High prevalence of Helicobacter pylori in saliva demonstrated by a novel PCR assay.

AIMS--To investigate the prevalence of Helicobacter pylori in the saliva of patients infected with this bacterium. METHODS--A novel polymerase chain reaction (PCR) assay was developed to detect H pylori in saliva and gastric biopsy specimens from patients undergoing endoscopy. RESULTS--Our PCR assay amplified a 417 base pair fragment of DNA from all 21 DNAs derived from H pylori clinical isolates but did not amplify DNA from 23 non-H pylori strains. Sixty three frozen gastric biopsy and 56 saliva specimens were tested. H pylori specific DNA was detected by PCR in all 39 culture positive biopsy specimens and was also identified from another seven biopsy specimens which were negative by culture but positive by histology. H pylori specific DNA was identified by PCR in saliva specimens from 30 (75%) of 40 patients with H pylori infection demonstrated by culture or histological examination, or both, and in three patients without H pylori infection in the stomach. CONCLUSION--The results indicate that the oral cavity harbours H pylori and may be the source of infection and transmission.     

Diagnosis of Helicobacter pylori infection by specific gastric mucosal IgA and IgG pylori antibodies.

AIMS--To investigate the diagnostic value of mucosal IgA and IgG Helicobacter pylori antibodies. METHODS--The study population comprised 209 consecutive patients with severe dyspeptic complaints referred for upper gastrointestinal endoscopy. A positive culture or histological identification of H pylori in gastric biopsy specimens, or both, were used to confirm infection. Specific IgA and IgG H pylori antibodies were determined using a modified ELISA technique. RESULTS--Of the 209 patients, 137 were infected with H pylori. The diagnostic value of systemic IgA and IgG H pylori antibodies was confirmed. Systemic IgA antibodies had a sensitivity of 76.6% (95% confidence interval 69.5-83.7) and a specificity of 94.4% (89.1-99.7). The sensitivity and specificity for systemic IgG antibodies were, respectively, 97.1% (94.3-99.9) and 98.6% (95.9-100). A moderate but clinically important correlation was found between local and systemic IgA and IgG. Mucosal IgA H pylori antibodies had a sensitivity of 98.5% (96.5-100) and a specificity of 91.7% (85.3-98.1), while for IgG these figures were, respectively, 88.3% (82.9-93.7) and 98.6% (95.9-100). As a diagnostic test mucosal IgA H pylori antibodies were comparable with culture and histology. CONCLUSION--Determination of local IgA and IgG H pylori antibody levels is a highly sensitive and specific test for the diagnosis of H pylori infection.     

Histology compared with chemical testing for urease for rapid detection of Helicobacter pylori in gastric biopsy specimens.

Gastric biopsy specimens from 283 patients with ulcer and non-ulcer dyspepsia attending five gastroenterology clinics in the northern region of the United Arab Emirates (UAE) were tested by the agar gel test (n = 115) or the ultra-rapid endoscopy room test (n = 168) for the presence of Helicobacter pylori urease. Results were compared with a histological technique using the Romanowsky type (Diff-3) stain for detecting H pylori in both antral and body type gastric mucosa. A sensitivity of 94% and specificity of 100% using the agar gel test compared with 87% sensitivity and 99.3% specificity for the ultra-rapid endoscopy room test. Grading of H pylori in gastric biopsy specimens showed that the higher the histological grade, the more likely that the urease test would be positive. Both forms of urease tests have high specificity for detecting H pylori in gastric biopsy specimens, although the urea agar test has a higher sensitivity than the ultra-rapid test. Low numbers of H pylori in gastric biopsy specimens are the most important determinant of a false negative urease test.     

Evaluation of enzyme immunoassay for detection of salivary antibody to Helicobacter pylori.

The Helisal test is a quantitative enzyme immunoassay for the measurement of Helicobacter pylori-specific immunoglobulin G antibodies in saliva. This test was evaluated in comparison with culture and histopathologic examination of gastric biopsy specimens obtained from 195 patients who underwent 200 endoscopic procedures for the investigation of gastrointestinal symptoms. Forty-one (21%) patients were found to have peptic ulcer disease, and one other patient had a gastric carcinoma. H. pylori was detected in gastric biopsy specimens obtained from 98 (49%) of the procedures. The sensitivity, specificity, and positive and negative predictive values of the Helisal test were 81, 75, 76, and 80%, respectively. The test was negative for 16 (38%) of the 42 patients with peptic ulcer disease or a gastric malignancy diagnosed at endoscopy. These results suggest that the Helisal assay is only moderately accurate for the detection of H. pylori infection in symptomatic patients.     

