14C-urea breath test for assessment of gastric Helicobacter pylori colonization and eradication.

BACKGROUND AND OBJECTIVE: Urea breath test (UBT) is a reliable noninvasive technique for detecting gastric Helicobacter pylori colonization. 14C isotope-based test requires simple equipment and is inexpensive. We studied the utility of 14C-UBT in diagnosis of gastric H. pylori infection. METHODS: Presence of H. pylori was studied using antral histology and culture in patients with rapid urease test (RUT)-positive peptic ulcer. 14C-UBT was performed using a 185-kBq dose. Radioactivity in 15-min breath samples was measured using a beta-scintillation counter and result expressed as % dose recovered/mmol CO2. H. pylori was considered positive when any two tests were positive. All tests were repeated one month after completion of H. pylori eradication therapy. RESULTS: Among 41 patients (duodenal ulcer 36, gastric ulcer 5), H. pylori was detected by histology in 23 (56%) and by culture in 27 (66%). Overall, H. pylori was detected in 28 (68%) patients. Follow-up assessment was possible in 28 patients: 26 cleared the infection (all three tests negative). Mean 14C recovery values at 15 minutes associated with H. pylori-positive status were significantly higher (12.3 [SD 6.8] x 10(-3); n=30; p<0.001) than those associated with H. pylori-negative status (2.1 [0.9] x 10(-3); n=26). Using receiver-operating-characteristic analysis of 15-minute 14C recovery values, a cut-off of 6.5x10(-3) gave the best separation of H. pylori-positive and -negative cases. 14C-UBT had 93% sensitivity, 96% specificity and 95% accuracy. CONCLUSION: 14C-UBT appears to be a reliable noninvasive test for diagnosis of H. pylori infection.     

Immunological rapid urease test using monoclonal antibody for Helicobacter pylori

BACKGROUND AND AIM: The current diagnostic methods for detecting Helicobacter pylori infection include rapid urease test (RUT), urea breath test (UBT), histology, culture, and serum antibody detection. The present study evaluated the efficacy of a novel highly specific test, an immunological RUT (IRUT), that uses a monoclonal antibody against H. pylori urease. METHODS: The clinical evaluation of the IRUT was performed in 100 subjects. Each gastric mucus sample obtained during endoscopic examination was incubated for 15 min with a solid tip coated with monoclonal antibody for H. pylori urease, and then the tip was introduced into a pH-monitoring cell containing urea solution. The change in pH of the solution after the enzymatic reaction (delta pH) was measured. The performance of the IRUT was compared with culture, histology, RUT, and UBT. RESULTS: Of the 47 H. pylori-positive subjects, 43 were IRUT positive (sensitivity, 91.5%), and of the 53 H. pylori-negative subjects, 52 were negative (specificity, 98.1%). Compared with the usual diagnostic methods, IRUT had high sensitivity and specificity for the detection of H. pylori and was no less efficient. CONCLUSIONS: IRUT is a sensitive, specific and very rapid (within 20 min) method of detecting H. pylori infection.     

Evaluation of 13C-urea breath test to confirm eradication of Helicobacter pylori]

This study aimed to evaluate the effectiveness of the 13C-urea breath test (UBT) for assessment of Helicobacter pylori eradication after treatment. One hundred twenty six patients were enrolled with 85 receiving proton pomp inhibitor based triple therapy. They were underwent upper gastrointestinal endoscopy with biopsies for diagnosis and assessment of H. pylori infection using culture, histology, rapid urease test (RUT) and 13C-UBT. Assessment of eradication needs to be performed 4 weeks or more after completion of treatment. Breath samples were taken 15 minutes after the ingestion of 100 mg 13C-urea. Breath samples were analyzed on a mass spectrometer system. The gold standard for H. pylori infection was a positive culture or positive histology + positive RUT; negative for infection was defined as negative results of all three biopsy tests. Based on ROC curves, the most appropriate cut-off value for diagnosis of H. pylori infection was identified as 2.5/1000, which provided 96.2% sensitivity, 100% specificity, and 96.8% accuracy as judged by the gold standard. However, when confirming the eradication of H. pylori, it was 3.5/1000, which provides for 100%, 95.8%, and 96.5%, respectively. Ten patients (11.8%) had delta13C values that were 2.5-5.0/1000 4-12 weeks after therapy. Eight patients were considered cured of H. pylori infection, and 2 were considered to still have H. pylori infection following 13C-UBT, serology, and H. pylori specific antigen test. The false-positive rate of 13C-UBT was 9.4% (8/85). When the grey zone of 13C-UBT was set at a level of 2.5 to 5.0/1000 (2.5 > : negative, 5.0 < or = : positive) after eradication therapy, the sensitivity and specificity of 13C-UBT was 100% and 98.4% compared to the gold standard. It was concluded that to avoid false-positive results of 13C-UBT, the grey zone of 13C-UBT needs to be set at a level of 2.5 to 5.0/1000; thus improving the accuracy of test for the assessment of eradication of H. pylori infection.     

