Comparison of the Clinical Feasibility of Three Rapid Urease Tests in the Diagnosis of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> Infection

Rapid urease tests (RUTs) are a fast, accurate, and inexpensive method to diagnose H. pylori infection in the endoscopy suite. Of these, the CLO test is both common and widely used. The aim of our study was to evaluate the accuracy and positive reaction times of two new rapid urease tests (ProntoDry and HpONE) in comparison with the CLO test. Fifty-one patients (26 men, 25 women; mean age, 52.4 years) were included in this study, and all underwent esophagogastroduodenoscopy (EGD). None of the patients had received any prior H. pylori eradication therapy. H. pylori infection status was evaluated by histology, culture, ¹³C–UBT, and RUT. H. pylori infection was considered to be positive if the culture was positive or if two of the other three tests (histology, RUT, and ¹³C–UBT) were positive. If culture was negative and only one of the other three tests was positive, or if all four tests were negative, the result was interpreted as negative. Of these 51 patients, 2 were excluded and 29 (59.1%) were infected with H. pylori. The sensitivities, specificities, positive predictive values, and negative predictive values of the three RUTs were not significantly different. The mean positive reaction times of the three RUTs (CLO test, ProntoDry, and HpONE) were 67.8 ± 12.0, 16.5 ± 2.2, and 17.8 ± 2.1 min, respectively. ProntoDry (P < 0.001) and HpONE (P < 0.001) had significantly faster reaction times than the CLO test, but there was no significant difference between ProntoDry and HpONE. Different media of RUTs may influence the rapidity of a positive reaction time. Both ProntoDry and HpONE were superior to the CLO test in terms of accuracy, reaction time, and cost-effectiveness.     

Accuracy of Rapid Urease Test in Diagnosing Helicobacter pylori Infection in Patients using NSAIDs

Background/Aim:

This study aimed to determine the effect of nonsteroidal anti-inflammatory drugs (NSAIDs) on the results of rapid urease test (RUT).

Patients and Methods:

The study evaluated 210 consecutive patients for the diagnosis of Helicobacter pylori (H. pylori) infection. They were divided into case and control groups based on history of NSAID use (n=70 each). Two biopsy specimens were collected from antrum and corpus of stomach during endoscopy and sent for rapid urease testing and histopathology. Sensitivity, specificity, and accuracy rate of RUT test were compared against histology.

Results:

The average age was 55.2±12.9 and 43.3±12.1 years in the case and control groups, respectively. Among NSAID users, RUT sensitivity, specificity and accuracy rate were all 100%. The sensitivity, specificity and accuracy rate of RUT in patients without history of NSAID use were 97.37, 98.57 and 98.14%, respectively. The overall sensitivity, specificity and accuracy rate of RUT were 98.57, 99.29, and 99.04%, respectively.

Conclusion:

Our study shows that sensitivity, specificity and accuracy rate of RUT are not affected by NSAID use. Rapid urease test remains a reliable test for diagnosis of H. pylori in patients on NSAIDs.     

Detection ofHelicobacter pylori by polymerase chain reaction assay using gastric biopsy specimens taken for CLOtest

The concordance rate between a rapid urease test (CLOtest) and polymerase chain reaction (PCR) assay for the detection ofHelicobacter pylori in gastric biopsy samples was investigated. To avoid the bias produced by patchy distribution of the organism in the stomach, the samples used for these two tests were not obtained from two different sites of the antrum. Instead, the PCR assay was performed with the the same biopsy sample that was taken for the CLOtest. Among 82 biopsy samples included for this study, 56 were positive and 26 were negative by CLOtest. Of the 56 CLOtest-positive samples, 52 (93%) were also positive by PCR assay, and of the 26 CLOtest-negative samples, 20 (78%) were negative by PCR assay. The total concordance rate of these two tests was 87.6%. Of the 4 cases with CLOtest-positive and PCR-negative results, 3 had been treated with long-term H₂ blockers. Of the 6 patients with CLOtest-negative and PCR-positive results, 4 suffered from recurrent or poorly healing duodenal ulcers. Interestingly, a significantly lower density of the PCR products was observed during electrophoresis analysis for all the 6 cases, presumably due to a small number ofH. pylori in these samples. These results indicated that PCR might be used as a complementary assay for CLOtest. False negative results by CLOtest might occur when only a small amount ofH. pylori was present in the samples, which could be detected by subsequent PCR assays using the same biopsy specimens. The clinical significance of such CLOtest-negative and PCR-positive cases requires further study.     

