Campylobacter pylori infection in biopsy specimens of gastric antrum: laboratory diagnosis and estimation of sampling error

Evaluation of urea breath test as a diagnostic tool for Helicobacter pylori infection in adult dyspeptic patients

In this editorial, we discuss the article in the World Journal of Gastroenterology. The article conducts a meta-analysis of the diagnostic accuracy of the urea breath test (UBT), a non-invasive method for detecting Helicobacter pylori (H. pylori) infection in humans. It is based on radionuclide-labeled urea. Various methods, both invasive and non-invasive, are available for diagnosing H. pylori infection, including endoscopy with biopsy, serology for immunoglobulin titers, stool antigen analysis, and UBT. Several guidelines recommend UBTs as the primary choice for diagnosing H. pylori infection and for reexamining after eradication therapy. It is used to be the first choice non-invasive test due to their high accuracy, specificity, rapid results, and simplicity. Moreover, its performance remains unaffected by the distribution of H. pylori in the stomach, allowing a high flow of patients to be tested. Despite its widespread use, the performance characteristics of UBT have been inconsistently described and remain incompletely defined. There are two UBTs available with Food and Drug Administration approval: The 13C and 14C tests. Both tests are affordable and can provide real-time results. Physicians may prefer the 13C test because it is non-radioactive, compared to 14C which uses a radioactive isotope, especially in young children and pregnant women. Although there was heterogeneity among the studies regarding the diagnostic accuracy of both UBTs, 13C-UBT consistently outperforms the 14C-UBT. This makes the 13C-UBT the preferred diagnostic approach. Furthermore, the provided findings of the meta-analysis emphasize the significance of precise considerations when choosing urea dosage, assessment timing, and measurement techniques for both the 13C-UBT and 14C-UBT, to enhance diagnostic precision.

A pilot study of non-invasive diagnostic tools to detect Helicobacter pylori infection and peptic ulcer disease

Helicobacter pylori (H. pylori) infection can lead to various digestive system diseases, making accurate diagnosis crucial. However, not all available tests are equally non-invasive and sensitive. This study aimed to compare the efficacy of non-invasive and invasive diagnostic tools for H. pylori infection and assess their correlation with esophagogastroduodenoscopic (EGD) findings. The study utilized the Campylobacter-Like Organism (CLO) test, serum anti-HP IgG blood test, and C-13-urea breath test (UBT) to diagnose H. pylori infection. A total of 100 patients with peptic ulcer symptoms, including 45 males and 55 females, were recruited for the study. Symptomatic patients between the ages of 20-70, eligible for EGD examination, were enrolled. Each diagnostic test and any combination of two positive tests were considered the reference standard and compared against the other diagnostic methods. Additionally, the relationship between these diagnostic tests and EGD findings was evaluated. Among the participants, 74.0% were diagnosed with peptic ulcer disease through EGD. The UBT demonstrated the highest Youden's index, ranging from 58 to 100%, against all the non-invasive tests. The IgG blood test displayed the highest sensitivity at 100%, with a specificity of 60-70%. On the other hand, the CLO test exhibited the highest specificity at 100% and a sensitivity of 50-85%. Furthermore, only the CLO test showed a significant association with esophageal ulcers (p-value = 0.01). The IgG blood test holds promise as a primary screening tool due to its exceptional sensitivity. While the UBT is relatively expensive, its non-invasive nature and high sensitivity and specificity make it a potential standalone diagnostic test for H. pylori infection. Moreover, the noteworthy negative correlation between the CLO test and esophageal ulcers provides evidence of the differing effects of H. pylori infection on antral-predominant and corpus-predominant gastritis.

Role of New Anatomy, Biliopancreatic Reflux, and Helicobacter Pylori Status in Postgastrectomy Stump Cancer

Distal gastrectomy for benign gastroduodenal peptic disease has become rare, but it still represents a widely adopted procedure for advanced and, in some countries, even for early distal gastric cancer. Survival rates following surgery for gastric malignancy are constantly improving, hence the residual mucosa of the gastric stump is exposed for a prolonged period to biliopancreatic reflux and, possibly, to Helicobacter pylori (HP) infection. Biliopancreatic reflux and HP infection are considered responsible for gastritis and metachronous carcinoma in the gastric stump after oncologic surgery. For gastrectomy patients, in addition to eradication treatment for cases that are already HP positive, endoscopic surveillance should also be recommended, for prompt surveillance and detection in the residual mucosa of any metaplastic-atrophic-dysplastic features following surgery.

The necessity and appropriate range of the diagnostic "gray zone" of 13C-urea breath test

BACKGROUND

The ¹³C-urea breath test (¹³C-UBT) is preferred for non-invasive detection of Helicobacter pylori (H. pylori); however, its accuracy drops when results fall between 2‰ and 6‰ (called the gray zone). This study aimed to evaluate the accuracy of ¹³C-UBT (cut-off point 4‰) between 2‰ and 6‰, find a more appropriate gray zone, and identify the factors influencing ¹³C-UBT.

METHODS

Patients with ¹³C-UBT results 2‰-6‰, over an eight-year period, were studied. H. pylori infection was diagnosed if patients were positive for either Warthin-Starry staining or quantitative real-time polymerase chain reaction (real-time PCR), and excluded if both were negative. Accuracy of ¹³C-UBT under different cut-off points was calculated, and the factors affecting ¹³C-UBT were analyzed.

RESULTS

A total of 208 patients were included, of whom 129 were H. pylori-positive. Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of ¹³C-UBT were 71.32%, 83.54%, 64.08%, and 87.62%, respectively. When the cut-off point was changed to 2.15‰, the NPV of ¹³C-UBT reached a maximum (76.47%); when the cut-off point was changed to 4.95‰, PPV reached its maximum (93.22%). Therefore, the original gray zone (2‰-6‰) was adjusted to 2‰-4.95‰. Gastric antral intestinal metaplasia (OR = 3.055, 95% CI: 1.003-9.309) was an independent risk factor for false-negative ¹³C-UBT.

CONCLUSIONS

Accuracy of ¹³C-UBT over 2‰-6‰ was poor, and the gray zone was changed to 2‰-4.95‰. ¹³C-UBT results over 2‰-4.95‰ should be interpreted with caution during mass screening of H. pylori, especially for patients with gastric antral intestinal metaplasia.

Where to Biopsy to Detect Helicobacter pylori and How Many Biopsies Are Needed to Detect Antibiotic Resistance in a Human Stomach

This study aims to determine the gastric distribution, density, and diversity of Helicobacter pylori infection. Subtotal resection of the stomachs of three H. pylori-infected and asymptomatic obese patients were collected after a sleeve gastrectomy. Distribution and density of H. pylori were determined using culture and RT-PCR on multiple gastric sites (88, 176, and 101 biopsies per patient). Diversity of H. pylori strains was studied using antibiotic susceptibility testing, random amplified polymorphism DNA (RAPD) typing and cagA gene detection on single-colony isolates (44, 96, and 49 isolates per patient). H. pylori was detected in nearly all analyzed sites (354/365 biopsies, 97%). Antral density was higher in one patient only. The three stomachs were almost exclusively infected by an antibiotic-susceptible strain. One clarithromycin-resistant isolate in one biopsy was detected in two stomachs (1/44 and 1/49 isolates), while in the third one, eight (8/96 isolates) metronidazole-resistant isolates were detected. DNA typing showed infection with cagA-negative strains for one patient, cagA-positive strains for a second patient and the third patient was infected with two different strains of distinct cagA genotypes. Infection with H. pylori is shown to spread to the whole surface of the stomach, but a possibility of minor sub-population of antibiotic-resistant clones, undetectable in routine practice.

