Significance of transiently positive enzyme-linked immunosorbent assay results in detection of Helicobacter pylori in stool samples from children

Diagnosis of Helicobacter pylori infection in the elderly using an immunochromatographic assay-based stool antigen test

The diagnostic value of Helicobacter pylori stool antigen (HpSA) tests in elderly subjects remains unclear. The objective of this study was to assess the diagnostic accuracy of the immunochromatographic assay‐based HpSA test in a male elderly cohort and identify factors affecting the accuracy. Data for asymptomatic elderly male citizens (≥65 years old) who received health checkups at the Chinese PLA General Hospital between July 2007 and November 2018 were collected. The diagnostic accuracy of the HpSA test was determined using the ¹³C‐urea breath test as a reference standard. Associations between baseline comorbidities and the accuracy of the HpSA test were analyzed. In total, 316 participants were enrolled, including 193 in the pre‐treatment group (77.2 ± 7.8 years old) and 123 in the post‐treatment group (78.7 ± 8.3 years old). The accuracy (91.5%, 91.2%, and 91.9%) and specificity (97.6%, 98.7%, and 96.0%) were high in all participants, pre‐ and post‐treatment groups, respectively. However, sensitivities were only 68.7%, 65.1%, and 75.0%, respectively. In the pre‐treatment group, constipation was associated with decreased sensitivity (p = 0.039), while colorectal polyps were associated with increased sensitivity (p = 0.010). Multivariate analysis indicated that constipation and colorectal polyps are independent factors for the sensitivity of HpSA in the pre‐treatment group. The immunochromatographic assay‐based HpSA test achieved high accuracy with high specificity but suboptimal sensitivity in the elderly male cohort. Constipation and colorectal polyps were negatively and positively associated with HpSA sensitivity, respectively, in the pre‐treatment group.

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.

Study of the clinical relevance of Helicobacter pylori virulence genes to gastric diseases among Egyptian patients

BACKGROUND AND STUDY AIMS

Helicobacter pylori infection is common in Egypt. It has been associated with gastritis, ulcers and it is a risk factor for gastric cancer. We aimed to study the correlation between the presence of H. pylori virulence factors and the histopathological and endoscopic findings in gastric biopsies.

PATIENTS AND METHODS

Gastric biopsies from thirty seven patients scheduled for diagnostic endoscopy in Cairo University hospital were included in the study. All gastric biopsies were subjected to histopathological examination and PCR assay for detection of 16S rRNA gene to diagnose H. pylori infection, detection of H. pylori virulence factors by PCR for cagA and vacA genotypes and serological analysis of H. pylori (cagA, vacA, P25, and P19) IgG antibodies by immunoblot assay were done.

RESULTS

H. pylori infection was detected in 23 (62.2%) cases by histopathology while 28/37 (75.7%) were positive for H. pylori 16S rRNA gene by PCR. By PCR seventeen samples out of 37 (45.9%) were positive for cagA gene and five (13.5%) for cag empty site gene.

CONCLUSION

The most common vacA genotype identified was vacA s2m2 genotype in 10 (27.02%). No statistical correlation was found between IgG antibodies against different antigens of H. pylori virulence factors (cagA, vacA, p25, and p19) and the degree of gastritis except for IgG antibodies against the UreA antigen.

Reliability of stool antigen tests: investigation of the diagnostic value of a new immunochromatographic Helicobacter pylori approach in dyspeptic patients

BACKGROUND

A diagnosis of H. pylori infection can be made by invasive or non-invasive methods. Several noninvasive diagnostic tests based on the detection of H. pylori stool antigen (HpSA) have been developed. The Genx H. pylori stool antigen card test is a new rapid, non-invasive test that is based on monoclonal immunochromatographic assay. The aim of this study was to determine its sensitivity, specificity, and diagnostic accuracy for diagnosing H. pylori infection in adult patients.

MATERIALS AND METHODS

A total of 162 patients were included in the study. A gastric biopsy was collected for histopathology and rapid urease testing. Stool specimens for HpSA testing were also collected. Patients were considered H. pylori positive if two invasive tests (histological and rapid urease tests) were positive.

RESULTS

Using the reference test, 50.6% of the samples were positive for H. pylori infection. The Genx H. pylori antigen test was positive in 19.7% of patients. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of the Genx H. pylori antigen test were 51.6%, 96.0%, 88.8%, 76.1%, and 79.0%, respectively.

CONCLUSIONS

The Genx H. pylori stool antigen card test is a new non-invasive method that is fast and simple to perform but provides less reliable results.

