Evaluation of a new biopsy urease test: Pronto Dry, for the diagnosis of Helicobacter pylori infection

A Malaysian consensus report on the diagnosis and treatment of Helicobacter pylori infection

Helicobacter pylori is one of the most common chronic bacterial infections in humans and responsible for 90% of duodenal ulcers and 70-90% of gastric ulcers. Despite this, many misconceptions regarding the appropriate diagnostic method and treatment strategies still exist in the Malaysian clinical practice. Under the initiative of the steering committee, an expert panel consisting of nine key opinion leaders in the field of gastroenterology convened to develop a set of consensus statements that are relevant to the Malaysian healthcare practice. The panel members reviewed the current evidence on the management of H. pylori infection, focusing on the best practices that are relevant to the Malaysian population based on clinical experience and published clinical evidence. Using the modified Delphi method, the panel achieved consensus in three areas of H. pylori infection management: indications for testing, diagnosis, and treatment. The panel proposed a set of 19 consensus statements, which were synthesized via two rounds of blinded voting and group discussions. The recommendations provided are relevant to the Malaysian population and can be used as a guide by physicians across various healthcare settings to facilitate appropriate diagnostic testing and treatment of H. pylori infection.

Intraprocedural gastric juice analysis as compared to rapid urease test for real-time detection of Helicobacter pylori

BACKGROUND

Endofaster is an innovative technology that can be combined with upper gastrointestinal endoscopy (UGE) to perform gastric juice analysis and real-time detection of Helicobacter pylori (H. pylori).

AIM

To assess the diagnostic performance of this technology and its impact on the management of H. pylori in the real-life clinical setting.

METHODS

Patients undergoing routine UGE were prospectively recruited. Biopsies were taken to assess gastric histology according to the updated Sydney system and for rapid urease test (RUT). Gastric juice sampling and analysis was performed using the Endofaster, and the diagnosis of H. pylori was based on real-time ammonium measurements. Histological detection of H. pylori served as the diagnostic gold standard for comparing Endofaster-based H. pylori diagnosis with RUT-based H. pylori detection.

RESULTS

A total of 198 patients were prospectively enrolled in an H. pylori diagnostic study by Endofaster-based gastric juice analysis (EGJA) during the UGE. Biopsies for RUT and histological assessment were performed on 161 patients (82 men and 79 women, mean age 54.8 ± 19.2 years). H. pylori infection was detected by histology in 47 (29.2%) patients. Overall, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value (NPV) for H. pylori diagnosis by EGJA were 91.5%, 93.0%, 92.6%, 84.3%, and 96.4%, respectively. In patients on treatment with proton pump inhibitors, diagnostic sensitivity was reduced by 27.3%, while specificity and NPV were unaffected. EGJA and RUT were comparable in diagnostic performance and highly concordant in H. pylori detection (κ-value = 0.85).

CONCLUSION

Endofaster allows for rapid and highly accurate detection of H. pylori during gastroscopy. This may guide taking additional biopsies for antibiotic susceptibility testing during the same procedure and then selecting an individually tailored eradication regimen.

Intraprocedural gastric juice analysis as compared to rapid urease test for real-time detection of Helicobacter pylori

BACKGROUND

Endofaster is an innovative technology that can be combined with upper gastrointestinal endoscopy (UGE) to perform gastric juice analysis and real-time detection of Helicobacter pylori (H. pylori).

AIM

To assess the diagnostic performance of this technology and its impact on the management of H. pylori in the real-life clinical setting.

METHODS

Patients undergoing routine UGE were prospectively recruited. Biopsies were taken to assess gastric histology according to the updated Sydney system and for rapid urease test (RUT). Gastric juice sampling and analysis was performed using the Endofaster, and the diagnosis of H. pylori was based on real-time ammonium measurements. Histological detection of H. pylori served as the diagnostic gold standard for comparing Endofaster-based H. pylori diagnosis with RUT-based H. pylori detection.