The Diagnostic Validity of Citric Acid-Free, High Dose (13)C-Urea Breath Test After Helicobacter pylori Eradication in Korea

BACKGROUND

The (13)C-urea breath test ((13)C-UBT) is a noninvasive method for diagnosing Helicobacter pylori (H. pylori) infection. The aims of this study were to evaluate the diagnostic validity of the (13)C-UBT cutoff value and to identify influencing clinical factors responsible for aberrant results.

METHODS

(13)C-UBT (UBiTkit; Otsuka Pharmaceutical, cutoff value: 2.5‰) results in the range 2.0‰ to 10.0‰ after H. pylori eradication therapy were compared with the results of endoscopic biopsy results of the antrum and body. Factors considered to affect test results adversely were analyzed.

RESULTS

Among patients with a positive (13)C-UBT result (2.5‰ to 10.0‰, n = 223) or a negative (13)C-UBT result (2.0‰ to < 2.5‰, n = 66) after H. pylori eradication, 73 patients (34.0%) were false positive, and one (1.5%) was false negative as determined by endoscopic biopsy. The sensitivity, specificity, false-positive rate, and false-negative rate for a cutoff value of 2.5‰ were 99.3%, 47.1%, 52.9%, and 0.7%, respectively, and positive and negative predictive values of the (13)C-UBT were 67.3% and 98.5%, respectively. Multivariate analysis showed that a history of two or more previous H. pylori eradication therapies (OR = 2.455, 95%CI = 1.299-4.641) and moderate to severe gastric intestinal metaplasia (OR = 3.359, 95%CI = 1.572-7.178) were associated with a false-positive (13)C-UBT result.

CONCLUSION

The (13)C-UBT cutoff value currently used has poor specificity for confirming H. pylori status after eradication, and this lack of specificity is exacerbated in patients that have undergone multiple prior eradication therapies and in patients with moderate to severe gastric intestinal metaplasia. In addition, the citric-free (13)C-UBT would increase a false-positive (13)C-UBT result.

Accuracy of urea breath test in Helicobacter pylori infection: Meta-analysis

AIM: To quantitatively summarize and appraise the available evidence of urea breath test (UBT) use to diagnose Helicobacter pylori (H. pylori) infection in patients with dyspepsia and provide pooled diagnostic accuracy measures.

METHODS: We searched MEDLINE, EMBASE, Cochrane library and other databases for studies addressing the value of UBT in the diagnosis of H. pylori infection. We included cross-sectional studies that evaluated the diagnostic accuracy of UBT in adult patients with dyspeptic symptoms. Risk of bias was assessed using QUADAS (Quality Assessment of Diagnostic Accuracy Studies)-2 tool. Diagnostic accuracy measures were pooled using the random-effects model. Subgroup analysis was conducted by UBT type (¹³C vs¹⁴C) and by measurement technique (Infrared spectrometry vs Isotope Ratio Mass Spectrometry).

RESULTS: Out of 1380 studies identified, only 23 met the eligibility criteria. Fourteen studies (61%) evaluated ¹³C UBT and 9 studies (39%) evaluated ¹⁴C UBT. There was significant variation in the type of reference standard tests used across studies.Pooled sensitivity was 0.96 (95%CI: 0.95-0.97) andpooled specificity was 0.93 (95%CI: 0.91-0.94). Likelihood ratio for a positive test was 12 and for a negative test was 0.05 with an area under thecurve of 0.985. Meta-analyses were associated with a significant statistical heterogeneity that remained unexplained after subgroup analysis. The included studies had a moderate risk of bias.

CONCLUSION: UBT has high diagnostic accuracy for detecting H. pylori infection in patients with dyspepsia. The reliability of diagnostic meta-analytic estimates however is limited by significant heterogeneity.

The diagnostic validity of the (13)c-urea breath test in the gastrectomized patients: single tertiary center retrospective cohort study

BACKGROUND

This study was conducted to evaluate the diagnostic validity of the (13)C-urea breath test ((13)C-UBT) in the remnant stomach after partial gastrectomy for gastric cancer.

METHODS

The (13)C-UBT results after Helicobacter pylori eradication therapy was compared with the results of endoscopic biopsy-based methods in the patients who have received partial gastrectomy for the gastric cancer.

RESULTS

Among the gastrectomized patients who showed the positive (13)C-UBT results (≥ 2.5‰, n = 47) and negative (13)C-UBT results (< 2.5‰, n = 114) after H. pylori eradication, 26 patients (16.1%) and 4 patients (2.5%) were found to show false positive and false negative results based on biopsy-based methods, respectively. The sensitivity, specificity, false positive rate, and false negative rate for the cut-off value of 2.5‰ were 84.0%, 80.9%, 19.1%, and 16.0%, respectively. The positive and negative predictive values were 44.7% and 96.5%, respectively. In the multivariate analysis, two or more H. pylori eradication therapies (odds ratio = 3.248, 95% confidence interval= 1.088-9.695, P = 0.035) was associated with a false positive result of the (13)C-UBT.

CONCLUSIONS

After partial gastrectomy, a discordant result was shown in the positive (13)C-UBT results compared to the endoscopic biopsy methods for confirming the H. pylori status after eradication. Additional endoscopic biopsy-based H. pylori tests would be helpful to avoid unnecessary treatment for H. pylori eradication in these cases.

Low Helicobacter pylori primary resistance to clarithromycin in gastric biopsy specimens from dyspeptic patients of a city in the interior of São Paulo, Brazil

BACKGROUND

Clarithromycin, amoxicillin, and a pump proton inhibitor are the most common drugs recommended as first-line triple therapy for H.pylori treatment, which results in eradication rates close to 80%, varying regionally, principally due to emergency cases and increases of clarithromycin resistant strains. Nucleotide substitutions at the H. pylori domain V of the 23S rRNA fraction are involved in the macrolide resistance and the A2142G and A2143G mutations are predominant in clinical isolates worldwide including in Brazil. As H. pylori culture is fastidious, we investigated the primary occurrence of H. pylori A2142G and A2143G rDNA 23S mutations using a molecular approach directly on gastric biopsies of dyspeptic patients consecutively attended at Hospital das Clinicas of Marilia, São Paulo, Brazil.

METHODS

Biopsy specimens obtained from 1137 dyspeptic patients, were subjected to histopathology and H. pylori diagnosis by histology and PCR. PCR/RFLP assay was used to detect A2142G and A2143G point mutations at domain V of the H. pylori 23S rDNA associated with clarithromycin resistance. Through the developed assay, a 768 bp PCR amplicon corresponding to1728 to 2495 bp of the 23S H. pylori rDNA is restricted with MboII for A2142G mutation detection and with BsaI for A2143G mutation detection. Occurrence of 23S rDNA A2142G results in two DNA fragments (418 and 350 bp) and of 23S rDNA A2143G results in three DNA fragments (108, 310 and 350pb), due to a conserved BsaI restriction site.

RESULTS

The PCR method used to diagnose H. pylori presented sensitivity, specificity and accuracy of 77,6%, 79,3% and 78,6%, respectively, compared to histology, the gold standard method for H. pylori diagnosis used in our routine. Prevalence of H.pylori with clarithromycin resistant genotypes was 2,46%, with predominance of A2143G 23S rDNA point mutation.

