Comparison between a rapid office-based and ELISA serologic test in screening for Helicobacter pylori in children

Helicobacter pylori Infection Does Not Protect Against Allergic Diseases: Evidence From a Pediatric Cohort From Northern Sardinia, Italy

BACKGROUND

The "hygiene hypothesis" states that reduced exposure to microbial antigens due to an excessively hygienic environment can increase the risk of developing autoimmune diseases, including atopic disorders and asthma. In recent decades, there has been a progressive decline in the prevalence of numerous microorganisms following improved hygienic-sanitary conditions. More specifically, several studies reported an inverse association between the reduction in Helicobacter pylori infection and the rise of asthma and allergic disorders.

AIM

To evaluate the prevalence of atopic disorders in a pediatric population in relation to seropositivity against H. pylori.

METHODS

Children from Northern Sardinia, Italy, referred to the local Children's Hospital for any reason, were investigated to identify risk factors, especially H. pylori infection, associated with atopic disorders. A validated questionnaire, including demographics, house size, history of breastfeeding, residence, school or daycare center attendance, exposure to animals, and a defined diagnosis of atopy-including asthma-was filled out by a trained pediatrician according to parents' answers and child records. A blood sample was collected from each participant and immunoglobulin G against H. pylori was assessed by a locally validated ELISA test.

RESULTS

The seroprevalence of H. pylori infection was 11.7% among 492 children (240 females). Thirty-two children had a confirmed diagnosis of asthma and 12 of allergy. No one child showed both conditions. Statistically significant differences in H. pylori seropositivity were not detected between children with or without atopy (8.4% vs. 12.6; p = 0.233). Although atopic disorders were more frequent in children exposed to traditional atopic risk factors, none of them showed to be significant after adjusting for all covariates.

CONCLUSIONS

Serologically assessed H. pylori infection was not significantly associated with a reduced risk of atopic diseases in children.

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.

A rapid serologic test and immunoblotting for the detection of Helicobacter pylori infection in children

The gold standard for the diagnosis of Helicobacter pylori infection requires an endoscopic biopsy of gastric mucosa for histological examination, urease test and culture. Noninvasive serological tests are useful as a screening test for H. pylori infection. The aim of this study was to evaluate the performance of a rapid office-based serologic test, using immunochromatography ICM, and the immunoblotting for the diagnosis of H. pylori infection in Thai children. Eighty-two symptomatic children, 30 boys and 52 girls (mean age 9.2+/-3.8 years; range, 1.2-16.0 years) who had no previous treatment for H. pylori underwent upper endoscopy. Biopsies were obtained from the gastric body and antrum for histopathology and rapid urease test. Serum samples collected from all patients were tested for H. pylori IgG antibodies using ICM (Assure H. pylori Rapid Test, Genelabs Diagnostics, Singapore). Immunoblotting (HelicoBlot 2.1, Genelabs Diagnostics, Singapore) was tested in sera of 75 patients to detect antibodies to specific antigens of H. pylori. Positive H. pylori status was defined as positive for both histology and rapid urease test. Of 82 patients, 25 (30.5%) were H. pylori positive, 56 (68.3%) were H. pylori negative and one was equivocal. ICM assay yielded a positive result in 24 of the 25 H. pylori-positive patients (96.0%) and 3 of the 56 H. pylori-negative patients (5.4%). The immunoblotting yielded a positive result in all of 22 H. pylori-positive patients (100%) and in 2 of the 52 H. pylori-negative patients (3.8%). Obtained ICM's sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 96.0, 94.6, 88.9, 98.1 and 95.1%, with immunoblotting 100.0, 96.2, 91.6, 100.0, and 97.3%, respectively. The immunochromatographic and immunoblot tests are non-invasive, reliable and useful for the diagnosis of H. pylori infection in Thai children.

Accuracy of office-based immunoassays for the diagnosis of Helicobacter pylori infection in children

BACKGROUND

Rapid non-invasive diagnostic tests that can reliably document the presence or absence of Helicobacter pylori infection are urgently required. The aim of this study was to determine the accuracy of two immunoassays (Flex-Sure and MedMira), developed for use outside the laboratory setting by practitioners, in the setting of a low prevalence of H. pylori infection.

