Serological assessment of Helicobacter pylori eradication

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.

Detection of Helicobacter pylori in bladder biopsy specimens of patients with interstitial cystitis by polymerase chain reaction

The cause of interstitial cystitis (IC) is still unknown. Several features suggest that it may be an infectious disease and it has compelling similarities to chronic gastritis. The identification of Helicobacter pylori as the cause of chronic gastritis focused attention on this organism. Many studies have been done investigating the role of H. pylori in the etiology of IC. Previous studies mostly determined the presence of H.pylori with antibodies in the serum samples of IC patients, but these methods may lead to false positive or negative results. We therefore investigated the presence of H.pylori in bladder biopsy specimens by using polymerase chain reaction (PCR), which is accepted as the most sensitive and specific test for detecting this organism. A total of 32 patients with IC were enrolled into the study. The PCR assay was performed on cold cup bladder biopsies of IC patients. Both positive and negative controls were included in each set of PCR reactions. Gastric biopsy specimens of peptic ulcer patients with proven H. pylori infection were used as positive controls. Bladder biopsies of all IC patients were negative for H. pylori DNA. PCR showed the presence of H. pylori in the positive controls in each cycle demonstrating that the PCR assay was working properly. Thus, there is no evidence that IC is the result of H. pylori infection. This study does not negate the possibility that other infectious agents may play a role in the etiology of IC.

Specific identification of three low molecular weight membrane-associated antigens of Helicobacter pylori

BACKGROUND

A large number of Helicobacter pylori proteins are antigenic, but antibodies to these proteins persist in spite of the eradication of the infection.

METHODS AND RESULTS

The analysis of sera from H. pylori-infected and non-infected patients, before and 3 and 5 months after eradication, showed that the antibody response against unknown H. pylori antigens at 32, 30, 22 and 14 kDa in sodium dodecylsulphate polyacrylamide gel electrophoresis decreased by > or = 60% at 3 months and > or = 70% at 5 months after treatment. Two-dimensional gel electrophoresis and mass spectrometry allowed the identification of eight proteins at these positions: neuraminyl-lactose-binding haemagglutinin precursor, 3-oxoadipate CoA-transferase subunit A, elongation factor P, peptidoglycan-associated lipoprotein precursor, hypothetical protein HP0596, adhesin-thiol peroxidase, 50S ribosomal protein L7/L12 and subunit b' of the F(0) ATP synthase. Three of these eight, expressed as recombinant proteins (32 kDa neuraminyl-lactose-binding haemagglutinin precursor, 30 kDa peptidoglycan-associated lipoprotein precursor and 22 kDa hypothetical protein HP0596), reacted specifically with sera from infected patients, while the 14 kDa 50S ribosomal protein L7/L12 cross-reacted with one out of five sera from H. pylori-negative patients. The other recombinant proteins did not show significant immunoreactivity.

CONCLUSIONS

Four low molecular weight antigens were identified by these methods, three of which were specific. Immunoreaction with these three proteins (neuraminyl-lactose-binding haemagglutinin precursor, peptidoglycan-associated lipoprotein precursor and hypothetical protein HP0596) could provide a serological assessment not only of H. pylori infection, but also of eradication.

Detection of Helicobacter pylori antigen in faeces by enzyme immunoassay

The detection of Helicobacter pylori antigen directly in faecal specimens may offer an alternative non-invasive method for determining the presence of H. pylori infection. This study compared the performance of the Premier Platinum HpSA enzyme immunoassay (HpSA) with histology and CLOtest, a rapid urease test. Of 134 patients undergoing upper gastrointestinal endoscopy, 37 (28%) were H. pylori-positive by histology and CLOtest. Using the HpSA test, H. pylori was detected in 35 H. pylori-positive patients (95% sensitivity) and one H. pylori-negative patient (99% specificity). The positive and negative predictive values for HpSA were 97 and 98%, respectively. HpSA is a rapid, easily performed, non-invasive method for detecting H. pylori.