CONCLUSIONS

The PCR/RFLP assay was a rapid and accurate H.pylori diagnostic and clarithromycin resistance determination method useful for routine practice. As prevalence of primary resistance of H.pylori to clarithromycin due to A2142G and A2143G mutations remains low in Marilia, the standard clarithromycin containing triple therapy is still valid.

Comparison of salivary and serum enzyme immunoassays for the diagnosis of Helicobacter pylori infection

Infection with Helicobacter pylori has been established as an important risk factor for the development of peptic ulcer disease, gastritis and gastric cancer. The diagnosis of H pylori infection can be established by invasive or noninvasive techniques. Two noninvasive enzyme immunoassays (EIAs) for antibody detection - HeliSal and Pylori Stat - were compared with histology. Both assays detect immunoglobulin (Ig) G directed against purified H pylori antigen. The test populations consisted of 104 consecutive patients scheduled for upper gastrointestinal endoscopy. Of these patients, 97 (93%) had symptoms compatible with peptic ulcer disease. Saliva and serum were collected simultaneously at the time of endoscopy. Salivary EIA had a sensitivity of 66%, specificity of 67%, positive predictive value of 67% and negative predictive value of 66% compared with the serum EIA, where the results were 98%, 48%, 64% and 96%, respectively. Although the salivary EIA is an appealing noninvasive test, it was not a sensitive and specific assay. The serum EIA also lacked specificity, but was highly sensitive with a good negative predictive value. Although a negative serum EIA rules out H pylori infection, a positive result must be interpreted in the clinical context and confirmed with a more specific measure.

Absence of Helicobacter pylori high tetracycline resistant 16S rDNA AGA926-928TTC genotype in gastric biopsy specimens from dyspeptic patients of a city in the interior of São Paulo, Brazil

Background

Treatment effectiveness of Helicobacter pylori varies regionally and is decreasing worldwide, principally as a result of antibiotic resistant bacterium. Tetracycline is generally included in second line H. pylori eradication regimens. In Brazil, a high level of tetracycline resistance (TetR) is mainly associated with AGA926-928TTC 16 S rDNA nucleotide substitutions. As H. pylori culture is fastidious, we investigated the primary occurrence of H. pylori 16 S rDNA high level TetR genotype using a molecular approach directly on gastric biopsies of dyspeptic patients attending consecutively at Hospital das Clinicas of Marilia, São Paulo, Brazil.

Methods

Gastric biopsy specimens of 68 peptic ulcer disease (PUD) and 327 chronic gastritis (CG) patients with a positive histological diagnosis of H. pylori were investigated for TetR 16 S rDNA genotype through a molecular assay based on amplification of a 16 S rDNA 545 bp fragment by polymerase chain reaction and HinfI restriction fragment length polymorphism (PCR/RFLP). Through this assay, AGA926-928TTC 16 S rDNA TetR genotype resulted in a three DNA fragment restriction pattern (281, 227 and 37 bp) and its absence originated two DNA fragments (264 and 281 bp) due to a 16 S rDNA conserved Hinf I restriction site.

Results

The 545 bp 16 S rDNA PCR fragment was amplified from 90% of gastric biopsies from histological H. pylori positive patients. HinfI RFLP revealed absence of the AGA926–928TTC H. pylori genotype and PCR products of two patients showed absence of the conserved 16 S rDNA HinfI restriction site. BLASTN sequence analysis of four amplicons (two conserved and two with an unpredicted HinfI restriction pattern) revealed a 99% homology to H. pylori 16 S rDNA from African, North and South American bacterial isolates. A nucleotide substitution abolished the conserved HinfI restriction site in the two PCR fragments with unpredicted HinfI RFLP, resulting in an EcoRI restriction site.

Conclusions

H. pylori AGA926-928TTC 16 S rDNA gene substitutions were not found in our population. More research is required to investigate if H. pylori TetR has a different genetic background in our region and if the nucleotide substitutions of the uncultured H. pylori 16 S rRNA partial sequences have biological significance.

Validation of an in-house made rapid urease test kit against the commercial CLO-test in detecting Helicobacter pylori infection in the patients with gastric disorders

BACKGROUND

H. pylori is a urease positive organism, and this activity in a gastric biopsy could be considered as a proof of the presence of H. pylori. For the reasons of high price and difficult accessibility to the commercial CLO-test in Iran, we designed an affordable equivalent test with high specificity, accuracy and availability.

METHODS

Biopsy samples from 80 symptomatic patients with gastrointestinal problems were included in this study. The results of our in-house made rapid urease kit were compared with the commercial CLO-test up to 3 hours and 24 hours after inoculation of the biopsy samples. Culture results and gram staining were proposed as gold standard.

RESULTS

Helicobacter pylori was isolated from 36 patients (45.0%) after cultivation of biopsy samples. After 3 hours, 33 (91.6%) cases of positive samples for H. pylori, showed urease positive reaction using both, in-house made and CLO-test kits. However, 2 (5.5%) cases showed urease reaction at 24 hours using both the kits. The specificity of 100% was determined for both, in-house made and commercial CLO-test kits after 3 hours. The sensitivity for both the kits was estimated at 97.1% after 3hours. However, after 24 hours, sensitivity and specificity of 97.1% and 88.64% was estimated for the in-house and 97.2 % and 95.4% for the commercial CLO-test kits, respectively.

CONCLUSION

Specificity and sensitivity of 100% and 97.1 % for up to 3 hours follow biopsy sampling, could be considered as an advantage for our in-house rapid urease kit. Moreover, the rapid urease agar media designed in our lab is cost-effective with adequate sensitivity and specificity levels for the detection of H. pylori, compared with the commercial CLO-test.

Progress in detection of gastric Helicobacter pylori infection

Precise tests or methods are the key points to improve diagnosis of Helicobacter pylori (H pylori) infection and to evaluate clinical therapeutic effect. According to the sampling location, these methods can be classified as: 1) those sampling from stomach, including morphological examination, bacterial culture, urease-dependent assays; and 2) other approaches, including serum test, gene analysis, H pylori stool antigen (H pylori-SA) detection, urine or saliva H pylori antibody detection, etc. This article reviews these methods systematically.

Non-invasive diagnosis of H pylori infection: Evaluation of serological tests with and without current infection marker CIM

AIM: To evaluate the performance of commercially available immunochromatographic (ICT) and immunoblot tests covering the current infection marker CIM and conventional ELISA for the diagnosis of H pylori infection in adult dyspeptic patients.

METHODS: Consecutive non-treated dyspeptic patients undergoing diagnostic endoscopy were tested for H pylori infection by culture, rapid urease test, and histology of gastric biopsy specimens. Serum from 61 H pylori infected and 21 non-infected patients were tested for anti-H pylori IgG antibodies by commercial ELISA (AccuBind^TM ELISA, Monobind, USA), ICT (Assure^®H pylori Rapid Test, Genelabs Diagnostics, Singapore), and immunoblot (Helico Blot 2.1, Genelabs Diagnostics, Singapore) assays. ICT and immunoblot kits cover CIM among other parameters and their performance with and without CIM was evaluated separately.

RESULTS: Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of ELISA were 96.7%, 42.8%, 83.1%, 81.8%, and 82.9%, of ICT were 90.1%, 80.9%, 93.2%, 73.9%, and 87.8%, of ICT with CIM were 88.5%, 90.4%, 96.4%, 73.0%, and 89.0%, of immunoblot were 98.3%, 80.9%, 93.7%, 94.4%, and 93.9%, and of immunoblot with CIM were 98.3%, 90.4%, 96.7%, 95.0%, and 96.3%, respectively.