UreC PCR based diagnosis of Helicobacter pylori infection and detection of cag A gene in gastric biopsies

Polymerase chain reaction assay using ureC gene specific primers for the detection of Helicobacter pylori in gastric biopsy specimens from 116 dyspeptic patients was compared with other routine invasive diagnostic methods (culture, rapid urease test [RUT] and histology). In parallel, gastric biospy specimens from 54 patients and their corresponding Helicobacter pylori isolates were subjected to PCR with cagA targeting primers using standard protocols. Helicobacter pylori were detected in 53%, 43%, 48% and 50% of patients by PCR, RUT, culture and histological examination respectively. Based on histology and culture positive and at least three test positive result, 44 (37%), 46 (39%) and 26 (22%), and 56 (48%), 52 (44%) and 8 (6%) patients were classified as Helicobacter pylori positive, negative and indeterminate respectively. The sensitivity and specificity of PCR assay was the highest-95% and 100% when compared with both culture and histology positive, and at least any three positive results respectively. The result of cagA positivity in 54 gastric biopsy specimens and their corresponding Helicobacter pylori isolates were identical; 18 of 20 (90%) duodenal ulcer patients and 23 of 28 (82%) patients with chronic gastritis and 2 (40%) of 5 patients with portal hypertension and one gastric biopsy specimens from gastric cancer patients were found to be cagA positive. PCR-based method to detect Helicobacter pylori and the virulence gene cag A directly from gastric biopsy specimens appears to be promising and can curtail the lengthy process of culture-based approaches. The procedure proved to be rapid and reliable and could be utilized for diagnostic purposes.     

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

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

Evaluation of a commercial ELISA for serodiagnosis of Helicobacter pylori infection.

A commercial ELISA for the detection of Helicobacter pylori IgG antibodies was evaluated using serum from 242 patients attending an endoscopy clinic. The efficacy of the ELISA was assessed in relation to the histological detection of H pylori on antral mucosal biopsy specimens. In patients under 61 years of age (n = 138) the ELISA was 97.5% sensitive and 85.5% specific for H pylori infection, with a positive predictive value of 91% and a negative predictive value of 96%. Over the whole group the sensitivity of the ELISA was 93.8% and the specificity 79.3%. The positive predictive value and negative predictive values were, respectively, 90% and 87%. These results suggest that the Bio-Rad GAP IgG H pylori ELISA is suitable for serodiagnosis of H pylori infections for most clinical purposes and thus makes H pylori serology available to routine diagnostic laboratories.     

Differentiation of Helicobacter pylori strains directly from gastric biopsy specimens by PCR-based restriction fragment length polymorphism analysis without culture.

Recent studies have shown the usefulness of PCR-based restriction fragment length polymorphism (RFLP) analysis for differentiating Helicobacter pylori strains isolated by culture. For this study, a PCR-based RFLP assay was developed for directly typing H. pylori strains from gastric biopsy specimens. Nineteen gastric biopsy specimens obtained from patients undergoing endoscopy for gastrointestinal complaints were cultured for isolation of H. pylori. Genomic DNA preparations from these gastric biopsy specimens and the corresponding H. pylori isolates were tested by our PCR-based RFLP assay. The 1,179-bp H. pylori DNA fragments amplified by the PCR assay were digested with the restriction enzymes HhaI, MboI, and AluI and analyzed by agarose gel electrophoresis. HhaI, MboI, and AluI digestion produced 11, 10, and 6 distinguishable digestion patterns, respectively, from the 19 H. pylori isolates tested and generated 13, 11, and 6 different patterns, respectively, from the 19 gastric biopsy specimens. The patterns from 13 of the 19 gastric biopsy specimens matched those of the H. pylori isolates from the corresponding patients. The patterns from the remaining six biopsy specimens appeared to represent infection by two strains of H. pylori; the pattern of one strain was identical to that of the isolate from the corresponding patient. By combining all the restriction enzyme digestion patterns obtained by using HhaI, MboI, and AluI, we observed 19 distinct RFLP patterns from the 19 specimens. The results suggest that the PCR-based RFLP analysis method may be useful as a primary technique to identify and distinguish H. pylori strains directly from gastric biopsy specimens without culture of the organisms.     