METHODS

Serum samples collected in four previous studies (n = 349) were employed to detect the presence of H. pylori-specific immunoglobulin G, compared to previous results obtained using endoscopic biopsies, serology, flow cytometry, and urease breath testing. Serum samples included 52 obtained from adults (parents and grandparents of symptomatic children), 123 sera collected from children and adolescents undergoing diagnostic upper endoscopy for upper gastrointestinal tract symptoms, and 174 samples drawn from children in the primary care setting with or without recurrent abdominal pain.

RESULTS

Overall, 16% of subjects were infected by the gastric pathogen. Both the specificity (%) and negative predictive value (%) of the two tests were high (FlexSure: 91 and 92; Medmira: 97 and 94, respectively). In adults, both tests also demonstrated high sensitivity (83% and 86%) and positive predictive values (79% and 83%, respectively). However, in children where the prevalence of infection was 12% (37 of 297 subjects), the sensitivity (59% and 71%) and positive predictive values (55% and 88%, respectively) of the immunoassays were lower.

CONCLUSIONS

These findings indicate that, in the setting of a low prevalence of H. pylori infection, the MedMira office-based test provides satisfactory results and utility. However, the low positive-predictive value of the FlexSure kit may limit applicability of this test in children.

[Study of the validity of "rapid" serology in diagnosing Helicobacter pylori infection]

OBJECTIVE

To evaluate prospectively the validity of a <<rapid>> serology diagnosis method (using capillary blood) in our ambit, taking for reference a combination of standard diagnostic methods.

DESIGN

Prospective. The endoscopist, pathologist and those responsible for interpreting the rapid urease test, the breath test and <<rapid>> serology did not know the results of the other diagnostic methods.

SETTING

Gastro-enterology service of a tertiary hospital.Participants. 30 consecutive patients with symptoms attributable to the upper digestive tract and who underwent an oral gastroscopy. Main measurements. Gastric biopsies for histology examination and for the rapid urease test and a breath test with 13C-urea were conducted. For <<rapid>> serology, the commercial SureStep HP WB test kit was used. A patient was considered infected when at least two of the three validated techniques (rapid urease test, histology, breath test) were positive; and not infected, when all three were negative.

RESULTS

30 patients, 30% male, with a mean age of 51, were included. The reference standard indicated 61% prevalence of infection, with two cases classed as undetermined. <<Rapid>> serology was positive in 8 patients and negative in 22. Sensitivity, specificity, positive predictive value and negative predictive value were, respectively, 41% (95% CI, 18-65), 91% (74-100), 87% (65-100) and 50% (28-72). The positive probability quotient was 4.5; and the negative, 0.65.

CONCLUSION

The <<rapid>> serology used in the current study has deficient diagnostic accuracy. Therefore, it should not be used in clinical practice to identify H. pylori infection.

Helicobacter pylori infection in children

A number of scientific breakthroughs since H pylori first became recognized as a human pathogen have increased our understanding of the pathogenesis of gastroduodenal disease. In particular, advances in molecular bacteriology and the complete sequencing of the H pylori genome in 1999, and soon thereafter the human genome, provide tools allowing better delineation of the pathogenesis of disease. These molecular tools for both bacteria and host should now be applied to multicenter pediatric studies that evaluate disease outcome. More recent developments indicate that a better understanding of the microbial-host interaction is critical to furthering knowledge with respect to H pylori-induced diseases. Studies are needed to evaluate either DNA-based or more traditional protein-based vaccines, to evaluate more specific antimicrobials that confer minimal resistance, and to evaluate probiotics for the management of H pylori infection. Multicenter multinational studies of H pylori infection in the pediatric population, which include specific, randomized controlled eradication trials, are essential to extend current knowledge and develop better predictors of disease outcome.

Infants differ from teenagers: use of non-invasive tests for detection of Helicobacter pylori infection in children

Reliable non-invasive tests that are feasible in early childhood are essential to the study of transmission of Helicobacter pylori, since most individuals get infected during the first years of life. New tests are validated by comparison with a "gold standard", but no single test for detection of H. pylori infection can be used as a fully reliable reference method. Therefore, concordant results of at least two biopsy-based tests (histology, culture, rapid urease test) are considered as the "gold standard". Most of the validation studies in children included only a few infants and toddlers, with low numbers particularly for H. pylori-infected individuals. Only when increasing numbers of patients were tested and separated into subgroups by age it became apparent that the accuracy of most tests is lower in young children if the same cut-off values are used as established for older children or adults. Therefore, statements such as "a test has been validated with good results in children" must be interpreted with caution, unless different age groups are considered with sufficient numbers of infected and non-infected children in each age group.

