Advantages and disadvantages of current diagnostic tests for the detection of Helicobacter pylori

Establishment of Noninvasive Methods for the Detection of Helicobacter pylori in Mongolian Gerbils and Application of Main Laboratory Gerbil Populations in China

Identifying Helicobacter pylori (H. pylori, Hp) infection in animals before and after artificial infection influences the subsequent experiment. We established effective and noninvasive detection methods, including the gastric fluid nested polymerase chain reaction (PCR) method and the ¹³C-urea breath test, which can detect Hp before modeling Hp infection in Mongolian gerbils. We designed a gas collection equipment for gerbils. Hp nested PCR was also performed on gastric fluid, gastric mucosa, duodenal contents, and faeces of gerbils challenged with Hp. Conventional Hp detection methods, including rapid urease assay and immunohistochemistry, were compared. Moreover, we assessed the natural infection of Hp in 135 gerbils that had never been exposed to Hp artificially from the major laboratory gerbil groups in China. In 10 Hp infected gerbils, the positive detection results were 100%, 100%, 90%, and 10% in gastric fluid, gastric mucosa, duodenal contents, and faeces with nested PCR, respectively. A rapid urease test performed on gastric mucosa showed that all animals were infected with Hp. Immunohistochemical detection and bacteria culture of gastric mucosa samples that were positive by the nested PCR method also confirmed the presence of Hp. 9% (3/35) and 6% (2/31) natural infection rates were found in conventional gerbil groups from the Capital Medical University and Zhejiang Laboratory Animal Center. In conclusion, we established two noninvasive Hp detection methods that can be performed before modelingHp infection, including the gastric fluid nested PCR method and the ¹³C-urea breath test.

Environmental protection based on the nanobiosensing of bacterial lipopolysaccharides (LPSs): material and method overview

Lipopolysaccharide (LPS) or endotoxin control is critical for environmental and healthcare issues. LPSs are responsible for several infections, including septic and shock sepsis, and are found in water samples. Accurate and specific diagnosis of endotoxin is one of the most challenging issues in medical bacteriology. Enzyme-linked immunosorbent assay (ELISA), plating and culture-based methods, and Limulus amebocyte lysate (LAL) assay are the conventional techniques in quantifying LPS in research and medical laboratories. However, these methods have been restricted due to their disadvantages, such as low sensitivity and time-consuming and complicated procedures. Therefore, the development of new and advanced methods is demanding, particularly in the biological and medical fields. Biosensor technology is an innovative method that developed extensively in the past decade. Biosensors are classified based on the type of transducer and bioreceptor. So in this review, various types of biosensors, such as optical (fluorescence, SERS, FRET, and SPR), electrochemical, photoelectrochemical, and electrochemiluminescence, on the biosensing of LPs were investigated. Also, the critical role of advanced nanomaterials on the performance of the above-mentioned biosensors is discussed. In addition, the application of different labels on the efficient usage of biosensors for LPS is surveyed comprehensively. Also, various bio-elements (aptamer, DNA, miRNA, peptide, enzyme, antibody, etc.) on the structure of the LPS biosensor are investigated. Finally, bio-analytical parameters that affect the performance of LPS biosensors are surveyed.

Accuracy of invasive and noninvasive methods of Helicobacter pylori infection diagnosis in Saudi children

BACKGROUND/AIM

Helicobacter pylori (H. pylori) infection is one of the most common chronic infections in the world. The prevalence of H. pylori is high in Saudi Arabia, but there are no studies in children on the accuracy of invasive and noninvasive methods to diagnose H. pylori infection. The aim of this study was to evaluate the accuracy of six methods for diagnosis of H. pylori infection; four invasive [rapid urease test (RUT), histology, antral nodularity (AD), and biopsy culture (BC)] and two noninvasive methods [serologic test and stool antigen test (SAT)].

PATIENTS AND METHODS

A prospective cross-sectional study was performed among symptomatic children in National Guard hospitals who underwent esophagogastroduodenoscopy from 2010 to 2013. The gold standard diagnosis of H. pylori was positive tissue culture. If the culture was unsuccessful or not done, concordant-positive results for histology and RUT were considered to indicate a positive H. pylori. The variables analyzed as diagnostic methods included RUT, BC, histology, AD, serologic test, and SAT.

RESULTS

A total of 303 children were included in the study. The overall prevalence of H. pylori infection was 49.8%. Most diagnostic tests showed high specificity and moderate-to-low sensitivity when compared to the gold standard test. Sensitivity of AD, SAT, and RUT to detect H. pylori were 62% (95% CI: 0.51-0.74), 69% (95% CI: 0.58-0.79), and 87% (95% CI: 0.79-0.95), respectively (P value 0.040, 0.0023, and <0.0001, respectively). RUT showed the lowest specificity, 65% (95% CI: 0.58-0.71) in contrast to BC and histology which showed moderate-to-high specificities of 88% (95% CI: 0.82-0.95) and 89% (95% CI: 0.82-0.95), respectively (P <0.0001).

CONCLUSION

RUT is a valuable diagnostic method for identifying H. pylori with the highest sensitivity compared to AD and SAT. All diagnostic tests showed moderate-to-high specificities but BC and histology showed the highest specificity.

Diagnosis of Helicobacter pylori Using Invasive and Noninvasive Approaches

Helicobacter pylori (H. pylori) as gram-negative and spiral microorganism is responsible for colonization in the gastric microniche for more than 50% of world population. Recent studies have shown a critical role of H. pylori in the development of peptic ulcers, gastric mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric cancer. Over the past decade, there has been a sharp interest to use noninvasive tests in diagnosis of the H. pylori infection. During the years after discovery by Marshall and Warren, it has been frequently declared that the rapid urease test (RUT) is one of the cheapest and rapid diagnostic approaches used in detecting the infection. Although the specificity and sensitivity are durable for this test, clinical experiences had shown that the ideal results are only achieved only if we take biopsies from both corpus and antrum at the same time. Given the diagnosis of the H. pylori in clinical samples, gastroenterologists are facing a long list of various molecular and nonmolecular tests. We need more in-depth researches and investigations to correctly generalize rapid and accurate molecular tests determining both bacterial identity and antibiotic resistance profile.

Review: Diagnostic accuracy of PCR-based detection tests for Helicobacter Pylori in stool samples

BACKGROUND

Although different methods have been established to detect Helicobacter pylori (H. pylori) infection, identifying infected patients is an ongoing challenge. The aim of this meta-analysis was to provide pooled diagnostic accuracy measures for stool PCR test in the diagnosis of H. pylori infection.

METHODS

In this study, a systematic review and meta-analysis were carried out on various sources, including MEDLINE, Web of Sciences, and the Cochrane Library from April 1, 1999, to May 1, 2016. This meta-analysis adheres to the guidelines provided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses report (PRISMA Statement). The clinical value of DNA stool PCR test was based on the pooled false positive, false negative, true positive, and true negative of different genes.

RESULTS

Twenty-six of 328 studies identified met the eligibility criteria. Stool PCR test had a performance of 71% (95% CI: 68-73) sensitivity, 96% (95% CI: 94-97) specificity, and 65.6 (95% CI: 30.2-142.5) diagnostic odds ratio (DOR) in diagnosis of H. pylori. The DOR of genes which showed the highest performance of stool PCR tests was as follows: 23S rRNA 152.5 (95% CI: 55.5-418.9), 16S rRNA 67.9 (95%CI: 6.4-714.3), and glmM 68.1 (95%CI: 20.1-231.7).

CONCLUSIONS

The sensitivity and specificity of stool PCR test are relatively in the same spectrum of other diagnostic methods for the detection of H. pylori infection. In descending order of significance, the most diagnostic candidate genes using PCR detection were 23S rRNA, 16S rRNA, and glmM. PCR for 23S rRNA gene which has the highest performance could be applicable to detect H. pylori infection.

