Effect of antimicrobial therapy on the specific serological response to Helicobacter pylori infection

Pepsinogen testing for evaluation of the success of Helicobacter pylori eradication at 4 weeks after completion of therapy

BACKGROUND AND OBJECTIVE

Pepsinogen levels in plasma are increased by inflammation in the gastric mucosa, including inflammation resulting from Helicobacter pylori infection. A decrease in pepsinogen II level has been suggested as a reliable marker to confirm the successful eradication of infection. The aim of our study was to evaluate the potential role of pepsinogens I and II, gastrin-17 and H. pylori antibodies in confirming successful eradication.

MATERIAL AND METHODS

Altogether 42 patients (25 women, 17 men), mean age 45 years (range 23-74), were enrolled. Pepsinogens I and II, gastrin-17 and H. pylori IgG antibodies were measured in plasma samples using an ELISA test (Biohit, Oyj., Finland) before the eradication and 4 weeks after completing the treatment. The success of eradication was determined by a urea breath test.

RESULTS

Eradication was successful in 31 patients (74%) and unsuccessful in 11 patients (26%). Pepsinogen II decreased significantly in both the successful (P=0.029) and unsuccessful (P=0.042) eradication groups. Pepsinogen I decreased significantly in the successful (P=0.025) but not the unsuccessful (P=0.29) eradication group. The pepsinogen I/II ratio increased in the successful eradication group (P=0.0018) but not in the group in which treatment failed (P=0.12). There were no differences in gastrin-17 or H. pylori antibody values.

CONCLUSIONS

A decrease in pepsinogen II levels cannot be used as a reliable marker for the successful eradication of H. pylori 4 weeks after the completion of treatment. The increase in pepsinogen I/II ratio reflects differences in pepsinogen production following the eradication irrespective of improvement in atrophy.

H pylori status and angiogenesis factors in human gastric carcinoma

AIM: To investigate H pylori expression in gastric cancer patients in relation to primary tumor angiogenic markers, such as microvessel density (MVD), thymidine phosphorylase (TP), vascular endothelial growth factor receptor-1 (VEGF-R1), p53 and circulating VEGF levels.

METHODS: Angiogenic markers were analyzed immunohistochemically in 56 primary gastric cancers. H pylori cytotoxin (vacA) and the cytotoxin-associated gene (cagA) amplification were evaluated using PCR assay. Serum H pylori IgG antibodies and serum/plasma circulating VEGF levels were detected in 39 and 38 patients by ELISA, respectively.

RESULTS: A total of 69% of patients were positive for circulating IgG antibodies against H pylori. cagA-positive H pylori strains were found in 41% of gastric patients. vacA was found in 50% of patients; s1 strains were more highly expressed among vacA-positive patients. The presence of the s1 strain was significantly associated with cagA (P = 0.0001). MVD was significantly correlated with both tumor VEGF expression (r = 0.361, P = 0.009) and serum VEGF levels (r = -0.347, P = 0.041). Conversely, neither VEGF-R1 expression nor MVD was related to p53 expression. However, H pylori was not related to any angiogenic markers except for the plasma VEGF level (P = 0.026).

CONCLUSION: H pylori antigen is related to higher plasma VEGF levels, but not to angiogenic characteristics. It can be hypothesized that the toxic effects of H pylori on angiogenesis occurs in early preclinical disease phase or in long-lasting aggressive infections, but only when high H pylori IgG levels are persistent.