Laboratory tests for the evaluation of Helicobacter pylori infections

Helicobacter pylori is a highly motile bacterium with multiple unipolar flagella, and it produces the urease enzyme. The flagella and urease are the virulence factors of H. pylori. H. pylori often establishes a chronic infection in the stomach that may lead to gastric and duodenal ulcers, gastric cancers, gastric lymphomas, and other gastrointestinal diseases. There are several different invasive and noninvasive clinical laboratory tests for H. pylori. Laboratory testing is not indicated in asymptomatic patients and should be considered only if treatment of H. pylori infection is planned. Invasive tests for H. pylori, such as tissue histology, culture, and rapid urease tests, are used if an endoscopy is performed on the patient. The noninvasive tests for H. pylori, such as enzyme antibody and urea breath tests, are recommended in patients whose symptoms do not warrant endoscopy. The urea breath test is very useful and is recommended to evaluate effectiveness in the eradication and treatment of H. pylori infections. Nucleic acid tests can complement other diagnostic procedures, and are useful in evaluating fixed biopsy tissue, environmental samples, gastric juices, oral secretions, and stool samples.

An evaluation of whole blood testing for Helicobacter pylori infection in the Chinese population

BACKGROUND

Near patient tests for Helicobacter pylori were developed to assist in the management of dyspepsia patients in general practice. Most studies were performed in western populations.

AIM

To evaluate the rapid whole blood test (Flexpack HP) for H. pylori in the Chinese population.

METHODS

Consecutive dyspeptic patients referred for upper endoscopy were recruited. During upper endoscopy, biopsies were taken from the antrum and corpus for rapid urease test (CLO test) and histological examination. After endoscopy, the whole blood test (FlexPack HP) was performed according to the manufacturer's instruction. Patients then received a 13C-urea breath test. Results of the whole blood test were compared with the gold standard (CLO test, histology and 13C-urea breath test).

RESULTS

A total of 294 consecutive patients gave a valid Flexpack HP result for interpretation. The mean age of patients was 47.7 (range 15-85) years. Analysis showed a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 58%, 92%, 91%, 63% and 73% respectively.

CONCLUSION

The FlexPack HP whole blood test showed good specificity but lacked sensitivity. It is not sensitive enough to be used in a general practice setting for the test-and-treat approach in the Chinese population.

Isolation of Helicobacter pylori from vomitus in children and its implication in gastro-oral transmission

OBJECTIVE

The route of transmission of Helicobacter pylori (H. pylori) is unclear. Gastro-oral transmission via contaminated vomitus has been proposed as an important mode of transmitting H. pylori, especially in children. This pilot study attempted to isolate H. pylori from the vomitus of children.

METHODS

Children presenting for evaluation with gastroenteritis-associated vomiting were studied. Fresh vomitus samples were collected for detection of H. pylori by bacteriological culture and polymerase chain reaction, (PCR). A rapid, whole blood test was used to determine the H. pylori status of patients.

RESULTS

A total of 18 children with mean age of 6 yr were studied; four had a positive serology test. Among these four children, H. pylori was isolated from vomitus by culture in one child and by PCR in two. An 18-month-old girl with negative serology had H. pylori detected in vomitus by PCR. Six months later, she had seroconversion confirmed, suggesting that she had an acute H. pylori infection on initial presentation.

CONCLUSIONS

This is the first study reporting successful isolation of H. pylori from naturally produced vomitus. The result implies that transmission of H. pylori infection by vomitus, especially in children, is possible.