CONCLUSION: Immunoblot with CIM had the best performance. ICT with CIM was found to be more specific and accurate than the conventional ELISA and may be useful for non-invasive diagnosis of H pylori infection.

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.

[Helicobacter pylori identification by brush gastric cytology: a comparison with histologic method]

The purpose of this study was to verify the efficacy of brush gastric cytology for diagnosis of Helicobacter pylori infection in patients, submitted to elective gastroscopy, compared to the method of endoscopic histology. Endoscopy was performed on 157 patients, divided into two dyspeptic groups: group A (n = 27) with duodenal ulcer; and group B (n = 130) without ulcer. In group A, the percentage of positive cases detected by brush cytology (77.8%) was similar to histology (74.1%; p = 0.3). While in group B, brush cytology (71.5%) was superior to histology (63.1%; p = 0.00002). Brush cytology is a simple and useful diagnostic method. It was efficient for identification of Helicobacter pylori infection in both groups.

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.

A new, practical, low-dose 14C-urea breath test for the diagnosis of Helicobacter pylori infection: clinical validation and comparison with the standard method

The carbon-14 urea breath test (UBT) is a reliable and non-invasive technique for the diagnosis of Helicobacter pylori (HP) infection. In this study we evaluated the diagnostic performance of a new, practical and low-dose (14)C-UBT system for the diagnosis of HP and compared the results with those obtained using the standard method. Seventy-five patients (56 female, 19 male) with dyspepsia underwent (14)C-UBT and endoscopy with antral biopsies for histological analysis. The rapid urease test (CLO test) was applied to 50 of these patients. After a 6-h fasting period, a 37-kBq (14)C-urea capsule was swallowed for UBT. Breath samples were collected and counted using two different methods, the Heliprobe method and the standard method. In the Heliprobe method, patients exhaled into a special dry cartridge system (Heliprobe BreathCard) at 10 min. The activities of the cartridges were counted using a designated small GM counter system (Heliprobe analyser). Results were expressed both as counts per minute (HCPM) and as grade (0, not infected; 1, equivocal; 2, infected) according to the counts. In the standard method, breath samples were collected by trapping in a liquid CO(2) absorber. Radioactivity was counted as disintegrations per minute (SDPM) using a liquid scintillation counter after addition of a liquid scintillation cocktail. Histological examination was used as a gold standard. Two patients were excluded from the study because of inadequate biopsy sampling. Forty-eight patients (65%) were found to be HP positive on histology. The Heliprobe method correctly classified 48 of 48 HP-positive patients and 19 of 25 HP-negative patients (sensitivity 100%, specificity 76%, PPV 88%, NPV 100%, accuracy 91%). The standard method correctly classified 48 of 48 HP-positive patients and 20 of 25 HP-negative patients (sensitivity 100%, specificity 80%, PPV 90%, NPV 100%, accuracy 93%). On the other hand, the CLO test identified 26 of 32 HP-positive and 12 of 16 HP-negative patients (sensitivity 81%, specificity 75%, PPV 86%, NPV 66%, accuracy 79%). With the Heliprobe method, all of the positive results were grade 2, and all of the negative results were grade 0. No patients were defined as having grade 1 results. Counts allowed clear discrimination of HP-positive and -negative patients with both methods, the difference being statistically significant in each case ( P<0.001). A significant correlation was found between HCPM and SDPM ( r 0.863, P<0.001). According to the ROC analysis, the area under the curve was nearly the same with HCPM (AUC, 0.888; 95% CI, 0.785-0.992) and SDPM (AUC, 0.898; 95% CI, 0.802-0.994). In conclusion, the new (14)C-UBT system is a highly accurate method for the diagnosis of HP infection. It is rapid and practical, and therefore suitable for clinical and office practice.

Diagnostic methods for Helicobacter pylori detection and eradication

Helicobacter pylori is the principal cause of peptic ulcer disease and an important risk factor for the development of gastric cancer. The efficacy of 1 week triple therapies, which often have eradication rates of>90%, is undermined by poor patient compliance and bacterial antimicrobial resistance. The development of new anti-H. pylori therapies presents enormous challenges to clinical pharmacologists, not only in the identification of novel targets, but also in ensuring adequate drug delivery to the unique gastric mucus niche of H. pylori. Animal models of H. pylori infection have been developed but their clinical validity has yet to be established. Vaccination, to prevent or treat infection, has been demonstrated in animal models, but human studies have not been so encouraging.

Mucosal changes in the gastric remnant: long-term effects of bile reflux diversion and Helicobacter pylori infection

OBJECTIVE

Bile reflux is thought to be responsible for reflux gastritis and stump carcinoma occurring after partial gastrectomy for peptic ulcer. Gastritis and gastric carcinoma are also correlated with Helicobacter pylori. The aim of this study was to investigate whether diversion of enteric reflux and the presence of H. pylori infection alter long-term histological developments in the gastric remnant.

METHODS

Twenty-nine patients partially gastrectomized for peptic ulcer were reoperated on with re-resection and a Roux-en-Y reconstruction because of reflux gastritis (12 patients) or severe dysplasia/early gastric cancer (17 patients). The resected specimens and subsequent biopsies from the new anastomotic region taken at endoscopies 5-17 years after reoperation were evaluated regarding the presence of H. pylori, the grade of active and non-active chronic gastritis, and the premalignant changes--atrophy, intestinal metaplasia and dysplasia.

RESULTS

A progression of active chronic gastritis, atrophy, intestinal metaplasia and dysplasia was seen after re-resection and Roux-en-Y reconstruction. Non-active chronic gastritis remained unchanged. The development was, in general, independent of H. pylori infection.

CONCLUSIONS

Enteric reflux may perhaps induce a histological transformation of the gastric mucosa that cannot be reversed, even if the reflux is diverted. In our study, H. pylori infection had no impact on the histological development. Factors other than enteric reflux and H. pylori infection might also be of importance.

Management of peptic ulcer disease not related to Helicobacter pylori or NSAIDs

Helicobacter pylori (H. pylori) infection is widely accepted as the most important factor in the pathogenesis of duodenal ulcer. However, in parallel with more effective eradication of H. pylori, the prevalence of H. pylori is changing, and H. pylori-negative peptic ulcer disease appears to be increasing. When making a diagnosis of H. pylori-negative peptic ulcer disease, it is essential to avoid misclassification because of inaccurate diagnosis. In addition, secondary causes may need to be excluded with appropriate investigations. In the absence of H. pylori, nonsteroidal anti-inflammatory drug usage is the most common cause of peptic ulcer; surreptitious nonsteroidal anti-inflammatory drug usage is a cause of unexplained ulcer disease in up to 60% of patients. Hypersecretory syndromes such as Zollinger-Ellison syndrome, although rare, need to be excluded. Once all known etiological factors are excluded, there remains a group of patients with so-called "idiopathic ulcers." The interplay of etiological factors in the pathogenesis of idiopathic peptic ulcer disease is poorly defined but may include a genetic predisposition, altered acid secretion, rapid gastric emptying, defective mucosal defense mechanisms, psychological stress, and smoking. The management of idiopathic peptic ulcers is not defined; they appear to be more resistant to standard therapy, can be associated with more frequent complications, and those that relapse may require long-term maintenance therapy.

Effectiveness of two quadruple, tetracycline- or clarithromycin-containing, second-line, Helicobacter pylori eradication therapies

BACKGROUND

There are no guidelines on second-line therapies for Helicobacter pylori eradication failures of omeprazole-clarithromycin-amoxicillin triple therapy.