Differences in bone structure and unloading-induced bone loss between C57BL/6N and C57BL/6J mice

The C57BL/6 mouse, the most frequently utilized animal model in biomedical research, is in use as several substrains, all of which differ by a small array of genomic differences. Two of these substrains, C57BL/6J (B6J) and C57BL/6N (B6N), are commonly used but it is unclear how phenotypically similar or different they are. Here, we tested whether adolescent B6N mice have a bone phenotype and respond to the loss of weightbearing differently than B6J. At 9 weeks of age, normally ambulating B6N had lower trabecular bone volume fraction but greater bone formation rates and osteoblast surfaces than corresponding B6J. At 11 weeks of age, differences in trabecular indices persisted between the substrains but differences in cellular activity had ceased. Cortical bone indices were largely similar between the two substrains. Hindlimb unloading (HLU) induced similar degeneration of trabecular architecture and cellular activity in both substrains when comparing 11-week-old HLU mice to 11-week-old controls. However, unloaded B6N mice had smaller cortices than B6J. When comparing HLU to 9 weeks baseline control mice, deterioration in trabecular separation, osteoblast indices, and endocortical variables was significantly greater in B6N than B6J. These data indicate specific developmental differences in bone formation and morphology between B6N and B6J mice, giving rise to a differential response to mechanical unloading that may be modulated, in part, by the genes Herc2, Myo18b, and Acan. Our results emphasize that these substrains cannot be used interchangeably at least for investigations in which the phenotypic makeup and its response to extraneous stimuli are of interest.

Clinical applications of bacterial glycoproteins

There is an ongoing race between bacterial evolution and medical advances. Pathogens have the advantages of short generation times and horizontal gene transfer that enable rapid adaptation to new host environments and therapeutics that currently outpaces clinical research. Antibiotic resistance, the growing impact of nosocomial infections, cancer-causing bacteria, the risk of zoonosis, and the possibility of biowarfare all emphasize the increasingly urgent need for medical research focussed on bacterial pathogens. Bacterial glycoproteins are promising targets for alternative therapeutic intervention since they are often surface exposed, involved in host-pathogen interactions, required for virulence, and contain distinctive glycan structures. The potential exists to exploit these unique structures to improve clinical prevention, diagnosis, and treatment strategies. Translation of the potential in this field to actual clinical impact is an exciting prospect for fighting infectious diseases.

Diagnosis of Helicobacter pylori: Changes towards the Future

Since the first evidence demonstrating the dramatically high incidence of H. pylori infection and the subsequent medical challenges it incurs, health management of H. pylori infection has been a high priority for health authorities worldwide. Despite a decreasing rate of infection in western countries, prevalence of H. pylori infection in developing and in some industrial countries is still very high. Whereas treatment and vaccination against H. pylori is a contemporary issue in medical communities, selective treatment and prior high-throughput screening of the subject population is a major concern of health organizations. So far, diagnostic tests are either elaborative and require relatively advanced medical care infrastructure or they do not fulfill the criteria recommended by the Maastricht IV/Florence consensus report. In this review, in light of recent scientific studies, we highlight current and possible future approaches for the diagnosis of H. pylori. We point out that novel non-invasive tests may not only cover the requirements of gold standard methods in H. pylori detection but also offer the potential for risk stratification of infection in a high throughput manner.

Three Tests Used to Identify Non-Culturable Form of Helicobacter pylori in Water Samples

Background:

Helicobacter pylori, causing the most common chronic bacterial infection, exist in two forms; bacilli and coccoid. The coccoid form is identified as viable but non-culturable bacteria.

Objectives:

The current study aimed to conduct culture, polymerase chain reaction (PCR), and loop-mediated isothermal amplification (LAMP) tests to identify coccoid forms of H. pylori.

Materials and Methods:

The PCR and LAMP tests were optimized using specific primers for glmM gene. The sensitivity and specificity of the tests were determined. The current experimental study was conducted on 10 different strains isolated from clinical cases (H1-H10). The isolates were added to tap water and incubated at three different temperatures for one and two months intervals. After pure-culturing of the bacteria, DNAs were extracted and PCR and LAMP were performed.

Results:

Ten copies of targeted DNA were required for PCR detection whereas only five copies gave a positive reaction by LAMP assay, with 100% specificity. Of the 10 isolates inoculated in water for one and two months at three different temperatures 4, 22, and 37°C, only three cases (5%) were found positive in the first month; 13 (21.6%) and 29 cases (48.3%) were also positive by PCR and LAMP tests in the first and second months.

Conclusions:

Results of the current study confirmed that molecular methods such as PCR and LAMP were much more sensitive, rapid, and specific than culturing to identify non-culturable coccoid forms of H. pylori in water.

Evaluation of methods for H. pylori detection in PPI consumption using culture, rapid urease test and smear examination

BACKGROUND

Culture, rapid urease test (RUT) and smear examination have been used as reliable methods for diagnosis of H. pylori infection. Accurate performance of these tests requires good quality biopsies with considerable number of bacterial cells. However, consumption of proton pump inhibitors (PPIs) affects growth and urease activity of H. pylori, leading to false negative results. In this study the efficacy of culture, RUT and smear examination was assessed and the effect of PPI consumption was evaluated.

METHODS

Two antral biopsies from 530 dyspeptic patients with and without PPI consumption were used for RUT, culture and smear examination. Statistical analysis was used to determine the association between results of culture, RUT or smear examination and PPI consumption. Sensitivity and specificity of three tests were calculated by standard methods.

RESULTS

H. pylori infection was detected in 40% of patients by culture, 48.3% by RUT and 21.1% by smear examination and the overall detection rate was 54%. A strong correlation was found between PPI consumption and negative results of culture and RUT (P<0.05) but not smear examination. The sensitivity of RUT was reduced as a result of PPI consumption. This reduction was more profound in 1-hr RUT (92.2% to 74.4%) compared with 24-hr RUT (93.9% to 81.6%).

CONCLUSIONS

Prevalence of H. pylori was declined, compared with previous studies. This decrement could be due to false negative results of H. pylori diagnostic tests, among which culture and RUT are mostly affected by PPI. Accordingly, PPI consumption should be stopped before performance of endoscopy.

Performance of Routine Helicobacter pylori Invasive Tests in Patients with Dyspepsia

Background. This study was designed to compare the accuracy of three different invasive methods for the detection of Helicobacter pylori (H. pylori) infection in patients with dyspepsia. These tests included culture, histology, and the rapid urease test (CLO test). Methods. H. pylori infection was diagnosed prospectively in 246 untreated dyspeptic patients who underwent upper gastrointestinal endoscopy. The gold standard for H. pylori infection was based on a positive culture or both a positive histological examination and a CLO test. Results. H. pylori was diagnosed in 33.3% of the patients. The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy were as follows: histology from the antrum (95.12; 95.12; 90.7; 97.5; 95.12%); histology from the antrum and corpus (95.12; 95.12; 90.7; 97.5; 95.12%); histology from the corpus (76.83; 96.95; 92.65; 89.33; 90.24%); culture (91.46; 100; 100; 95.91; 97.15%); a CLO test from the antrum and corpus (85.59; 100; 100; 93.71; 95.52%); a CLO test from the antrum (64.63; 100; 100; 84.97; 88.21%); a CLO test from the corpus (69.51; 100; 100; 96.77; 89.83%), respectively. Conclusions. Antral biopsy histology and culture are the best methods for the diagnosis of H. pylori infection in our cohort of patients with dyspepsia.

Diagnosis of Helicobacter pylori infection by means of reduced-dose ¹³C-urea breath test and early sampling of exhaled breath

OBJECTIVE

The aim of this study was to evaluate the accuracy of reduced-dose ¹³C-urea breath test (¹³C-UBT) and early sampling of exhaled breath for the detection of Helicobacter pylori infection in children and adolescents.

