificities of Vidas, Chorus and Genedia were 89.7%, 100% and 100% and 85.5%, 75.4% and 80.7%, respectively. We found no differences in sensitivity between the Vidas and Chorus (P=0.125), Chorus and Genedia (P=0.125) and Vidas and Genedia (P=1.000) assays. There were also no differences in specificity between the Vidas and Chorus (P=0.070), Chorus and Genedia (P=0.508) and Vidas and Genedia (P=0.549) assays. In Korean adults, the Genedia H. pylori ELISA, Chorus helicobacter IgG and Vidas H. pylori IgG assays exhibited a high concurrence rate with similar diagnostic accuracy. Thus, both the Korean and Western non-invasive assays are reliable for serodiagnosis of H. pylori in Korean individuals.

Rapid detection of S. mutans surface antigen I/II using a sensitive monoclonal anti-Ag I/II antibody by ELISA

The cell-surface protein antigen I/II (Ag I/II) is expressed in oral streptococci, which are known as the causative agent of a number of diseases including dental caries, endocarditis, gingivitis, and periodontal disease. Consequently, monoclonal antibodies (MAb) capable of recognizing the streptococcal Ag I/II protein could be a useful tool for the diagnosis and cure of these diseases. In this study, a previously generated monoclonal anti-Ag I/II antibody, ckAg I/II, was used to detect a small amount of Streptococcus mutans (S. mutans) surface antigen Ag I/II. The ckAg I/II was proved to be very sensitive and able to detect as little as 1 ng of recombinant Ag I/II protein within 5 min and Ag I/II in saliva within 10 min, as well as native Ag I/II in 20 μL of culture supernatant by ELISA. These results suggest that ckAg I/II can be used as a fast and efficient diagnostic tool to detect Ag I/II.

Helicobacter pylori detection and antimicrobial susceptibility testing

The discovery of Helicobacter pylori in 1982 was the starting point of a revolution concerning the concepts and management of gastroduodenal diseases. It is now well accepted that the most common stomach disease, peptic ulcer disease, is an infectious disease, and all consensus conferences agree that the causative agent, H. pylori, must be treated with antibiotics. Furthermore, the concept emerged that this bacterium could be the trigger of various malignant diseases of the stomach, and it is now a model for chronic bacterial infections causing cancer. Most of the many different techniques involved in diagnosis of H. pylori infection are performed in clinical microbiology laboratories. The aim of this article is to review the current status of these methods and their application, highlighting the important progress which has been made in the past decade. Both invasive and noninvasive techniques will be reviewed.

Detection of anti-Helicobacter pylori antibodies in serum and duodenal fluid in peptic gastroduodenal disease

AIM: To study the diagnosis of Helicobacter pylori (H pylori) infection through the determination of serum levels of anti-H pylori IgG and IgA antibodies, and the levels of anti-H pylori IgA antibodies in duodenal fluid.

METHODS: Data were collected from 93 patients submitted to upper digestive endoscopy due to dyspeptic symptoms. The patients were either negative (group A) or positive (group B) to H pylori by means of both histological detection and urease tests. Before endoscopy, peripheral blood was collected for the investigation of anti-H pylori IgG and IgA antibodies. To perform the urease test, biopsies were obtained from the gastric antrum. For the histological evaluation, biopsies were collected from the gastric antrum (greater and lesser curvatures) and the gastric body. Following this, duodenal fluid was collected from the first and second portions of the duodenum. For the serological assaying of anti–H pylori IgG and IgA, and anti-H pylori IgA in duodenal fluids, the ELISA method was utilized.

RESULTS: The concentration of serum IgG showed sensitivity of 64.0%, specificity of 83.7%, positive predictive value of 82.0%, negative predictive value of 66.6% and accuracy of 73.1% for the diagnosis of H pylori infection. For the same purpose, serum IgA showed sensitivity of 72.0%, specificity of 65.9%, positive predictive value of 72.0%, negative predictive value of 67.4% and accuracy of 69.8%. If the serological tests were considered together, i.e. when both were positive or negative, the accuracy was 80.0%, sensitivity was 86.6%, specificity was 74.2%, positive predictive value was 74.2% and negative predictive value was 86.6%. When values obtained in the test for detecting IgA in the duodenal fluid were analyzed, no significant difference (P = 0.43) was observed between the values obtained from patients with or without H pylori infection.

