Polymerase chain reaction： A sensitive method for detecting Helicobacterpyloriinfection in bleeding peptic ulcers

AIM: To assess the sensitivity and specificity of polymerase chain reaction (PCR) in detecting Helicobacter pylori(H pylon) infection in patients with bleeding peptic ulcers, and to compare its diagnostic efficacy with other invasive and non-invasive tests. METHODS: From April to September 2002, H pylori status in 60 patients who consecutively presented with gastroduodenal ulcer bleeding was examined by rapid urease tests (RUT), histology, culture, PCR, serology and urea breath tests (UBT). RESULTS: The sensitivity of PCR was significantly higher than that of RUT, histology and culture (91% vs 66%, 43% and 37%, respectively; P = 0.01, <0.001, <0.001, respectively), but similar to that of serology (94%) and UBT (94%). Additionally, PCR exhibited a greater specificity than serology (100% vs 65%, P<0.01). However, the specificity of PCR did not differ from that of other tests. Further analysis revealed significant differences in the sensitivities of RUT, culture, histology and PCR between the patients with and those without blood in the stomach (P<0.01, P= 0.09, P<0.05, and P<0.05, respectively). CONCLUSION: PCR is the most accurate method among the biopsy-based tests to detect H pylori infection in patients with bleeding peptic ulcers. Blood may reduce the sensitivities of all biopsy-based tests.     

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.     

Accuracy of an enzyme immunoassay for the detection of Helicobacter pylori in stool specimens in the diagnosis of infection and posttreatment check-up

OBJECTIVE: The aim of this study was to assess the reliability of a newly developed enzyme immunoassay for Helicobacter pylori-specific antigen detection in stools (HpSA) compared to other standardized diagnostic techniques such as histology (H), rapid urease test (RUT) and 13C-urea breath test (UBT) to diagnose H. pylori infection and to evaluate its usefulness in determining H. pylori status after treatment. METHODS: One hundred eighty-eight patients referred to our department for upper gastrointestinal endoscopy were included. H. pylori infection was confirmed in all patients by HpSA test in stools, RUT, UBT, and H. Patients were defined as positive for H. pylori if RUT and UBT or H were positive. A total of 142 symptomatic patients received eradication treatment and were reassessed 6 wk after therapy; for 70 of these patients, stool samples were also collected at 24 h and 6 months after finishing eradication treatment. In the posttreatment follow-up, UBT was used as gold standard. RESULTS: The sensitivity of HpSA test for the diagnosis of H. pylori infection using a cut-off value of 0.130 was 89.5% and its specificity 77.8%. This specificity was lower than that obtained with UBT, H, and RUT. In the early follow-up the sensitivity of HpSA test was null. At 6 weeks and at 6 months post-treatment its sensitivity was 70.4% and 50% and its specificity was 81.6% and 79.3%, respectively. CONCLUSIONS: The HpSA stool test, using a cut-off value of 0.130, may be useful for the primary diagnosis of H. pylori infection, with sensitivity similar to that obtained with other standard tests, but with less specificity. HpSA test is not useful for early monitoring of treatment efficacy. At 6 wk and at 6 months posttreatment, HpSA test lacks accuracy as compared to UBT for evaluating the outcome of the eradication treatment.     

Validity and cost comparison of ~(14)carbon urea breath test for diagnosis of H Pylori in dyspeptic patients

AIM: To validate and compare the cost of microdose 14C urea breath test (UBT) with histology and rapid urease test for the diagnosis of H Pylori. METHODS: Ninety-four consecutive patients with dyspeptic symptoms undergoing gastroscopy were enrolled. Gastric biopsies were taken for histology and rapid urease test. UBT was performed after gastroscopy by microdose 14C urea capsules. Sensitivity, specificity and accuracy of UBT were calculated and compared with histology and rapid urease test. Cost comparison of these tests was also performed. RESULTS: H pylori was diagnosed by histology and rapid urease test in 66 (70%) and 61 (65%) patients, while 14C UBT detected infection in 63 (67%). Accuracy of UBT was 93% in comparison with histology while its positive and negative predictive values were 97% and 84%, respectively. Comparison of 14C UBT with rapid urease test gives an accuracy of 96%, with positive and negative predictive values of 95% and 97%, respectively. These results were highly reproducible with a Kappa test (P value < 0.001). Cost of histology or rapid urease test with gastroscopy was 110 USD or 95 USD respectively while the cost of UBT was 15 USD. CONCLUSION: Microdose 14C UBT was comparable to histology and rapid urease test. 14C UBT is an economical, self sufficient and suitable test to diagnose active H pylori infection in less developed countries.     