METHODS

Patients up to 20 years old that underwent upper gastrointestinal endoscopy with gastric biopsies were included. The ¹³C-UBT was performed after a 4-hour fasting period with 4 points of collection: baseline (T₀), and at 10, 20, and 30 minutes (T₁₀, T₂₀, and T₃₀) after ingestion of 25 mg ¹³C-urea diluted in 100 mL of apple juice. The infection status was defined through 3 invasive methods, and a patient was considered infected with a positive culture or concomitant positive histology and rapid urease test. The absence of infection was defined by all negative histology, rapid urease test, and culture. Analysis of exhaled breath samples was performed with an isotope-selective infrared spectrometer. A receiver-operating characteristic curve analysis was done to define cutoff delta over baseline (DOB) values.

RESULTS

A total of 129 patients between the ages of 2.1 and 19 years (median 11.6 years; mean age ± standard deviation 11.5 ± 3.8 years; F:M 85:44) were included. The prevalence of infection was 41.1%. The sensitivity (S) and specificity (Sp) were at T₁₀ (cutoff DOB 2.55‰), S 94.7% (95% confidence interval [CI] 90.9-98.5) and Sp 96.8% (95% CI 93.4-100); at T₂₀ (DOB 2.5‰), S 96.2% (95% CI 92.9-99.5) and Sp 96.1% (95% CI 93.7-99.8); and at T₃₀ (DOB 1.6‰), S 96.2% (95% CI 92.9-99.5) and Sp 94.7% (95% CI 90.8-98.6).

CONCLUSIONS

Low-dose ¹³C-UBT with early sampling is accurate for diagnosing H pylori infection in children and adolescents.

PCR-Based Detection and Genotyping of Helicobacter pylori in Endoscopic Biopsy Samples from Brazilian Patients

Helicobacter pylori (H. pylori) is considered the second most prevalent infection in man. A precise diagnosis is important for treating patients with the indicative gastrointestinal symptoms. The present study analyzes the effectiveness of a molecular biology method (PCR) comparing the results obtained with the histology and with the rapid urease tests. PCR was used in the detection and genotyping of the H. pylori urease-C gene and the patterns which were obtained from the patients studied. 141 biopsy samples from 131 patients were evaluated. 59 paraffin biopsies samples were positive for H. pylori according to the histological examination. Of those, 59/12 (20.3%) were amplified using PCR. Of the 82 samples from the fresh biopsies, 64 were positive for H. pylori according to the rapid urease test (78%); there was an agreement of 100% with PCR. Sixty positive H. pylori samples were genotyped (58 samples of fresh biopsies and 2 samples of paraffin biopsies) using two restriction enzymes. The patterns observed were analyzed with the computational program BIO 1D; 11 patterns with the enzyme HhaI and 12 patterns with the enzyme MboI were found. However, it was not possible to find a statistically significant correlation between the specific genotypes and digestive pathologies. Accordingly, future research should be performed to confirm a statistically significant relationship between genotyping and gastrointestinal symptoms.

Correlation of serum antibody titres with invasive methods for rapid detection of Helicobacter pylori infections in symptomatic children

Helicobacter pylori (H. pylori) is causally associated with peptic ulcer disease and gastric carcinoma. Typically, children get infected during the first decade of life, but diseases associated with H. pylori are seen mainly in adults. Multiple diagnostic methods are available for the detection of H. pylori infection. The aim of this study was to evaluate the correlation and diagnostic accuracy of three invasive methods [rapid urease test (RUT), histology and bacterial culture] and one non-invasive method (IgG serology) for diagnosis of H. pylori infection in a prospective cohort study conducted on 50 symptomatic children between two and eighteen years of age. Endoscopies with gastric biopsies were performed for RUT, culture and histopathological examination, respectively. IgG antibodies were measured in patient sera using a commercially available enzyme-linked immunosorbent assay (ELISA). RUT and positive H. pylori IgG antibodies were concordant in 88% (44/50) of patients. Both tests were negative in 32% (16/50), and both were positive in 56% (28/50). Disagreement occurred in 12% (6/50) of the patients: three of them (6%) had positive RUT and negative H. pylori IgG, and another three (6%) had negative RUT and positive H. pylori IgG. A combination of RUT with non-invasive serology constituted the optimum approach to the diagnosis of H. pylori infection in symptomatic children. The non-invasive serological test (ELISA) could not be used alone as the gold standard because it cannot distinguish between active and recently treated infection; and bacterial culture could not be used alone because of its low sensitivity.

The role of routine immunohistochemistry for Helicobacter pylori in gastric biopsy

Helicobacter pylori infection is associated with gastritis, gastric ulcer, gastric adenocarcinoma, and mucosal associated lymphoid tissue lymphoma. Documenting the presence of H pylori in a gastric biopsy is essential for appropriate patient care. Several special stains and immunohistochemistry (IHC) stain for H pylori are available, and many laboratories are routinely using one of them. We introduced routine IHC for H pylori about a year ago, and this study aims to investigate the value of this protocol. A total of 224 patients qualified for the study criteria during this period. The diagnoses were chronic active gastritis (68), chronic gastritis (76), no pathologic abnormality (50), reactive gastropathy (24), and polyps (6). Fifty-four cases were positive for H pylori on IHC, including 50 chronic active gastritis and 4 chronic gastritis. The IHC positive rate was 73.5% (50/68) in chronic active gastritis, 5.3% (4/76) in chronic gastritis, and 0% (0/80) in other diagnoses. The sensitivity/specificity of finding H pylori by blindly reviewing hematoxylin and eosin slides was 100%/100%, 100%/100%, 95%/100%, and 100%/100% from the 4 authors. Our results showed that many gastric biopsies (35.7%, 80/224) had no pathologic abnormality or reactive gastropathy and did not need a routine IHC for H pylori. Hematoxylin and eosin slide review had a very good sensitivity and specificity with all levels of observers. In summary, IHC for H pylori should not be routinely used, especially during these economically challenging times. Immunohistochemistry should be reserved for unexplained gastritis and previously treated patients with likely low organism density.

Marching cohort ofHelicobacter pyloriinfection over two decades (1988–2007): combined effects of secular trend and population migration

The prevalence ofHelicobacter pyloriinfection is decreasing in developed countries. In this study we included 22 612 patients in whom a first culture of gastric biopsy (routinely performed in our medical centres) yielded an interpretable result over a 20-year period (1988–2007) in Brussels. The effects of patients' age, gender and ethnic background were analysed. The overall proportion ofH. pylori-infected patients was 37·7%, with a progressive decline over time (P<10−5). A gender effect was observed in adults. The lowest infection rate was observed in Western European patients (n=11 238) with respectively 36·2% and 15·2% infected subjects in 1988 and 2007, compared to 71·7% and 40% in North African patients (n=3200) (P<10−5). However, no trend of decline was observed over time in North African children aged ⩽9 years. These data show the effects of time, age and ethnicity on the prevalence ofH. pyloriinfection, and its complex heterogeneity in the same cosmopolitan urban area.

Restriction fragment length polymorphism of urease C and urease B genes of Helicobacter pylori strains isolated from Brazilian patients with peptic ulcer and chronic gastritis

The aim of the present work is to identify the presence of Helicobacter pylori bacterium in samples of gastric mucosa fragments, obtained by gastric biopsy, from Brazilian patients with peptic ulcer and chronic gastritis and also to determine differences among the prevalent strains in these two diseases by urease C and urease B genes amplification utilizing nested polymerase chain reaction (PCR) and PCR. We encountered 17 genotyping patterns for urease C and 7 for urease B and, although no significant differences were found among the patterns encountered for both diseases, we found predominant groups for each disease. Typing methods of the products obtained by nested PCR and PCR show a functional scheme and are of great importance for epidemiologic studies and H. pylori strain characterization, in addition to allowing correlation among the several strains and their role in the diseases caused by this microorganism.

Touch cytology in diagnosing Helicobacter pylori: comparison of four staining methods

OBJECTIVES

Helicobacter pylori (Hp), a major cause of peptic ulcer disease and an important risk factor for gastric malignancy, can be diagnosed by several methods. Touch cytology (TC) of the gastric mucosa has been noted to give good results and has been found to be very simple, inexpensive and rapid. However, evidence regarding the accuracy of different staining methods of TC is lacking. The present study aims at defining the diagnostic accuracy of four different staining methods of TC.