Use of a novel enzyme immunoassay based on detection of circulating antigen in serum for diagnosis of Helicobacter pylori infection

Recently, noninvasive diagnostic tests for Helicobacter pylori infection have gained in significance. We have developed a sensitive and specific noninvasive immunoassay based on the detection of an H. pylori circulating antigen (HpCA) in sera from H. pylori-infected individuals. Monospecific antibody and Western blot analyses were used to demonstrate the presence of the target antigen in H. pylori cell lysate and serum samples. A novel enzyme-linked immunosorbent assay (ELISA) was developed for the detection of HpCA in serum. Endoscopic biopsy specimens from the gastric antra of 221 individuals (143 males and 78 females) with dyspeptic symptoms were evaluated for H. pylori infection, with culture used as a "gold standard" for diagnosis. The target H. pylori antigen was identified at 58 kDa. HpCA has been detected by ELISA with high degrees of sensitivity, specificity, and efficiency (>90%), and ELISA results show no significant difference (P > 0.05) from results of H. pylori culture of gastric biopsy specimens. The test's positive and negative predictive values were also high (95 and 86%, respectively). In conclusion, a sensitive and specific immunoassay was developed for the detection of HpCA in human serum. This test can be applied for noninvasive laboratory and field diagnoses of H. pylori infection.     

Role of ELISA in H. pylori detection and its correlation with urease test

Helicobacter pylori is one of the most common chronic bacterial infection in humans linked to acid peptic diseases, gastric carcinomas and lymphomas. The bacilli produces large amounts of urease and this property has formed the basis of detection of H. pylori by the Christensen's urease test. Where endoscopy is not clinically indicated, serology may be used to establish the diagnosis. This study was undertaken to diagnose H. pylori with the help of Christensen's urease test on endoscopic biopsy specimens & correlated with the detection in Sera, of IgG antibodies against H. pylori, by ELISA technique. The study was conducted on 100 patients suffering from acid peptic disorders out of which 40 (40%) tested positive for H. pylori both by urease and serology. Christensen's urease and ELISA were found to have sensitivities of 85.7% & 90.9% and specificities of 96% and 87.5% respectively. Christensen's urease was taken as a standard method of diagnosis and its correlation with ELISA worked out to (+1) which meant there was a strong positive association between both the tests. Hence either test could be used for primary diagnosis of H. pylori instead of histopathological study and/or culture of H. pylori.     

Diagnosis of Helicobacter pylori infection by PCR: comparison with other invasive techniques and detection of cagA gene in gastric biopsy specimens.

A PCR assay for the detection of Helicobacter pylori in gastric biopsy specimens with specific primers for ureC gene amplification (herein referred to as ureC PCR) was compared with other routine invasive methods (culture, the rapid-urease test, and Giemsa staining of histological sections) with samples from a group of 104 consecutive dyspeptic patients. Bacteria were found in 40 (38.5%), 38 (36.5%), 36 (34.6%), and 35 (33.7%) of the patients by ureC PCR, culture, the rapid-urease test, and Giemsa stain, respectively. Sixty-three patients had negative cultures, negative histological examinations, and negative rapid-urease test results, and 61 of these patients were also negative by ureC PCR. ureC PCR detected H. pylori in two culture-negative patients. In parallel, a PCR-based assay to detect the H. pylori cytotoxin-associated antigen (cagA) gene, a putative virulence gene, was also developed. To assess the likelihood of detection of H. pylori genes directly from gastric biopsy samples and from the corresponding H. pylori isolates, specimens from 31 patients were subjected to PCR with ureC- and cagA-targeting primers. All 31 biopsy specimens and the corresponding H. pylori isolates were positive in the ureC PCR. H. pylori strains that were cagA positive also gave positive cagA PCR fragments with biopsy specimens from the same patients. All ureC PCR-positive patients were examined; biopsy specimens from 10 of 11 (91.7%) duodenal ulcer patients harbored H. pylori cagA-positive strains, whereas 19 of26 (73%) of those from patients with chronic gastritis only were found to be cagA positive.(ABSTRACT TRUNCATED AT 250 WORDS)     

Detection of Helicobacter pylori gastritis by PCR: correlation with inflammation scores and immunohistochemical and CLOtest findings