Utility of [13C] Urea Breath Test for Helicobacter pylori Detection in Partial Gastrectomy Patients

Many reports on the diagnostic efficacy of the [13C] urea breath test ([13C] UBT) for the detection of Helicobacter pylori in the residual stomach have shown negative results. We previously reported on the utility of [13C] UBT and conducted an evaluation to establish a standardized protocol with a shorter sampling time for [13C] UBT in partial gastrectomy patients. Sixty-two patients who had undergone partial gastrectomy were included. The [13C] UBT protocol included ingestion of 100 mg [13C] urea, use of mouthwash, and the body in a horizontal position on the left side. The sensitivity of [13C] UBT was 95.7%. Thirty minutes and a cutoff of 2.0 per thousand were found to be optimal for the test, with the body position horizontal on the left side. In the present protocol [13C] UBT appears to be a reliable and convenient tool with the same accuracy rate as other routine tests in patients with a remnant stomach.     

Helicobacter pylori Seroprevalence in Patients with Coronary Artery Disease

Recent studies have suggested that chronic infections such as Helicobacter pylori may be a risk factor for coronary artery disease (CAD). The aim of thIS study was to investigate the seroprevalence of H. pylori in patients with CAD. We enrolled 151 patients with CAD (93 men and 58 women, aged 48.1 ± 17.3 years [mean ± SD]) and 149 control subjects matched by age and sex (90 men and 59 women, aged 51.4 ± 13.9 years). An enzyme-linked immunosorbent assay immunoglobulin (Ig) G test for H. pylori diagnosis was performed on all enrolled subjects (CAD patients and controls). Ninety-one of 151 patients with CAD (60.2%) and 86 of the 149 subjects in the control group (57.7%) were H. pylori positive (P > 0.05). H. pylori infection rates were similar in patients with CAD and control groups. The main conclusion of this study is that H. pylori infection is not a risk factor for developing CAD. Further studies should be undertaken to confirm our results.     

Detection of Helicobacter pylori in Gastric Aspirates Using a Monoclonal Antibody-Based Test

Background/Aims

The objective of this study was to evaluate a monoclonal antibody-based test to detect Helicobacter pylori-specific antigen in gastric aspirates from humans.

Methods

Sixty-one volunteers were enrolled in the study. All of the subjects underwent a ¹³C-urea breath test (UBT) before esophagogastroduodenoscopy. Gastric aspirates were analyzed for pH and ammonia and used for polymerase chain reaction (PCR), culture, and monoclonal antibody-based detection of H. pylori. Multiple biopsies of the gastric antrum and body were obtained for a rapid urease test (RUT) and histological evaluation.

Results

Thirty-six subjects were H. pylori-positive and 25 were H. pylori-negative according to the UBT results. Compared with the H. pylori-negative subjects, H. pylori-positive subjects had a higher pH (4.77±1.77 vs 3.49±1.30, p<0.05) and ammonia level (1,130.9±767.4 vs 184.2±126.3, p<0.0001). The sensitivities and specificities of the PCR test, RUT, culture test, and monoclonal antibody-based test were 100% and 72%, 89% and 100%, 47% and 100%, and 78% and 100%, respectively.

Conclusions

The monoclonal antibody-based test for diagnosing H. pylori infection in gastric aspirates has increased sensitivity compared with the culture test and specificity as high as that of the RUT. The test may be useful as an additive test for examining gastric aspirates.     