METHODS

Biopsy specimens were taken from the antral mucosa of one hundred consecutive patients referred for upper gastrointestinal endoscopy (UGIE) for various indications. TC slides were processed by four staining methods: Wright, Giemsa, Papanicolaou and Gram. Rapid urease test (RUT) and histological examination of specimens were also performed. The same experienced pathologist evaluated the coded samples. A patient's Hp status was established by minimum concordance of the three tests, including histology, RUT, and 'Touch mean'. The latter was defined positive when at least three of the four TC staining methods were positive.

RESULTS

Forty-six patients (46%) were positive for Hp according to Hp status. TC stained by Wright had excellent agreement with both histology (kappa = 0.80, P < 0.001) and RUT (kappa = 0.84, P < 0.001). Regarding Hp status, histology was 100% sensitive and RUT was 100% specific. Wright-stained TC (88.89%) was significantly more specific than both Giemsa- (74.07%; P < 0.05) and Papanicolaou-stained (70.37%; P < 0.05) TC.

CONCLUSIONS

RUT should still be acknowledged as the primary test in diagnosing Hp following UGIE. If RUT is negative and Hp detection is intended only, Wright-stained TC can safely substitute for histology. However, when assessment for severity of mucosal damage or cell atypias is meant, histology cannot be neglected.

Use of NSAIDs and infection with Helicobacter pylori--what does the rheumatologist need to know?

OBJECTIVES

NSAID-induced gastroduodenal lesions are a frequent and potentially serious health problem in patients with rheumatic diseases. Helicobacter pylori (H. pylori) has also been recognized as a major risk factor for the development of ulcer disease. However, the role of H. pylori in the pathogenesis of NSAID-induced gastroduodenal lesions has remained controversial, and there is currently no clear consensus on the management of NSAID users who are infected with H. pylori.

METHODS

To clarify this situation we have performed a systematic literature search to find randomized controlled trials comparing the efficacy of eradication in patients receiving NSAIDs to prevent ulcer development.

RESULTS

Seven randomized controlled trials and one meta-analysis were identified. There were three papers on NSAID-naive patients. According to this data, NSAID-naive users benefit from testing for H. pylori infection and subsequent H. pylori eradication therapy prior to the initiation of NSAID. In contrast, H. pylori eradication alone does not protect chronic NSAID users with recent ulcer complications from further gastrointestinal (GI) events. To prevent recurrent ulcer bleeding long-term acid suppressive therapy is needed.

CONCLUSIONS

In conclusion, ulcer risk reduction after H. pylori eradication therapy is clearly more marked in patients beginning NSAID therapy than in patients who were already receiving and tolerating NSAID therapy. Thus, the management of H. pylori infection and the prevention of GI complications in NSAID users need to be individualized on the basis of recently published data.

Isocitrate dehydrogenase of Helicobacter pylori potentially induces humoral immune response in subjects with peptic ulcer disease and gastritis

Background

H. pylori causes gastritis and peptic ulcers and is a risk factor for the development of gastric carcinoma. Many of the proteins such as urease, porins, flagellins and toxins such as lipo-polysaccharides have been identified as potential virulence factors which induce proinflammatory reaction. We report immunogenic potentials of isocitrate dehydrogenase (ICD), an important house keeping protein of H. pylori.

Methodology/Principal Findings

Amino acid sequences of H. pylori ICD were subjected to in silico analysis for regions with predictably high antigenic indexes. Also, computational modelling of the H. pylori ICD as juxtaposed to the E. coli ICD was carried out to determine levels of structure similarity and the availability of surface exposed motifs, if any. The icd gene was cloned, expressed and purified to a very high homogeneity. Humoral response directed against H. pylori ICD was detected through an enzyme linked immunosorbent assay (ELISA) in 82 human subjects comprising of 58 patients with H. pylori associated gastritis or ulcer disease and 24 asymptomatic healthy controls. The H. pylori ICD elicited potentially high humoral immune response and revealed high antibody titers in sera corresponding to endoscopically-confirmed gastritis and ulcer disease subjects. However, urea-breath-test negative healthy control samples and asymptomatic control samples did not reveal any detectable immune responses. The ELISA for proinflammatory cytokine IL-8 did not exhibit any significant proinflammatory activity of ICD.

Conclusions/Significance

ICD of H. pylori is an immunogen which interacts with the host immune system subsequent to a possible autolytic-release and thereby significantly elicits humoral responses in individuals with invasive H. pylori infection. However, ICD could not significantly stimulate IL8 induction in a cultured macrophage cell line (THP1) and therefore, may not be a notable proinflammatory agent.

How labile is gastric infection with H pylori?

It is known that patients infected with H pylori can spontaneously become free from infection, and that the reverse change can occur. The time-scale of these conversions is expressed as percentages per year. Since they have been investigated in terms of serology, the changes are called sero-reversion and sero-conversion respectively. Using serological evidence to investigate these phenomena is open to the criticisms that positive serology can be present in the absence of all other evidence of infection, and that a time-lag of 6-12 mo or longer can occur between eradication of the infection and sero-reversion. Investigations using direct evidence of current infection are sparse. The few that exist suggest that some individuals can seroconvert or sero-revert within six to twelve weeks. If these findings are confirmed, it means that some patients have an ability that is variable in time to resist, or spontaneously recover from, H pylori infection. Evidence suggests that the deciding factor of susceptibility is the level of gastric secretion of acid.

Is the remarkable contradiction between histology and 14C urea breath test in the detection of Helicobacter pylori due to false-negative histology or false-positive 14C urea breath test?

We assessed the diagnostic value of the 14C urea breath test (UBT) in the detection of Helicobacter pylori compared with histology and the rapid urease test (RUT). The study included 68 patients (22 men and 46 women) with dyspeptic symptoms. H. pylori status was evaluated by 14C UBT, RUT and histology. Sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy were determined for 14C UBT and for RUT. Histology revealed dense yeast-like micro-organisms in the biopsy specimens in all patients with false-positive results by 14C UBT (n = 8), a significantly higher proportion than in patients with negative 14C UBT (five of 31). The low specificity of the H. pylori 14C UBT should not be neglected by accepting histology results as false-negative. Gastric mucosal colonization by yeast-like micro-organisms with urease activity can account for the high frequency of false-positive results for 14C UBT.

[Late follow-up of gastrectomized patients for peptic ulcer: clinical, endoscopic and histopathological aspects]

BACKGROUND

The gastrectomy is an uncommon procedure because the proton bomb inhibitors associated to the antibiotic outlines used to eradicate the Helicobacter pylori changed the focus of the peptic ulcer treatment.

AIMS

Later evaluation on those patients who underwent partial gastrectomy as a treatment for peptic ulcer, at that time when any drug to eradicate the Helicobacter pylori was not used. The clinical evaluation included the late postoperative symptoms and postgastrectomy syndromes like dumping, diarrhea, alkaline gastritis and nutritional aspects. The upper digestive endoscopy analysed the surgery reconstruction and the gastric stump, the duodenum and the jejunum mucosa aspects. The histopathological evaluation included looking for Helicobacter pylori by using two different methods: histology and urease test.

CASUISTIC AND METHODS

Fifty-nine patients, 44 (74.6%) male, median age 55.5 years old (range from 31 to 77 years old), who underwent a clinical interview and an upper digestive endoscopy. Paraffin blocks from the surgical specimen were reviewed in order to find out if the patients did have or did not have Helicobacter pylori before surgery.