We developed a polymerase chain reaction (PCR) assay to detect Helicobacter pylori in gastric and/or gastroesophageal biopsy specimens of adults with dyspepsia, compared the method with immunohistochemical analysis and CLOtest (Ballard Medical Products, Draper, UT), and correlated the results of each test with the histologic features of infection. H pylori was identified in 36 (60%) of 60 patients irrespective of biopsy site and testing method. In the gastric biopsy specimens, PCR detected H pylori in 29 (52%) of 56 cases, including 11 (100%) of 11 immunohistochemically and/or CLOtest-positive cases. PCR-positive gastric biopsy specimens correlated with a higher average cumulative inflammatory score compared with PCR-negative specimens (P = .001). In gastroesophageal biopsy specimens, PCR detected H pylori in 15 (34%) of 44 cases, including 1 (20%) of 5 immunohistochemically positive specimens. PCR-positive gastroesophageal junction biopsy specimens did not correlate with a higher average cumulative inflammatory score. Overall, PCR detected an additional 23 cases negative by immunohistochemical analysis and/or CLOtest. This PCR assay identified a significant number of H pylori infections that would not be detected by immunohistochemical analysis and/or CLOtest.     

Evaluation of diagnostic methods for Helicobacter pylori gastritis

The authors evaluated the use of direct Gram-stained smears, 1- and 24-hour urease broth tests, histologic examination, and culture to detect Helicobacter pylori in 100 gastric biopsy specimens from 97 patients with epigastric symptoms. Twenty-six patients had positive cultures and 27 had H. pylori identifiable in hematoxylin and eosin-stained sections. The gastric biopsy specimens from the 29 patients with culture and/or histologic findings positive for H. pylori showed active gastritis in 27 cases (93%), compared with 26 cases (37%) without H. pylori (P less than 0.0001). Chronic gastritis was present in 25 cases (86%) with H. pylori and 40 cases (56%) without H. pylori (P less than 0.01). Twenty patients had positive Gram-stained smears. Fifteen patients had positive 1-hour urease tests, and 3 had delayed positive 24-hour urease tests. There were no false-positive Gram's stain results, three false-positive 24-hour urease tests, two false-negative histologic results, and three false-negative cultures (one inadvertently incubated anaerobically). The sensitivities of the methods were as follows: 62% for the 24-hour urease test, 69% for direct Gram's stain, 90% for culture, and 93% for histologic examination. The authors conclude that the urease test used in this study has low sensitivity and limited specificity; that the direct Gram-stained smear is a useful, highly specific, rapid screening test; and that the lengthier methods of culture and histologic examination have comparably high sensitivity for the definitive diagnosis of H. pylori gastritis.     

Comparative evaluation of conventional methods and ELISA based IgG antibodies detection for diagnosis of Helicobacter pylori infection in cases of dyspepsia

Seventy five gastric biopsy specimens and 75 serum samples of same patients complaining of dyspepsia were collected. Biopsy specimens were processed for rapid urease test, gram staining and culture. Serum samples were used for detecting IgG antibodies against 128 kDa external protein (Cog A) of H. pylori using a commercially available ELISA kit. Rapid urease test was positive in 54 (72%), culture in 21 (28%) and gram staining in 15 (20%). Significant IgG levels were detected in 57 (76%) cases. It was therefore concluded that for diagnosis of H. pylori infection in cases of dyspepsia, determination of IgG levels can act as an important screening procedure.     

Improvement of gastric inflammation and resolution of epithelial damage one year after eradication of Helicobacter pylori.

AIMS--To investigate the effect of eradication of Helicobacter pylori infection on gastric epithelial damage and gastritis, scored according to the Sydney system. METHODS--Gastritis scores and epithelial damage were assessed in gastric biopsy specimens before, and five weeks and one year after anti-H pylori therapy in 66 patients with H pylori related gastritis. RESULTS--The mean initial levels of activity, inflammation, atrophy, intestinal metaplasia, and H pylori scores were higher in the antrum than in the corpus or fundus. Eradication of H pylori resulted in an improvement in the mean inflammatory score in antral biopsy specimens from 2.23 before treatment to 1.32 and 1.06, respectively, five weeks and one year after treatment. Corresponding values for fundic biopsy specimens were 1.30, 0.36 and 0.35. Activity scores improved from 1.41 before treatment to 0.13 and zero, respectively, five weeks and one year after treatment in antral biopsy specimens and from 0.60 before treatment to zero in fundic biopsy specimens. Before treatment, epithelial damage was present in 51% of biopsy specimens taken from the antrum and 23% of those from the corpus. Five weeks after eradication of H pylori none of the biopsy specimens revealed evidence of epithelial damage. CONCLUSION--Eradication of H pylori is followed by a rapid, significant improvement in the gastritis score and resolution of epithelial damage in antral and fundic mucosa.     