Validity and cost comparison of 14carbon urea breath test for diagnosis of H Pylori in dyspeptic patients

AIM: To validate and compare the cost of microdose 14C urea breath test (UBT) with histology and rapid urease test for the diagnosis of H Pylori. METHODS: Ninety-four consecutive patients with dyspeptic symptoms undergoing gastroscopy were enrolled. Gastric biopsies were taken for histology and rapid urease test. UBT was performed after gastroscopy by microdose 14C urea capsules. Sensitivity, specificity and accuracy of UBT were calculated and compared with histology and rapid urease test. Cost comparison of these tests was also performed. RESULTS: H pylori was diagnosed by histology and rapid urease test in 66 (70%) and 61 (65%) patients, while 14C UBT detected infection in 63 (67%). Accuracy of UBT was 93% in comparison with histology while its positive and negative predictive values were 97% and 84%, respectively. Comparison of 14C UBT with rapid urease test gives an accuracy of 96%, with positive and negative predictive values of 95% and 97%, respectively. These results were highly reproducible with a Kappa test (P value<0.001). Cost of histology or rapid urease test with gastroscopy was 110 USD or 95 USD respectively while the cost of UBT was 15 USD. CONCLUSION: Microdose 14C UBT was comparable to histology and rapid urease test. 14C UBT is an economical, self sufficient and suitable test to diagnose active H pylori infection in less developed countries.     

Evaluation of endoscopy-based diagnostic methods for the detection of Helicobacter pylori.

BACKGROUND: Helicobacter pylori is an etiological factor in duodenal ulcer. Few studies have objectively assessed the accuracy of diagnostic methods for the detection of H. pylori. METHODS: The sensitivity and specificity of histology, touch smear, rapid urease test (RUT) and brush cytology of endoscopic antral biopsy from patients with duodenal ulcer were compared. Forty-nine patients were evaluated before, and 34 after, eradication therapy. Each time, sampling was done for all 4 tests. The infection status for each sample was established by a positive concordance of results of three of four tests. RESULTS: The highest degree of agreement was between RUT and cytology (kappa = 0.69). Brush cytology (100%) followed by RUT (94.5%) were the most sensitive tests. Histology had the highest specificity (89.3%). A combination of RUT or brush cytology with histology had the maximum chance of detecting H. pylori. As single tests, brush cytology and touch smear had high diagnostic accuracies with a Youdin J value of 1.79 and 1.78, respectively. CONCLUSION: The best method for diagnosis of H. pylori is a combination of the rapid urease test or brush cytology with histology. Brush cytology or touch smear are diagnostic tests of choice if a single test is desired.     

四种检测幽门螺杆菌感染方法的评价──病理组织学、血清学、~(13)C呼气试验和快速尿素酶试验

目的检测幽门螺杆菌（HelicobacterpyloriHp）的方法很多，本文对病理组织学，血清学，快速尿素酶和13C呼气试验进行分析评价．方法对70例有消化道症状的患者进行以上四种方法检测幽门螺杆菌，其中二项阳性者认为有Hp感染。结果病理组织学，血清学，13C呼气试验，快速尿素酶检测的敏感性分别为83．33％，90．74％，96．30％，85．52％；特异性分别为100％，100％，81．25％，75％。四种方法的阳性预测值分别为11％，100％，94．55％，92％；阴性预测值分别为64％，76．19％，86.67％，60％。结论病理组织学与呼气试验是检测Hp感染的较准确的测定方法，呼气试验更能反映“全胃”Hp感染状况，目前可作为抗Hp药物疗效监测的“金标准”。血清学检测和快速尿素酶法操作方便，费用低，是临床常用的检测手段。     

Diagnostics of Helicobacter pylori infection in patients with peptic ulcer bleeding