RESULTS

The final results show that most of the patients had very good and good clinical evolution (Visick I e II) in 96%. The most common symptoms on late postoperative are mild dyspepsia with or without Helicobacter pylori, and diarrhea, anemia and dumping occurred in, respectively, 11 (18.6%), 2 (3.4%) and 2 (3.4%) cases. The Billroth I reconstruction had the best clinical results on statistical rate. The endoscopic finding showed normal results in the most number of cases, and reflux alkaline gastritis or erosive gastritis in a few cases. Ulcer recurrences were diagnosed in two patients (3.4%), and both had positive Helicobacter pylori. Most of the patients had Helicobacter pylori (86%) before surgery and also in the postoperative time (89.9%).

CONCLUSIONS

The patients had a very good clinical evolution after the gastrectomy. The Billroth I reconstruction had the best clinical results. The Helicobacter pylori is still present on gastric stump in late postoperative time, and we believe that it does not bring any negative influence to surgical results.

Antral exfoliative cytology for the detection of Helicobacter pylori in the stomach

AIM: To evaluate the efficacy of antral exfoliative cytology method in the diagnosis of Helicobacter pylori (H pylori) infection in the stomach.

METHODS: Fifty patients were submitted to upper digestive tract endoscopy due to complaints of dyspepsia. The material for exfoliative cytology was obtained by extensive brushing of the gastric antral mucosa and Papanicolaou stain was used to identify the bacteria. The authors also performed gastric biopsies to collect material for urease tests and histologic studies, with hematoxylin-eosin and fucsin stains in order to identify the microorganism. The gold standard used to detect the presence of H pylori was an analysis of the combined results from the gastric biopsies by urease test and histological method.

RESULTS: Antral exfoliative cytology method exhibited 90.3% sensitivity, 66.6% specificity, accuracy of 81.6%, positive predictive value of 82.3% and negative predictive value of 80.0%, in this population with a prevalence of 63.3%.

CONCLUSION: Antral exfoliative cytology was demonstrated to be a sensitive, accurate and easy to perform method for investigating H pylori infection in the stomach.

Enzyme immunoassay and immunoblotting analysis of Helicobacter pylori infection in Turkish asymptomatic subjects

Approximately half of the world population is infected with Helicobacter pylori, particularly in developing countries. The aims of the study were to detect H. pylori infection in asymptomatic Turkish subjects, correlate the infection with the associated risk factors, and to evaluate the cytotoxin-associated gene (CagA) status and other H. pylori antigens. Three hundred nine asymptomatic subjects (124 female) 1-82 years of age (average: 31 years) were serologically tested by enzyme immunoassay and immunoblotting. The enzyme immunoassay detected IgG anti-H. pylori antibodies in sera of 216 (70%) out of 309 subjects, 132 (61%) male. Infection rates of 42% in subjects <10 years of age, 55% in 10-19 years, 66% in 20-29 years, 78% in 30-39 years, 79% in 40-49 years, 91% in 50-59 years, 100% in 60-69 years, and 80% in those >70 years of age were detected. Subjects >45 years of age had significantly higher antibody responses, odds ratio = 0.16 (95% confidence interval: 0.07-0.37), than those <45 years. H. pylori infection was significantly higher in married subjects, odds ratio = 0.38 (95% confidence interval: 0.20-0.73), and those with low socioeconomic status. No correlation between gender, education, smoking, and nonsteroidal anti-inflammatory drug intake and infection was detected. Immunoblots revealed antibodies to CagA in 58 (83%) of 70 samples tested. H. pylori infection is prevalent in the asymptomatic Turkish subjects. Marital and socioeconomic status was significantly associated with the acquisition of H. pylori. Antibodies to CagA antigen were highly prevalent in these subjects.

HpSA fecoprevalence in patients suspected to have Helicobacter pylori infection in Istanbul, Turkey

OBJECTIVE

This study aims to investigate the Helicobacter pylori antigen in the stool samples of patients suspected to have H. pylori infection. It also aims to determine the fecoprevalence in different age groups and to look for the relationship between the clinical symptoms seen in patients and the existence of H. pylori. Current information in Turkey is insufficient.

METHODS

The Helicobacter pylori antigen was investigated in the stool samples of 445 patients of whom 148 were in the 2-15 year age group, 96 in the 16-30 year age group, 85 in the 31-40 year age group and 116 in the 41-48 year age group. The main clinical complaints of the patients (stomach pain, heart burn, indigestion, gas, nausea, vomiting, diarrhea, abdominal pain) were recorded.

RESULTS

The Helicobacter pylori antigen was found in 36.6% (163/445) of the patients and in the statistical evaluation made for different age groups, a significant linear relationship was found between age and infection (chi2=14.77, p=0.002).

CONCLUSION

It was found that stomach pain was seen at a higher rate in patients with H. pylori antigen compared to those without it. The difference was highly statistically significant (chi2=117.70, p<0.001, OR=20.36, 95% CI=10.56-39.27).

Analysis of eight different methods for the detection of Helicobacter pylori infection in patients with dyspepsia

BACKGROUND

The present study was designed to compare the accuracy of eight different methods for the detection of Helicobacter pylori (H. pylori) infection in patients with dyspepsia. These tests included culture, histology, rapid urease test (CLO test), serology, saliva IgA, gastric juice IgA, and two in-house methods, namely in-house urease test and Gram stain.

METHODS

H. pylori infection was diagnosed prospectively in 200 untreated patients who underwent upper gastrointestinal endoscopy at King Chulalongkorn Memorial Hospital, Bangkok, Thailand, between July 1999 and August 2001. The gold standard for H. pylori infection was based on a positive culture or both a positive histological examination and CLO test.

RESULTS

The culture provided a sensitivity of 55.9% whereas saliva IgA and gastric juice IgA had a sensitivity of 26.8% and 22.2%, respectively. In contrast, the other tests provided satisfactory sensitivities ranging between 89.3% and 100% (Gram stain 89.3%, histology 93.5%, serology 96.8%, CLO test 99.0%, in-house urease test 100%). The specificities of the tests ranged between 75% and 100% (culture 100%, CLO test 91.9%, histology 90.4%, in-house urease test 88.9%, Gram stain 93.5% serology 96.8%, gastric juice IgA 91.7% and saliva IgA 75%).

CONCLUSIONS

Majority of invasive and non-invasive tests in this study were accurate for the diagnosis of H. pylori infection. However, the secretory IgA-based techniques in saliva and gastric juice seem to be inappropriate for determining H. pylori status in our populations due to their low sensitivities.

Immunoblotting for the serodiagnosis of Helicobacter pylori infection in Brazilian patients with and without gastric carcinoma

We evaluated the performance of a commercial immunoblotting in the serodiagnosis of Helicobacter pylori infection in Brazilian patients. The presence of anti-H. pylori antibodies was also investigated in a group of 20 duodenal ulcer patients after successful treatment. One hundred and ninety one patients were studied. Among the 164 infected patients, 46 had gastric carcinoma. The duodenal ulcer patients were treated with antimicrobial drugs and the eradication of the microorganism was confirmed in all of them one month after the end of the treatment by the 13C-urea breath test. Sera were assayed for H. pylori antibodies using the Helicoblot 2.0 (Genelabs Diagnostics, Singapore). The sensitivity, specificity, positive, and negative predictive values of the test were 93.9%, 92.6%, 98.7%, and 71.4%, respectively. The sensitivity of the test was similar in patients with (93.5%) and without (95.7%) gastric carcinoma. Twenty-four months after the end of the treatment, the band of 116 kDa was still detected in one of the patients. In conclusion, the Helicoblot 2.0 is an accurate test to diagnose H. pylori infection and although it can not be employed to monitor the bacterium eradication, it may be useful for diagnosing past infection, especially in gastric carcinoma patients.

What is the role of serology in assessing Helicobacter pylori eradication?

AIM

To assess the decline in Helicobacter pylori antibodies after eradication of infection.

METHODS

The H. pylori status was determined at entry (D0) by culture and histology performed on antral biopsies and after eradication treatment at day 42 (day 42) and after 6 months (M6) by the 13C-urea breath test. The EIA kits used to determine the anti-H. pylori antibody titre were HM-CAP (immunoglobulin-G) and PP-CAP (immunoglobulin-A) kits (Enteric Products, Inc.) and Pyloriset EIA-G (Orion Diagnostica).