AIM

To compare the efficacy of two second-line therapies for persistent H. pylori infection.

METHODS

Over a 6-year period, patients with persistent H. pylori infection following omeprazole-clarithromycin-amoxicillin eradication therapy were randomized to receive omeprazole, 20 mg twice daily, bismuth, 120 mg four times daily, metronidazole, 500 mg twice daily, and either tetracycline, 500 mg four times daily, or clarithromycin, 500 mg twice daily, given for 7 days. Before therapy, patients underwent endoscopy with biopsies for histology, culture and antibiotic susceptibility tests. H. pylori infection was confirmed by histology.

RESULTS

Of the 95 randomized patients, 88 (93%) completed the study. Age, sex, smoking, ulcer/non-ulcer dyspepsia ratio and antibiotic resistance were not significantly different between the treatment groups. On intention-to-treat analysis, eradication was achieved in 41 of the 49 patients (84%; 95% confidence interval, 70.4-92.7%) and 27 of the 46 patients (59%; 95% confidence interval, 43.3-73.0%) of the tetracycline- and clarithromycin-containing groups, respectively (P=0.007). On multivariate regression analysis, the sensitivity of H. pylori to metronidazole had a likelihood ratio of 5.2 (P=0.022), followed by the type of quadruple therapy (likelihood ratio, 4.4; P=0.036).

CONCLUSIONS

Tetracycline-containing quadruple rescue therapy is highly effective in treating H. pylori eradication failures of the omeprazole-amoxicillin-clarithromycin regimen.

Lymphoid hyperplasia of the stomach: radiographic findings in five adult patients

OBJECTIVE

The purpose of our study was to report the radiographic findings of biopsy-proven lymphoid hyperplasia of the stomach in five adult patients.

CONCLUSION

Lymphoid hyperplasia of the stomach is characterized by distinctive findings on double-contrast upper gastrointestinal tract barium examinations; all five patients had innumerable tiny (1--3 mm in diameter) round frequently umbilicated nodules that carpeted the mucosa of the gastric antrum or antrum and body. Three of these five patients had associated Helicobacter pylori gastritis. The diagnosis of gastric lymphoid hyperplasia, therefore, can be suggested on the basis of the radiographic findings.

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.

Reuse of negative CLOtest kits in children

BACKGROUND

The rapid urease test, CLOtest, is used frequently in endoscopy suites. In the developed world, a negative CLOtest result is extremely common. The question of whether reuse of previously negative CLOtest kits is appropriate in children and the cost saving of such a practice were investigated.

METHODS

Children who underwent diagnostic endoscopic procedures were prospectively recruited to the study. In each procedure gastric biopsy specimens were obtained for 2 rapid urease tests, one a new kit and the other a used negative kit obtained from previous procedures. In addition gastric specimens were also obtained for routine histologic examination.

RESULTS

In 121 (99.2%) patients a complete concordance between new and used CLOtests was observed. Chi-square analyses showed a significant association between CLOtest results and each of the following factors: gastritis, the presence of Helicobacter pylori organisms, and H pylori-associated gastritis. Assuming an average rate of 15% positive CLOtest results in our pediatric population, the annual savings at the rural hospital was $265 and at the urban children's hospital, $1958.

CONCLUSION

Reuse of a negative CLOtest is reliable and may reduce costs, especially in facilities with a high volume of endoscopic procedures.

Increased prevalence of Helicobacter pylori in patients with diabetes mellitus

BACKGROUND

Whilst upper gastrointestinal disturbances are frequently observed in patients with diabetes mellitus, little is known about the prevalence of Helicobacter pylori infection and peptic disease in these patients.

AIM

To evaluate prevalence of Helicobacter pylori infection and peptic disease lesions in diabetics with dyspeptic symptoms.

PATIENTS AND METHODS

Study population comprises 74 consecutive diabetes mellitus patients with dyspepsia and 117 consecutive non diabetic dyspeptic patients. Upon enrolment, each patient completed an interview screening questionnaire to obtain information concerning presence and severity of dyspepsia. All patients underwent upper gastrointestinal endoscopy with biopsy specimens being collected from gastric antrum and body Helicobacter pylori was evaluated in each patient by rapid urease test and histology (Giemsa). Gastritis was classified according to the Sydney System. Statistical analysis was performed by chi-square, Fisher exact or t test and logistic regression analysis. A p value <0.05 was considered significant.

RESULTS

Prevalence of Helicobacter pylori infection was found to be significantly higher in diabetics than in controls. The prevalence rate of endoscopic lesions was comparable in the two groups, but the association between endoscopic lesions and Helicobacter pylori infection was significantly higher in diabetics. Overall, the presence of chronic gastritis, both non atrophic and atrophic, as well as intestinal metaplasia were comparable in the two groups of patients, whilst the association between chronic gastritis and Helicobacter pylori infection or gastritis activity were significantly higher in diabetics. In neither group, was any correlation found between severity of dyspepsia and presence of endoscopic lesions, chronic gastritis or Helicobacter pylori infection.

CONCLUSIONS

These data show a higher prevalence of Helicobacter pylori infection in diabetes mellitus patients with dyspepsia. Helicobacter pylori infection was significantly associated both with the presence of endoscopic lesions and chronic gastritis in diabetic patients, but not in the controls.

Management of Helicobacter pylori in duodenal ulcer: a cost-effectiveness analysis

BACKGROUND

Empirical eradication therapy of H. pylori has been proposed as a therapeutic alternative for duodenal ulcer.

AIM

To identify the cost-effectiveness of empirical eradication therapy vs. test-and-treatment for the management of patients already diagnosed with a duodenal ulcer.

METHODS

A decision analysis was performed to compare the cost-effectiveness of empirical eradication therapy of H. pylori diagnosed duodenal ulcer vs. eradication therapy after confirmatory diagnosis of Helicobacter pylori infection by means of several diagnostic tests.

RESULTS

The empirical eradication therapy of duodenal ulcer was found to be the most effective and cost-effective strategy of all the alternatives. Amongst the alternatives, which included the previous performance of confirmatory diagnostic tests, the best cost-effectiveness ratio used a serology test. The model was robust in the face of changes in the values of therapeutic effectiveness, sensitivity and specificity of the diagnostic tests, prevalence of H. pylori infection in duodenal ulcer, duration of the antisecretory therapy, and number of medical visits.

CONCLUSIONS

Based on our cost-effectiveness analysis, a treat approach is more effective and cost-effective than a test-and-treat approach in the clinical management of already diagnosed duodenal ulcer.

Validation of serological tests forHelicobacter pylori infection in an Irish population

BACKGROUND

Serological tests for Helicobacter pylori using laboratory and 'office' formats are commonly used, easy to perform, inexpensive and widely available. Local validation of test performance is required.

AIMS

This study examined the performance of a laboratory and 'office' ELISA in a population of Irish dyspeptics presenting for endoscopy.

METHODS

Consecutive patients presenting for endoscopy had blood drawn at sedation. Samples were analysed using two ELISA formats; a standard laboratory format and an 'office' ELISA test card. H. pylori infection was diagnosed by analysis of antral and corpus biopsies using the rapid urease test, culture and histology. A combination of two positive invasive tests was considered indicative of infection.

RESULTS

The sensitivity and specificity of laboratory ELISA was 82.4% and 85% respectively while the values for the 'office' ELISA were 87.7% and 85.7% respectively. In patients under 45 years sensitivities and specificities of the 'office' test exceeded 90%. The two serological tests agreed in 87.5% of subjects.