CONCLUSION: The results of serum IgG and IgA tests for H pylori detection when used simultaneously, are more efficient in accuracy, sensitivity and negative predictive value, than those when used alone. The concentration of IgA antibodies in duodenal fluid is not useful in identifying patients with or without H pylori.

Changing rates of Helicobacter pylori testing and treatment in patients with peptic ulcer disease

OBJECTIVES

The aim of this study was to identify temporal trends in the rate of Helicobacter pylori (H. pylori) testing, prevalence, and treatment among patients with peptic ulcer disease in Olmsted County, MN, from 1984 through 1997.

METHODS

All 3317 Olmsted County residents with a clinical diagnosis of peptic ulcer disease at the Mayo Clinic from 1984 through 1997 were identified. The complete medical records of an age-, sex-, and calendar year-stratified random sample were reviewed (n = 720); 298 patients (41%) had confirmed peptic ulcer disease. Changes in proportions of H. pylori testing, infection, and treatment over time were analyzed by logistic regression.

RESULTS

Of the 298 patients with confirmed peptic ulcer disease, 32% were tested for H. pylori; 36% were positive for infection, of whom 66% received antibiotic therapy. The rate of testing for H. pylori increased from 0% in 1984 to 96% in 1997, but the prevalence of infection did not change (36.4% vs 36.5%). The rate of treatment of those infected increased from 0% to 95%. By logistic regression, calendar year was associated with H. pylori testing and treatment but not infection. Recent use of nonsteroidal anti-inflammatory drugs was reported by 58% of patients, and 44% presented with GI bleeding.

CONCLUSIONS

Physicians' practice of testing and treating for H. pylori in patients with confirmed peptic ulcer disease has steadily increased over the past 14 yr. However, in our study, only 36% of these patients were infected with H. pylori, whereas the majority used nonsteroidal anti-inflammatory drugs (NSAIDs). Therefore, testing seems to be more appropriate than empiric treatment in patients with peptic ulcer disease.

[Evaluation of enzyme-linked immunosorbent assay for the diagnosis of Helicobacter pylori infection in children and adolescents]

BACKGROUND

Helicobacter pylori infection is recognized as the most frequent cause of chronic gastritis in adults and children. The diagnosis is accomplished with invasive methods in fragments of endoscopic gastric biopsies and non-invasive methods. The enzyme-linked immunosorbent assay constitutes a simple, fast exam and of low cost with high sensibility in adult patients.

AIM

The purpose of this study was to evaluate the ELISA method for the infection diagnosis for Helicobacter pylori in children and adolescents using the Cobas Core II kit (Roche). Helicobacter pylori was positive when the rapid urease test and the histology were both positive or when the culture was positive and Helicobacter pylori negative when all the tests were negative.

PATIENTS/METHODS

Eleven hundred patients were studied, their age ranged from 3 months and 16 years, (mean = 8y 7m +/-; 4.0; median = 9y 5m). Helicobacter pylori infection was diagnosed in 47.7% (53/111).

RESULT

Sensitivity was 83.0% and 86.0%; specificity was 70.6% and 71.0%, using the cutoff of 7 U/mL and 5 U/mL, respectively. When only the positive culture was used as gold standard and the cutoff of 5 U/mL, the sensitivity was 93.3%. In patients older than 10 years, the sensibility was 90.6% and 96.8%; specificity was 71.0% and 61.9%, with the cutoff of 7 U/mL and 5 U/mL, respectively.

CONCLUSION

ELISA method had good sensitivity in children older than 10 years, using the cutoff 5 U/mL, but the specificity was low.

Seroconversion and seroreversion in IgG antibodies to Helicobacter pylori: a serology based prospective cohort study

STUDY OBJECTIVES

To assess the incidence of seroconversion and seroreversion in IgG antibodies to Helicobacter pylori within a 11 year observation period using these events as markers for acquisition and loss of the infection, respectively.

DESIGN

Population based prospective cohort study.

SETTING

Northern part of Copenhagen County, Denmark.