RESULTS

A total of 198 patients were prospectively enrolled in an H. pylori diagnostic study by Endofaster-based gastric juice analysis (EGJA) during the UGE. Biopsies for RUT and histological assessment were performed on 161 patients (82 men and 79 women, mean age 54.8 ± 19.2 years). H. pylori infection was detected by histology in 47 (29.2%) patients. Overall, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value (NPV) for H. pylori diagnosis by EGJA were 91.5%, 93.0%, 92.6%, 84.3%, and 96.4%, respectively. In patients on treatment with proton pump inhibitors, diagnostic sensitivity was reduced by 27.3%, while specificity and NPV were unaffected. EGJA and RUT were comparable in diagnostic performance and highly concordant in H. pylori detection (κ-value = 0.85).

CONCLUSION

Endofaster allows for rapid and highly accurate detection of H. pylori during gastroscopy. This may guide taking additional biopsies for antibiotic susceptibility testing during the same procedure and then selecting an individually tailored eradication regimen.

Evaluation of Accuracy and Feasibility of a New-Generation Ultra-Rapid Urease Test for Detection of Helicobacter pylori Infection

Helicobacter pylori (Hp) infection can be diagnosed by invasive and noninvasive methods, and, among the former, Rapid Urease Tests (RUTs) are an important option. Accuracy and rapidity of results are fundamental for RUTs. The aim of the study is to prospectively evaluate the sensitivity, specificity and time to positivity of a new-generation ultra-rapid urease test (iNatal duo test) for Hp detection and compare the results with other available RUTs [CLO Test (Campylobacter-Like Organism Test), CP Test (Campylobacter pylori Test) and Pronto Dry]. Gastric biopsies were taken in consecutive patients undergoing upper endoscopy: two in the antrum and two in the body for histology, and one in the antrum and one in the body for each RUT. RUTs were read at 1, 5, 15, 30 and 60 min, 3 h and 24 h after biopsy insertion into the reagent. Histology was considered as “gold standard”. The performance of the tests was evaluated in patients not taking proton pump inhibitors (PPI) (n = 924) by calculation of sensitivity, specificity and positive and negative predictive value. Agreement rate (κ) for every RUT and histology was calculated and compared. The performance of the iNatal duo test was also tested in a subgroup of patients taking PPI (n = 198). Hp was positive in 225/924 patients (24.3%) not taking PPIs and in 56/198 (28.3%) who were taking PPIs. The iNatal duo test was more sensitive than the other RUTs for detecting Hp at every time point. The sensitivity at 5 min was 96.2% in patients not taking PPIs and 92.2% in patients taking PPIs. κ with histology was higher for the iNatal duo test than any other RUT (at 30 min: iNatal duo 0.99, CLO 0.60, CP 0.78, Pronto 0.85, at 15 min: iNatal duo 0.99, CLO 0.46, CP 0.63, Pronto 0.71). In a prospective study, the iNatal duo test demonstrated high accuracy and rapidity for Hp detection, both in patients with and without PPI therapy. This new generation of ultra-rapid urease test could be useful for the rapid and correct management of patients undergoing upper GI endoscopy for suspected Hp infection.

Effect of Helicobacter pylori eradication and high-density lipoprotein on the risk of de novo gastric cancer development

BACKGROUND AND AIMS

The effect of Helicobacter pylori eradication on de novo gastric cancer is controversial, although meta-analyses suggest a reduction in gastric cancer after eradication. The effect of high-density lipoprotein (HDL) on gastric cancer has been rarely reported.