Comparison of different criteria for interpretation of immunoglobulin G immunoblotting results for diagnosis of Helicobacter pylori infection

Gastric infection with Helicobacter pylori is one of the most common chronic infections in humans, causing substantial morbidity and mortality. The diagnosis of H. pylori infection usually involves upper endoscopy with biopsy since the only noninvasive method of comparable accuracy, the [(13)C]urea breath test, requires technical equipment that is not available in most gastroenterological units. Serological methods for detection of H. pylori infection have reached sufficient accuracy to be used as screening tests before endoscopy or for seroepidemiological surveys. In the present study we evaluated different interpretation criteria for use with immunoglobulin G immunoblotting for the diagnosis of H. pylori infection. We applied five different sets of interpretation criteria, four of which had been published previously, to the Western blot results of 294 patients with different gastrointestinal symptoms. Since it is known that less than 2% of patients who are infected with H. pylori fail to seroconvert, an optimally sensitive Western blotting system should be able to detect approximately 98% of active infections. When the different criteria were applied to our patient population, it became apparent that the abilities of the systems to detect active H. pylori infection were quite varied. The results for the sensitivity and specificity, according to the different applied criteria, ranged from 62.8 to 95.9% and from 85.7 to 100.0%, respectively. Positive predictive values and negative predictive values, according to the published criteria, ranged from 97.2 to 100.0% and from 37.7 to 82.4%, respectively. Recommendations for the optimal use of the different interpretation criteria are discussed.

Clinical and pathological implications of IgG antibody responses to Helicobacter pylori and its virulence factors in non-ulcer dyspepsia

AIM

To determine whether pre-treatment antibody response to Helicobacter pylori virulence factors predicts eradication success and symptom relief 12 months after triple therapy in non-ulcer dyspepsia.

METHODS

H. pylori-positive patients with non-ulcer dyspepsia received 1-week omeprazole-based triple therapy, or omeprazole plus placebos. Symptoms were assessed using a validated Likert scale. Gastric biopsies taken before and 12 months after treatment were used for histological examination. Pre-treatment blood samples were used for the detection of anti-H. pylori immunoglobulin G (IgG) antibodies, and specific IgG antibodies to 19.5-, 26.5-, 30-, 35-, 89- (VacA) and 116-kDa (CagA) antigens of H. pylori.

RESULTS

IgG antibodies to the six antigens were detected in 62%, 96%, 88%, 47%, 54% and 78% of patients, respectively. The presence of antibody to 19.5-, 26.5- or 30-kDa antigen was associated with an increased anti-H. pylori IgG absorbance index. IgG absorbance indices were greater in those with H. pylori eradication (vs. persistent infection). The prevalence of antibodies to the six antigens was not significantly different between those with symptom relief vs. those without. The 19.5-kDa antigen (P = 0.018) and VacA (P = 0.001) were independent risk factors for body gastritis.

CONCLUSIONS

An increased pre-treatment anti-H. pylori IgG absorbance index may be a useful predictor of the success of eradication therapy. Although the 19.5-kDa antigen and VacA were associated with body gastritis, none of the six antigens tested predicted symptom relief after triple therapy.

Reliability of Helicobacter pylori and CagA serological assays

Background serological assays for Helicobacter pylori are commonly used without knowledge of reliability. This information is needed to define the ability of serological tests to determine either new cases of infection or loss of infection in longitudinal studies. We evaluated the reproducibility and the interrelationships of serological test results for H. pylori and cytotoxin-associated gene product A (CagA) enzyme-linked immunoassays within a subset of participants in a population-based study. Stored samples from 1,229 participants in the third U.S. National Health and Nutrition Examination Survey were replicate serologically tested for H. pylori and CagA. Overall disagreement was 3.4% between duplicate tests for H. pylori (or 2.3% if equivocal results were disregarded). Six percent of samples positive on the first test had an immune serum ratio at least 30% lower on repeat testing. The odds ratio for H. pylori seropositivity on retesting was 2.8 (95% confidence interval [CI] = 1.8 to 4.5) when CagA serology was positive versus when it was negative. CagA antibody was found among 47.8% of H. pylori-equivocal and 7.0% of H. pylori-negative samples. CagA-positive yet H. pylori-negative samples were more likely to occur among Mexican Americans (odds ratio, 5.2; 95% CI = 2.4 to 11.4) and non-Hispanic blacks (odds ratio, 5.5; 95% CI = 2.3 to 13.0) than among non-Hispanic whites. Relying on repeated H. pylori serological tests over time to determine infection rates may result in misinterpretation due to limits in test reproducibility. CagA testing may have a role in verifying infection.