Association Between Helicobacter pylori Infection and Cirrhosis in Patients with Chronic Hepatitis C Virus

We evaluated, employing a logistic regression model, the association between Helicobacter pylori infection and cirrhosis in a cohort of 106 patients (57 males; mean age, 52.9 years; range, 20–78 years) with chronic hepatitis C virus (HCV) from Rosario, Argentina. HCV was confirmed by ELISA and PCR. H. pylori status was determined by ELISA. Of the 106 patients evaluated, 47 (44.3%) had cirrhosis. A total of 70.2% (33/47) of cirrhotic patients and 47.5% (28/59) of noncirrhotic patients were H. pylori-positive. In univariate analyses, cirrhosis was associated with age (P = 0.016) and H. pylori-positive status (P = 0.019) but not with gender (P = 0.28) or length of infection (P = 0.35). In multivariate analysis, H. pylori infection (P = 0.037; OR = 2.42; 95% CI = 1.06–5.53) and age (P = 0.033; OR = 1.04; 95% CI = 1.00–1.07) of patients remained significant and independently associated with cirrhosis. In conclusion, our results demonstrate an association between H. pylori infection and cirrhosis in patients with hepatitis C virus.     

[14C]Urea Breath Test Is Not Sensitive for Detection of Acute Helicobacter pylori Infection in Rhesus Monkeys (Macaca mulatta)

The urea breath test is sensitive and specific for detection of chronic infection with H. pylori. We sought to determine the sensitivity of the [¹⁴C]urea breath test for detection of acute H. pylori infection using experimentally infected rhesus monkeys. Eighteen monkeys were inoculated with H. pylori. Serial [¹⁴C]urea breath tests and cultures of gastric biopsies were performed before and up to 10 weeks after inoculation. Cultures from all 18 monkeys were positive for H. pylori at each time point. The sensitivity of the [¹⁴C]urea breath test increased systematically from 43% at two weeks after inoculation up to 93% at 10 weeks after inoculation. Quantitative cultures of H. pylori showed a tendency to decline over time following inoculation. We conclude that the [¹⁴C]urea breath test is not sensitive for detection of acute H. pylori infection in rhesus monkeys until 10 weeks after inoculation. While this may reflect a gradual increase in bacterial load that was not detected by limited sampling, our data are not consistent with this hypothesis.     

13C-Urea Breath Test Values and Helicobacter pylori Eradication

Delta over baseline (DOB) values of ¹³C-urea breath test (UBT) have been shown to be predictive of H. pylori eradication following therapy. This was a post hoc analysis of a large, double-blind, randomized trial. Consecutive patients with a positive UBT underwent upper endoscopy. H. pylori strains were tested for clarithromycin resistance. All patients received an eradication therapy with either a standard 10-day triple therapy or a 10-day sequential regimen. The infection was considered cured when two consecutive UBTs were negative. Basal DOB values were categorized as low (<16), intermediate (16–35), or high (>35). A total of 282 patients were selected. Eradication rates did not differ between patients with high and low DOB values. No significant difference in DOB values emerged between patients infected with clarithromycin-susceptible and clarithromycin-resistant strains. Under multivariate analysis, DOB values did not influence the bacterial eradication, which was significantly affected only by the presence of clarithromycin resistance. This large analysis failed to demonstrate a role for DOB value in H. pylori eradication with either a 10-day triple or sequential therapy.     

Serum and Tissue Beta-2 Microglobulin Levels in Patients with Helicobacter pylori Infection

Background and aim Beta-2 microglobulin (β₂-m) is a minor plasma protein, secreted from the plasma membranes as a result of the continuous regeneration of membrane proteins in the cell surface of all nucleated cells. The relationship between Helicobacter pylori and β₂-m has not been adequately established in studies. In this study, we aimed to compare the levels of serum and tissue β₂-m in patients with and without H. pylori infection, and to examine the relationship between levels of serum and tissue β₂-m. Material and methods About 30 patients with H. pylori gastritis and 22 healthy persons were enrolled in this study. Gastric biopsies were histologically analyzed and compared according to tissue and serum β₂-m levels. Results Serum β₂-m levels were comparable in H. pylori and control groups. There was no significant link between tissue H. pylori grade and serum β₂-m levels. Subendothelial β₂-m was detected in 19 (63.3%) cases with H. pylori and none of the control group with immunohistochemical staining (P < 0.001). There was no correlation between serum and tissue levels of β₂-m. Conclusion β₂-m accumulates in the majority of gastric tissues of patients with active chronic gastritis who were H. pylori (+), whereas no accumulation was found in H. pylori (−) control subjects.     