METHODS

In this large retrospective cohort study, participants underwent endoscopy and H pylori testing from 2003 to 2011 and underwent follow-up endoscopy and H pylori testing until 2013. H pylori infection was detected using a rapid urease test or histologic test. The H pylori eradication group was defined as successful eradication, whereas the H pylori persistent group was defined as noneradication or eradication failure. The risk of cancer was measured with hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Among 10,328 healthy subjects (5951 men; mean age, 48.7 years), 31 gastric cancers were detected during a median follow-up of 5.5 years. De novo gastric cancer developed in 21 of 3508 subjects (.6%) in the noneradication group, 4 of 2050 subjects (.2%) in the successful eradication group, and 6 of 4770 participants (.13%) in the absence of H pylori group. In the adjusted analysis, H pylori eradication decreased de novo gastric cancer risk (HR, .29; 95% CI, .10-.86) compared with the persistent group. The risk of de novo gastric cancer in absence of H pylori was also much lower compared with the persistent group (HR, .24; 95% CI, .09-.60). Low serum HDL increased the risk of de novo gastric cancer (HR, 2.67; 95% CI, 1.14-6.16).

CONCLUSIONS

Successful H pylori eradication reduced de novo gastric cancer, whereas low HDL increased its risk.

Gender-specific Effect of Micronutrient on Non-erosive Reflux Disease and Erosive Esophagitis

Background/Aims

The effect of dietary micronutrients on non-erosive reflux disease (NERD) and reflux esophagitis is unclear. We aim to evaluate the gender-specific effect of micronutrient on erosive esophagitis and NERD.

Methods

A total of 11 690 participants underwent endoscopy and completed 3-day recordings for dietary intake and questionnaires for reflux symptoms from 2004 to 2008. To evaluate the effect of dietary micronutrients on NERD or erosive esophagitis, adjusted regression analysis with odds ratio (OR) and 95% confidence interval (CI) was used. In addition, we performed gender-specific analysis.

Results

Prevalence of NERD and erosive esophagitis was 6.8% and 11.2% in men and 9.1% and 2.4% in women. In adjusted analysis, high intake of vitamin A (OR, 0.78; 95% CI, 0.64–0.96), retinol (OR, 0.73; 95% CI, 0.59–0.90), vitamin B2 (OR, 0.68; 95% CI, 0.54–0.87), vitamin B6 (OR, 0.75; 95% CI, 0.58–0.96), folic acid (OR, 0.77; 95% CI, 0.62–0.96), calcium (OR, 0.66; 95% CI, 0.53–0.82), and iron (OR, 0.68; 95% CI, 0.53–0.87) had an inverse association with NERD. However, erosive esophagitis has no relationship with micronutrients except vitamin C (OR, 0.78; 95% CI, 0.62–0.98). High dietary intake of calcium reduced the risk of NERD in men and high dietary intake of many micronutrients reduced NERD in women.

Conclusions

While many dietary micronutrients reduced NERD, they had no effect on erosive esophagitis. The effect of micronutrient on NERD was more prominent in women than men.

Association of current Helicobacter pylori infection and metabolic factors with gastric cancer in 35,519 subjects: A cross-sectional study

Background

The effect of current infection of Helicobacter pylori on gastric cancer has rarely been studied in a large population. We investigated the association of current H. pylori infection and metabolic factors with gastric cancer in a large population.

Methods

Persons who made their first visit to the National Cancer Center for a health examination, including endoscopy and H. pylori testing using gastric tissue between 2003 and 2013, were included. The association of H. pylori with gastric cancer was estimated using odds ratios (ORs) and 95% confidence intervals (CIs).

Results

Among 35,519 people, 113 gastric cancer and 158 gastric dysplasia cases were detected. In the adjusted analysis, gastric cancer was associated with current H. pylori infection (OR, 2.39; 95% CI, 1.53-3.74), age (OR, 1.06; 95% CI 1.04-1.08), first-degree relatives with gastric cancer (OR, 2.08; 95% CI, 1.30-3.32) and hyperglycaemia (OR, 1.66; 95% CI, 1.04-2.65), whereas it was inversely associated with high-density lipoprotein (HDL) (OR, 0.49; 95% CI, 0.22-0.94). In the subanalysis, gastric cancer was associated with first-degree relatives with gastric cancer (OR, 3.23; 95% CI, 1.39-7.50) in the absence of H. pylori, whereas it was associated with hyperglycaemia (OR, 1.98; 95% CI, 1.16-3.39) in the presence of H. pylori.