Serological and direct diagnosis of Helicobacter pylori in gastric carcinoma: a case-control study

This study evaluated the sensitivity of serological and direct methods for the diagnosis of Helicobacter pylori infection in 127 patients with gastric carcinoma and in 127 controls without this disease, matched for age and sex. Antral and oxyntic mucosal specimens were obtained from all patients, at operation in patients with gastric carcinoma and at endoscopy from controls. The urease test, microscopy of stained smears and culture for H. pylori were performed on all specimens. Sera from all patients were tested for antibodies to H. pylori by a highly sensitive and specific IgG-ELISA. Culture, urease test, stained smear and ELISA were significantly less sensitive in the patients with gastric carcinoma than in control subjects. However, the combination of several methods improved the diagnosis of H. pylori infection in the gastric carcinoma group. Infection was significantly more frequent in the gastric carcinoma patients than in the controls. H. pylori infection was associated with an increased risk of developing gastric carcinoma.     

Diagnostic yield of gastric biopsy specimens when screening for preneoplastic lesions

The Sydney system recommends sites and numbers of stomach biopsies (mapping) for evaluation of Helicobacter pylori-associated lesions. The diagnostic yield of the recommended mapping technique in populations at high risk for gastric preneoplastic lesions has not been established. We evaluated pathology data from 733 endoscopies performed as part of an intervention study that assessed the effects of H. pylori treatment on preneoplastic conditions. Two pathologists assessed whether the mapping sequence of the 7 biopsy specimens obtained during each endoscopy was correctly followed and graded the specimens using the Sydney classification for gastritis. If the mapping sequence was followed, then we evaluated whether the amount of information obtained from 3 biopsy samples approximated that obtained from 5 and 7 biopsy samples. The mapping sequence was followed in only 239 (33%) endoscopies, indicating that experienced endoscopists can inadvertently misidentify sites in the stomach when obtaining specimens. When data from 7 specimens were used, H. pylori was found in 205 endoscopies, atrophy in 152, metaplasia in 135, and dysplasia in 22. When data from 3 specimens were used, the sensitivity was 99% for presence of H. pylori, 82% for atrophy and metaplasia, and 81% for dysplasia. When data from 5 specimens were used, the sensitivity was 100% for H. pylori, 96% for atrophy, and 95% for metaplasia and dysplasia. Although site-specific biopsy mapping is difficult in practice, the recommendations of the Sydney system as to the location and number of gastric biopsy specimens can adequately identify significant gastric histopathology.     

Helicobacter pylori in gastroduodenal diseases

OBJECTIVE: To determine the prevalence and disease association of Helicobacter pylori (H. pylori) in dyspeptic patients in southwest Nigeria. Setting: Obafemi Awolowo University Teaching Hospitals Complex, Ile-lfe, Nigeria. METHODS: Consecutive dyspeptic patients for upper gastrointestinal endoscopy from January 1996 to March 1997 were investigated for H. pylori in gastric biopsy by histopathology and culture. Patients without gastroduodenal ulcerations or neoplastic lesions constituted the nonulcer dyspeptic (NUD) group. RESULTS: 138 (92 males, 46 females) patients aged 4.5-85 years [mean (7) = 45+/-SD 17.8 years] who had upper gastrointestinal endoscopy were analyzed for presence of H. pylori. Eighty-three had histopathology alone, while 55 others had both histology and culture. Endoscopic diagnosis included duodenal ulcer (DU) (n=35, 23%); gastric ulcer (n=4, 3%); gastric cancer (n=14, 9%); NUD, including gastritis (n=49, 32%); duodenitis (n=47, 31%); and normal (n=16, 11%). Overall, H. pylori was positive in 107 of 138 (77.5%) patients. There was a significant association of H. pylori with DU and NUD (p<0.000). Three-quarters of cases of normal endoscopy harbored H. pylori. The finding of 80% and 85% H. pylori in gastritis and duodenitis, respectively, was of interest. CONCLUSIONS: These findings suggest that DU and NUD were the main clinical expressions of H. pylori infection in southwest Nigerian dyspeptic patients similar to what is found in developed nations. Of note is the high incidence of H. pylori in endoscopically normal patients.     