PARTICIPANTS AND METHODS

A random sample of 2527 Danish adults were examined and blood obtained in 1983 and in 1994. Matching pairs of sera were analysed for the presence of IgG and IgM antibodies to H pylori with an in house enzyme linked immunosorbent assay. Participants who were seronegative at study entry and seropositive at follow up and had a fourfold increase in baseline IgG antibody levels were categorised as seroconverters and regarded as having acquired H pylori infection. Participants who were seropositive at study entry and had at least a fourfold decrease in baseline IgG antibody levels at follow up were assumed to have lost the infection (seroreverters).

RESULTS

The seroprevalence of H pylori infection was 24.7 (95% confidence intervals (95% CI) 23.0, 26.4) % in 1983 and 24.5 (95% CI 22.8, 26. 2) % in 1994. A total of 14 participants seroconverted within the observation period (cumulative 11 year incidence proportion: 1.0 (95% CI 0.5, 1.5) %). Having increased IgM antibody levels at study entry significantly increased the likelihood of IgG seroconversion (relative risk 6.4 (95% CI 2.1, 19.6). Seroreversion was seen in 48 participants (cumulative 11 year incidence proportion: 7.7 (95% CI 5. 6, 9.8) %).

CONCLUSIONS

Changes in H pylori infection status with time are rare in Danish adults. Few adults become infected with H pylori in Denmark.

Antibody response of patients with Helicobacter pylori-related gastric adenocarcinoma: significance of anti-cagA antibodies

The aim of this study was to search for a specific antibody pattern in sera from patients suffering from Helicobacter pylori-related gastric adenocarcinoma (GAC). The serological response of 22 patients suffering from GAC, 31 patients with gastroduodenal ulcer, and 39 asymptomatic subjects was analyzed using immunoblotting performed with three H. pylori strains: strain ATCC 43579; strain B110, isolated from a patient with ulcers; and strain B225, isolated from a patient with GAC. In addition, the latex agglutination test Pyloriset Dry was used to analyze ambiguous sera. H. pylori seropositivity was 75% in the GAC group, 61.3% in the ulcer group, and 56.4% in the asymptomatic group. Anti-CagA antibodies were found more often in the GAC group (48.8%) and in the ulcer group (47.3%) than in the asymptomatic group (21.2%). These percentages depended on the strain used as an antigen: in the GAC group, the anti-CagA frequencies were 93.3, 40, and 13.3% with strains B225, B110, and ATCC 43579, respectively. Thus the presence of anti-CagA antibodies was increased in patients suffering from H. pylori-related GAC, in particular when the CagA antigen was from a GAC strain. These data suggest the existence of a CagA protein specifically expressed by H. pylori strains isolated from GAC patients.

Association of Helicobacter pylori infection with lifestyle, chronic disease, body-indices, and age at menarche in Danish adults

This study examines the association between lifestyle factors, chronic disease, body-indices, and the seroprevalence of Helicobacter pylori infection in Danish adults. The relationship between age at menarche and H. pylori infection is also assessed. A random sample of 3,608 Danish adults completed a questionnaire about lifestyle factors (smoking habits, alcohol consumption, and coffee and tea intake), doctor diagnosed chronic diseases (heart conditions, diabetes, chronic bronchitis, and hypertension), menarche, and socio-demographic factors. A total of 2,913 participants were eligible for the present study. Electrocardiographs were recorded and blood pressure and serum lipid levels (HDL cholesterol, triglyceride, and cholesterol) were measured. Height and weight were determined and body mass index (BMI) calculated. Sera were analysed with an enzyme-linked immunosorbent assay for the presence of H. pylori specific IgG antibodies. The seroprevalence of H. pylori infection was associated with weekly alcohol intake > or = 6 drinks (odds ratio 0.7, 95% confidence interval 0.6-0.9) due to a low rate of H. pylori infection among wine drinkers (odds ratio 0.6, 95% confidence interval 0.5-0.7). No associations were found with smoking habits or serum lipids. People with upper quartile BMI (> or = 26.8 kg/m2) were more likely to be seropositive for antibodies to H. pylori (odds ratio 1.6, 95% confidence interval 1.1-2.4). Chronic bronchitis (odds ratio 1.6, 95% confidence interval 1.1-2.5) and unspecified heart condition (odds ratio 2.0, 95% confidence interval 1.1-3.3) was more often seen in IgG seropositive women than in uninfected women. The likelihood of being seropositive for IgG antibodies to H. pylori increased with age at menarche (odds ratio per year 1.10, 95% confidence interval 1.02-1.19). Previously reported associations with age and socioeconomic status were confirmed. We conclude that wine drinking is associated with lower rates of H. pylori infection in Danish adults. The seroprevalence of H. pylori infection is increased in people with high BMI. H. pylori infection may relate to a history of late menarche and chronic bronchitis in Danish women.