CONCLUSIONS

Both tests performed satisfactorily. However, indeterminate results impaired the usefulness of the laboratory ELISA particularly when using a new cut-off. The 'office' ELISA performed particularly well in young patients. A simpler test using antigens from locally prevalent strains to optimise accuracy is awaited.

Establishment of BALB/c mice model infected with Helicobacter pylori

OBJECTIVES

Considering the geographic differences in the prevalence of virulence factors such as CagA or VacA of H. pylori isolated from Korean adults compared with those from western countries, the establishment of a mouse model infected with H. pylori isolated from Korean adults is needed to investigate the pathogenesis and to develop vaccines against H. pylori infection in Korea. The aim of this study was to establish the BALB/c mouse model infected with H. pylori isolated from Korean.

METHODS

Six-week-old BALB/c mice were inoculated intragastrically with 10(9) CFU of H. pylori. Loss of glandular architecture, erosions and infiltration of inflammatory cells within the lamina propria compared with normal gastric mucosa were scrutinized. Evidence for H. pylori infection was assessed by rapid urease test of gastric mucosa and by microscopic examination using the H & E stain and Warthin-Starry silver stain.

RESULTS

Rapid urease test was positive in 55% of all inoculated mice. Definite histologic changes and the evidence of H. pylori colonization were observed in the H. pylori infected group. Significant infiltration of inflammatory cells was observed 6 weeks after the last inoculation and the level of serum IgG against H. pylori was increased from 2 weeks after the last inoculation.

CONCLUSIONS

The H. pylori isolated freshly from Korean adults could colonize the stomach of BALB/c mice and induce pathologic alterations that mimics human gastric diseases. This model would facilitate the investigations for the pathogenetic mechanisms of H. pylori infection.

Helicobacter pylori heat shock protein A: serologic responses and genetic diversity

Helicobacter pylori synthesizes an unusual GroES homolog, heat shock protein A (HspA). The present study was aimed at an assessment of the serological response to HspA in a group of Chinese patients with defined gastroduodenal pathologies and determination of whether diversity is present in the nucleotide sequences encoding HspA in isolates from these patients. Serum samples collected from 154 patients who had an upper gastrointestinal pathology and the presence of H. pylori defined by biopsy were tested for an immunoglobulin G (IgG) serologic response to H. pylori HspA by an enzyme linked immunosorbant assay. HspA-encoding nucleotide sequences in H. pylori isolates from 14 patients (7 seropositive and 7 seronegative for HspA) were analyzed by PCR and direct sequencing of the PCR products. The sequencing results were compared to those of 48 isolates from other parts of the world. Of the 154 known H. pylori-positive patients, 54 (35.1%) were seropositive for HspA. The A domain (GroES homology) of HspA was highly conserved in the 14 isolates tested. Although the B domain (metal-binding site unique to H. pylori) resembled that in the known major variant, particular amino acid substitutions allowed definition of an HspA variant associated with isolates from East Asia. There were no associations between patient characteristics and HspA seropositivity or amino acid sequences. We confirmed in this study that the clinical outcomes of H. pylori infection are not related to HspA antigenicity or to sequence variation. However, B-domain sequence variation may be a marker for the study of the genetic diversity of H. pylori strains of different geographic origins.

Five micro-curie urea breath test for the diagnosis of Helicobacter pylori infection: evaluation in a South-East Asian population

BACKGROUND

Helicobacter pylori is an important pathogen responsible for significant morbidity and mortality. Its prevalence varies widely in different geographical locations and is especially high in parts of Asia.

METHODS

A double-blind study was carried out to evaluate the use of the 5 microCi (185 KBq) [14C]-urea breath test ([14C]-UBT) in a South-East Asian population by validating its diagnostic accuracy against histology and the CLO test.

RESULTS

The sensitivity and specificity of the [14C]-UBT was 100% when compared against the CLO test. When histology was used as the 'gold standard', the sensitivity and specificity were 100% and 97.2%, respectively. There was no overlap or indeterminate values between positive and negative results on the [14C]-UBT.

CONCLUSIONS

Among South-East Asian populations where the prevalence of H. pylori infection is high, the high sensitivity of the 5 microCi [14C]-UBT makes it a very important test in the detection of H. pylori.

Comparison of two rapid urease tests for detection of Helicobacter pylori infection

Rapid urease tests are widely used at endoscopy to determine the presence of Helicobacter pylori infection. In this prospective study, we compared the accuracy of two rapid urease tests, CLOtest and PyloriTek, using histology as the gold standard. Histologic staining was performed using both H&E and Giemsa, and all slides were reviewed by a single pathologist who was blinded to the results of the rapid urease tests and endoscopic findings. One hundred two patients were enrolled; their mean age was 59 years (range 16 to 95 years), and there were 45 males and 57 females. Histology confirmed the presence of H. pylori infection in 39% of patients. The proportions of false positives for CLOtest (8.0%) and PyloriTek measured at 1 hr (29.0%) were significantly different (Z = 2.90, P = 0.0038). No significant difference was seen between the proportions of false negatives. We conclude that the clinical usefulness of PyloriTek urease test is limited by its lack of specificity.

Four-year trends in Helicobacter pylori IgG serology following successful eradication

PURPOSE

Detection of anti-Helicobacter pylori antibodies is accurate in the diagnosis of the infection, and there is a decline in IgG titers after successful eradication. It is not known whether these titers continue to decline during the next 3 to 4 years.

PATIENTS AND METHODS

Patients had been successfully treated for H pylori with triple therapy (metronidazole, tetracycline, and bismuth subsalicylate) during 1990 and 1991. Those who had frozen serum samples available from that time were contacted to have follow-up serum collected in 1994. A simultaneous [13C]urea breath test was done to confirm H pylori infection status. Serology was determined by quantitative enzyme-linked immunosorbent assay (ELISA) and qualitative immunoassay.

RESULTS

All 29 patients who agreed to participate were free of H pylori infection. They had a mean decrease in H pylori IgG titers of 51% from baseline (P <0.001). Titers remained stable from 1 year to a mean of 3.5 years after therapy (range 2.8 to 4.4). Of the 29 patients, 21 (72%) remained seropositive by ELISA 3.5 years after successful H pylori treatment, and 18 (62%) remained positive by rapid serum immunoassay.

CONCLUSION

IgG titers against H pylori plateau at a 50% decrease after therapy. Helicobacter pylori serology, either quantitative or qualitative, will yield false positive results in patients who have previously been treated for H pylori and should not be used to determine infection status in this population.

Diagnosis of Helicobacter pylori infection after gastric surgery for peptic ulcer: is the rapid urease test useful?

BACKGROUND

The usefulness of the rapid urease test (RUT) in diagnosing Helicobacter pylori infection after peptic ulcer surgery is unknown.

METHODS

Patients who had undergone peptic ulcer surgery were offered endoscopic examination if they presented with dyspepsia or gastrointestinal bleeding. Biopsy specimens were taken for RUT and histology from the corpus and the stoma in patients who had undergone partial gastrectomy or from the corpus and the antrum in patients who had undergone vagotomy. Histologic examination using haematoxylin and eosin stain and Warthin-Starry stain were used as the gold standard.

RESULTS

Ninety patients were studied (69 had partial gastrectomy and 21 had vagotomy). Forty-three patients (32 in the partial gastrectomy group and 11 in the vagotomy group) were positive for H. pylori by histology. The respective sensitivity of RUT was 59% (stoma) and 75% (corpus) in the partial gastrectomy group (P = 0.36) and 55% (antrum) and 73% (corpus) in the vagotomy group (P = 0.51).