RESULTS

Ninety-three patients were included. For 82 patients who were successfully treated, no kit was sufficiently accurate at D42 to show eradication. The antibody titre decreased for HM-CAP, PP-CAP and Pyloriset EIA-G by a mean of 35.6%, 41.2% and 64.7% between D0 and M6, respectively. According to the cut-off values defined by the manufacturers, 8.5% (PP-CAP, Pyloriset EIA-G) and 9.7% (HM-CAP) of the patients became H. pylori negative at M6. Using a 25% decrease in antibody titre between D0 and M6 as a threshold for H. pylori eradication, specificity was 100% for HM-CAP, 89.9% for Pyloriset EIA-G and 100% for PP-CAP, whereas the sensitivity was 76.8%, 98.8% and 72%, respectively.

CONCLUSION

An antibody titre decrease of 25% at M6 was found to be accurate in confirming H. pylori eradication.

Breath test is very reliable for diagnosis of Helicobacter pylori infection in real clinical practice

AIMS

To determine the accuracy of the most common available tests for the diagnosis of Helicobacter pylori infection in an unselected and untreated population of patients.

PATIENTS AND METHODS

Prospective study including 314 unselected patients from a population of 814 patients referred for upper endoscopy at one hospital. H. pylori infection was diagnosed by rapid urease test (RUT), histology, culture and 13C-urea-breath test (UBT) and serum IgG (EIA). H. pylori infection was defined as positive if culture or at least two of the other tests were positive.

RESULTS

The prevalence of H. pylori infection in this population was 72%. The diagnostic test with the greatest combination of sensitivity (97%) and specificity (100%) was the UBT. EIA had a good sensitivity (96%), but it was the test with the least specificity (71%). RUT, histology and culture showed a high specificity (>98%) but a sensitivity lower than 90%. In elderly patients (>65 years old, n=120), UBT was also the test with the greatest combination of sensitivity (94%) and specificity (100%).

CONCLUSIONS

In conditions of real clinical practice the 13C-urea-breath test is a reliable test for H. pylori diagnosis, both in young and elderly patients.

Levofloxacin based regimens for the eradication of Helicobacter pylori

BACKGROUND

A 7 day treatment scheme based on rabeprazole/levofloxacin/amoxycillin or tinidazole achieved an eradication rate over 90%. However, the combination of drugs and duration of treatment for the correct use of levofloxacin in the eradication of are still unclear.

OBJECTIVE

To compare the efficacy and tolerability of rabeprazole/levofloxacin based dual therapies given for 5, 7 or 10 days with rabeprazole/levofloxacin/amoxycillin triple therapy for 7 days.

METHODS

One hundred and sixty patients with infection documented by the C-urea breath test and histology were included in this prospective, open label study. Subjects were randomized in four groups: (1) levofloxacin (500 mg o.d.), amoxycillin (1 g b.d.) and rabeprazole (20 mg o.d.) for 7 days; (2) levofloxacin (500 mg o.d.) and rabeprazole (20 mg o.d.) for 5 days; (3) levofloxacin (500 mg o.d.) and rabeprazole (20 mg o.d.) for 7 days; and (4) levofloxacin (500 mg o.d.) and rabeprazole (20 mg o.d.) for 10 days. Six weeks after the end of therapy status was checked by using the C-urea breath test.

RESULTS

All patients completed the therapeutic regimens. The eradication rate was not significantly modified by treatment duration in the dual therapy schemes (5 days: 20/40, 50%; 7 days: 28/40, 70%; 10 days: 26/40, 65%). The eradication rate of the 1 week levofloxacin based triple therapy was significantly higher than that observed using any dual therapies (36/40). No major adverse effects were observed.

CONCLUSIONS

A rabeprazole/levofloxacin dual eradication regimen is simple and well tolerated but does not achieve an acceptable eradication rate when compared to a 1 week rabeprazole/levofloxacin/amoxycillin triple therapy. The eradication rate did not increase with a longer regimen.

Bleeding peptic ulcers and presence of Helicobacter pylori by various tests: a case-control study

BACKGROUND

Virulence factors of Helicobacter pylori are associated with peptic ulcer disease and may be also associated with bleeding peptic ulcers (BPU).

AIM

To determine whether H. pylori and/or the cytotoxin-associated gene (cagA) can increase the risk of bleeding in peptic ulcers.

PATIENTS

Sixty-seven patients were studied. Thirty had BPU, 20 had non-bleeding peptic ulcers (NBPU), and 17 were control subjects (NPU).

METHODS

The prevalence of H. pylori was assessed by the urease fast test, histological examination, serology, and 16S ribosomal RNA and cagA gene amplification by polymerase chain reaction (PCR).

RESULTS

Histology and PCR showed greater sensitivity for diagnosis of H. pylori under bleeding circumstances when compared with other tests. Association of H. pylori was greater in the NBPU group (odds ratio [OR] 4.91, P = 0.06) than in the BPU group (OR 1.27, P = NS) when compared with the control group. When the BPU and NBPU groups were compared, H. pylori was found more often in the NBPU group (OR 0.26, P < 0.10 ). The cagA-positive gene showed a similar distribution in the three groups. The titres for anti-CagA immunoglobulin A (IgA) antibodies were higher in NBPU patients (83%) than in BPU or control patients. Furthermore, anti-urease immunoglobulin G (IgG) was detected more frequently among BPU and NBPU patients.

CONCLUSIONS

NBPU patients had the highest prevalence of H. pylori by PCR. It seems unlikely that either H. pylori or the cagA-positive gene act as significant risk factors for bleeding in peptic ulcers. The lower prevalence of the microorganism among patients who bleed cannot be explained as an artificial finding.

Prevalence of Helicobacter pylori infection in asymptomatic subjects in Libya

Helicobacter pylori infection is very common infection worldwide particularly in the developing countries. No detailed study on such infection is being recorded so far in Libya. The aims of the study were to detect H. pylori prevalence in asymptomatic Libyan subjects, to determine the rate of infection among different age groups and to correlate the prevalence of H. pylori with age, sex, smoking, non-steroidal anti-inflammatory drugs intake, marital status, education, and socioeconomic status. Three hundred and sixty asymptomatic subjects 1->70 years of age (average 36) with no previous history of epigastric pain were selected randomly from the Libyan population. Serum samples were obtained and a questionnaire was filled for each subject. The ELISA test was used to detect IgG anti-H. pylori antibodies. An overall prevalence of 76% was detected in these subjects. A 50% infection rate were in subjects 1-9 years of age that increased to 84% in subjects 10-19 years and continued with increasing age and reached up to 94% in those over 70 years of age. Subjects > 45 years of age had significantly higher antibody response than those <45 years. H. pylori prevalence was higher in married subjects (84%) as compared to singles (68%) and similarly in illiterates (89%) and low socioeconomic subjects (91%). No difference in sex, smoking and NSAIDs intake was recorded. Infection with H. pylori is highly prevalent in the Libyan asymptomatic subjects. Infection acquired early in childhood and reached up to 94% in older age. Prevalence of H. pylori was significantly increased in association with marital status, education and low socioeconomic status.