The accuracy of the Helicobacter pylori stool antigen test in diagnosing H. pylori in treated and untreated patients

OBJECTIVE AND DESIGN

To evaluate the performance of the Helicobacter pylori stool antigen test (HpSA test) in detecting H. pylori infection and monitoring the effect of treatment. This was done in two separate studies using either a biopsy or the 13C-urea breath test based 'gold standard' (in untreated and treated patients, respectively).

SETTING

Endoscopy units of two general hospitals.

PATIENTS

One hundred and twenty-eight dyspeptic patients undergoing endoscopy in the first study. Sixty-five patients receiving anti-H. pylori treatment in the second study.

RESULTS

Sensitivity and specificity in untreated patients were 96.3% and 81.8%, respectively. Seven days after treatment, these figures were 20% and 95%, and 4 weeks after treatment they were 40% and 95%.

CONCLUSION

The HpSA test is accurate in untreated patients but fails in monitoring treatment success.

[Basal concentrations of gastrin and pepsinogen I and II in gastric ulcer: influence of Helicobacter pylori infection and usefulness in the control of the eradication]

AIM

To study the influence of Helicobacter pylori eradication on basal gastrin and pepsinogen I and II levels in patients with gastric ulcer over a 1-year follow-up period, and to assess the usefulness of these values in confirming H. pylori eradication after treatment.

METHODS

Fifty-six patients with gastric ulcer and H. pylori infection were prospectively studied. At the beginning of the study, endoscopy with biopsies for histologic examination and urease testing was carried out, as were 13C-urea breath test and blood samples for determination of gastrin and pepsinogen I and II values by radioimmunoassay and serology. Histologic study, 13C-urea breath test and laboratory determinations were repeated at months 1, 6 and 12 after completion of eradication treatment.

RESULTS

H. pylori infection was eradicated in 82.1% of patients. In patients with successful H. pylori eradication, the initial mean gastrin value was 75.5 +/- 39.1 pg/ml, while at 1 month after treatment this value decreased to 49.2 +/- 21 pg/ml (p < 0.0001). No further reductions were noted. Initial pepsinogen I and II values were 104 +/- 58 and 15.8 +/- 10 ng/ml, respectively, whereas at month 1 after treatment these values were 77 +/- 42 and 7.3 +/- 4 ng/ml, respectively (p < 0.0001) and were 72 +/- 41 and 6.7 +/- 3 ng/ml respectively at month 6 (p < 0.01); no further variations were observed thereafter. The area under the ROC curve which reveals eradication through reductions in hormonal values was 0.70 for gastrin, 0.78 for pepsinogen I, 0.93 for pepsinogen II and 0.92 for the pepsinogen I/II ratio. At months 6 and 12 after treatment completion, differences in mean gastrin and pepsinogen I and II values between the patients with normal histologic findings and those with chronic gastritis were significant (p < 0.05).

CONCLUSIONS

a) H. pylori eradication is associated with an early fall in basal gastrin values and a progressive decrease in basal pepsinogen I and II values. b) In patients with gastric ulcer, determination of the decrease in basal pepsinogen II levels is a useful and early non-invasive method for confirming eradication. c) Determination of gastrin and pepsinogen I and II values may be useful for assessing improvement in gastritis 6 months after treatment completion.