BACKGROUND: In peptic ulcer bleeding, the sensitivity of H. pylori tests, in particular of the rapid urease test (RUT), has been reported to be insufficient. AIM: To validate the RUT, serology and the urea breath test were carried out in patients with bleeding peptic ulcers, and to study the influence of H. pylori suppressive treatment (HpSuT), i. e., antibiotics and proton pump inhibitors. PATIENTS AND METHODS: 123 consecutive patients (mean age 65.5 years) with a relevant bleeding from gastric or duodenal ulcers were prospectively tested for H. pylori infection by directs tests (RUT, histology, culture, urea breath test) and by IgG serology as an indirect test. Positive H. pylori status was defined by positive histology or culture. RESULTS: In patients without HpSuT during the preceding four weeks (N = 83), the sensitivity and specificity of RUT was 94 and 84 %, that of serology 83 and 68 % respectively. The sensitivity of urea breath test decreased from 82 to 60 % after even one day of HpSuT. In the overall group, the duration of HpSuT and preceding hospitalization were independent factors linked with negative results of all direct tests. CONCLUSIONS: In peptic ulcer bleeding, RUT combined with histology is an adequate diagnostic approach. However, false negative results have to be considered following even short-term HpSuT or hospitalization. Non-invasive diagnosis based on serology alone is inaccurate and should be complemented by the urea breath test prior to starting HpSuT.     

Evaluation of urine ELISA test for detecting Helicobacter pylori infection in Taiwan： A prospective study

AIM: To evaluate the diagnostic accuracy and clinical utility of a new ELISA (URINELISA) test for detecting Helicobacter pylori(H pylori) antibody in the urine of Taiwanese population. METHODS: In this prospective study, 317 consecutive dyspeptic patients (171 men, 146 women; mean age, 51.0 years) were included. They underwent gastroendoscopy for evaluation. Invasive tests, including culture, histology, and rapid urease test (RUT), and non-invasive ~(13)C-urea breath test were preformed. At the same time, urine specimens were collected for URINELISA. The status of H pylori infection was considered as positive when either culture was positive, or when two of the other, RUT, histology or 13C-UBT, were positive. RESULTS: The sensitivity, specificity, positive predictive value, and negative predictive value of URINELISA are 91.7% (211/230), 90.8% (79/87), 96.3% (211/219), and 80.6% (79/98) respectively. CONCLUSION: This URINELISA test is reliable, inexpensive and easy-to-use. The high diagnostic accuracy warrants the use of URINELISA as a first-line screening tool for diagnosis of H pylori infection in untreated patients.     

Urease-positive bacteria other than Helicobacter pylori in human gastric juice and mucosa

BACKGROUND AND AIM: Many bacteria carry the urease enzyme in different human ecosystems, but Helicobacter pylori is the only known bacterium showing urease activity in gastric ecosystems. For this reason, the rapid urease test (RUT) on gastric biopsies and urea breath test (C-UBT) are used to detect H. pylori infection.The aim of this study was to evaluate the presence of urease-positive bacteria other than H. pylori in gastric juice and mucosa in hypochlorhydric subjects. METHODS: Twenty-five hypochlorhydric and 10 normochlorhydric patients were analyzed for the presence of H. pylori and bacterial overgrowth both in gastric juice and on the mucosa. During upper gastrointestinal endoscopy at 8.00 a.m. gastric juice samples and biopsy specimens were taken from the antrum and corpus. All samples were analyzed using standard microbiological procedures like aerobic/anaerobic growth, gram-staining, gas chromatography, API test, 96-clone method, and selective medium to search for specific bacteria. In addition, all strains isolated were screened for urease activity using the CP-test. Urease positive strains were tested for the capacity to survive in an acid environment with or without urea (10 mM/L), at pH 7, 4, 3, and 2, respectively, at different times (0, 20, 30, and 60 min). RESULTS: Six hypochlorhydric patients had 10 strains of urease-positive non-H. pylori bacteria among which Staphylococcus capitis urealiticum showed the strongest urease activity. CONCLUSIONS: Hypochlorhydric patients present many urease-positive bacteria other than H. pylori. The strong urease activity may be responsible for false positive results at RUT or UBT test in patients with suspected H. pylori infection.     