Immunological Rapid Urease Test for Detecting Helicobacter pylori: Comparative Study of Biopsy Specimens and Gastric Mucus

Abstract: A variety of reliable methods are available for the detection of H. pylori during upper gastrointestinal endoscopy. We evaluated the clinical utility of an analyzer for H. pylori urease composed of a solid-phase tip coated with a monoclonal antibody against H. pylori urease and ion-sensitive field effect transistor-based pH sensor system. Samples of both gastric mucus and gastric mucosal specimens were collected and the results from this system were compared. Sensitivity and specificity were 97% and 100% for mucus samples and 92% and 97% for mucosal specimens in the present system; compared to 95% and 96% for histological examination, 92% and 100% for bacteriological test, and 89% and 100% for rapid urease test, respectively. These results confirmed that the present system had high clinical sensitivity and specificity, especially for testing of mucus samples. This method has the advantage of requiring only one sample per patient because mucus can be collected from a broad area of the stomach lumen by stroking the mucosal surface with a brush. (Dig Endosc 1999; 11: 42–46)     

Helicobacter pylori Infection Is Not Associated with Subclinical Hepatic Encephalopathy in Stable Cirrhotic Patients

The importance of ammonia-producing Helicobacter pylori infection as a cause of subclinical encephalopathy in cirrhosis was investigated. In addition, a single psychometric test that can reliably detect subclinical hepatic encephalopathy was sought. Out-patients with cirrhosis and no overt encephalopathy underwent [¹⁴C]urea breath testing once and psychometric testing on two separate occasions, with an intervening course of clarithromycin/omeprazole if they had subclinical encephalopathy (two of four psychometric tests abnormal). Subclinical encephalopathy was present in 27 of 69 patients (39%), and Helicobacter pylori infection in 14 of 69 (20%). There was no association between the two conditions (P = 0.769). Subclinical encephalopathy resolved in 75% of treated Helicobacter pylori-positive patients and 37.5% of treated Helicobacter pylori-negative patients (P = 0.285). Number connection test-B had high reproducibility among untreated patients (R = 0.655) and high correlation (P 0.01) with three surrogate gold standards. In stable cirrhotic patients, subclinical hepatic encephalopathy was found to: (1) have a high prevalence, (2) not be associated with Helicobacter pylori infection, and (3) be readily detected with the number connection test-B alone.     

Efficacy of Triple Therapy Plus Cetraxate for the Helicobacter pylori Eradication in Partial Gastrectomy Patients

In the present study, we aimed to establish an additional standardized protocol with a higher H. pylori eradication rate in the remnant stomach. Fifty-five H. pylori–positive patients were randomly allocated to one of three regimens: LAC—lansoprazole, amoxicillin, and clarithromycin b.i.d. for 7 days (n = 17); LAC+CET—LAC b.i.d. plus cetraxate q.i.d. for 7 days (n = 20); and LEFT—LAC for 7 days in a horizontal body position on the left side for 30 min (n = 18). Patient compliance and side effects were checked via interviews. H. pylori eradication was successful in 75, 72, and 41% in LAC+CET, LEFT, and LAC, respectively. The eradication rate was significantly higher in LAC+CET than in LAC (P = 0.024) but not in LEFT (P = 0.058). Adverse events that occurred in each group were almost all mild ones. Cetraxate plus LAC for 1 week is a safe and effective regime for the eradication of H. pylori in patients after partial gastrectomy.     