Detection of Helicobacter pylori antigen in stool by enzyme immunoassay

Invasive techniques for diagnosis of Helicobacter pylori (H. pylori) infection require an endoscopic examination which is expensive and inconvenient and may cause complications. Stool cultures for H. pylori or a direct detection of H. pylori antigen in stools by PCR are expensive, tedious, and have a low sensitivity. We recently used an enzyme immunoassay (EIA) to detect H. pylori antigen in stool specimens. A total of 41 patients were seen at Inha University Hospital, Inchon, Korea between September and October 1998. There were 26 men and 15 women who had an average age of 37.6 years which ranged from 5 to 71 years in the present study. All of these patients came to the hospital complaining of an upper abdominal discomfort and were subjected to endoscopy and biopsies. Fifteen had a gastric ulcer, 13 had a duodenal ulcer, 1 had an early gastric cancer, and there were 12 chronic gastritis patients as shown by endoscopy. The biopsy specimens were examined by histology, CLO test, and cultures and these results were used as gold standards. Stool specimens were tested for the H. pylori antigen by EIA. A dual wavelength cut-off of 0.100 that was recommended by the manufacturer gave a good performance (87.1% sensitivity, 100% specificity, 100% positive predictive value, 71.4% negative predictive value, and a 90.2% efficiency). But the adjusted cut-off value using the receiver operating characteristic curve improved the performance of the test (using the cut-off value of 0.024, the sensitivity, specificity, PPV, NPV, and efficiency were 100%, 90.0%, 96.9%, 100%, and 97.6% respectively). Re-evaluation of the cut-off value may be needed for Korean patients. This technique is non-invasive, rapid, easy-to-use, and shows good performance characteristics for diagnosis of H. pylori infections. Therefore, this technique may be a substitute for gastric endoscopy especially in children and some patients who are unable to tolerate an endoscopic examination and it may be substituted for a serologic test in epidemiological research.     

Evaluation of a commercially available second-generation immunoglobulin G enzyme immunoassay for detection of Helicobacter pylori infection.

We evaluated a commercially available second-generation anti-H. pylori immunoglobulin G enzyme immunoassay (EIA) (Cobas Core Anti-Helicobacter pylori EIA; Roche S. A., Basel, Switzerland) for serodiagnosis of H. pylori infection. The results of the assay were assessed in relation to the results of bacterial culture, urease testing, and histological Giemsa stain of gastric biopsy specimens from 1,134 patients with a variety of symptoms relating to the upper gastrointestinal tract. H. pylori was detected in biopsy specimens from 660 (58.2%) patients: 6 had a normal mucosa, 123 had chronic gastritis only, and 531 were found to have chronic active gastritis by histology; endoscopy showed duodenal and gastric ulcers in 137 and 64 patients of the last two groups, respectively. The test was evaluated with different age and ethnic groups. The prevalence, sensitivity, specificity, and positive and negative predictive values were, respectively, (i) for Belgian patients between 18 and 40 years old, 34, 93, 95, 91, and 96%; (ii) for Belgian patients more than 40 years old, 53, 96, 91, 93, and 95%; and (iii) the Mediterranean patients more than 17 years old, 87, 94, 70, 95, and 64%. All sera showing discordant immunoassay results compared with the results of histology and culture of biopsy specimens, as well as those with borderline immunoassay results, were tested further by immunoblotting. Among the EIA results considered false negative, we demonstrated an absence of seroconversion in 14 of 19 patients tested by immunoblotting. Among the EIA results considered false positive, immunoblotting showed the presence of specific antibodies in 28 of 37 patients tested. Among the borderline results obtained in the first assay with 22 patients' sera, a second assay showed positive results in 10 patients (8 were positive by immunoblotting) and negative reactions in 10 patients (9 were negative by immunoblotting), whereas 2 remained borderline. These data indicate that sera showing borderline immunoassay results must be tested again. In conclusion, this commercially available second-generation EIA, which is easy and quick to perform, was found highly reliable for the serodiagnosis of H. pylori infection.