Validity and cost comparison of "carbon urea breath test for diagnosis of H Pylori in dyspeptic patients

AIM: To validate and compare the cost of microdose 14C urea breath test (UBT) with histology and rapid urease test for the diagnosis of H Pylori.METHODS: Ninety-four consecutive patients with dyspeptic symptoms undergoing gastroscopy were enrolled. Gastric biopsies were taken for histology and rapid urease test. UBT was performed after gastroscopy by microdose "C urea capsules. Sensitivity, specificity and accuracy of UBT were calculated and compared with histology and rapid urease test. Cost comparison of these tests was also performed.RESULTS: H pylori was diagnosed by histology and rapid urease test in 66 (70%) and 61 (65%) patients, while 14C UBT detected infection in 63 (67%). Accuracy of UBT was 93% in comparison with histology while its positive and negative predictive values were 97% and 84%, respectively. Comparison of 14C UBT with rapid urease test gives an accuracy of 96%, with positive and negative predictive values of 95% and 97%, respectively. These results were highly reproducible with a Kappa test (P value < 0.001). Cost of histology or rapid urease test with gastroscopy was 110 USD or 95 USD respectively while the cost of UBT was 15 USD.CONCLUSION: Microdose 14C UBT was comparable to histology and rapid urease test. 14C UBT is an economical, self sufficient and suitable test to diagnose active Hpylori infection in less developed countries.     

Evaluation of a new enzyme immunoassay for detecting Helicobacter pylori in feces: a prospective pilot study

OBJECTIVE: There is an increasing interest in noninvasive tests for detecting Helicobacter pylori (H. pylori) infection. Unlike serological and urea breath tests, the possibility of searching for H. pylori in feces has been scarcely investigated. The aim of this prospective pilot study was to evaluate the usefulness of a new enzyme immunoassay for detecting H. pylori antigens in feces, as a predictor of H. pylori status in the pre- and posttreatment settings. METHODS: One hundred and fifty-four symptomatic, anti-H. pylori untreated patients (Group A) and 116 anti-H. pylori treated patients (Group B) underwent gastroscopy with biopsies of the antrum and corpus for histology (H) and rapid urease test (RUT). In the anti-H. pylori treated group, a 13C-urea breath test (UBT) was also performed. In Group A, H. pylori status was defined as positive or negative when both H and RUT gave concordant positive or negative results. In Group B, the patients were considered eradicated if all three tests were negative. A stool specimen was collected from all patients the day after gastroscopy, and tested by using an enzyme immunoassay commercial kit for detecting H. pylori antigens in feces (HpSAT). RESULTS: Eighty-five patients in Group A (55%) and 44 in Group B (38%) were H. pylori infected. On the whole, HpSAT showed a sensitivity of 94% and specificity of 86%. In Group A and Group B, sensitivity and specificity were 94% versus 93%, and 90% versus 82%, respectively (p < 0.05). CONCLUSIONS: HpSAT seems to be a reliable method for predicting H. pylori status in anti-H. pylori untreated patients. Conversely, the test appears less suitable to evaluate the outcome of the eradicating treatment. Consequently, it is likely to be accepted for the primary diagnosis of H. pylori status, particularly in dyspeptic young patients.     

A study of the relationship between Helicobacter pylori microbial susceptibility, 13C-urea breath test values

BACKGROUND/AIMS: Diagnostic methods for Helicobacter pylori (H. pylori) infection can be divided into invasive endoscopic methods and non-invasive methods. A typical and widely used non-invasive method is the 13C urea breath test (UBT). In this study, the possibility of a correlation between pre-treatment UBT values with H. pylori antimicrobial resistance is investigated. METHODOLOGY: The subjects were 119 consecutive patients who attended this hospital for H. pylori testing. Average age was 47.5 +/- 13.2 years, with a male:female ratio of 2.05:1. The diagnosis was gastric ulcer in 43 subjects, duodenal ulcer in 27, gastroduodenal ulcer in 21 and chronic gastritis in 28. Subjects underwent UBT as well as upper gastrointestinal endoscopy (UGITE). The diagnosis of H. pylori infection was examined by the results of culture, histological examination and the rapid urease test (RUT). The mean inhibitory concentration (MIC) was determined for each antimicrobial agent in the bacterial isolates that could be cultured. RESULTS: In this study, the sensitivity and specificity were excellent at 97.0% and 100% with a cut-off point of 3.5 per thousand for UBT respectively. Clarithromycin resistance was more common in the group with high UBT values. No correlation at all was seen between UBT values and metronidazole, sparafloxacin, cefaclor and amoxicillin susceptibility. CONCLUSIONS: It is possible that UBT values also tend to be higher in cases of CAM resistance.     