Role of corpus gastritis and cagA-positive Helicobacter pylori infection in reflux esophagitis

Considering that the role of Helicobacter pylori infection in gastroesophageal reflux and reflux esophagitis (GERD) is still controversial and that the role of virulence markers of the bacterium has not been evaluated in most studies of GERD, we investigated the association among H. pylori infection with cagA-positive and -negative strains, corpus gastritis, and GERD in a large group of patients by controlling for confounding factors. We studied prospectively 281 consecutive adult patients: 93 with GERD and 188 controls. H. pylori infection status was diagnosed by culture, by the preformed urease test, with a carbolfuchsin-stained smear, and by histology. The cagA status was determined by PCR of H. pylori isolates and gastric biopsy specimens. H. pylori infection was diagnosed in 191 (68.0%) of 281 patients. Among the 93 patients with GERD, 84 presented with mild or moderate esophagitis and 9 presented with severe esophagitis. In the multivariate analysis, the age of the patients and the degree of oxyntic gastritis were associated with GERD. Among the strains isolated from patients with GERD and from the control group, 24.4 and 66.9%, respectively, were positive for cagA (P < 0.001). Compared to infection with cagA-negative strains, infection with cagA-positive H. pylori strains was associated with a more intense gastritis in the corpus (P = 0.001). cagA status (odds ratio [OR] = 0.16, 95% confidence interval [CI] = 0.07 to 0.40), gastritis of the corpus (OR = 0.69, 95% CI = 0.48 to 0.99), and age (OR = 1.04, 95% CI = 1.01 to 1.07) were associated with GERD. In conclusion, the study provides evidence supporting the independent protective roles of cagA-positive H. pylori strains and the degree of corpus gastritis against GERD.

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

BACKGROUND

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

AIM

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

PATIENTS/METHODS

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

RESULT

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

CONCLUSION

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

Evaluation of a Western blot test, Helico blot 2.1, in the diagnosis of Helicobacter pylori infection in a pediatric population

BACKGROUND

Noninvasive diagnostic tests are useful as screening tools for Helicobacter pylori infection in pediatric populations. The aim of this study was to evaluate performance of the immunoblot assay, Helico Blot 2.1, for the diagnosis of H. pylori infection in symptomatic children.

MATERIALS AND METHODS

Immunoblot assay was used for detection of IgG antibodies to specific H. pylori proteins and to a recombinant H. pylori antigen, CIM marker. The study was performed on sera collected from 134 symptomatic, untreated children (mean age, 9.1 +/- 3.2 years; range, 1-14 years). H. pylori infection status was determined by culture, histology and rapid urease test.

RESULTS

Immunoblot assay yielded a positive result in 71 of the 72 infected patients (sensitivity 98.6%) and in eight of the 62 noninfected ones (specificity 87.1%). The predictive values for a positive and a negative result were 89.9% and 98.2%, respectively. The performance of the CIM band alone, as a marker for H. pylori infection status, was also evaluated. This band was present on the blot of 71 infected patients and on four of the 62 H. pylori-negative patients. The sensitivity, specificity, PPV and NPV of the CIM antigen were 98.6%, 93.5%, 94.7% and 98.3%, respectively.

CONCLUSIONS

The immunoblot assay Helico Blot 2.1 is a suitable noninvasive test for the serodiagnosis of H. pylori infection in children. The good level of performance demonstrated by the novel recombinant antigen CIM suggests it may be a useful contribution to the qualitative and quantitative performance of the Helico Blot 2.1 in pediatric populations.

13C-urea breath test threshold calculation and evaluation for the detection of Helicobacter pylori infection in children

BACKGROUND

The 13C-urea breath test (UBT) is performed in adults and children with epigastric pain for non-invasively diagnosing a suspected H. pylori infection. Criteria for UBT interpretation have not been generally agreed on and test reliability has not been established in children of different ages. This study aimed at identifying reliable UBT thresholds in children by using 251 UBTs in conjunction with reference histology and by analyzing 1232 UBTs.

METHODS

At baseline and 30 and 60 minutes after the administration of 75 mg 13C-urea to children and adolescents (0.25 to 18 years of age), the differences (Delta) of 13CO2/12CO2 ratio in exhaled air (delta) were determined by mass spectrometry. UBT Deltadelta value thresholds were calculated in random subgroups and evaluated in complementary subgroups using logistic regressions on reference histology or bimodal distribution analyses of Deltadelta values from UBTs alone.

RESULTS

Deltadelta values were higher (median, 15.4 per thousand) in positive (133/251, 53 %) than in negative histology (2.4 per thousand). At 30 minutes, the calculated cut-off was 5.3 per thousand (mean regression determination R2 = 0.91), and sensitivity (0.95), specificity (0.97), positive (0.97) and negative predictive values (0.95) were higher than at 60 minutes (threshold 6.8 per thousand, R2 = 0.85). Similar thresholds resulted from UBTs analysis (5.8 per thousand and 6.2 per thousand) when sensitivity and specificity were maximized (concordance probabilities, 0.99 and 0.99). There was no systematic age effect.

CONCLUSIONS

In children, 13C UBT cut-offs were obtained and specially validated, entailing high accuracy of non-invasively testing for gastric H. pylori infection.

Review article: diagnosis of Helicobacter pylori infection

Helicobacter pylori (H. pylori) infection can be diagnosed by invasive techniques requiring endoscopy and biopsy (histological examination, culture, polymerase chain reaction) and by noninvasive techniques (serology, urea breath test, urine or blood, detection of H. pylori antigen in stool specimen). At present, no single test can be absolutely relied upon to detect colonization by H. pylori, and a combination of two tests is recommended if feasible. The tests used should depend on the clinical circumstances, the likelihood ratio of positive and negative tests, the cost-effectiveness of the testing strategy, and the availability of the tests. Some clinical circumstances warrant invasive studies, principally patients with alarm symptoms (bleeding, weight loss, etc.) as well as older patients with new-onset dyspepsia. Endoscopy may also be advisable in patients who have failed eradication therapy and need culture and antimicrobial sensitivity testing to determine an appropriate regimen. Recent studies have also demonstrated that a strategy to 'test and treat' for H. pylori in uninvestigated, young (< 50 years), dyspeptic patients in primary care is safe and reduces the need for endoscopy. Indeed, a number of clinical guidelines recommend noninvasive testing followed by treatment of H. pylori for dyspeptic patients in primary care based on clinical and economic analyses.

Diagnosis of Helicobacter pylori infection

A number of invasive and non-invasive techniques are available for the diagnosis of infection with Helicobacter pylori. These can be used to establish whether infection is present and to confirm that eradication has been achieved after treatment. Invasive techniques require biopsy of the gastric mucosa; such techniques include histology, bacterial culture, the rapid urease test and the polymerase chain reaction (PCR) technique. The principal non-invasive techniques are the 13C-urea breath test and serological assays in serum or saliva samples. Histological examination of gastric biopsy samples should be mandatory at the initial presentation of the patient because it also gives insight on the status of the gastric mucosa. The rapid urease test can be used to give a rapid diagnosis of infection. Eradication should also be confirmed by histological examination, though other sensitive tests such as bacterial culture, PCR or the 13C-urea breath test may also be used.

Immune response to a 26-kDa protein, alkyl hydroperoxide reductase, in Helicobacter pylori-infected Mongolian gerbil model

BACKGROUND

The host immune response is thought to play an important role in the outcome of Helicobacter pylori infection. The successful development of the H. pylori-infected Mongolian gerbil model that mimics human disease has enabled study of the antibody response against H. pylori antigens.

MATERIALS AND METHODS

Serum samples from ulcer and carcinogenesis models of H. pylori-infected gerbils were used to screen for H. pylori antigens that cause a humoral immune response in the infected hosts. H. pylori alkyl hydroperoxide reductase (AhpC) is one such antigen on which we report here. The tsaA gene encoding AhpC was amplified by PCR from H. pylori ATCC 43504 strain, cloned into pMAL(TM)-c2 expression vector and expressed in Escherichia coli. Maltose-binding protein fusion protein (MBP-AhpC) was purified by a MBP affinity column. Using purified recombinant AhpC protein as an antigen, the antibody response and changes of antibody levels against AhpC in the gerbil models were studied by Western blotting and ELISA.

RESULTS

Antibody against AhpC was negative in the early stages of infection, and became positive in the gerbils with the emergence of gastric diseases such as chronic active gastritis, gastric ulcer and gastric cancer. The antibody levels (ELISA) increased gradually over time and were higher in gerbils with gastric ulcer than that in gerbils without ulcers.

CONCLUSIONS

Use of the gerbil model that mimics human H. pylori infection is likely to provide insights into the role of H. pylori-specific antigens possibly related to the subsequent development of gastric diseases.