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.

Serodiagnosis of Helicobacter pylori infection by Cobas Core ELISA in adults from Minas Gerais, Brazil

We evaluated the accuracy of a 2nd generation ELISA to detect Helicobacter pylori infection in adults from a developing country in view of variations in sensitivity and specificity reported for different populations. We studied 97 non-consecutive patients who underwent endoscopy for evaluation of dispeptic symptoms. The presence of H. pylori was determined in antral biopsy specimens by culture, by the preformed urease test and in carbolfuchsin-stained smears. Patients were considered to be H. pylori positive if at least two of the three tests presented a positive result or if the culture was positive, and negative if the three tests were negative. Sixty-five adults (31 with peptic ulcer) were H. pylori positive and 32 adults were H. pylori negative. Antibodies were detected by Cobas Core anti-H. pylori EIA in 62 of 65 H. pylori-positive adults and in none of the negative adults. The sensitivity, specificity and positive and negative predictive values of the test were 95.4, 100, 100 and 91.4%, respectively. The Cobas Core anti-H. pylori EIA presented high sensitivity and specificity when employed for a population in Brazil, permitting the use of the test both to confirm the clinical diagnosis and to perform epidemiologic surveys.

Use of immunoblot assay to define serum antibody patterns associated with Helicobacter pylori infection and with H. pylori-related ulcers

Serology has been used worldwide to detect Helicobacter pylori infection. Using an immunoblot assay with an antigen from strain ATCC 43579, we sought to determine the antibodies which were good markers of colonization and the antibody patterns associated with ulcers or atrophy. Out of 98 dyspeptic patients, 41 were colonized by H. pylori, based on a positive culture or on positive results of both a urease test and direct examination. These 41 patients were seropositive by an enzyme immunoassay, and 12 of them had ulcers and 29 had evidence of atrophy. Fifty-seven of the 98 patients were noncolonized. Twenty-five of the 57 had evidence of gastric atrophy, and 10 were seropositive; 5 of these 10 had ulcers. By Western blot analysis, 12 antibodies were significantly more frequent in sera from colonized patients, and they produced immunoreactive bands at 125, 87, 74, 66, 54, 48, 46, 42, 35, 30, 16 and 14 kDa. The presence of at least one band at 54, 35, or 42 kDa was the best marker of infection (sensitivity, 95%; specificity, 82%). In the group of colonized patients, none of the antibody patterns were correlated to gastric atrophy. Conversely, the presence of a band at 125, 87, or 35 kDa was statistically associated with the presence of an ulcer. The simultaneous presence of bands at 87 and 35 kDa predicted the risk of ulcers with 83% sensitivity and 69% specificity. By using CagA-positive and VacA-positive strains and CagA-negative and VacA-negative isogenic mutants, the antigens corresponding to the bands at 125 and 87 kDa were shown to be CagA and VacA, respectively. On the other hand, the 35-kDa antigen is a novel uncharacterized component of H. pylori. These results may help to optimize the composition of antigenic preparations for serologic detection of H. pylori colonization. Immunoblot assay would be useful for screening patients at high risk of ulcers.

Comparison of Helicobacter pylori infection between Fukuoka, Japan and Chinju, Korea

BACKGROUND

Helicobacter pylori is the causative agent of type B chronic gastritis, and plays a major role in the pathogenesis of gastroduodenal ulcer and gastric cancer. Because gastric cancer has been the leading cause of cancer mortality in Japan and Korea, we conducted a seroepidemiological study to estimate the prevalence of H. pylori infection in Japan and Korea in order to explain the current change in the gastric cancer incidences between two countries.