~(13)C-尿素呼气试验诊断幽门螺杆菌感染的研究

本研究旨在评估~(13)C,尿素呼气试验检测幽门螺杆菌感染的可靠性。方法:我们在82例因胃病而行胃镜检查的患者胃窦和胃体取多个活检标本,作组织学、牯膜涂片和快速尿素酶试验,以决定是否感染幽门螺杆菌,并作~(13)C-尿素呼气试验。~(13)C-尿素呼气试验的敏感性、特异性、阳性预测值、阴性预测值是与组织学和尿素酶方法检测幽门螺杆菌的结果比较而计算得到。结果:~(13)C-尿素呼气试验的敏感性97.92％,特异性100％,阳性预测值100％,阴性预测值97.14％,准确性98.78％。结论:~(13)C-尿素呼气试验有高度敏感性和特异性,对确定患者的幽门螺杆菌感染状态是一可靠的无创伤的诊断方法。     

14C]-urea breath test to confirm eradication of Helicobacter pylori

BACKGROUND: Treatment for Helicobacter pylori reduces ulcer recurrence. Eradication rates of the organism vary with different drug regimens from 30% to 90%. There is a need to identify patients who have failed treatment. [14C]-Urea breath test (UBT) is non-invasive, sensitive, safe and highly reliable test for diagnosis of H. pylori infection. As there is a paucity of reports on the utility of [14C]-UBT in confirming H. pylori eradication, this study was undertaken. METHODS: Thirty-eight patients (age 34 +/- 17 years, range 16-84 years, 27 men) with upper gastrointestinal symptoms underwent upper gastrointestinal endoscopy. Baseline H. pylori infection was diagnosed by identification of the organism on antral biopsies and positive rapid urease test (RUT). After 1 month of completion of treatment, repeat RUT and histological examination of antral endoscopic biopsies were performed. Eradication of H. pylori was defined as absence of the organism on histology, and negative RUT. The [14C]-UBT was performed using 185 kBq [14C]-urea dissolved in 300 mL water. Breath samples were collected once before ingestion of [14C]-urea, and subsequently at 5 and 15 min. Results were expressed as 14CO2/mmol CO2 exhaled as per cent of administered urea. RESULTS: Endoscopy revealed antral gastritis (n = 14), duodenal ulcer (n = 8), duodenitis (n = 2), oesophagitis (n = 1), antral gastritis and duodenal ulcer (n = 3), antral gastritis and duodenitis (n = 7) and normal upper gastrointestinal endoscopy (n = 3). All the 20 patients who were negative for H. pylori on RUT and histology, tested negative for H. pylori on [14C]-UBT. However, of 18 patients shown to have H. pylori infection on RUT and histology, 16 were positive for H. pylori on [14C]-UBT. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of [14C]-UBT were 100, 89, 91, 100 and 95% respectively. CONCLUSIONS: The [14C]-UBT is a reliable indicator of H. pylori eradication after treatment. It can obviate the need for antral biopsies to confirm eradication of H. pylori after completion of treatment.     

Quantitative result of 13C urea breath test at 15 minutes may correlate with the bacterial density of H. pylori in the stomach.