Composition and gene expression of the cag pathogenicity island in Helicobacter pylori strains isolated from gastric carcinoma and gastritis patients in Costa Rica

The composition and in vitro expression of the cag pathogenicity island genes in a group of Helicobacter pylori strains obtained from patients suffering from chronic gastritis-associated dyspepsia (n = 26) or gastric carcinoma (n = 17) were analyzed. No significant difference in the distribution of the 10 studied regions was found between the cases and the controls. Nine strains did not harbor any of the selected regions: eight (30.8%) isolated from patients with gastritis only and one (5.9%) from a patient with gastric carcinoma. No association was found between the number of repeated sequences at the 3' end of the cagA gene or the presence of tyrosine phosphorylation motifs and the clinical origin of the strains. The virB10 homolog gene was the sole gene studied to be significantly expressed more often in cancer strains than in gastritis strains (P = 0.03).

Evaluation of invasive and non-invasive methods for the diagnosis of Helicobacter pylori infection in symptomatic children and adolescents

CONTEXT

Multiple diagnostic methods are available for the detection of Helicobacter pylori infection, but at present no single one can be used as the gold standard.

OBJECTIVE

The aim of this study was to evaluate the diagnostic accuracy of 3 invasive and 2 non-invasive methods for detection of Helicobacter pylori infection in symptomatic children and adolescents.

DESIGN

Prospective cohort study

SETTING

Peptic Disease outpatients service, Discipline of Pediatric Gastroenterology, Universidade Federal de São Paulo / Escola Paulista de Medicina.

PATIENTS

Forty-seven patients who underwent endoscopy because of dyspeptic symptoms.

DIAGNOSTIC METHODS

Endoscopy with gastric biopsies for 3 invasive (rapid urease test, histology and culture) and 2 non-invasive methods (a commercial ELISA serology and 13carbon urea breath test - isotope ratio mass spectrometry) for detection of Helicobacter pylori infection.

MAIN MEASUREMENTS

Sensitivity, specificity, positive and negative predictive values of each method and agreement and disagreement rates between the methods.

RESULTS

Forty-seven patients [mean age, 11y9mo (SD 2y10mo), 27 female and 20 male]; 62% of them were Helicobacter pylori-positive. All methods agreed in 61%, and were negative in 21% and positive in 40%. The greatest concordance between 2 methods occurred between the invasive methods: histology and rapid urease test (89.6%) and histology and culture (87.5%). The greatest sensitivity, considering Helicobacter pylori-positive cases, for any combination of 3 or more tests, was achieved by the rapid urease test (S=100%), followed by histology, serology and 13carbon-urea breath test (S=93.1%) and lastly by culture (S=79.3%). The highest specificity was obtained by histology (100%) and culture (100%), followed by the rapid urease test (84.2%), serology (78.9%) and 13carbon-urea breath test (78.9%).

CONCLUSIONS

Our results suggest that among invasive methods, an association between the rapid urease test and histology constituted the best choice for the detection of Helicobacter pylori infection. If results of histology and the rapid urease test are different, serology may be recommended.

An intelligent rapid odour recognition model in discrimination of Helicobacter pylori and other gastroesophageal isolates in vitro

Two series of experiments are reported which result in the discrimination between Helicobacter pylori and other bacterial gastroesophageal isolates using a newly developed odour generating system, an electronic nose and a hybrid intelligent odour recognition system. In the first series of experiments, after 5 h of growth (37 degrees C), 53 volatile 'sniffs' were collected over the headspace of complex broth cultures of the following clinical isolates: Staphylococcus aureus, Klebsiella sp., H. pylori, Enterococcus faecalis (10(7) ml(-1)), Mixed infection (Proteus mirabilis, Escherichia coli, and E. faecalis 3 x 10(6) ml each) and sterile cultures. Fifty-six normalised variables were extracted from 14 conductive polymer sensor responses and analysed by a 3-layer back propagation neural network (NN). The NN prediction rate achieved was 98% and the test data (37.7% of all data) was recognised correctly. Successful clustering of bacterial classes was also achieved by discriminant analysis (DA) of a normalised subset of sensor data. Cross-validation identified correctly seven 'unknown' samples. In the second series of experiments after 150 min of microaerobic growth at 37 degrees C, 24 volatile samples were collected over the headspace of H. pylori cultures in enriched (HPP) and normal (HP) media and 11 samples over sterile (N) cultures. Forty-eight sensor parameters were extracted from 12 sensor responses and analysed by a 3-layer NN previously optimised by a genetic algorithm (GA). GA-NN analysis achieved a 94% prediction rate of 'unknown' data. Additionally the 'genetically' selected 16 input neurones were used to perform DA-cross validation that showed a clear clustering of three groups and reclassified correctly nine 'sniffs'. It is concluded that the most important factors that govern the performance of an intelligent bacterial odour detection system are: (a) an odour generation mechanism, (b) a rapid odour delivery system similar to the mammalian olfactory system, (c) a gas sensor array of high reproducibility and (d) a hybrid intelligent model (expert system) which will enable the parallel use of GA-NNs and multivariate techniques.

Immunoblot analysis of humoral immune response to Helicobacter pylori in children with and without duodenal ulcer

Several studies have demonstrated that enzyme-linked immunosorbent assay is not a sensitive and specific method to diagnose Helicobacter pylori infection in children, especially in the younger ones. Since serum immune response can also be determined by immunoblotting and it permits the detection of antibodies to virulence factors such as CagA and VacA, we evaluated the accuracy of a commercial immunoblotting test to diagnose H. pylori infection and to assess the humoral immune response to different H. pylori antigens in 122 children who underwent upper gastrointestinal endoscopy. The presence of H. pylori was determined in antral biopsy specimens by culture, preformed urease test, and histological analysis. H. pylori was identified by microbiological and histopathological methods in 66 children (including all of the 21 who had duodenal ulcer). Antibodies to H. pylori were detected in 63 infected children and in 8 noninfected ones. The sensitivity, specificity, and positive and negative predictive values of the immunoblotting test were 95.5, 85.7, 88.7, and 94.1%, respectively. The number of immunoreactive bands increased with age (P = 0.003), and the bands of 35 kDa (P = 0.013); 89 kDa, the VacA antigen (P = 0.001); and 116 kDa, the CagA antigen (P = 0.00004) were more frequently observed in older children. The frequency of the bands of 89 kDa (P = 0.001) and 116 kDa (P = 0.03) was higher in children with duodenal ulcer than in H. pylori-positive children without the disease. In conclusion, the immunoblotting test appears to be useful for the diagnosis of H. pylori infection in children, even in the younger ones.

13C-Urea breath test is superior in sensitivity to detect Helicobacter pylori infection than either antral histology or rapid urease test

There is no single technique which fulfils the criterion for a reference method to detect Helicobacter pylori (Hp) infection. The aim was to compare the results of antral histology (H), rapid urease test (U) and urea breath test (UBT) from antral biopsy samples in patients having gastric or duodenal lesions during upper GI endoscopy. We used the following methods: 1) biopsy specimens for histology (Warthin-Starry staining); 2) rapid urease test; and 3) 13C-urea breath test with infrared spectrometry. The total number of patients was 166 examined by H, U, and UBT. H, U and UBT were negative (-) in 64 patients and positive (+) in 51. The true positivity and false negativity (%, number of patients in parentheses) of each method based upon the positivity of the other two tests were: H+, U+ (54): UBT+, 94.4% (51) and UBT-, 5.6% (3); H+, UBT+ (57): U+, 89.5% (51) and U-, 10.5% (6); U+, UBT+ (65): H+, 78.5% (51) and H-, 21.5% (14). If Hp infection is considered to be positive when at least two tests detect the presence of Hp, UBT shows the highest sensitivity in comparison to histology of biopsy specimens and urease test. UBT is highly recommended as a screening test for Hp infection in patients presenting upper GI endoscopic alterations.