Concordance between noninvasive tests in detecting Helicobacter pylori and potential use of serology for monitoring eradication in gastric ulcer

Our aim was to determine concordance between 13C-urea breath test and serology in detecting Helicobacter pylori and to study their potential use for monitoring eradication in patients with gastric ulcer. We prospectively studied 73 gastric ulcer patients. On endoscopy, biopsies were taken for hematoxylineosin staining and rapid urease testing. Blood samples were drawn for immunoglobulin G antibody determination by enzyme-linked immunosorbent assay (ELISA). A 13C-urea breath test was performed as well. Histology, serology, and urea breath tests were all repeated 1, 6, and 12 months after therapy completion in 56 infected patients. A proportion of positive agreement between serology and breath test results as high as 0.95 was found. McNemar statistic was 3 (p = 0.08), whereas kappa statistic was 0.83 (p < 0.0001). At month 6, significant differences in patients successfully treated relative to baseline serologic values were observed (chi2 = 11.7; p < 0.001). The area under the receiver operating characteristic (ROC) curve for diagnostic efficiency was 0.76, sensitivity was 74%, and specificity was 90% (for H. pylori eradication) when the fall of at least one category in serologic levels was considered as cut-off point. No further decreases in serologic levels were noted over the next 6 months, and 48.8% of patients remained seropositive 1 year after completion of successful treatment. A high concordance between serology and 13C-urea breath test results is observed when the two procedures are used for H. pylori infection diagnosis in patients with gastric ulcer. Also, serology can be successfully used for monitoring H. pylori eradication 6 months after therapy completion.

Noninvasive evaluation of Helicobacter pylori therapy: role of fasting or postprandial gastrin, pepsinogen I, pepsinogen II, or serum IgG antibodies

OBJECTIVE

We evaluated the potential value of a change in serum IgG antibodies, fasting or meal-stimulated gastrin levels, and pepsinogen I (PGI) or pepsinogen II (PGII) levels for identifying Helicobacter pylori (H. pylori) status after antibiotic therapy.

METHODS

A total of 32 men and one woman with peptic ulcer disease and documented H. pylori infection were enrolled. Fasting and 30-min postprandial blood samples were obtained at 0, 2, 7, 11, 17, 23, 27, and 39 wk of the study and were analyzed for the factors evaluated.

RESULTS

Treatment was successful in 25 patients and failed in seven. Serum IgG antibodies, meal-stimulated gastrin, and both fasting and meal-stimulated pepsinogen I and II levels fell throughout the study, and pepsinogen I:II ratios increased in those whose infection was cured. The mean levels at wk 0 versus wk 7 were: fasting gastrin (fmol/ml) 12.4 and 11, meal-stimulated gastrin 26.5 and 15.4, PGI (ng/ml) 83.7 and 59, PGII (ng/ml) 24.5 and 13.6, PGI/PGII 3.5 and 4.7, and enzyme-linked immunosorbent assay value 4.8 and 4.55. The sensitivity, specificity, and positive and negative predictive values for the data analyzed using different percent changes (e.g., 80%, 50%, and 20%) were calculated. The specificity and sensitivity remained <80% at all time points.

CONCLUSIONS

Despite a significant fall in serum markers of H. pylori infection in groups of individuals, no marker tested could be used to reliably determine posttherapy H. pylori status for individual patients.

Long-term follow-up study of serum immunoglobulin G and immunoglobulin A antibodies after Helicobacter pylori eradication

OBJECTIVE

There have been few studies concerning serum titers of anti-Helicobacter pylori immunoglobulin G (IgG) antibody >12 months after eradication of the original infection. Moreover, clinical usefulness of immunoglobulin A (IgA) antibody levels remains to be established. The purpose of this study was to investigate long-term responses of serum IgG-specific and IgA-specific antibodies to H pylori in children after eradication therapy.

STUDY DESIGN

A total of 34 children, 2 to 17 years of age (mean: 11.7 years) with H pylori-associated gastroduodenal disease received eradication therapy (proton pump inhibitor-based dual or triple regimens). Diagnoses included nodular gastritis (n = 8), gastric ulcer (n = 7), and duodenal ulcer (n = 19). Upper gastrointestinal endoscopy and biopsy were performed before the therapy and at 1 to 2 months' posttreatment. H pylori infection and eradication were defined by biopsy-based tests; eradication was successful in 28 patients and unsuccessful in 6. Pretreatment IgG was positive in 30 patients (88. 2%), and the IgA was positive in 31 (91.2%), who were entered into this study (duration </=24 months). Serum samples were obtained before treatment and at 1, 3, 6, 12, 18, and 24 months' posttreatment. IgG and IgA antibodies were measured using commercial enzyme immunoassay kits (HM-CAP and PP-CAP; Enteric Products, Inc, New York, NY).