Pathogenic properties of enterohepatic Helicobacter spp. isolated from rhesus macaques with intestinal adenocarcinoma

Considerable progress has been made in understanding the roles of Helicobacter pylori in inflammation and gastric cancer; however, far less is known about the roles of enterohepatic Helicobacter species (EHS) in carcinogenesis and their zoonotic or pathogenic potential. We determined the prevalence of EHS infection in a cohort of geriatric rhesus monkeys in which intestinal adenocarcinoma (IAC) is common and investigated the association between EHS infection and IAC. The cohort consisted of 36 animals, 14 of which (age 26-35 years) had IAC. Of the 36 rhesus, 35 (97%) were positive for EHS using PCR or bacterial isolation from faeces, colonic or tumour tissues. Only a single rhesus, which had IAC, was negative for EHS by all detection methods. The EHS identified by 16S rRNA sequencing in this study were from three Helicobacter taxa: Helicobacter macacae (previously rhesus monkey taxon 1), Helicobacter sp. rhesus monkey taxon 2, previously described from strain MIT 99-5507, and Helicobacter sp. rhesus monkey taxon 4, related to Helicobacter fennelliae. Thirteen of 14 monkeys with IAC were positive for either H. macacae (7/13, 54%), EHS rhesus monkey taxon 4 (4/13, 31%) or a mixture of the two EHS (2/13, 15%). These results indicate that EHS are prevalent among aged rhesus macaques with IAC. Using Helicobacter genus-specific florescent in situ hybridization, EHS were detected on the surface of colonic epithelia of infected monkeys. All Helicobacter isolates, including H. macacae, effectively adhered to, invaded, and significantly induced proinflammatory genes, including IL-8, IL-6, TNF-α and iNOS, while downregulating genes involved in the function of inflammasomes, particularly IL-1β, CASPASE-1, NRLP3, NLRP6 and NLRC4 in the human colonic T84 cell line (P<0.0001). These results suggest that EHS may represent an aetiological agent mediating diarrhoea, chronic inflammation, and possibly intestinal cancer in non-human primates, and may play a role in similar disease syndromes in humans. Downregulation of inflammasome function may represent an EHS strategy for long-term persistence in the host and play a role in inducing pathological changes in the host's lower bowel.

Comparison of the diagnostic accuracy of five different stool antigen tests for the diagnosis of Helicobacter pylori infection

BACKGROUND

Several noninvasive diagnostic tests based on the detection of Helicobacter pylori stool antigen (HpSA) have been developed. The aim of the study was to compare the diagnostic accuracy of 5 HpSA tests-2 monoclonal enzyme immunoassay tests (EIAs: the Premier Platinum HpSA Plus test and Helicobacter pylori Antigen (Hp Ag) test) and 3 rapid immunochromatographic assay (ICA) tests (the ImmunoCard STAT! HpSA test, one step HpSA test, and H. pylori fecal antigen test)--for diagnosing H. pylori infection in adult patients with dyspeptic symptoms before eradication therapy.

MATERIALS AND METHODS

A total of 198 patients with dyspeptic symptoms were included in the study. A gastric biopsy was collected for histopathology and rapid urease testing. Stool specimens for HpSA testing were also collected. Patients were considered H. pylori positive if two invasive tests (histological and rapid urease tests) were positive.

RESULTS

The sensitivity and specificity were 92.2% and 94.4%, respectively, for the Premier Platinum HpSA Plus test; 48.9% and 88.9%, respectively, for the HP Ag test; 86.7% and 88.9, respectively, for the One Step HpSA test; 68.9% and 92.6%, respectively, for the ImmunoCard STAT! HpSA test; and 78.9% and 87%, respectively, for the H. Pylori fecal antigen test.

CONCLUSIONS

The Premier Platinum HpSA Plus EIA test was determined to be the most accurate stool test for diagnosing H. pylori infections in adult dyspeptic patients. The currently available ICA-based tests are fast and easy to use but provide less reliable results.

Natural history of Helicobacter pylori infection in Mexican schoolchildren: incidence and spontaneous clearance

OBJECTIVES

The aim of the present study was to estimate the incidence and spontaneous clearance rate of Helicobacter pylori infection and the effect of some variables on these outcomes in schoolchildren.