CONCLUSIONS

RUT is not sensitive for detecting H. pylori after acid reduction surgery.

Accuracy of seven different tests for the diagnosis of Helicobacter pylori infection and the impact of H2-receptor antagonists on test results

BACKGROUND

In this study we compared the accuracy of seven diagnostic tests in diagnosing Helicobacter pylori infection.

METHODS

Over 1 year 351 consecutive dyspeptic patients were tested for H. pylori infection by means of antral biopsy specimens for the rapid urease test (RUT), culture, microscopy (acridine stain), and the laboratory urease test (LUT) and, in addition, with 14C urea breath test (UBT), IgG serology, and IgA serology (Orion Diagnostica Pyloriset New EIA-G and New EIA-A). The criterion for H. pylori infection was a minimum of three positive tests. Before being tested, 38% of the patients had used an H2-receptor antagonist (H2RA).

RESULTS

Two-hundred and twenty-four patients (64%) were H. pylori-positive. The sensitivity and specificity of the tests were as follows (percentages): RUT, 85, 99; culture, 93, 100; microscopy, 81, 98; LUT, 80, 100; UBT, 95, 95; IgG serology, 99, 91; and IgA serology, 88, 91. The accuracy of the RUT and LUT was reduced in patients receiving H2RA therapy (P=0.04 and 0.01, respectively).

CONCLUSIONS

Culture, UBT, and IgG serology were all superior to the other four tests in diagnosing H. pylori infection. Invasive urease-based tests were less accurate in patients receiving H2RAs.

Evaluation and comparison of two immunodiagnostic assays for Helicobacter pylori antibodies with culture results

Several commercially available serological kits have been used as an alternative to endoscopy for the diagnosis of Helicobacter pylori infection. We evaluated the performance of two such kits, Serion H. pylori immunotab kit (Serion, Wurzberg, West Germany) and Pyloragen H. pylori test kit (Hypcor Biomedical Inc., Irvine, CA). Gastric biopsy and serum samples were collected from 345 consecutive dyspeptic patients. The culture and or direct smear of the biopsy was positive for H. pylori in 228 patients (66%), whereas 117 patients (34%) were found to be H. pylori negative. We determined the serological response of the patients using the two kits, both of which are based on the principle of enzyme-linked immunosorbent assay. Comparing the serum immunoglobin G (IgG) and IgA (in a limited number of cases) responses to H. pylori status, the sensitivity, the specificity, positive predictive value, and negative predictive value were calculated. The corresponding data for the different tests were 64%, 79%, 84%, and 56% for Serion IgC, 32%, 94%, 88%, and 52% for Serion IgA, and 88%, 17%, 62%, and 46% for Pyloragen IgG, respectively. We conclude that there is a poor correlation between the presence of H. pylori infection and the antibody response, which could be explained either because of low sensitivities and specificities of the commercial kits used for the measurement of antibodies to H. pylori in the serum or because of poor immunological response in our patients to H. pylori antigens.

Urease-based tests for Helicobacter pylori gastritis. Accurate for diagnosis but poor correlation with disease severity

To determine whether the urease-based CLOtest or low-dose 14C urea breath test can predict severity of gastritis or the presence of peptic ulcers, we studied 84 patients presenting for upper endoscopy. Antral biopsies were obtained for histologic analysis and CLOtesting, and urea breath testing was performed. The time to a positive CLOtest and the breath test peak values were correlated with endoscopic findings, severity of gastritis, and bacterial burden. Twenty-four patients had positive urea breath test results (22 with positive CLOtests). Patients with positive breath test results were more likely to have duodenal ulcers, higher grades of gastritis, and increased bacterial burden (p < 0.01 for all comparisons). Correlation between the time to a positive CLOtest or peak breath test values and gastritis severity or bacterial burden was poor (p > 0.05 for all comparisons). In patients with positive tests, no difference was observed between the time to a positive CLOtest or peak breath test value in patients with or without peptic ulcers (p < 0.2 for all comparisons). The low-dose 14C urea breath test and the CLOtest are both accurate for Helicobacter pylori diagnosis. However, neither test predicts the severity of the gastritis, the degree of bacterial burden, or the presence of peptic ulcers.

The best gastric site for obtaining a positive rapid ureas test

BACKGROUND

Rapid ureas tests (RUTs) provide a simple, sensitive method of detecting Helicobacter pylori infection.

OBJECTIVES

Our aim, therefore, was to determine whether the yield of detecting H. pylori infection by RUT varied depending on the site of gastric biopsy.

MATERIALS AND METHODS

Gastric biopsies were obtained from 50 patients for RUT by use of hpfast (GI Supply, Camp Hill, PA). Biopsies were taken from the prepyloric greater curve antrum, from the gastric angle, and from the greater curve in mid-corpus. One biopsy specimen was placed in the RUT gel, and the biopsy from the adjacent mucosa was placed in formalin for subsequent histological evaluation by using the Genta stain. RUTs were examined and scored at intervals of 5, 10, 15, 30, and 45 minutes and after 1, 2, 4, and 24 hours.

RESULTS

Fifty patients were entered in the rest (150 RUTs), 32 having H. pylori infection. There were no false-positive RUTs (specificity, 100%). The gastric angle site was positive in 100%. The prepyloric site was positive in 87%, and the corpus site was positive in 84.4% (p < .052 for angle or prepyloric antrum versus corpus). The most common pattern was for all to be positive (74%). The median time to positivity was similar with angle and prepyloric sites (37.5 and 60 minutes, respectively, p = not significant) and shorter than the corpus biopsy (180 minutes); (p < .05 for angle or prepyloric antrum versus corpus).

CONCLUSION

The maximum probability for detecting H. pylori infection using a RUT is to obtain a biopsy from the gastric angle. To prevent missing a positive result when intestinal metaplasia is present, we recommend that (at a minimum) biopsies be taken from both the angle and the corpus.

Diagnosis of Helicobacter pylori infection

A number of diagnostic tests have been developed for the detection of H. pylori. Diagnostic techniques can be divided into invasive and noninvasive methods. The invasive methods require upper gastrointestinal endoscopy and involve culture of gastric biopsy specimens, examination of stained biopsies and detection of urease activity in the biopsies themselves. In addition, we have developed endoscopic diagnosis of H. pylori infection in gastric mucosa using phenol red dye-spraying. The noninvasive methods include urea breath test and serological techniques. Although there has been considerable improvement in the techniques, a combination of at least two different techniques should be used in order to optimize the diagnostic yield. We recommend the use of one rapid test in the combination. The rapid urease test, cytology and the phenol red dye-spraying endoscopy give results available before the patient leaves the endoscopy suite.

Brush cytology: a reliable method to detect Helicobacter pylori

This study was conducted to verify the reliability of brush cytology in detecting Helicobacter pylori in an unselected group of patients with duodenal ulcer (DU) and nonulcer dyspepsia (NUD). Endoscopy was performed on 416 consecutive patients: group A, 94 with active DU; group B, 176 patients with DU after omeprazole (n = 78), ranitidine (n = 43), or triple anti-H. pylori therapy (n = 55); and group C, 146 patients with NUD. During endoscopy, the gastric mucosa was brushed and two biopsy samples from the antrum and body were obtained for histology. In 65 patients, culture of the brush-collected materials also was performed as was that from of biopsy samples. The overall frequency of H. pylori presence detected by brush cytology was significantly higher compared with that of histology (p < 0.001), particularly in group A (p < 0.05), group C (p < 0.05), and in patients with DU after omeprazole treatment (p < 0.01), but not in patients with DU after ranitidine or anti-H. pylori treatment. The overall frequency of H. pylori-positive cultures from the brush-collected material was higher compared with cultures from the biopsy samples (38.5% vs. 24.6%), particularly in the NUD group (32.6% vs. 16.3%). Brush cytology is more sensitive than histology, besides being faster and cheaper, for the assessment of H. pylori infection, particularly when the density of the bacteria is low.