RESULTS

Compared with pretreatment values, IgG and IgA antibodies significantly and steadily decreased at 1 through 24 months' posttreatment in successfully treated patients. A decrease in titer of the IgA class was significantly greater than that of the IgG class at 1 to 12 months' follow-up. There was no significant decrease in titer of either antibody in all but 2 patients with eradication failure. A >/=30% decrease in titer of the IgA antibody at 6 months indicated eradication with sensitivity of 90.5% and specificity of 100%. For the IgG antibody, a 30% decrease at 12 months showed equal sensitivity and specificity. Seroreversion rates of IgG and IgA antibodies were 53% and 48% at 12 months and were 86% and 81% at 24 months, respectively. The mean periods from the completion of eradication therapy to seroreversion of IgG and IgA antibodies were 11.2 +/- 7.0 and 11.6 +/- 7.8 months, respectively (not significantly different). A higher pretreatment titer of IgG antibody was related to a longer period of seroreversion (r = 0.44). In one patient, (13)C-urea breath test-confirmed reinfection was accompanied by reappearance of significant titers of the IgG and IgA antibodies.

CONCLUSIONS

A serology test is useful for evaluating eradication in children. Approximately half of patients with successful eradication remained to be IgG-seropositive and IgA-seropositive at 12 months' posttreatment. When a decrease titer in antibody is used for assessing eradication, an endpoint of >/=6 months is required. The IgA antibody may be a more convenient indicator of H pylori status than is the IgG antibody.

No difference in seroprevalences of Helicobacter pylori infection between patients with pulmonary tuberculosis and those without

A previous article reported a possible relationship between a history of tuberculosis and Helicobacter pylori infection. Epidemiologic similarities exist between the two infections: Mycobacterium tuberculosis and H. pylori are transmitted from person to person and the risk of acquiring them is elevated in underprivileged environment. This study was conducted to investigate the relationship between the two infections. Serum concentrations of anti-H. pylori IgG antibody were measured in 40 tuberculosis inpatients on antituberculosis chemotherapy for no more than 3 months (group I; 52.4 +/- 21.4 years of age), 43 tuberculosis inpatients on it for more than 3 months (group II; 57.3 +/- 16.3 years), and 60 nontuberculosis outpatients (control subjects; 55.9 +/- 16.7 years). H. pylori seropositivities were similar among control subjects (73.3%), group I (65%), and group II (69.8%). The difference in the antibody concentrations was significant between control subjects and group I (353.7 +/- 321.2 vs. 176.5 +/- 197.9 U/ml) but was not significant between control subjects and group II (353.7 +/- 321.2 vs. 229.9 +/- 249.5 U/ml). The seroprevalences may not be different between patients with pulmonary tuberculosis and those without, and antituberculosis therapy may not decrease the antibody concentrations.

Serological assessment of the early response to eradication therapy using an immunodominant outer membrane protein of Helicobacter pylori