METHODS

From May 2005 to December 2010, 718 schoolchildren enrolled in 3 public boarding schools in Mexico City participated in the follow-up. At the beginning of the study and every 6 months thereafter, breath samples were taken to detect H pylori infection; blood samples and anthropometric measurements were taken to evaluate nutritional status. Data on sociodemographic characteristics were collected.

RESULTS

The prevalence of H pylori infection was 38%. The incidence rate was 6.36%/year. Schoolchildren with anemia or iron deficiency at the beginning of the study (who received iron supplements) showed a higher infection acquisition rate than those with normal iron nutritional status, hazard ratio (HR) 12.52 (95% confidence interval [CI] 4.01%-39.12%), P < 0.001 and HR 2.05 (95% CI 1.09%-3.87%), P = 0.027, respectively. The spontaneous clearance rate of the infection was 4.74%/year. The spontaneous clearance rate was higher in children who had iron deficiency (who received iron supplements), HR 5.02 (95% CI 1.33%-18.99%), P = 0.017, compared with those with normal nutritional iron status. It was lower in schoolchildren with ≥ 2 siblings compared with schoolchildren with 1 or no siblings, HR 0.23 (95% CI 0.08%-0.63%), P = 0.004.

CONCLUSIONS

H pylori infection status is dynamic in schoolchildren. Variables related to health status and infection transmission, such as iron status and number of siblings, are important for the incidence and spontaneous clearance of H pylori infection.

Non-invasive genotyping of Helicobacter pylori cagA, vacA, and hopQ from asymptomatic children

BACKGROUND

Helicobacter pylori infection is usually acquired in childhood, but little is known about its natural history in asymptomatic children, primarily due to the paucity of non-invasive diagnostic methods. H. pylori strains harboring cagA and specific alleles of hopQ and vacA are associated with increased risk for gastric cancer. Many studies of H. pylori virulence markers in children have the bias that symptomatic subjects are selected for endoscopy, and these children may harbor the most virulent strains. Our aim is to genotype cagA, hopQ, and vacA alleles in stool DNA samples of healthy Colombian children residing in an area with high incidence of gastric cancer, to avoid selection bias resulting from endoscopy.

METHODS

H. pylori status of 86 asymptomatic children was assessed by (13) C-urea breath test (UBT) and PCR. H. pylori 16S rRNA, cagA, hopQ, and vacA genes were amplified from stool DNA samples and sequenced.

RESULTS

UBT was positive in 69 (80.2%) of 86 children; in stool DNA analysis, 78.3% were positive by 16S rRNA PCR. cagA, vacA, and hopQ were detected in 66.1%, 84.6%, and 72.3% of stool DNA samples from 16S rRNA-positive children. Of the children's DNA samples, which revealed vacA and hopQ alleles, 91.7% showed vacA s1 and 73.7% showed type I hopQ. Type I hopQ alleles were associated with cagA positivity and vacA s1 genotypes (p < 0.0001).

CONCLUSIONS

Using stool DNA samples, virulence markers of H. pylori were successfully genotyped in a high percentage of the asymptomatic infected children, revealing a high prevalence of genotypes associated with virulence. Type I hopQ alleles were associated with the presence of cagA and the vacA s1 genotype.

Coinfection with Enterohepatic Helicobacter species can ameliorate or promote Helicobacter pylori-induced gastric pathology in C57BL/6 mice

To investigate how different enterohepatic Helicobacter species (EHS) influence Helicobacter pylori gastric pathology, C57BL/6 mice were infected with Helicobacter hepaticus or Helicobacter muridarum, followed by H. pylori infection 2 weeks later. Compared to H. pylori-infected mice, mice infected with H. muridarum and H. pylori (HmHp mice) developed significantly lower histopathologic activity index (HAI) scores (P < 0.0001) at 6 and 11 months postinoculation (MPI). However, mice infected with H. hepaticus and H. pylori (HhHp mice) developed more severe gastric pathology at 6 MPI (P = 0.01), with a HAI at 11 MPI (P = 0.8) similar to that of H. pylori-infected mice. H. muridarum-mediated attenuation of gastritis in coinfected mice was associated with significant downregulation of proinflammatory Th1 (interlukin-1beta [Il-1β], gamma interferon [Ifn-γ], and tumor necrosis factor-alpha [Tnf-α]) cytokines at both time points and Th17 (Il-17A) cytokine mRNA levels at 6 MPI in murine stomachs compared to those of H. pylori-infected mice (P < 0.01). Coinfection with H. hepaticus also suppressed H. pylori-induced elevation of gastric Th1 cytokines Ifn-γ and Tnf-α (P < 0.0001) but increased Th17 cytokine mRNA levels (P = 0.028) at 6 MPI. Furthermore, mRNA levels of Il-17A were positively correlated with the severity of helicobacter-induced gastric pathology (HhHp>H. pylori>HmHp) (at 6 MPI, r² = 0.92, P < 0.0001; at 11 MPI, r² = 0.82, P < 0.002). Despite disparate effects on gastritis, colonization levels of gastric H. pylori were increased in HhHp mice (at 6 MPI) and HmHp mice (at both time points) compared to those in mono-H. pylori-infected mice. These data suggest that despite consistent downregulation of Th1 responses, EHS coinfection either attenuated or promoted the severity of H. pylori-induced gastric pathology in C57BL/6 mice. This modulation was related to the variable effects of EHS on gastric interleukin 17 (IL-17) responses to H. pylori infection.