Helicobacter pylori and Clostridium difficile in Cystic Fibrosis Patients

We describe the prevalence of H. pylori and toxigenic Clostridium difficile (CD) infection and its relationship with gastrointestinal symptoms and pancreatic sufficiency (PS) or insufficiency (PI) in cystic fibrosis (CF) patients. Stool specimens from 30 consecutive patients with CF, aged 1–44, and from 30 healthy similarly aged subjects were tested for the H. pylori antigen by specific monoclonal antibodies and for CD toxins by Tox A/B assay and Tox A assay. CF patients were assessed clinically and tested for specific H. pylori serum antibodies and for mutations. In CF patients, the prevalence of H. pylori antigen was 16.6% (5/30), compared to 30% (9/30) in controls. Of the 26 CF patients with PI, only 2 (7.6%) were infected by H. pylori, compared with 3 of the 4 (75%) patients with PS (P=0.001). H. pylori infection was diagnosed in 3 of 5 (60%) CF patients carrying mild mutations, compared to 1 of 25 (4%) CF patients carrying severe mutations (P=0.01). Fourteen of 30 (46.6%) stool specimens from CF patients tested positive in the ToxA/B assay, and 3 of 14 tested positive for ToxA. No significant differences in antibiotic use, severity of lung disease, PI, chronic abdominal pain, or genotype were found between the two groups. None of the controls was positive for CD toxins. Prevalence of H. pylori infection in CF patients was lower than in similarly aged non-CF controls. CF patients with PI or a history of distal intestinal obstruction syndrome and those carrying mutations associated with a severe phenotype were protected against H. pylori infection. Almost half of the CF patients were asymptomatic carriers of CD producing mostly toxin B. More studies are needed to confirm our results in a larger group of CF patients.     

Helicobacter pylori Seroprevalence in Patients with Autoimmune Hepatitis

Autoimmune hepatitis is characterized by a continuing hepatocyte necrosis that usually progresses to liver cirrhosis. Autoimmunity is also a feature of chronic infection by Helicobacter pylori, a gram-negative bacterium involved in the pathogenesis of peptic ulcer and upper gastrointestinal bleeding, with both events frequently occurring in patients with chronic liver disease. A newly described pathogenetic mechanism for chronic hepatitis and hepatocellular carcinoma in the mouse is linked to Helicobacter spp. infection. A high prevalence of H. pylori infection was demonstrated in patients with viral-related cirrhosis but never studied in cases of autoimmune hepatitis. In a case-control study, we examined 31 consecutive patients (25 women and 6 men, age range 20–66, mean age 46 ± 4.3 years) suffering from autoimmune hepatitis and 62 sex- and age-matched blood donors (50 women, 12 men, age range 20–65, mean age 46 ± 5.4 years) resident in the same area. Antibodies to H. pylori were present in 20 of 31 (64.5%) autoimmune patients compared to 33 of 62 (53.2%) controls (P = 0.3, odds ratio 1.60, 95% CI 0.60–4.28). The difference was not statistically significant either in female or male patients. In conclusion, the prevalence of H. pylori infection in patients and controls was similar in our study of patients with chronic autoimmune hepatitis.     

Modified rapid urease test for Helicobacter pylori detection in relation to an immunohistochemical stain

BACKGROUND: The rapid urease test and touch cytology have been used for the rapid detection of Helicobacter pylori infection. Recently, a modified rapid urease (MRU) test, which provides results in 20 min has been available on a commercial basis. To date, few reports have evaluated the accuracy of this test. This study evaluated the sensitivity, specificity, and accuracy of the MRU test and touch cytology to detect H. pylori in relation to the density of H. pylori infection determined semi-quantitatively by using immunohistochemical stains. METHODS: Biopsy specimens obtained from a total of 60 patients who underwent endoscopy for evaluation of gastroduodenal diseases were studied by using the MRU test, Giemsa stain for touch smear tissue and histological methods. An immunohistochemical stain was used as a standard, and the density of H. pylori infection was graded according to the number of individual bacteria seen as follows: grade 0 = 0; grade 1+ = 1-9; grade 2+ = 10-29; grade 3+ = 30-99; grade 4+ > or = 100. The severity of gastritis was evaluated histologically in each specimen and compared with the density of H. pylori infection. RESULTS: The MRU test had an overall sensitivity of 73%, specificity of 100% and accuracy of 85%. The Giemsa stain had a sensitivity of 91%, specificity of 100% and accuracy of 95%.The sensitivities of the MRU test and Giemsa stain decreased in mild H. pylori infection. In the MRU test, the sensitivity was 47% when the density of H. pylori infection was 1+, while 80-100% sensitivities were obtained when the densities of infection were > or = 2+. With the Giemsa stain, the sensitivity was 80% when the density was 1+, while the sensitivity increased to 100% when the densities were > or = 2+. The severity of gastritis determined by the Rauws scores showed a positive correlation with the density of H. pylori infection as evaluated by immunohistochemical staining. CONCLUSIONS: The MRU test had high sensitivity and specificity for moderate to severe H. pylori infection, but it may result in false-negative results in tests for mild infection. As the MRU test has the advantages of shorter incubation times and low cost, a combination of the MRU test and the Giemsa stain for touch cytology may be the most time- and cost-efficient tests in a clinical setting for the diagnosis of H. pylori infection.     