14C-尿素呼气试验对幽门螺杆菌感染的诊断价值

目的：评估^14C-尿素呼气试验（^14C-UBT）对幽门螺杆菌（HP）感染的诊断价值。方法：对2000例1月内未曾使用可能影响HP检测结果的药物者同步完成快速尿酶试验（RUT）、病理、^14C-UBT检测，以病理（HE染色）、RUT均阳性为诊断HP感染的标准，评价^14C-UBT对HP感染的诊断价值。结果：^14C-UBT的敏感性89.7％，特异性98.4％，阳性预测值98.4％，准确性93.4％，阴性预测值88.1％。结论：^14C-UBT是HP感染无创伤、敏感而特异的诊断方法。     

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.     

Human gastric mucosal hydrophobicity does not decrease with Helicobacter pylori infection or chronological age.

BACKGROUND AND AIMS: Infection with cytotoxin-associated gene A (cagA) Helicobacter pylori is associated with severe gastric diseases. Previous studies in humans have reported a decreased gastric hydrophobicity with H pylori infection. The aim of the present study was to differentiate between the effect of cagA+ and cagA- strains on gastric mucus hydrophobicity. METHODS: One hundred patients without peptic ulcers and not on medication were randomly recruited from endoscopy clinics; each patient had six biopsies. Contact angle measurements were performed using a goniometer assisted by computer software. H pylori status was assessed by histology, Campylobacter-like organism test and culture, and cagA+ status was determined by polymerase chain reaction. RESULTS: In age- and sex-matched patients, there was no significant difference (P=0.27) in contact angle between H pylori-positive (61+/-2.8 degrees ) and H pylori-negative patients (65.5+/-3.0 degrees ). There was also no significant difference (P=0.36) in contact angle among H pylori-negative, cagA- and cagA+ patients (65.5+/-3.0 degrees , 58.6+/-3.6 degrees and 63.4+/-4.9 degrees , respectively). However, a trend of increased mean contact angles in cagA+ compared with cagA- and H pylori-negative patients was observed in patients 50 years and younger (68.3+/-8.3 degrees , 61.1+/-6.1 degrees and 63.6+/-2.2 degrees , respectively; P=0.70) and in patients without atrophy (71.1+/-8 degrees , 59.6+/-4 degrees and 66+/-2 degrees , respectively; P=0.30). In addition, there was no significant correlation between contact angles and patient age (r=0.104, P=0.306). CONCLUSIONS: The present study shows that H pylori infection and the chronological age have no effect on the gastric mucus hydrophobicity, but it highlights a trend of increased mucus hydrophobicity with cagA+ infection that needs to be supported by future studies.     

幽门螺杆菌感染诊断方法的比较

338例病人同时进行了快速尿素酶试验(简称RUT)。Warthin-Starry染色(简称W-S染色)、培养法、~(13)C-尿素呼气试验(~(13)C-UBT)、血清IgG、IgM等6种诊断方法中任意3种检查,以同时2种(或以上)检查方法一致的结果作为诊断幽门螺杆菌(Hp)是否存在的标准。对上述6种方法的敏感性、特异性、符合率、阳性预测值、阴性预测值分别给予评价,结果显示:RUT、W-S染色、~(13)C-UBT三法诊断Hp的敏感性、特异性等较高,均接近或高于90％。     

Helicobacter pylori stool antigen (HpSA) test--a simple, accurate and non-invasive test for detection of Helicobacter pylori infection