Evaluation of a new antigen for diagnosis of Helicobacter pylori infection in stool of adult and children

BACKGROUND

Nowadays, there is an increasing interest in noninvasive methods to diagnose Helicobacter pylori infection. Indeed, they can profitably replace endoscopy in predicting the diagnosis. The stool antigen test for H. pylori is a noninvasive immunoassay to diagnose active infection with this bacterium in human fecal samples. The aim of this study was detection of alkyl hydroperoxide reductase protein (AhpC) antigen by immunoblotting in stool samples for diagnosis of H. pylori.

MATERIALS AND METHODS

Chromosomal DNA from H. pylori was isolated. AhpC gene was amplified by PCR, These amplicons were cloned into pTZ57R/T cloning vector then subcloned into pQE30 expression vector and overexpressed using isopropyl-beta-D-thiogalactopyranoside in E. coli M15. AhpC protein was purified by affinity chromatography. Rabbits were immunized with the purified AhpC protein for the production of antibodies. To determine the accuracy of the test for diagnosing H. pylori infection from stool, we evaluated 84 patients (6-81 years old) using Western blot analysis by rabbit anti-AhpC antibody. Positive rapid urease test on biopsy samples was considered as the gold standard.

RESULTS

AhpC gene was overexpressed, and AhpC protein was purified. Rabbit anti-AhpC antibody produced after immunization with the purified AhpC protein. By immunoblotting, we detected AhpC protein in the positive stool samples. The test showed a 83.3% sensitivity (95% CI: 69.8-92.5%) and a 91.7% specificity (95% CI: 77.5-98.2). Among the children, the sensitivity was 88.2% (95% CI: 63.6-98.5) and the specificity was 100% (95% CI: 69.2-100); in adults, the sensitivity and specificity were 80.6% (95% CI: 62.5-92.5) and 88.5% (95% CI: 69.8-97.6), respectively.

CONCLUSIONS

Using of AhpC antigen for diagnosis of H. pylori infection is a useful noninvasive method, accurate in adolescents and children, and can be used for the development of a stool antigen detection kit for H. pylori.

Persistent infection of rhesus monkeys with 'Helicobacter macacae' and its isolation from an animal with intestinal adenocarcinoma

A novel helicobacter, 'Helicobacter macacae', was previously isolated from a colony of rhesus and cynomolgus monkeys in which diarrhoea from chronic idiopathic colitis was enzootic. A survey performed in a second colony of rhesus monkeys without a history of chronic diarrhoea determined that 57 % were faecal-culture positive for Helicobacter species. Ten years after the survey, one of the animals from which 'H. macacae' had been isolated, a 23-year-old, intact male rhesus monkey (Macaca mulatta), presented with partial inappetence and progressive weight loss. Subsequent evaluation of the monkey revealed anaemia, hypoproteinaemia, hypoalbuminaemia and a palpable abdominal mass. Contrast radiography suggested partial intestinal obstruction. The animal was euthanized and a diagnosis was made of intestinal adenocarcinoma of the ileocaecocolic junction with metastasis to regional lymph nodes and liver. Microaerobic culture of caecal tissue yielded a helicobacter organism identified as 'H. macacae' by 16S rRNA gene sequencing - the same species of bacteria isolated 10 years previously. The liver, small intestine and colon were also positive by PCR for Helicobacter species. Intestinal adenocarcinoma is the most common malignancy of aged macaques. Faeces or caecal tissue from five out of five monkeys that remained from the original cohort and that were colonized with 'H. macacae' in the initial survey were positive for the organism. The apparent persistence of 'H. macacae' in these animals, the isolation of the bacterium from animals with colitis and the recognition of the importance of inflammation in carcinogenesis raise the possibility of an aetiological role in the genesis of intestinal adenocarcinoma in aged rhesus monkeys.