MATERIALS AND METHODS

Samples used for this study included 1204 sera from Chinju, Korea and 580 sera from Fukuoka, Japan. Immunoblotting, using a sonicated crude H. pylori antigen and 1:5 dilution of serum, was performed, considering the immunoblot shows reactivity to the 120 Kd antigen of H. pylori as a specific marker of H. pylori infection.

RESULTS

Seroepidemiology data from Fukuoka, Japan showed a prevalence of H. pylori infection of 20% before school age, 40% by teenage years, and over 80% beyond 20 years of age. Seroepidemiology data from Chinju, Korea, showed a 50% infection rate in preschool ages, and over 80% prevalence rate after 7 years of age.

CONCLUSIONS

Lower rates of childhood H. pylori infection in Fukuoka may explain the recent decline and shift in the incidence of stomach cancer in Japan, supporting the hypothesis that H. pylori is a major determinant in the pathogenesis of stomach cancer.

A new histological procedure for re-evaluation of the serological test for Helicobacter pylori

To re-evaluate the accuracy of the serological test for Helicobacter pylori, fixation of biopsy specimens with Carnoy's solution (preserving the mucous layer in tissue preparations) followed by immunohistochemical staining (a new histological procedure) was used as the reference histological method instead of 10% formalin fixation followed by hematoxylin-eosin staining (the conventional histological procedure). Biopsy specimens (antrum and body) from 114 patients with gastritis (including non-ulcer dyspepsia) or gastric and/or duodenal ulcers were obtained by endoscopy and used for both bacteriological culture and histological examination. Serum samples were taken from all patients at the time of endoscopy. The serum levels of specific IgG and IgA antibodies for Helicobacter pylori were measured by commercial enzyme immunoassay kits. The reliability of the IgG and IgA measurements was evaluated by analyzing receiver operating characteristic curves obtained using the two histological procedures. With the conventional histological procedure as the reference, the sensitivity and specificity levels of the serological test were 87.2% and 82.1%, respectively. With the new histological procedure as reference, sensitivity and specificity were 94% and 96.7%, respectively. The insufficient accuracy reported for the serological test could be due to false-positive or false-negative results obtained when the conventional histological procedure is used as the reference. The new histological procedure used here revealed that the serological test for Helicobacter pylori is more reliable than previously thought.

Evaluation and comparison of two immunodiagnostic assays for Helicobacter pylori antibodies with culture results

Several commercially available serological kits have been used as an alternative to endoscopy for the diagnosis of Helicobacter pylori infection. We evaluated the performance of two such kits, Serion H. pylori immunotab kit (Serion, Wurzberg, West Germany) and Pyloragen H. pylori test kit (Hypcor Biomedical Inc., Irvine, CA). Gastric biopsy and serum samples were collected from 345 consecutive dyspeptic patients. The culture and or direct smear of the biopsy was positive for H. pylori in 228 patients (66%), whereas 117 patients (34%) were found to be H. pylori negative. We determined the serological response of the patients using the two kits, both of which are based on the principle of enzyme-linked immunosorbent assay. Comparing the serum immunoglobin G (IgG) and IgA (in a limited number of cases) responses to H. pylori status, the sensitivity, the specificity, positive predictive value, and negative predictive value were calculated. The corresponding data for the different tests were 64%, 79%, 84%, and 56% for Serion IgC, 32%, 94%, 88%, and 52% for Serion IgA, and 88%, 17%, 62%, and 46% for Pyloragen IgG, respectively. We conclude that there is a poor correlation between the presence of H. pylori infection and the antibody response, which could be explained either because of low sensitivities and specificities of the commercial kits used for the measurement of antibodies to H. pylori in the serum or because of poor immunological response in our patients to H. pylori antigens.