Recrudescence and reinfection with Helicobacter pylori after eradication therapy in Bangladeshi adults

BACKGROUND & AIMS

In developing countries where Helicobacter pylori infection is widespread, posttherapeutic recurrence rates may be high. Many of the limited studies available have methodological problems and show varied recurrence rates. We determined late recrudescence rates, true reinfection, and ulcer recurrence.

METHODS

One hundred five Bangladeshi patients with H. pylori infection and duodenal ulcer disease were treated with a triple therapy. Follow-up included 13C-urea breath tests, endoscopy, and biopsy-based tests. In reinfected patients, genomic typing compared pretherapeutic and posttherapeutic strains.

RESULTS

Recrudescence, associated with nitroimidazole-based treatment, occurred in 15 of 105 patients (14%) within the first 3 months, but only 8 of 105 patients tested positive 4 weeks after therapy ended. True reinfection was diagnosed in 11 of 105 patients between 3 and 18 months after therapy. The annual reinfection rate was 13%, based on a total follow-up of 84.7 patient years. Ulcer relapse occurred in 2 of 15 (13%) recrudescence cases and in 6 of 11 (55%) reinfection cases, but also in 4 of 73 (5%) H. pylori-negative patients.

CONCLUSIONS

In Bangladesh, late recrudescence of H. pylori after eradication therapy occurs within the first 3 months. The reinfection rate is high and might influence cost-benefit analyses for determining diagnostic and therapeutic procedures.

Peptic ulcer disease

Peptic ulcer disease is a common gastrointestinal disease whose management and treatment has changed dramatically over the last 25 years. Treatment of peptic ulcer disease has evolved from dietary modifications and antacids to gastric acid suppression with H2-receptor antagonists and proton pump inhibitors to eradication of Helicobactor pylori infection. Treatment of patients infected with H pylori using antibiotics has changed the natural history of peptic ulcer disease. As a result of H pylori treatment and other unknown factors ulcer disease is declining and complications from ulcer disease have diminished significantly.

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.

Value of quantitative serology for confirmation of Helicobacter pylori eradication: an 18-month follow-up study

In this study several therapies were administered to 124 H. pylori-positive patients and IgG antibody titers were measured by ELISA at months 0, 2, 3, 6, 12, and 18 months. Serum titers of IgG antibody progressively decreased after H. pylori eradication; at 3 months, the area under the receiver operating characteristic curve for the decrease of IgG antibody titers for confirming H. pylori eradication was 0.99, with 100% sensitivity and 99% specificity (when the cutoff point was set at 3 U/mL). We conclude that a decrease in serum titers of IgG antibody to H. pylori relatively early after completion of therapy (1 month after ranitidine or bismuth therapy is completed and 2.5 months after antibiotic therapy is completed) can be used as a noninvasive, simple, and inexpensive method to confirm H. pylori eradication.

Use of a dry latex agglutination test to measure eradication of Helicobacter pylori infection

BACKGROUND AND METHODS

A total antibody latex serology test was compared with enzyme immunoassay serology after treatment for Helicobacter pylori infection in 22 patients.

RESULTS

Nineteen patients were cured of infection, but only nine (47%) were negative by the latex test after 6 months. However a significant decline in immunoglobulin (Ig)G was seen in 90% of the cured patients.

CONCLUSIONS

Although the latex test is suitable for initial diagnosis of H. pylori infection, it is not suitable for monitoring treatment success. A decline in IgG of more than 40% correlates well with successful eradication of H. pylori.