Concurrent Helicobacter bilis infection in C57BL/6 mice attenuates proinflammatory H. pylori-induced gastric pathology

Because coinfections can alter helicobacter gastritis, we investigated whether enterohepatic Helicobacter bilis modulates Helicobacter pylori gastritis in C57BL/6 mice. Thirty mice per group were sham dosed, H. bilis or H. pylori infected, or H. bilis infected followed in 2 weeks by H. pylori and then evaluated at 6 and 11 months postinfection (mpi) for gastritis and premalignant lesions. Compared to H. pylori-infected mice, H. bilis/H. pylori-infected mice at 6 and 11 mpi had less severe gastritis, atrophy, mucous metaplasia and hyperplasia (P < 0.01) and, additionally, at 11 mpi, less severe intestinal metaplasia and dysplasia (P < 0.05). H. bilis/H. pylori-infected mice at 11 mpi exhibited less Ki67 labeling of proliferating epithelial cells, reduced numbers of FoxP3(+) T-regulatory (T(REG)) cells, and lower FoxP3(+) mRNA levels than did H. pylori-infected mice (P < 0.05). Proinflammatory interleukin-1beta (IL-1beta), gamma interferon, and tumor necrosis factor alpha mRNA levels were attenuated in H. bilis/H. pylori-infected mice at 6 and 11 mpi (P < 0.01), although anti-inflammatory IL-10, IL-13, and transforming growth factor beta1 mRNA levels were not consistently impacted by H. bilis coinfection. Decreased pathology in H. bilis/H. pylori-infected mice correlated with higher gastric H. pylori colonization at 6 mpi (P < 0.001) and lower Th1-associated immunoglobulin G2c responses to H. pylori at 6 and 10 mpi (P < 0.05). We hypothesized that reduced pathology in H. bilis/H. pylori-infected mice was due to H. bilis-primed T(REG) cells in the lower bowel that migrated to the gastric compartment and inhibited Th1 responses to subsequent H. pylori infection. Thus, H. pylori-induced gastric lesions may vary in mouse models of unknown enteric helicobacter infection status and, importantly, variable sequelae to human H. pylori infection, particularly in developing countries, may occur where coinfection with lower bowel helicobacters and H. pylori may be common.

Antibody-based detection tests for the diagnosis of Helicobacter pylori infection in children: a meta-analysis

Background

Numerous serologic tests are available for the diagnosis of H. pylori infection in children. Common designs of antibody-based detection tests are ELISA and Western Blot (WB). For developing countries with limited laboratory resources and access, ELISA would be the preferred method because of its simplicity, lower cost and speed. Although in adults ELISA has proven to be highly accurate in diagnosing H. pylori infection; in children, it has shown variable accuracy.

Methods/Findings

We conducted a systematic review and meta-analysis to assess the accuracy of antibody-based detection tests for the diagnosis of H. pylori infection in children. Selection criteria included participation of at least 30 children and the use of a gold standard for H. pylori diagnosis. In a comprehensive search we identified 68 studies. Subgroup analyses were carried out by technique, immunoglobulin class, and source of test (commercial and in-house). The results demonstrated: 1) WB tests showed high overall performance, sensitivity 91.3% (95% CI, 88.9–93.3), specificity 89% (95% CI, 85.7–91.9), LR+ 8.2 (95% CI, 5.1–13.3), LR− 0.06 (95% CI, 0.02–0.16), DOR 158.8 (95% CI, 57.8–435.8); 2) ELISA-IgG assays showed low sensitivity 79.2% (95% CI, 77.3–81.0) and high specificity (92.4%, 95% CI, 91.6–93.3); 3) ELISA commercial tests varied widely in performance (test for heterogeneity p<0.0001); and 4) In-house ELISA with whole-cell antigen tests showed the highest overall performance: sensitivity 94% (95% CI, 90.2–96.7), specificity 96.4% (95% CI, 94.2–97.9), LR+ 19.9 (95% CI, 7.9–49.8), LR− 0.08 (95% CI, 0.04–0.15) DOR 292.8 (95% CI, 101.8–841.7).

Conclusions/Significance

WB test and in-house ELISA with whole-cell antigen tests are the most reliable tests for the diagnosis of H. pylori infection in children. Antigens obtained from local strains of the community could partially explain the good overall accuracy of the in-house ELISA. Because of its cost and technical demands, in-house ELISA might be more suitable for use in developing countries.