BACKGROUND/AIMS: We tried to test the diagnostic efficacy of a new 13C-labeled urea agent made in Taiwan for urea breath test (UBT) of H. pylori infection, and to assess the correlation between the bacterial load of H. pylori in the stomach and the results of UBT from different timings. METHODOLOGY: One hundred and ninety-six dyspeptic patients without usage of antibiotics and proton pump inhibitors in the last 4 weeks were recruited for endoscopy, which included CLO test and H. pylori culture. Three additional bits of gastric biopsy (each one from antrum, body, and cardia) were taken for histology to assess the H. pylori density (HPD, range 0-5) in each specimen and the total bacterial density (TBD, a sum of HPD from three sites, range 0-15). Every study patient had been assigned to complete the UBT protocol. The gas samplings of UBT at baseline, 15 min and 30 min after ingestion of 100 mg 13C-labeled urea (INER-Hp 13C-tester, Taiwan) were collected for the ratio of 13CO2/12CO2 and labeled A, B, and C respectively. Both delta15 (B minus A) & delta30 (C minus A) were recorded to express the excess delta13CO2 per milliliter. During the 30 min period of UBT, the patient was scheduled to change lying positions every 5 minutes for even coating of the stomach with test agent. RESULTS: Based on two positive results of three invasive methods (CLO test, culture, and histology), 91 cases were confirmed to have H. pylori infection. The diagnostic efficacy of UBT was quite good with 96.7% sensitivity for both delta15 and delta30, and with 97.1% and 96.2% specificity for delta15 and delta30 respectively. Both delta15 and delta30 of UBT were well correlated with the TBD of H. pylori in histology (delta15: r=0.7574; delta30: r=0.7432, p<0.0001). CONCLUSIONS: The new C13-labeled urea for UBT can achieve a high diagnostic yield for H. pylori infection. Furthermore, the density of H. pylori in the stomach can be assessed indirectly by UBT by applying 15-minute gas sampling.     

A comparison of two rapid whole-blood tests and laboratory serology, in the diagnosis of Helicobacter pylori infection.

OBJECTIVE: To compare two rapid whole-blood serology tests for Helicobacter pylori and a laboratory serology assay against a gold standard. DESIGN: Prospective comparison of tests in 81 patients. SETTING: A hospital rapid access endoscopy clinic. PARTICIPANTS: Dyspeptic patients requiring assessment of H. pylori status. INTERVENTIONS: Measurement of H. pylori antibody status by Quickvue One-step, Helisal, and Premier H. pylori test; 13C urea breath test for H. pylori, and gastric biopsies for histology, culture and rapid urease test. MAIN OUTCOME MEASURE: Sensitivity and specificity of Quickvue One-step, Helisal and Premier tests, compared to a gold standard based on 13C urea breath test, biopsy culture, histology and urease test. RESULTS: The Quickvue assay has significantly greater sensitivity (81%) than Helisal (67%), but without appreciable loss of specificity (86% and 93%, respectively). The Premier laboratory assay is significantly more sensitive than both of the rapid blood tests (96%), with comparable specificity to the Quickvue assay. CONCLUSION: The rapid serology tests used in this study are quick and convenient to use, but do not approach the sensitivity of a laboratory assay in detecting H. pylori status in this group of dyspeptic patients attending an endoscopy clinic.     

The clinical utility of string-PCR test in diagnosing Helicobacter pylori infection