Recurrence of Gastric Ulcer Dependent Upon Strain Differences of Helicobacter pylori in Urease B Gene

To evaluate the role of different strains of Helicobacter pylori on the recurrence of gastric ulcer, we divided H. pylori into four types (I, II, III, and IV) according to the urease B gene using polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP). The relationship between the recurrence of gastric ulcer and the prevalence of H. pylori types was studied in 32 patients with benign open gastric ulcers using upper gastrointestinal endoscopy. The rate of recurrence was significantly lower in patients with type II than in patients with types I, III, and IV (P < 0.05). Using Mongolian gerbils, an animal model of H. pylori infection, we also showed that the occurrence of gastric ulceration following restraint water-immersion stress was significantly lower in type II compared with types I and III. These data indicate that in the context of ulcer recurrence, it is not necessary to eradicate H. pylori during infection with type II.     

The Diagnostic Yield of Various Tests for Helicobacter pylori Infection in Patients on Acid-Reducing Drugs

The diagnostic yield of various tests for Helicobacter pylori infection in patients on acid-reducing drugs, such as proton pump inhibitors (PPI) and histamine-2 receptor blocker (H2RB), was compared. Seventy-four consecutive patients on acid-reducing drugs were enrolled: 34 (46%) were on PPIs, 20 (27%) were on H2RBs and 20 (27%) were not on medications. For those patients on PPIs, RUT and histology results from antrum were negative in 28 (82%) and 17 (50%) patients, respectively (OR: 4.7; 95% CI: 1.4–16.6; P = 0.004), while those from the corpus were negative in was 28 (82%) and 18 (53%) patients, respectively (OR: 4.4, 95% CI: 1.3–15.5; P = 0.006). For patients on H2RBs, RUT and histology results from the antrum were negative in 12 (60%) and six (30%) patients, respectively (OR: 3.5; 95% CI: 0.8–16.1; P = 0.05), while those from the corpus were negative in 12 (60%) and nine (45%) patients, respectively (OR: 1.8; 95% CI: 0.4–7.8; P = 0.342). For those patients on PPIs, the diagnostic yield of both RUT and histology was reduced from both the antrum and corpus. In these patients, PCR for H. pylori is more sensitive than RUT and histology.     

Detection of Helicobacter pylori in paraffin-embedded specimens from patients with chronic liver diseases, using the amplification method

Helicobacter DNA has been detected in the liver specimens of patients with various hepato-biliary diseases. The aim of this study was to investigate the presence of H. pylori DNA in the liver tissue of Iranian patients with chronic liver diseases (CLD). Genomic DNA was extracted from the paraffin sections of 46 liver biopsies of patients with CLD and 13 from patients with metastatic adenocarcinoma as a control group. Polymerase chain reaction (PCR) analysis was carried out using primers for H. pylori 16S rRNA and cagA genes. On analysis, 17 of the 46 patient samples were positive in H. pylori 16S rRNA PCR and 2 of the 13 were positive from the control group. None of the samples were positive for the cagA gene. This study showed the greater presence of H. pylori-like DNA in the liver samples from patients with CLD than in controls.