Detection of enterohepatic and gastric helicobacter species in fecal specimens of children with Crohn's disease

BACKGROUND

Although there is compelling evidence to support the role of bacteria in Crohn's disease (CD), there is currently no solid evidence to support the role of any one specific bacterial causative agent. Recent studies have suggested that members of the Helicobacteraceae may play a role in the development of CD. The aim of this study was to further investigate the presence of members of the Helicobacteraceae in children with and without CD.

MATERIALS AND METHODS

Fecal specimens from 29 children with CD, 11 healthy, normal controls, and 26 symptomatic controls with non-inflammatory bowel disease (IBD) pathology were obtained for DNA extraction and subjected to Helicobacteraceae-specific polymerase chain reaction (PCR). All PCR-positive samples were sequenced. The association between the presence of members of the Helicobacteraceae and each study group was statistically analysed using the Fisher's exact test.

RESULTS

Based on Helicobacteraceae-specific PCR analysis, 59% (17 of 29) of the children with CD were positive, which was significantly higher than that in asymptomatic healthy children [9% (1 of 11); p = .01] and that in symptomatic children with non-IBD pathology [0% (0/26); p < .0001]. Sequencing of the 16S rRNA gene of positive samples revealed the presence of both enterohepatic Helicobacter species and Helicobacter pylori in fecal specimens.

CONCLUSIONS

For the first time, enterohepatic and gastric Helicobacter species have been identified in fecal specimens from children diagnosed with CD using PCR. Our data suggest that Helicobacter species may have a pathogenic role in the development of CD in a considerable proportion of children.

Evaluation of a novel monoclonal-based antigen-in-stool enzyme immunoassay (Premier Platinum HpSA PLUS) for diagnosis of Helicobacter pylori infection in Vietnamese children

BACKGROUND

Helicobacter pylori infection is difficult to diagnose in children, especially in developing countries where noninvasive methods such as urea breath test are often not available. We evaluate the sensitivity and specificity of a new monoclonal antibody-based antigen-in-stool enzyme immunoassay (Premier Platinum HpSA PLUS) for diagnosis of H. pylori infection in Vietnamese children.

MATERIALS AND METHODS

Sensitivity of the antigen-in-stool test was evaluated in 232 children, 3-15 years of age, who were positive for H. pylori infection by culture from biopsies. For evaluation of the specificity 98 children of similar age with nongastrointestinal conditions and who were negative for H. pylori infection by serologic assays were included with blood and stool samples.

RESULTS

Of the 232 culture-positive children, 224 were also positive by Premier Platinum HpSA PLUS. Of the 98 control children, 93 were H. pylori negative also in the stool test. The sensitivity of Premier Platinum HpSA PLUS was thus 96.6% (95% CI 93.3-98.5) and the specificity was 94.9% (95% CI 88.5-98.3).

CONCLUSIONS

The findings have demonstrated Premium Platinum HpSA PLUS to be a reliable method for detection of H. pylori infection also in children in our area.

Correspondence between Helicobacter pylori antibodies and urea breath test results in a US-Mexico birth cohort

The uncertain accuracy of methods for detecting Helicobacter pylori infection in young children complicates research on this infection in early life. The aim of the present report was to describe the correspondence between positive serology and positive urea breath test (UBT) in children followed from age 0 to 24 months in the Pasitos Cohort Study, conducted along the US-Mexico border at El Paso and Juarez. Children were recruited before birth during 1998-2000 and examined at target ages of 6, 12, 18 and 24 months. H. pylori infection was detected using an enzyme immunoassay for serum immunoglobulin G antibodies and the (13)C-urea breath test corrected for age-dependent variation in CO(2) production. Of 472 children, 125 had one or more positive UBT results and 46 had one or more positive serology results. The prevalence of H. pylori infection at target ages of 6, 12, 18 and 24 months was 7%, 14%, 16% and 19%, respectively, by UBT and 8%, 2%, 3% and 3%, respectively, by serology. Few (<1%) of those tested on both tests were positive on both at any age. Among UBT-positive children, 6% were concurrently seropositive and 6% became seropositive later. Because UBT positivity cut points were selected to minimise false positives, these results suggest that H. pylori infection occurred frequently in this cohort, but rarely produced detectable antibodies. For clinical or epidemiological investigations, serology should not be used as the sole method for detecting H. pylori infection in children aged 2 years or less.