BACKGROUND/AIMS: To access the reliability of a newly developed test, the Helicobacter pylori (H. pylori) stool antigen (HpSA) test was used for detection of H. pylori infection. METHODOLOGY: Stool specimens were collected from 33 consecutive patients (19 males and 14 females, age range: 16-73 years, mean: 49 years) who received upper gastrointestinal endoscopic examination for gastrointestinal symptoms. The H. pylori status was evaluated based on six different tests: culture, histology, biopsy urease test, 13C-urea breath test (13C-UBT), serology, and HpSA test. A commercial kit using an enzyme-linked immunosorbent assay examined HpSA in the stool. H. pylori status was defined as positive when the culture was positive or concordance of three of the other four tests (histology, biopsy urease test, 13C-UBT, and serology) was positive. RESULTS: Twenty patients were diagnosed as H. pylori-positive. The HpSA test was positive in 19 patients and negative in 14 patients. The sensitivity and specificity were 95.0% and 100%, respectively. The overall accuracy rate was 96.3%. CONCLUSIONS: The HpSA test is a new, simple, non-invasive method for accurate diagnosis of H. pylori infection.     

老年人幽门螺杆菌粪便抗原检测的价值

目的 评价一种新的酶联免疫法检测老年人粪便中幽门螺杆菌（helicobacter pylori,Hp）特异抗原的可靠性和临床应用价值。方法 因上消化道症状行胃镜检查的老年患者共199例，其中既往无胃手术史者151例，胃大部切除术后者48例。均行胃粘膜活检，作快速尿素酶试验（RUT）和组织学检查（W－S染色），以RUT和W－S染色为金标准，两项均阳性（或阴性）诊断为Hp阳性（或阴性）。所有患者均检查幽门螺杆菌粪便抗原（HpSA）和^13C－尿素呼气试验（^13C-UBT），分别与金标准比较，计算其敏感性和特异性。结果 经金标准诊断，无胃手术史患者中Hp阳性81例，阴性70例。HpSA检测的敏感性和特异性分别为96.3%和90.0%，^13C-UBT为92.6%和92.9%，两种方法的敏感性和特异性差异无显著性。胃大部切除术后患者中Hp阳性23例，阴性25例，HpSA检测的敏感性和特异性分别为91.3%和88.0%，^13C-UBT为65.2%和92.0%，两种方法敏感性差异有显著性（P＜0.05）。结论 HpSA在诊断老年人Hp感染方面准确、快速、简便，值得推广。对于胃大部切除术后的老年患者，其诊断Hp的敏感性明显优于^13C-UBT。     

Mucosal polymerase chain reaction for diagnosing Helicobacter pylori infection in patients with bleeding peptic ulcers

AIM: Helicobacter pylori (H pylon) has been linked to chronic gastritis, peptic ulcers, gastric cancer and MALT-lymphoma. Conventional invasive tests are less sensitive than non-invasive tests in diagnosing H pylori infection in patients with bleeding peptic ulcers. Polymerase chain reaction is a sensitive and accurate method for diagnosing H pylori infection. The aim of this study was to evaluate the diagnostic role of mucosai polymerase chain reaction for H pylori infection in patients with bleeding peptic ulcers. METHODS: In patients with bleeding, non-bleeding peptic ulcers and chronic gastritis, we checked rapid urease test, histology, bacterial culture and mucosai polymerase chain reaction fordetecting H pylori infection. Positive H pylori infection was defined as positive culture or both a positive histology and a positive rapid urease test. For mucosai polymerase chain reaction of H pylori, we checked vacA (s1a, s1b, s1c, s2, m1, m1T, m2), iceA1, iceA2. and cag A. RESULTS: Between October 2000 and April 2002,88 patients with bleeding peptic ulcers (males/females: 60/28, gastric ulcers/duodenal ulcers: 55/33), 81 patients with non-bleeding peptic ulcers (males/females: 54/27, gastric ulcers/duodenal ulcers: 45/36) and 37 patients with chronic gastritis (males/ females: 24/13) were enrolled in this study. In patients with bleeding peptic ulcers, non-bleeding peptic ulcers and chronic gastritis, 45 patients (51%), 71 patients (88%) and 20 patients (54%) respectively were found to have positive H pylori infection (P<0.001). In patients with bleeding peptic ulcers, non-bleeding peptic ulcers and chronic gastritis, polymerase chain reaction for H pylori infection was positive in 54 patients (61%), 70 patients (86%) and 20 patients (54%) respectively (P<0.001). The sensitivity, positive predictive value and diagnostic accuracy of mucosai polymerase reaction for H pylori infection were significantly lower in patients with bleeding peptic ulcers (84%, 79% and 81%) than in patients with non-bleeding peptic ulcers (99%, 99% and 98%) (P<0.001, P<0.01 and P<0.001 respectively). The sensitivity, negative predictive value and diagnostic accuracy of mucosal polymerase reaction for H py/ori were significantly lower in patients with bleeding peptic ulcers (84%, 83% and 81%) than in patients with chronic gastritis (100%, 100% and 100%) (P= 0.02, P= 0.02 and P=0.001). CONCLUSION: Mucosal polymerase chain reaction for detecting H pylori infection is not reliable in patients with bleeding peptic ulcers.     