BACKGROUND/AIMS: Non-invasive string test has been reported as being convenient and capable of yielding bacteria by means of gastric juice sampling in the diagnosis of Helicobacter pylori infection. Molecular methods, such as polymerase chain reaction for the amplification of DNA, are desirable for the detection of minute quantities of H. pylori. We planned to evaluate the diagnostic efficiency of the combination of the string test and polymerase chain reaction and determine whether the string polymerase chain reaction test could obtain more information in conditions where the bacterial load is so low that other diagnostic tests fail to confirm the presence of H. pylori. METHODOLOGY: We enrolled 48 dyspeptic patients, including 29 males and 19 females, with a mean age of 52.5 years. Each patient received endoscopy and biopsy-based tests, including RUT (rapid urease test), cultures, and histology, followed by 13C-UBT (13Carbon urea breath test). We used the string test, (Entero-Test H. pylori, HDC Corporation, CA, US), for gastric juice sampling. The specimen was further analyzed by polymerase chain reaction for the presence of H. pylori with the primer for cagA gene, which is highly prevalent in Taiwan. H. pylori infection was considered as positive when either culture yield was positive, or when two of the other three tests, including RUT, histology, and 13C-UBT, were positive. RESULTS: Of the total 48 patients, 34 patients were H. pylori-positive, and 14 were H. pylori-negative. A fragment of 349 bp of polymerase chain reaction products was detected by agarose gel electrophoresis in 32 out of 34 patients who was classified as H. pylori-positive. The sensitivity, specificity, positive predictive value, and negative predictive value of the string polymerase chain reaction test were 94.12%, 96.97%, 92.86%, and 86.67%, respectively. These results are comparable to 13C-UBT and RUT, and better than histology and culture. One subject, who tested as H. pylori-negative according to the diagnostic criteria, had positive 13C-UBT and string polymerase chain reaction test results. Further sequencing of the DNA obtained from the results of polymerase chain reaction product was performed and it showed 98% identities with the known sequence of cagA strain H. pylori (GenBank accession number: AF249275). CONCLUSIONS: The string polymerase chain reaction test is non-invasive and provides direct bacterial yields. Its diagnostic efficiency is comparable with 13C-UBT and RUT in detecting H. pylori infection. Also, with the assistance of polymerase chain reaction and DNA sequencing, we can diagnose H. pylori infection even when the bacterial load is low. Further application of string polymerase chain reaction test in the genetic analysis of virulent and resistant strains seems promising.     

Comparison of 13C- urea blood test to 13C-breath test and rapid urease test for the diagnosis of Helicobacter pylori infection

At present, the available methods to diagnose active H. pylori infection are endoscopy with biopsy for histology, culture, rapid urease tests, 13C or 14C urea breath test, urine antibody and the stool antigen test. The aims of this study were to simplify the 13C urea test by measuring 13C in blood rather than breath, and to evaluate the usefulness of the 13C urea blood test for the diagnosis of H. pylori infection. Patients who underwent upper endoscopy for standard clinical indications (e.g. dyspepsia, abdominal pain) were enrolled. A total of 161 patients (93F, 68M, mean age 47 +/- 14.2) were evaluated; 50 (31%) of them were H. pylori positive, and 111(69%) were H. pylori negative. H. pylori infection was diagnosed with a rapid urease test (CLO-test) and 13C urea breath test (UBT). Performance characteristics for the 13C urea blood test for diagnosis and evaluation of H. pylori eradication were calculated using UBT and CLO as gold standards. The fifty H. pylori-positive patients were treated with triple antibiotic therapy for two weeks. Four weeks after finishing antibiotic therapy patients were retested with a commercial UBT and urea blood test. The 13C blood test had sensitivities of 92 and 98% and specificities of 96 and 100% as compared with urea breath test and CLO, respectively. We conclude that the 13C urea blood test is highly sensitive and specific for the initial diagnosis and control of eradication of H. pylori infection.     

Comparison of a monoclonal antigen stool test （Hp STAR） with the ^13C-urea breath test in monitoring Helicobacter pylori eradication therapy

AIM: To evaluate the agreement between a mAb-based stool test (HP StAR) and the urea breath test (UBT) in monitoring (H pylori) infection after eradication therapy. METHODS: Patients with discordant results on UBT and Hp StAR underwent endoscopy with biopsies for rapid urease test, culture, and histology to confirm H pylori status. RESULTS: Among 250 patients (50±14 years), 240 (96.0%) had concordant UBT and Hp StAR tests with a significant correlation between DOB and 4 values (R=0.87; P<0.0001). The remaining 10 (4.0%) patients had discordant tests (positive Hp StAR and negative UBT) with the Hp StAR inaccurate in five cases (false positive) and UBT inaccurate in the other five cases (false negative). The "maximal expected" sensitivity, specificity, +PV, -PV, +LR, and -LR were 91%, 100%, 100%, 97.4%,∞, and 8.2 respectively, for the UBT, and 100%, 97.4%, 91%, 100%, 38.8, and 0, respectively, for the Hp StAR. Overall accuracy for both tests was 98%. CONCLUSION: Both the UBT and the Hp StAR are equally accurate in monitoring H pylori infection. Nowadays, the choice of the "best" non-invasive H pylori test in the post-treatment setting should be done not only in terms of diagnostic accuracy but also in view of cost and local facilities.