Conclusions

Gastric cancer was associated with current H. pylori infection, hyperglycaemia, and low HDL levels in a large population.

Rapid urease test (RUT) for evaluation of urease activity in oral bacteria in vitro and in supragingival dental plaque ex vivo

BACKGROUND

Urease is an enzyme produced by plaque bacteria hydrolysing urea from saliva and gingival exudate into ammonia in order to regulate the pH in the dental biofilm. The aim of this study was to assess the urease activity among oral bacterial species by using the rapid urease test (RUT) in a micro-plate format and to examine whether this test could be used for measuring the urease activity in site-specific supragingival dental plaque samples ex vivo.

METHODS

The RUT test is based on 2% urea in peptone broth solution and with phenol red at pH 6.0. Oral bacterial species were tested for their urease activity using 100 μl of RUT test solution in the well of a micro-plate to which a 1 μl amount of cells collected after growth on blood agar plates or in broth, were added. The color change was determined after 15, 30 min, and 1 and 2 h. The reaction was graded in a 4-graded scale (none, weak, medium, strong). Ex vivo evaluation of dental plaque urease activity was tested in supragingival 1 μl plaque samples collected from 4 interproximal sites of front teeth and molars in 18 adult volunteers. The color reaction was read after 1 h in room temperature and scored as in the in vitro test.

RESULTS

The strongest activity was registered for Staphylococcus epidermidis, Helicobacter pylori, Campylobacter ureolyticus and some strains of Haemophilus parainfluenzae, while known ureolytic species such as Streptococcus salivarius and Actinomyces naeslundii showed a weaker, variable and strain-dependent activity. Temperature had minor influence on the RUT reaction. The interproximal supragingival dental plaque between the lower central incisors (site 31/41) showed significantly higher scores compared to between the upper central incisors (site 11/21), between the upper left first molar and second premolar (site 26/25) and between the lower right second premolar and molar (site 45/46).

CONCLUSION

The rapid urease test (RUT) in a micro-plate format can be used as a simple and rapid method to test urease activity in bacterial strains in vitro and as a chair-side method for testing urease activity in site-specific supragingival plaque samples ex vivo.

Different effects of dietary factors on reflux esophagitis and non-erosive reflux disease in 11,690 Korean subjects

BACKGROUND

Although dietary factors seem to be associated with gastroesophageal reflux symptoms, their effects on reflux esophagitis and non-erosive reflux disease (NERD) are unclear. We evaluate dietary effects on NERD and reflux esophagitis.

METHODS

A total of 11,690 health check-up persons completed questionnaires for reflux symptoms and 3-day recordings for dietary intake and underwent esophagogastroduodenoscopy from 2004 to 2008. Multiple logistic regression with odds ratio (OR) and 95% confidence interval (CI) was used to evaluate the relationship of dietary components with NERD or reflux esophagitis.

RESULTS

Prevalence of NERD and reflux esophagitis was 7.7 and 7.2%, respectively. In adjusted analysis, highest quartile of beans (OR 0.78, 95% CI 0.64-0.95), 3rd quartile of vegetables (OR 0.74, 95% CI 0.60-0.91), 4th quartile of fruit (OR 0.78, 95% CI 0.64-0.95), 4th quartile of egg (OR 0.78, 95% CI 0.64-0.96), and 3rd quartile of fish (OR 0.80, 95% CI 0.66-0.98), and 4th quartile of milk (OR 0.78, 95% CI 0.65-0.94) reduced NERD. Reflux esophagitis had no association with food groups, whereas it was related with men, absence of H. pylori, hiatal hernia, BMI, and total energy intake. Furthermore, dietary effect on NERD was similar in men and women, whereas highest tertile of potato (OR 1.91) and milk (OR 1.87) increased reflux esophagitis only in women.

CONCLUSIONS

While many food groups affected NERD, reflux esophagitis was associated with BMI and total energy intake rather than dietary component. These results may suggest different approaches toward dietary management of NERD and reflux esophagitis.