~(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。     

Detecting Helicobacter pylori infection in hospitalized frail older patients: the challenge

OBJECTIVES: Helicobacter pylori infection has not been well studied in older people, especially in hospitalized, frail patients. The aim of our study was to evaluate the prevalence of the infection in this population using five H. pylori diagnostic tests. DESIGN: Prospective observational study. SETTING: Geriatric acute care unit of the Department of Geriatrics (H?pital Xavier Arnozan, Pessac, France). PARTICIPANTS: One hundred seven consecutively hospitalized patients with a diagnostic indication for upper gastrointestinal endoscopy. MEASUREMENTS: Geriatric assessment, information on drug intake, indication/results of gastric endoscopy, and results of H. pylori infection diagnostic tests (culture and histological analysis on biopsy specimens, serology, 13carbon-urea breath test (13C-UBT), detection of H. pylori stool antigens (HpSA)) were assessed for each included patient. RESULTS: Fifty-one patients (47.7%) were H. pylori positive with at least one test. 13C-UBT was more frequently positive than the other four tests, with a significant difference from culture, histological analysis, and HpSA (P <.05). Positive 13C-UBT results were significantly associated with H. pylori presence using histological analysis and neutrophil activity of the antrum and corpus. Antibiotic treatments significantly decreased the positivity rate of all of the tests performed, and severe corpus atrophy decreased the positivity rate of culture, histological analysis, and HpSA. CONCLUSIONS: Almost one-third of the H. pylori-positive patients would have remained undetected without performing the 13C-UBT. The low prevalence of H. pylori detection in these hospitalized, frail patients may be explained by the high frequency of current and previous antibiotic treatments.     

Diagnostic accuracy of the C-urea breath test in children: adjustment of the cut-off value according to age

BACKGROUND AND AIMS: The (13)C-urea breath test ((13)C-UBT) is a reliable non-invasive method of diagnosing Helicobacter pylori infection in adults and children. However, only a few validation studies have been performed on the (13)C-UBT in very young children. The purpose of the present study was to evaluate the diagnostic accuracy of the (13)C-UBT according to age, and to determine the optimal cut-off value in children. METHODS: A total of 307 (13)C-UBT were performed in 274 children. All were compared with the results of endoscopic biopsy-based methods to confirm H. pylori infection. Seventy-five milligrams of (13)C-urea was ingested without a test meal. Two breath samples were collected at 0 and 30 min. The optimal cut-off value of the (13)C-UBT was assessed by determining the sensitivity, specificity, false negative, and false positive results, at cut-off values ranging from 2.0 to 10.0 per thousand. RESULTS: The delta over baseline (DOB) values of the (13)C-UBT showed a significant negative correlation with age in both the H. pylori-positive group (r = -0.309; P = 0.005) and the H. pylori-negative group (r = -0.162; P = 0.015). High false positive results and low specificity were noted in children aged 6 years or less compared with children older than 6 years at a cut-off value of 4.0 per thousand (false positives; 8.3%vs 0.85%, specificity; 89.8%vs 98.8%). After adjusting the cut-off value, the optimal cut-off values were found to be 4.0 per thousand in children older than 6 years and 7.0 per thousand in children aged 6 years or less. CONCLUSIONS: The cut-off value of the (13)C-UBT recommended regardless of age must be adjusted in preschool children to reduce the false positive results.     