Evaluation of a rapid new stool antigen test for diagnosis of Helicobacter pylori infection in adult patients

The evaluation of a new rapid stool antigen test showed different levels of sensitivity for final readings of test results at 20 min (59.1%) and 30 min (76.9%). Significant differences in performance were observed between the two sexes and the various age categories, with higher efficiency in male patients and young adults. Generally, this test is efficient and can be used to detect H. pylori infection in adults. However, further studies are required to confirm its accuracy.

Isolation and characterization of a novel helicobacter species, "Helicobacter macacae," from rhesus monkeys with and without chronic idiopathic colitis

Chronic idiopathic colitis is a common clinical entity in young captive rhesus monkeys. Eight isolates, cultured from five monkeys in colony 1 with endemic diarrhea and three from colony 2 without diarrhea, were grown under microaerobic conditions on selective agar and were classified by full 16S rRNA sequence, biochemical, and phenotypic analysis as a novel helicobacter, "Helicobacter macacae" (proposed name). All eight strains of H. macacae had 99.5% identical 16S rRNA sequences.

A new model for the transmission of Helicobacter pylori: role of environmental reservoirs as gene pools to increase strain diversity

Twenty-five years after the first successful cultivation and isolation of Helicobacter pylori, the scientific community is still struggling to understand the way(s) this bacterium is transmitted among the human population. Here, both epidemiologic and microbiologic evidence addressing this matter is reviewed and explored to conclude that most H. pylori successful colonizations are derived from direct person-to-person contact and that even though exposure of humans to H. pylori from environmental sources is a very common event, in most occasions the host is able to fight off infection. In addition, under a new model developed here, we propose that the near elimination of environmental reservoirs is the main responsible for the lower prevalence observed in the more industrialized countries by acting on two levels: by decreasing the number of direct infections and by diminishing the number of intraspecies recombination events for producing strain variation within H. pylori.

Detection rate of Helicobacter pylori stool antigen in newborn infants and small children

AIMS

To investigate the prevalence of H. pylori antigen in the stools of Norwegian neonates and small children.

METHODS

A total of 249 children aged 0 days-3 years were tested for the presence of H. pylori antigen in feces using the HpSA immunoassay. For verification purposes, a selection of samples were analyzed with PCR targeting the 16 S rDNA Helicobacter gene.

RESULTS

H. pylori antigen in stool was detected in 52% (36/69) of the neonates, in 15% (7/46) of infants aged 7 days-1 month, and in 5% (7/134) of children aged 1 month-3 years. In neonates, H. pylori antigen detection was significantly associated with mode of delivery: 59% (30/51) with uncomplicated vaginal births were HpSA positive compared to only 10% (1/10) of infants delivered by cesarean section (P=0.02). Positive PCR results were found in 35% (9/26) of HpSA positive samples. Sequencing of PCR products revealed 97-100% homology with gene sequences from both H. pylori and other Helicobacter species.

CONCLUSIONS

The low H. pylori antigen detection rate in children >1 month of age is in accordance with previous prevalence studies from Western countries. The unexpected finding of a high H. pylori antigen detection rate in neonates suggests that transient colonization may occur in the neonatal period.

Gastroenteritis and transmission of Helicobacter pylori infection in households

The mode of transmission of Helicobacter pylori infection is poorly characterized. In northern California, 2,752 household members were tested for H. pylori infection in serum or stool at a baseline visit and 3 months later. Among 1,752 person considered uninfected at baseline, 30 new infections (7 definite, 7 probable, and 16 possible) occurred, for an annual incidence of 7% overall and 21% in children <2 years of age. Exposure to an infected household member with gastroenteritis was associated with a 4.8-fold (95% confidence interval [CI] 1.4-17.1) increased risk for definite or probable new infection, with vomiting a greater risk factor (adjusted odds ratio [AOR] 6.3, CI 1.6-24.5) than diarrhea only (AOR 3.0, p = 0.65). Of probable or definite new infections, 75% were attributable to exposure to an infected person with gastroenteritis. Exposure to an H. pylori-infected person with gastroenteritis, particularly vomiting, markedly increased risk for new infection.

Enterohepatic Helicobacter species isolated from the ileum, liver and colon of a baboon with pancreatic islet amyloidosis

Microaerobic bacteria were isolated from a baboon with pancreatic islet amyloidosis and hepatitis. Phenotypic and molecular analyses identified two distinct helicobacters. Analyses of 16S rRNA demonstrated "Helicobacter macacae" in the ileum and liver, and Helicobacter cinaedi in the colon. To the best of the authors' knowledge, this is the first report describing the isolation of enterohepatic Helicobacter species from a baboon.