Eradication of Helicobacter pylori infection cures gastritis and prevents recurrence of peptic ulcers. Endoscopy is usually used to evaluate the effectiveness of eradication therapy. We designed a new noninvasive assay system for the early evaluation of eradication of H. pylori infection in which a crude H. pylori outer membrane protein preparation (HPOmp) is used as an antigen, and we determined the sensitivity and specificity of the serological assay system. Immunoblot analysis showed that anti-HPOmp antibodies reacted to a protein with a molecular mass of approximately 29 kDa. In those patients who responded to therapy, the anti-HPOmp immunoglobulin G (IgG) titers measured by enzyme-linked immunosorbent assay (ELISA) at 1 month after the end of therapy were significantly lower than those before treatment (34.8% reduction; P < 0.001), and the posttreatment reduction in the antibody titer was significantly greater than that of the titer measured with a commercially available anti-H. pylori IgG ELISA (34.8% versus 16.1%; P < 0.001). When a 25% reduction of anti-HPOmp IgG titer at 1 month after the end of treatment was taken as the cutoff value for H. pylori eradication, the sensitivity and specificity of our new assay were 75% (51 of 68 treatment responders) and 96% (22 of 23 nonresponders), respectively. Our results indicate that the novel serological test with HPOmp might be a clinically useful tool for assessment of eradication of H. pylori.

Changes in serum pepsinogen, gastrin, and immunoglobulin G antibody titers in helicobacter pylori-positive gastric ulcer after eradication of infection

There are no studies of changes in immunoglobulin G (IgG) titers to Helicobacter pylori, serum pepsinogen, and gastrin in patients with H. pylori-positive gastric ulcers. We investigated the effect of therapy for H. pylori-positive gastric ulcer on IgG titers to H. pylori, serum pepsinogen I and II, and gastrin. Thirty-six patients with H. pylori-positive gastric ulcer were treated with lansorazole and antibiotics for 2 weeks. Serum pepsinogen I and II concentrations, serum gastrin, and IgG titers to H. pylori were measured before treatment and then at 4 and 12 weeks after stopping the treatment. The presence or eradication of H. pylori was determined using the rapid urease test and by histologic H. pylori staining. For 19 patients in whom H. pylori had been successfully eradicated, the pepsinogen I/II ratio increased, pepsinogen II levels decreased, and the anti-H. pylori IgG decreased compared with the results from before therapy and with those from 4 and 12 weeks after therapy. Gastrin levels decreased compared with pretreatment results and those from 4 weeks after the end of treatment. In 17 patients in whom the therapy failed to eradicate H. pylori infection, there were no sequential significant changes in the pepsinogen I/II ratio or in the levels of pepsinogen I, pepsinogen II, anti-H. pylori IgG, and gastrin. A decrease in the serum levels of the IgG antibody to H. pylori and gastrin and also an increase in the pepsinogen I/II ratio could be used as predictors for the eradication of H. pylori infection in gastric ulcer.

Review: Helicobacter pylori. Current issues and new directions

The present review outlines current management issues and controversies related to Helicobacter pylori infection. Clearance of this infection markedly reduces the likelihood of duodenal and gastric ulcer recurrence and may result in the regression of low grade primary gastric lymphoma. Recent therapeutic advances have seen the development of simpler drug regimens to treat H. pylori that have fewer side effects and are shorter in duration. Clearance of the infection can be achieved in 80-95% of patients treated, depending on the drug regimen used, compliance with medications and antibiotic sensitivity. In developed nations reinfection is uncommon after successful treatment. Data do not currently support treatment of this infection for non-ulcer dyspepsia or for the prevention of gastric cancer, although whether certain individuals or populations may benefit from such treatment remains to be clarified.

Helicobacter pylori: the missing link in perspective

Helicobacter pylori, an organism responsible for a common human infection, may act as a cofactor to produce gastrointestinal disease in a significant minority. The exact mechanisms of transmission are still unclear, but likely involve direct person-to-person spread and fecal-oral or waterborne/environmental transmission. Infection is a necessary condition for the development of duodenal ulcers and chronic nonspecific gastritis. It also likely contributes to the development of gastric ulcers, and the intestinal-type gastric carcinoma, but further studies are needed to confirm these hypotheses. Multiple effective treatment regimens currently exists. We recommend using bismuth, metronidazole, and tetracycline as the initial regimen of choice. Unfortunately, the relative importance of bacterial virulence factors is still unclear when compared with host susceptibility factors, and much knowledge needs to be gained about pathogenesis before vaccine development can proceed.