Effects of cagA+ and cagA- strains of Helicobacter pylori on the human gastric mucus layer thickness

BACKGROUND: Infection with cytotoxin-associated gene A (cagA) Helicobacter pylori is associated with severe gastric diseases, with contradictory views being expressed concerning the effect of H. pylori on the gastric mucus thickness. The aim of the present study was to differentiate between the effect of cagA+ and cagA- strains on gastric mucus thickness. METHODS: Ninety-nine patients without peptic ulcers who were not on medication were randomly recruited from consecutive endoscopy clinics: six biopsies (five antral, one body) were obtained from each patient. Cryostat sections (18 microm) were cut and stained using the modified periodic acid-Schiff/Alcian blue technique. Mucus thickness was measured using computer-assisted light microscopy. The H. pylori status was assessed by histology, Campylobacter-like organism (CLO)test and culture, and cagA+ status determined by polymerase chain reaction (PCR). RESULTS: There was no significant difference (P = 0.784) in mean mucus thickness between cagA+ (52.7 +/- 1.2 microm, n = 10), cagA- (46.6 +/- 1.1 microm, n = 18) or H. pylori-negative patients (51.3 +/- 1.1 microm, n = 30). In cagA- patients, mucus thickness was significantly reduced with increased H. pylori colonization density, Spearman (r(s)) = -0.805, P < 0.0001. In contrast, in cagA+ patients there was a weak positive, but not significant, association between mucus thickness and H. pylori colonization density, r(s) = 0.333, P = 0.381. CONCLUSIONS: The human gastric mucus thickness is not affected by infection with cagA+ or cagA- strains of H. pylori compared with uninfected. Although a trend of increased mucus thickness with cagA+ infection was observed.     

Urea breath test for Helicobacter pylori detection: present status.

Helicobacter pylori (H. pylori) is the commonest bacterial pathogen found worldwide and more than half the world population aged 40 years and above is colonized with it. The infection rate is >95 % in some African countries. In 1994, the International Agency for Research on cancer classified H. pylori as a class I carcinogen in humans. It causes chronic active gastritis, duodenal and gastric ulcer and gastric malignancy, and is thought to be associated with coronary artery disease, cerebral stroke, vitamin B12 and iron-deficiency anaemia, etc. Therefore, non-invasive test-and-treatment strategies are widely recommended in primary care settings. Conventionally, H. pylori infection can be diagnosed by invasive techniques using an upper gastrointestinal endoscope for obtaining multiple biopsies from different sites of the stomach for RUT, culture, histological examination, polymerase chain reaction (PCR), etc. and by non-invasive tests such as Urea breath test (UBT), stool antigen test and blood serology. At present, 13/14C-UBT is considered the test of choice for confirmation of H. pylori infection. The UBT is based on the principle, that isotopically labelled urea ingested by an H. pylori--infected patient is rapidly hydrolysed by the microbial urease. The released 13/14CO2 is absorbed across the mucous layer to the gastric mucosa and hence, excreted via the systemic circulation in the breath which is collected and measured. The non-hydrolysed urea is excreted completely in the urine within 3-4 days. 13C-UBT being non-radioactive, 13C-UBT can be used in pregnant women and children, and a user's license is not required. There is still no standard protocol accepted and followed internationally for this test. Although the methods are almost similar, various laboratories/clinics use variable tracer doses, test meals, timings and methods for breath collection, and different cut-off values, which make formal validation studies necessary. This review describes the present status of the UBT and its application in the detection of H. pylori infection.     

Diagnosis of Helicobacter pylori infection in patients with atrophic gastritis: comparison of histology, 13C-urea breath test, and serology

BACKGROUND: Atrophic gastritis, a risk factor for gastric cancer, is a late consequence of Helicobacter pylori infection in approximately one-third of the infected patients. It has been suggested that gastric cancer would develop less frequently if H. pylori were eradicated. However, the prevalence of H. pylori infection may be underestimated in patients with atrophic gastritis and intestinal metaplasia if only biopsy-based diagnostic methods are used. METHODS: We compared histology, 13C-urea breath test (13C-UBT), and serology in H. pylori diagnostics in 50 male patients with atrophic corpus gastritis. RESULTS: H. pylori was detected in 15 (30%) patients by histology and in 14 (28%) by 13C-UBT, whereas increased serum antibody levels indicating H. pylori infection were found in 41 (82%) patients (P < 0.0001 between serology and both histology and 13C-UBT). H. pylori infection was associated with atrophic corpus gastritis in 84% of the present patients (in one patient with normal antibody titres H. pylori was defined histologically). CONCLUSIONS: H. pylori infection would have been missed in most patients with atrophic gastritis without the analysis of H. pylori antibodies. Therefore, in patients with atrophic gastritis, the use of serology is encouraged in diagnosing H. pylori infection.     