Helicobacter pylori acquisition in infancy after decline of maternal passive immunity

We evaluated the natural history of Helicobacter pylori infection and the host immune response in 80 infants, and determined seroprevalence of H. pylori infection in their Taiwanese mothers. Decline in passively transferred maternal anti-H. pylori IgG antibodies and subsequent H. pylori infection was assessed in infants over 14 mo. A sensitive and specific, 96-well microtiter ELISA for the detection of H. pylori IgG antibodies was used to evaluate maternal serum (single specimen) and their infants (birth, 1, 2, 3, 6, 12, and 14 mo). Sera were also evaluated by ELISA for the presence of anti-H. pylori IgM antibodies in the infants. Maternal H. pylori IgG seroprevalence was 62.5% [50/80; 95% confidence intervals (CI), 51-73%]. All infants born to the 50 seropositive mothers passively acquired maternal H. pylori IgG. Transplacentally transferred maternal anti-H. pylori IgG lasted until about the 3rd mo of life, and disappeared in nearly all the infants by 6 mo of age. Seven and one-half percent of infants (6/80; 95% CI, 3-16%) acquired H. pylori infection; two were born to H. pylori-negative mothers. Among the six IgG seropositive infants, an IgM response specific for H. pylori antigens was detected and appeared to precede the rise in IgG in five. We conclude that maternal passive transfer of IgG antibodies occurs in the infant and disappears by 6 mo of age. H. pylori infection is acquired in infancy in this population; IgM antibodies against H. pylori are detectable, seem short-lived, and appear to precede IgG antibody development.

An apparent lack of association between Helicobacter pylori infection and risk of gastric cancer in China

Several prospective studies have shown a significant association between Helicobacter pylori seropositivity and the risk of gastric cancer. Only a small proportion of H. pylori-infected individuals will, however, develop gastric cancer, and it is unclear what effects other factors, such as diet, might have on the risk of cancer. Eighty-seven subjects with gastric cancer were identified during the first 6 years of follow-up (mean 2.4 years) of a cohort of middle-aged men from Shanghai, China. They were matched with 261 cancer-free controls, and serum samples from all subjects, obtained at recruitment, were assayed for anti-H. pylori IgG antibodies. Questionnaire data provided information on a wide range of socio-demographic life-style and dietary variables. H. pylori seropositivity rates in the cases and controls were 54% and 56%, respectively. Neither the overall risk of developing gastric cancer nor the risk of developing non-cardia gastric cancer was significantly associated with prior M. pylori seropositivity. Adjustment for any of the other medical, dietary or life-style variables studied had little effect on the risk of developing non-cardia gastric cancer; simultaneous adjustment for all of these factors yielded an odds ratio of 1.17. The results do not support the hypothesis that H. pylori plays a role in the process of gastric carcinogenesis in China. It is possible that this is an artefact resulting from the relatively short follow-up period to date.

Evaluation of Pyloriset Dry, a new rapid agglutination test for Helicobacter pylori antibody detection

We evaluated the performance of a new latex agglutination test, Pyloriset Dry (Orion Diagnostica, Espoo, Finland), in the simultaneous detection of immunoglobulin G (IgG), IgA, and IgM antibodies to Helicobacter pylori and compared it with that of the Pyloristat test (BioWhittaker, Fontenay-sous-Bois, France), an enzyme-linked immunosorbent assay detecting IgG to H. pylori, for 96 untreated dyspeptic patients who had undergone gastroduodenal endoscopy. Infection was diagnosed in 56 cases by positive culture and/or positive Giemsa stain and rapid urease test (antral biopsies) and was associated with chronic gastritis in 52 patients. Forty noninfected patients did not have chronic gastritis. The sensitivity of Pyloriset Dry was 91.1%. The sensitivity of Pyloristat was 91.1 or 82.1%, depending on whether equivocal results were considered positive or negative, respectively. Both tests had a specificity of 87.5%. Their performances were not statistically different. Thus, Pyloriset Dry is an alternative to serological tests for adults, particularly when a small number of serum samples has to be tested.

Is saliva serology useful for the diagnosis of Helicobacter pylori?

BACKGROUND

The Cortecs Diagnostics Helisal Assay test is a quantitative immunoassay for salivary IgG antibodies against Helicobacter pylori. Saliva can be obtained simply with the kit in the general practitioners surgery.

AIMS

To compare the new saliva serological test for H pylori with 'gold standard' evidence of H pylori infection (antral biopsy specimens for histology, culture, and urease test) and a new serum serological test.

PATIENTS

Eighty six unselected dyspeptic patients undergoing endoscopy.

METHODS

Each patient provided saliva and serum before endoscopy for H pylori serology, which was compared against 'gold standard' evidence of infection.