Impact of ELISA and immunoblot as diagnostic tools one year after eradication of Helicobacter pylori in a multicentre treatment study

The performance of serological tests for Helicobacter pylori infections is hampered by the persistence of antibodies after eradication therapy or spontaneous healing. Detection of different antigens or immunoglobulin classes might have an impact on the validity of serodiagnosis. The aim of this study was to assess the decrease in IgA and IgG antibody levels after eradication of H. pylori. Serum samples of 242 patients with active duodenal ulcer were tested with the ELISA and the immunoblot (IB) techniques for H. pylori-specific IgA and IgG antibodies before therapy and 1 year after successful eradication. From a total of 81 patients paired sera were available. At the end of the follow-up period ELISA antibody titres from the IgA class had decreased from a mean value of 6.69 to 4.26 units (P = 0.0001), and IgG class antibody titres from a mean value of 21.9 to 12.1 units (P = 0.0001). Regarding seroreversion, from 34 initially IgA positive sera 16 (47%), and from 74 IgG positive sera 18 (24%), had definitively reverted to 'negative'. One year after eradication, when tested with the immunoblot, the antibody responses against specific antigens of 37% IgA-positive sera (23/62) and 8% IgG-positive sera (6/78) reverted to 'negative', compared to a seroreversion rate of 27% of the anti-CagA IgA-positive sera (18/67) and of 9% of the anti-CagA IgG-positive sera (7/79). In conclusion, despite an overall significant decrease of H. pylori antibodies, both tests cannot be recommended for monitoring treatment success.

Diagnosis of Helicobacter pylori

In view of its potential risk for the development of gastrointestinal disease or even gastric cancer at a later age, the study of Helicobacter pylori infection in childhood is gaining increasing importance and H. pylori infection is being considered a major issue of public health. H. pylori infection can be detected by a variety of methods. Because of its easy use, affordability, and overall availability, serology is the preferred diagnostic test, especially for large epidemiological studies. Based on our results, one might consider treating a child with recurrent abdominal pain and positive serology for H. pylori without further work-up, and only perform additional investigations when an anti-H. pylori therapy fails to resolve the complaints. According to this proposition, endoscopy of the upper gastrointestinal tract remains indicated in children if the noninvasive tests for Helicobacter pylori are negative in the absence of a diagnosis, or if symptomatology persists despite treatment.

IgG and IgA antibodies in Helicobacter pylori infections

We compared Helicobacter pylori-specific IgG and IgA antibodies in serum, salivary and gastric juice of H. pylori-infected and noninfected patients using the ELISA method. Serum and salivary anti-H. pylori IgG and IgA titres were higher in H. pylori-positive than H. pylori-negative patients. Serum H. pylori IgG titres were higher than those of serum-specific IgA. In contrast, H. pylori IgA titres in saliva samples were higher than those of specific IgG. In all patients, the levels of IgG antibodies were very low in gastric juice. H. pylori-positive patients with increased levels of IgA in sera, also exhibited increased IgA levels in gastric juice. The determination of IgA antibodies in serum and saliva may be used as a test that complements the IgG antibody assay.

Immune and inflammatory responses to Helicobacter pylori infection

The gastroduodenal response to chronic Helicobacter pylori infection is characterized by the infiltration of plasma cells, lymphocytes, neutrophils and monocytes into the mucosa. Eradication studies have shown that this inflammatory response represents a specific reaction to the presence of H. pylori. As well as stimulating specific local T and B cell responses and a systemic antibody response, H. pylori infection also induces a local pro-inflammatory cytokine response. Interleukin-8 (IL-8), which is expressed and secreted by gastric epithelial cells, may be an important host mediator inducing neutrophil migration and activation. IL-8 mRNA and protein secretion in gastric epithelial cell lines can be up-regulated by the cytokines tumour necrosis factor-alpha and IL-1 and also by type I strains of H. pylori (expressing the vacuolating toxin and cytotoxin-associated protein, CagA). The gastric epithelium thus plays an active role in mucosal defence. Neutrophil activation and the production of reactive oxygen metabolites will be induced directly by bacterial factors and indirectly via host-derived cytokines, products of complement activation and bioactive lipids. Strain variation in the induction of both IL-8 from epithelial cells and the oxidative burst in neutrophils may be an important factor determining the extent of mucosal injury. There is now increasing evidence from both in vivo and in vitro studies that type I strains induce an enhanced inflammatory response and mucosal damage. An understanding of the bacterial mediators of mucosal inflammation is important in elucidating the role of chronic H. pylori infection in the pathogenesis of gastroduodenal disease.