Gastric acid secretion of normal Japanese subjects in relation to Helicobacter pylori infection, aging, and gender

BACKGROUND: In Japan, where the incidence of gastric cancer is high, Helicobacter pylori infection could affect gastric acid secretion differently from that in Western countries. The aim of this study was to investigate the relationship between H. pylori infection, acid secretion, aging, and gender in normal Japanese subjects. METHODS: The study comprised 193 Japanese subjects who had undergone routine endoscopy. Gastrin-stimulated acid output was performed during the routine endoscopic examination using the endoscopic method of gastric acid secretory testing (EGT: endoscopic gastrin test), which has been reported previously. H. pylori status was determined by histology, rapid urease test, and serology. RESULTS: Mean EGT values were 3.9 +/- 1.5 mEq/10 min in H. pylori-negative men, 1.6 +/- 2.5 in H. pylori-positive men, 2.2 +/- 0.9 in H. pylori-negative women, and 1.5 +/- 1.2 in H. pylori-positive women. Although acid secretion was lower in H. pylori-positive subjects compared with H. pylori-negative subjects in both men and women, the decrease was more marked in men with H. pylori infection. Multiple linear regression analysis showed that aging is positively associated with gastric acid secretion in the H. pylori-negative subjects, whereas a negative association was found between them in the H. pylori-positive subjects. CONCLUSIONS: In Japanese subjects, aging affects gastric acid secretion differently depending on the status of H. pylori infection. H. pylori infection showed a stronger inhibitory effect on the acid secretion in men than in women. This gender-related difference in the susceptibility of acid secretion to H. pylori infection may explain the higher rates of gastric cancer in men in Japan.     

广东地区幽门螺杆菌cagA基因与细菌定植及其致病性关系的研究

目的：分析广东地区细胞毒素相关基因（cagA）在幽门螺杆菌（H.pylori)中的分布情况及其与患者性别、年龄的关系；探讨H.pylori cagA在不同胃肠疾病发生中的作用及其与胃粘膜慢性炎症程度及H.pylori定植密度的关系。方法：采用改良Skirrow培养基分离培养得到191株H.pylori，用特定引物对各株细菌的cagA 3′端行聚合酶链反应（PCR）扩增鉴定；对其中83例患者再各取胃窦粘膜2块，经HE及Giemsa染色后观察胃粘膜慢性炎症程度及H.pylori定植密度。结果：广东地区H.pylori cagA阳性者占85.3%(163/191)；H.pylori cagA阳性率与患者的性别、年龄无关；消化性溃疡及胃癌患者的H.pylori cagA阳性率显著高于慢性胃炎患者；cagA阳性H.pylori菌株在胃粘膜表面的定植密度较cagA阴性菌株更高，引起的胃粘膜慢性炎症也更为严重；H.pylori的定植密度与其引起的慢性炎症程度呈正相关。结论：广东地区cagA阳性H.pylori感染者占绝大多数；cagA阳性菌株较cagA阴性菌株具有更强的致病力，可能引起更为严重的胃肠道损害。     

Validity of various diagnostic tests to evaluate cure ofHelicobacter pylori infection

Many diagnostic methods have been developed and used for detectingHelicobacter pylori to evaluate the success of treatment ofH. pylori infection. We investigated and compared the suitability of the rapid urease test (RUT), polymerase chain reaction (PCR),¹³C-urea breath test (¹³C-UBT), and serology with culture for evaluating cure ofH. pylori infection. Forty-sevenH. pylori-positive gastric ulcer patients received dual therapy of lansoprazole (30 mg u.i.d.) and clarithromycin (200 mg b.i.d.). Four weeks after the completion of treatment, RUT, PCR,¹³C-UBT, and culture were performed and the negative rates of these tests were compared. Anti-H. pylori IgG antibodies were measured by enzyme-linked immunosorbent assay (ELISA) before and 4 weeks after completion of the treatment to evaluate changes of titers during the treatment. The negative rate of RUT (55%) was significantly greater than that of culture (27%). Significant declines in titers were seen in the patients who had negative culture results, while the decline in the titer was not significant in the patients who had positive results. PCR assay and¹³C-UBT were suitable for the evaluation ofH. pylori eradication, but RUT was not suitable, because of its sensitivity. By monitoring anti-H. pylori IgG antibody titers, therapeutic failure can be detected early after completion of treatment.