Diagnosis of Helicobacter pylori infection

A growing interest in non-invasive tests for the detection of Helicobacter pylori has been observed recently, reflecting a large number of studies published this year. New tests have been validated, and the old ones have been used in different clinical situations or for different purposes. Stool antigen tests have been extensively evaluated in pre- and post-treatment settings both in adults and children, and the urea breath test has been studied as a predictor of bacterial load, severity of gastric inflammation, and response to eradication treatment. Several studies have also explored the usefulness of some serologic markers as indicators of the gastric mucosa status. With regard to invasive tests, molecular methods are being used more and more, but the breakthrough this year was the direct in vivo observation of H. pylori during endoscopy.

Epidemiology of Helicobacter pylori infection

Differences may occur in the mode of transmission of Helicobacter pylori between developed and developing countries: direct human-to-human contacts have been suggested as the primary route in the former while the fecal-oral route, also, through contaminated water, in the latter. Data on intrafamilial transmission of H. pylori among children continue to be produced. The importance of low socioeconomic conditions on the acquisition of H. pylori infection has been confirmed in a number of population-based studies. Due to the improvement of living standards, the prevalence of the infection has fallen dramatically in many countries. It varies from 8.9 to 72.8% among children from developed and developing countries, respectively, the re-infection rate being also significantly higher in the latter. Conflicting data have been reported on the effect of breastfeeding against H. pylori colonization in infancy as well as on the occupational risk for acquiring H. pylori. This review summarizes recent results from the literature on these topics.

Helicobacter pylori infection in pediatrics

This review summarizes the literature on Helicobacter pylori infection in childhood between April 2005 and March 2006, and includes guidelines of the Canadian Helicobacter Study Group Consensus Conference, noninvasive tests, optimum therapy regimens and problems with resistance, and reviews on immune mechanisms in the gastric mucosa that may lead to the development of an effective vaccine.

Nongastric Helicobacter species detected in the intestinal tract of children

The presence of members of the family Helicobacteraceae in the colon of children was investigated using PCR, denaturing gradient gel electrophoresis, and fluorescent in situ hybridization. The rate of detection of species belonging to the Helicobacteraceae family in children with inflammatory bowel disease (92%) and irritable bowel syndrome (100%) was found to be significantly higher than that in healthy children (25%) (P < 0.05).

Stool antigen tests for the detection of Helicobacter pylori in children

Stool specimens from 102 children (median age = 6.0 years; Helicobacter pylori in biopsy specimens, n = 43) were tested for H. pylori with the monoclonal antibody-based enzyme immunoassay HpStar. In 28 cases, the specimen was obtained with a rectal cotton swab during endoscopy. The sensitivity and specificity of the HpStar were 0.95 and 0.90, respectively, as compared with biopsy-based methods. The rectal cotton swab specimen gave accurate results in 24 of the 28 cases. Storage of specimens for 1, 3, or 7 days (n = 6) had a minor effect on the results, but one specimen's originally positive value on borderline turned negative when it was kept in room temperature. Forty-eight specimens were tested in parallel with all 3 tests used: HpStar, Premium Platinum HpSA, and the rapid test ImmunoCardSTAT! The accuracy rates of the tests were 98% for the HpSA and HpStar and 96% for the ImmunoCardSTAT! The performance of the stool antigen tests was excellent in young children.

Prevalence and risk factors of Helicobacter pylori infection among healthy 3- to 5-year-old Israeli Arab children

We determined the prevalence and risk factors of H. pylori infection among 197 healthy 3- to 5-year-old Israeli Arab children, in a population under socioeconomic and environmental transition. Data on the socioeconomic and environmental characteristics were obtained by personal interviews. The presence of H. pylori infection was identified using an ELISA kit for detection of H. pylori antigens in stool specimens. The prevalence rate of H. pylori infection was 49.7% (95% CI 42.8-56.67). It varied significantly among the different villages. In the univariate analysis stratified by village, the risk of infection increased according to household crowding, number of siblings younger than 5 years and siblings' H. pylori positivity. In the multivariate analysis the village of residence and siblings' H. pylori positivity were the only variables that remained strongly associated with H. pylori infection. In a population such as that described in this study the socioeconomic and living conditions are major risk factors of H. pylori infection and the intra-familial transmission of H. pylori in early childhood has an important role.