Testing for Helicobacter pylori in clinical practice

It is now accepted that cure of Helicobacter pylori infection will result in healing of chronic active gastritis and will change the natural history of gastroduodenal ulcer disease. A variety of highly sensitive and specific diagnostic methods have been developed over the past few years to establish whether a patient is infected with this organism. The two major categories of diagnostic tests for H. pylori are invasive methods, which require endoscopy, and noninvasive tests in which endoscopy is not necessary. Invasive tests include rapid urease tests, histology, and culture. Noninvasive tests include various methods of antibody detection and carbon-labeled urea breath tests. This review describes the characteristics, appropriate uses, and comparative accuracy of the available diagnostic tests for detection of H. pylori. It offers suggestions on the test of choice to establish a patient's H. pylori infection status in different clinical settings.

[Helicobacter pylori gastric infection in symptomatic patients from São Luís Island, MA: endoscopic, anatomicopathologic and microbiological correlations]

With previously defined criteria of inclusion and previous consent, twenty six consecutive patients (19 to 64 years old), with upper digestive symptoms, were submitted to endoscopy, with biopsy, constant of eight samples of the antropyloric region (four of the anterior aspect and four of the posterior aspect). Two samples were been for culture; two for free urease test, two for smears; all gathered in adequate transport medium over refrigeration. Two samples immersed in formaline to 10% for histopathologic exam. 25/26 (96%) of the patients showed infection by H. pylori by means of one or more methods utilized. In 16/26 (61%), alterations were observed in endoscopy (gastric inflammation in eleven, peptic ulcer in two and ulcer scars in three cases). Of the patients with endoscopic gastric inflammation, presented positive as well as all (100%) bearers of scar or peptic ulcer. A close relationship was observed between the presence of H. pylori and chronic gastric inflammation 24/25 (96%). Histopathologic slices stained by hematoxilin-eosin was the test of highest diagnostic sensitivity 24/25 (96%), followed by urease test 23%25 (92%), stained smears 19/25 (76%) and culture 18/25 (72%). Our conclusion is that the prevalence of gastric infection for H. pylori in symptomatic patients is high, correlated with chronic gastric inflammation and ulcers. Histopathologic slices stained by hematoxilin-eosin and free urease test are the most sensitive indicators of the presence of H. pylori. This study should proceed for further elucidation of questions realised and include a control group of symptomatics individuals paired for sex and age.

New noninvasive tests for Helicobacter pylori gastritis. Comparison with tissue-based gold standard

The current gold standard for diagnosing H. pylori gastritis requires antral biopsy for urease test (eg, CLOtest) and/or history. We compared this gold standard to a new low-dose capsule-based 1 microCi [4C]urea breath test (UBT) and a rapid serum test for anti-H. pylori antibodies (FlexSure HP) in 50 consecutive patients undergoing upper endoscopy. Antral biopsies within 3 cm of the pylorus were used for CLOtest and were stained with H&E and thiazine. Slides were reviewed by a single, blinded pathologist (Review) and compared to the pathology department report (Report). A true positive was defined as a positive CLOtest or Review. The prevalence of H. pylori infection by each test was: CLOtest 32%, Review 36%, gold standard 42%, UBT 38%, FlexSure HP 44%, Report 44%. UBT had sensitivity = 90%, specificity = 96%, positive predictive value = 95%, and negative predictive value = 93% and accurately determined H. pylori status in a subgroup of 10 patients who had completed treatment. The one false positive breath test occurred in a patient with 2+ chronic inflammation on biopsy and a positive antibody test. There were two false negative breath tests. Each had both negative CLOtests and negative antibody tests. FlexSure HP had sensitivity = 74%, specificity = 89%, positive predictive value = 88%, and negative predictive value = 77% in patients not previously treated, but had a high false-positive rate in the 10 patients after treatment. Pathology department Report and blinded pathologist Review had only 84% agreement, kappa = 0.67. Both CLOtest and UBT agreed better with Review (86%, 87%, kappa = 0.68, 0.73, respectively) than Report (78%, 77%, kappa = 0.53, 0.53, respectively) suggesting that Review is more accurate than Report. When biopsy is done, we recommend that a CLOtest be performed followed by histological examination if the CLOtest is negative to ensure adequate sensitivity. However, interpretation of histological slides has significant interobserver variability even in experienced hands and may be inaccurate at times. FlexSure HP has good PPV but inadequate sensitivity to rule out active infection and is not useful in patients after treatment. UBT is an excellent noninvasive test that should be considered in cases where EGD is otherwise not indicated.

Effect of specimen collection techniques, transport media, and incubation of cultures on the detection rate of Helicobacter pylori

Culture and histologic examination are considered "gold standard" methods for the detection of Helicobacter pylori, but discrepancies may occur with either method. Failure to detect Helicobacter pylori may be due to sampling error, inappropriate transport or culture media, or insufficient duration of the incubation period. Rates of detection of Helicobacter pylori by culture and histopathologic examination of gastric mucosal biopsy specimens were determined in 102 consecutive dyspeptic patients. In a separate group of 60 patients, rates of detection of Helicobacter pylori by culture of antral brushings and the length of incubation required in selective and nonselective culture media were studied. In the first group of 102 patients, the combination of culture and histologic examination detected 54 Helicobacter pylori-positive patients, whereas the separate techniques each detected 51 Helicobacter pylori-positive patients. In the second group of 60 patients evaluated by culture of antral brushings, the rate of detection of Helicobacter pylori was 25 of 60 and was similar for culture (25/60) and histologic examination (25/60). In the second group the length of incubation required to detect Helicobacter pylori was different for selective and nonselective media. In nonselective media, incubation of up to ten days was required to detect all Helicobacter pylori infections, whereas in selective media seven days was sufficient. Rates of detection of Helicobacter pylori by culture, histopathologic examination and culture from brushings were similar, whereas the combination of culture and histopathologic examination achieved a superior rate of detection. The incubation period required for the detection of Helicobacter pylori by culture was a minimum of seven days and was dependent on the culture medium used.

A new urea broth-based test to detect Helicobacter pylori presence in upper gastrointestinal biopsies

The aim of this study was to evaluate the performance of a simple and inexpensive homemade urea test (U-test) to detect Helicobacter pylori in upper digestive tract biopsies. We tested and compared the U-test with three other diagnostic methods: the Clo-test, and culture and pathology in 110 patients randomly chosen at the endoscopy clinic. When using culture and/or pathology as the "gold standard," H. pylori was found to exist in 54 patients. Pathology was positive in 50 cases (92.5%), culture in 49 (90.7%), the U-test in 45 (83.3%), and the Clo-test in 43 (79.6%). With regard to culture pathology, the sensitivities of the U-test and the Clo-test were 83.3% and 79.5%, respectively. Specificity was 100% for both methods. The kappa coefficient calculation between the U-test and the Clo-test was 0.98. The results show that the U-test is a reliable, fast, and inexpensive method for detecting H. pylori in upper gastrointestinal biopsies.