Helicobacter pylori antibody profile in household members of children with H. pylori infection

Intrafamilial spread is implicated as a major route for acquisition of Helicoobacter pylori infection. Investigating H. pylori cytotoxin-associated protein (CagA) and vacuolating toxin (VacA) antibodies within family members enabled the authors to evaluate this possibility further. Serum samples were collected prospectively from household members after their index children were diagnosed with active H. pylori infection. Serum samples were evaluated for anti-H. pylori immunoglobulin G antibody using the enzyme immunoassay (IEA) method and for H. pylori CagA and VacA antibodies with the commercially available immunoprobing Western blot kit. Ten different families participated in the study, including 10 pediatric patients and 31 household members. All patients and 28 household members (90%) were seropositive for H. pylori antibody by IEA and Western blot tests. Overall, 17 subjects (41.4%) were CagA positive, 14 (34.1%) were VacA positive, 11 (26.8%) were positive for both antibodies, and 22 (53.6%) were negative for both antibodies. A significant association in bacterial antibody profile was found between the patient index members and all household members (Cohen's kappa and Mentel-Haenszel methods). In four families, more than 66% of the household members harbored the same antibody profile, and in two families a completely different profile was observed. Moreover, a similar H. pylori antibody profile between the index patient and the mother was found in six families, and between the index patient and the father in two families. The data strongly suggest an intrafamiliar transmission for H. pylori infection.

Detection of Helicobacter pylori organisms by Hp-fast in children

Hp-fast is a new rapid urease test (RUT) that has not been evaluated in children. The aim of the study was to prospectively compare the Hp-fast test to the CLOtest in children. Children with gastrointestinal symptoms who undergo diagnostic upper endoscopy were prospectively enrolled to the study. Antral gastric biopsies were evaluated for histology and for CLO-test and Hp-fast. Results were then compared to histology. Of the 94 children who participated, gastritis was found in 38 (40%), of whom 16 (42%) had associated H. pylori organisms. In two children, H. pylori organisms were identified without gastritis. The concordance between both RUT tests was 98%. A significant correlation was found between RUT results and histological factors or serology. The accuracy rate of both RUT increased significantly when different gold standards were utilized to detect Hp infection in children. The best correlation was found when histology and serology were considered as the gold standard for the diagnosis of H. pylori infection in children (sensitivity: 100% compared to 43-80% with other standards, respectively). In conclusion, the Hp-fast test result is comparable to CLOtest, but neither alone is sufficient to establish the diagnosis of Hp infection in children.

Prevalence of CagA, VacA antibodies in symptomatic and asymptomatic children with Helicobacter pylori infection

BACKGROUND

Limited data are available on the prevalence of CagA and VacA Helicobacter pylori antibodies in children. The aim of this study was to investigate the antibody prevalence to the H. pylori virulence factors CagA and VacA in symptomatic and asymptomatic children with H. pylori infection and to correlate these antibodies with the severity of gastric inflammation or density of H. pylori organisms in the gastric mucosa.

MATERIALS AND METHODS

Twenty-three symptomatic children and 132 asymptomatic children with positive H. pylori serology participated in this study. Anti-H. pylori IgG antibody and CagA or VacA H. pylori antibodies were measured by enzyme immunoassay (HM-CAP; sensitivity and specificity > 90%) and Western immunoblot (Helicoblot 2.0) methods, respectively. Gastric inflammation and H. pylori density were graded histologically using the revised Sydney criteria.

RESULTS

The prevalence of CagA and VacA antibodies were 69% and 35% in symptomatic children and 54% and 52% in asymptomatic children, respectively. Multiple regression analysis showed a correlation between CagA antibody and the severity of gastritis but no correlation with other histological features, including the number of neutrophils or lymphoid follicles. Neither antibody correlated with the degree of bacterial density in the gastric mucosa.

CONCLUSION

CagA and VacA H. pylori antibodies are common in the pediatric population. The combined CagA/VacA antibodies correlated weakly with the degree of mucosal inflammation.

Comparison of two rapid whole-blood tests for Helicobacter pylori infection in Chinese patients

Consecutive Chinese patients undergoing endoscopy for dyspepsia were tested for Helicobacter pylori infection by two rapid whole-blood tests: FlexPack HP (Abbott Laboratories) and Helisal One-Step (Cortecs Diagnostics). Biopsy-based tests (rapid urease test and histology) and the [13C]urea breath test were used as the "gold standard." One hundred sixty-one consecutive patients were studied, and 88 (54.7%) were confirmed to have H. pylori infection. The sensitivities, specificities, and positive and negative predictive values were 81.8%, 83.6% (P = 0.008), 85.7% (P = 0.04), and 79.2% for FlexPack HP and 84.1%, 63.0% (P = 0.008), 73.3% (P = 0.047), and 76.7% for Helisal One-Step, respectively.