Serum pepsinogen C: a useful marker of Helicobacter pylori eradication?

Medical treatment for Helicobacter pylori (Hp) infection is now recommended in several types of gastroduodenal disease, and its success is usually monitored by hystology. The end-points of our work were to identify the most suitable serum index of Hp eradication among pepsinogen A (PGA), pepsinogen C (PGC), PGA/PGC ratio, gastrin, and IgG anti-Hp (IGG). We studied a total of 289 Hp positive (Giemsa staining) patients, who were treated with 40 mg/day omeprazole (140 cases) or with 480 mg/day bismuth subsalicylate (149 cases) for 4 weeks. All the patients also received 1 g/day metronidazole + 2 g/day amoxycillin for the first 2 weeks of treatment. Two months after the end of therapy, the patient underwent a second endoscopy and Hp histological assessment: the infection was eradicated in 192 and still present in the remaining 97 subjects. Gastrin, PGA, PGC, and IGG were measured before and after therapy. All indices significantly decreased after therapy in eradicated patients, while PGA and gastrin significantly decreased after therapy in both eradicated and noneradicated patients, although in the latter group the variations were less pronounced. We calculated the per cent decrease of the studied indices. PGC, with a decrease of more than 25%, was found to be the most accurate biochemical index. Variation in PGC levels before and after treatment were correlated with corresponding variations in Hp bacterial load. In conclusion, between the different biochemical parameters evaluated, PGC showed the highest clinical efficiency.

[Helicobacter pylori infection in children]

Helicobacter pylori (Hp) is a pathogen of human gastric mucosa and is considered as the major cause of chronic gastritis and duodenal ulcer disease recurrence. The prevalence rate of Hp infection increases with age and is related to low socioeconomic status in childhood. Childhood appears to be a high-risk period for Hp infection. Clinical and histological features of Hp infection are variable and often moderate in children. This is probably due to both genetic and environmental factors. Abdominal pain is the most frequent symptom and is usually associated with a mild chronic gastritis. Serology, 13C-urea breath test, bacterial culture and histological examination of biopsy specimen can be used for the diagnosis of Hp infection. Eradication of Hp infection is difficult and indications and modalities of treatment need to be specified in children. A better knowledge of epidemiology and natural history of Hp infection in childhood should permit to answer these questions.

Use of a receiver operating characteristic in the evaluation of two commercial enzyme immunoassays for detection of Helicobacter pylori infection

Two novel commercial IgG enzyme immunoassay (EIA) systems based on acid-glycine-extracted (Pyloriset IgG EIA, Orion Diagnostica) or fast protein liquid chromatography-purified (Cobas Core Anti-H. pylori EIA, Roche Diagnostic Systems) Helicobacter antigens were evaluated in a prospective study involving 127 patients. All patients underwent upper endoscopy with biopsy, and biopsies were examined for the presence of Helicobacter pylori by a rapid urease test, microscopy and culture. Of the 71 patients found to be infected with Helicobacter pylori, 69 (97.2%) and 65 (91.5%) tested positive with the Cobas Core and Pyloriset test, respectively. A detailed receiver operating characteristic analysis of the two tests showed that the Cobas Core assay was more sensitive and specific at every possible cut-off level; gave a better resolution of individual results, indicating a greater fine-sensitivity; and had no grey zone compared to a large grey zone encompassing 13.4% of the serum samples tested with the Pyloriset EIA. The Cobas Core assay appears to be a valuable tool for epidemiological purposes as well as for pre-endoscopic screening of dyspeptic patients.