RESULTS

Thirty two patients were H pylori positive by the 'gold standard' tests. At a cut off value of 0.15 EU/ml the saliva test had a sensitivity of 88% and a specificity of 71%, with a negative predictive value of 90%. If patients who were taking omeprazole or had recent antibiotics are excluded, the sensitivity is unchanged but the specificity increases to 79%. The serum test had a similar sensitivity of 85% but better specificity of 78%.

CONCLUSION

Serum testing remains the best serological test for H pylori in the hospital setting. Saliva testing may have a role in epidemiological studies and in screening dyspeptic patients in general practice, especially in children in whom venesection is more difficult.

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

AIMS

To determine the accuracy of eight commercially available kits for the serological diagnosis of Helicobacter pylori infection, and hence whether a serology service could be introduced to reduce endoscopy workload.

METHODS

Eighty four patients newly presenting to their general practitioners with dyspepsia were recruited. Gold standard diagnosis of H pylori infection was obtained both by a histological examination of gastroduodenal biopsy specimens and by the 14C-urea breath test (UBT). The performance of six quantitative and two qualitative enzyme linked immunosorbent assays for H pylori IgG, used according to the manufacturers' instructions, with serum samples obtained during the endoscopy visit, were compared.

RESULTS

The study population had a median age of 45 years, and the prevalence of H pylori infection was 35%. With one exception, where the patient had received a course of anti-H pylori treatment between endoscopy and UBT, there was 100% concordance in the results of the two gold standard techniques. Discordant serology results were more common in patients aged > 50 years (42% of the total) than in younger patients (21%), and this was most noticeable in uninfected patients. The sensitivity of the kits was good (90-100%), but specificity was more variable (76-96%), and the rate of equivocal results was unacceptably high in some cases (0-12%). The overall accuracy of the kits ranged from 83 to 98%. Two kits in particular performed well (Pylori-Elisa II, Bio-Whitaker and Premier, Launch; qualitative) with 98% and 100% accuracy, respectively.

CONCLUSIONS

In a symptomatic population with a prevalence of H pylori infection of 35%, particularly in patients aged < 50 years, some but not all serology kits may be used as a highly accurate and inexpensive alternative to the gold standard techniques.

Helicobacter pylori and recurrent abdominal pain in children

Recurrent abdominal pain is one of the most common presentations to pediatricians; yet an organic etiology can be found in only 10% of cases. Because infection with Helicobacter pylori in adults and children results in gastritis, a causative role for the organism has been postulated. To investigate this theory, we conducted a prospective case-control study in children with recurrent abdominal pain using serum H. pylori IgG antibodies measured by an enzyme immunoabsorbent assay. Age, sex, ethnicity, and socioeconomic status were adjusted in the statistical model. Five subjects (5.1%) and 14 controls (14.3%) had raised serum IgG antibodies to H. pylori (adjusted OR, 0.21; 95% confidence interval, 0.05, 0.85). The negative association between H. pylori and recurrent abdominal pain indicates that this organism is unlikely to have an important etiologic role in this disorder.

Prevalence of Helicobacter pylori infection in asymptomatic children

OBJECTIVE

To determine the prevalence of Helicobacter pylori infection in a sample of asymptomatic Australian children.

METHODOLOGY

A prospective observational study, during a 3 month period, of consecutive children aged 0 to 14 years undergoing minor elective surgical procedures in a Day Surgical Unit at a Melbourne paediatric hospital. Subjects without gastrointestinal symptoms or a family history of peptic ulcers had sociodemographic data recorded and serum collected. Serum anti-H. pylori immunoglobulin G antibodies were measured by an enzyme immunoabsorbent assay previously validated in children from the same population.

RESULTS

H. pylori antibodies were present in 21/147 (14.3%) children aged 3 months to 14 years. Prevalence was not influenced by age or sex, but was greatest in children whose parents migrated from developing nations and lowest in children with Caucasian Australian or Western European parents (25.8 vs 5.9%; P < 0.001). An inverse relationship between social class and infection was also observed (P = 0.02). Multivariate analysis demonstrated the father's ethnic background as the only significant independent risk factor for H. pylori infection (P = 0.002).

CONCLUSIONS

Although seroprevalence of H. pylori appears to be lower in Australian children than in developing countries there are some ethnic groups at substantially greater risk for the acquisition of H. pylori infection and its complications.