Comparison of PCR and other diagnostic techniques for detection of Helicobacter pylori infection in dyspeptic patients

A sensitive and specific PCR-based assay to detect the Helicobacter pylori 16S rRNA gene present in formalin-fixed paraffin-embedded gastric biopsy specimens has been developed. A total of 95 patients with dyspepsia were evaluated for the presence of chronic active gastritis and an infection with H. pylori through the use of diagnostic assays based on biopsy specimens and serology. The "gold standard" for the presence of the bacteria was direct detection in histological sections of biopsy specimens by Giemsa stain. The results obtained with the PCR assay performed on the biopsy specimens (94% sensitivity and 100% specificity) were equivalent to the detection of H. pylori immunoglobulin G antibodies by the commercially available second-generation Cobas Core anti-H. pylori immunoglobulin G enzyme immunoassay (94% sensitivity and 98% specificity) for the diagnosis of H. pylori infection. Urease testing and bacterial culture of the biopsy specimens were inferior (88 and 70% sensitivity and 96% and 98% specificity, respectively). A Western blot (immunoblot) analysis had slightly greater sensitivity (96%), although specificity was reduced to 93%. This research prototype PCR assay was shown to be highly reliable for the detection of infection with H. pylori and the presence of chronic active gastritis in the population studied.

A new method for detecting anti Helicobacter pylori antibodies: an analytical and clinical evaluation

The diagnosis of Helicobacter pylori (Hp) infection is an important goal in clinical practice. In this paper we evaluated 1. the analytical reliability of a new second-generation antigen based enzyme immunoassay (Cobas Core Anti Helicobacter pylori EIA) in detecting anti-Hp IgG antibodies, and 2. the behaviour of anti-Hp IgG in patients with chronic atrophic and non-atrophic gastritis as compared to healthy controls. The findings from the dilution curve, the values of intra and inter assay coefficients of variations (never above 10%) and of the recovery test (between 96 and 109%), confirm that the method is reliable. Serum IgG anti-Hp levels were found to be significantly higher in patients with histologically identified Hp infection, than in those negative at histology. Furthermore, the grade of histological positivity was correlated with serum IgG levels. However, we found a discrepancy between a low prevalence of Hp staining and a high prevalence of Hp seropositivity in patients with chronic atrophic or non-atrophic gastritis, but not in controls. This suggests that IgG serum determination may be more useful than histology in determining a present or previous infection in patients with chronic atrophic or non-atrophic gastritis.

Evaluation of a commercially available complement fixation test for diagnosis of Helicobacter pylori infection and for follow-up after antimicrobial therapy

Commercially available complement fixation test reagents (Institute Virion Ltd., Rüschlikon, Zurich, Switzerland) available in package format were evaluated for the serodiagnosis of Helicobacter pylori infection. The assay was compared with bacterial culture and histological Giemsa stain of gastric biopsy specimens obtained from 930 patients of different ages and from different ethnic groups, with a variety of upper gastrointestinal tract symptoms. The prevalence, sensitivity, specificity, and positive and negative predictive values, respectively, were 35, 71, 90, 80, and 85% for Belgian patients aged 40 years or younger, 50, 81, 93, 92, and 83% for Belgian patients older than 40 years, and 83, 83, 79, 95, and 48% for Mediterranean patients. Using 645 serum specimens from 226 patients, we also evaluated the complement fixation test for its ability to monitor the eradication of H. pylori following antimicrobial therapy. Overall, H. pylori was eradicated from 122 patients while 104 patients remained infected with the organism. A significant decrease in antibody levels was observed 3 to 6 months after the end of therapy in the group of patients from whom H. pylori was eradicated.