Diagnostic accuracy of reused Pronto Drytest and CLOtest in the detection of Helicobacter pylori infection

Background

Unchanged substrate in a negative rapid urease test may be reused to detect Helicobacter pylori (H. pylori). This could potentially reduce costs and wastage in low prevalence and resource-poor settings. We thus aimed to investigate the diagnostic accuracy of reused Pronto Dry® and CLOtest® kits, comparing this to the use of new Pronto Dry® test kits and histopathological evaluation of gastric mucosal biopsies.

Methods

Using a cross-sectional study design, subjects who presented for upper endoscopy due to various non-emergent causes had gastric biopsies obtained at three adjacent sites. Biopsy samples were tested for H. pylori using a reused Pronto Dry® test, a reused CLOtest®, a new Pronto Dry® test and histopathological examination. Concordance rates, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy were then determined.

Results

A total of 410 subjects were recruited. The sensitivity and diagnostic accuracy of reused Pronto Dry® tests were 72.60 % (95 % CI, 61.44 – 81.51) and 94.15 % (95 % CI, 91.44 – 96.04) respectively. For reused CLOtests®, the sensitivity and diagnostic accuracy were 93.15 % (95 % CI 85.95 – 97.04) and 98.29 % (95 % CI 96.52 – 99.17) respectively. There were more true positives for new and reused Pronto Dry® pallets as compared to new and reused CLOtests® when comparing colour change within 30 min vs. 31–60 min (P < 0.001 and P = 0.7 respectively).

Conclusion

Negative Pronto Dry® and CLOtest® kits may be reused in a low prevalence setting where cost issues remain paramount. Reused CLOtest® kits have better accuracy than reused Pronto Dry® tests. Reused Pronto Dry® tests however have a more rapid colour change whilst maintaining diagnostic accuracy.

Effects of Helicobacter pylori infection and its eradication on lipid profiles and cardiovascular diseases

BACKGROUND

We aimed to examine the relationship of current Helicobacter pylori infection with lipid profile and cardiovascular disease and its eradication effect.

METHODS

Healthy subjects, who underwent routine checkup between October 2003 and December 2007, were followed up until June 2009. Helicobacter pylori and lipid profiles were measured both baseline and follow-up. Multiple logistic regression models for odds ratios (ORs) and 95% confidence intervals (CIs) were used to estimate the effects of H. pylori infection and its eradication, on lipids and cardiovascular disease.

RESULTS

Current infection with H. pylori with 50.5% (6759/13383) at baseline increased low-density lipoprotein (LDL) and decreased high-density lipoprotein (HDL) than H. pylori-negative group. Successful eradication of H. pylori decreased the risk of high LDL compared with the persistent infection (OR 0.76, 95% CI 0.59-96), which was comparable to that of the persistent negative group (OR 0.82, 95% CI 0.70-0.97), and decreased the risk of low HDL (OR 0.68, 95% CI 0.49-0.96). Current infection of H. pylori increased the risk of cardiovascular disease (OR 3.27, 95% CI 1.31-8.14) at baseline, but its eradication failed to decrease the risk at a 2-year follow-up. However, persistent negative infection decreased the risk (OR 0.57, 95% CI 0.35-0.94) comparing to persistent positive infection at follow-up.

CONCLUSIONS

Current infection with H. pylori had a positive association with high LDL, low HDL, and cardiovascular disease. Successful H. pylori eradication decreased the risk of high LDL and low HDL, but did not reduce the risk of cardiovascular disease.

Normalized real-time PCR for diagnosis of H. pylori infection

Objectives: There is increasing interest in the use of quantitative PCR (q-PCR) for diagnosis of H. pylori infection. However, the assay remains largely unstandardized, making comparison between studies unreliable. The objective of this study was to assess accuracy of a normalized q-PCR assay for diagnosis of the infection. Subjects and methods: Seventy-six fresh gastric biopsy specimens were collected from patients undergoing upper gastrointestinal tract endoscopy and examined by rapid urease test (RUT), culture, and a commercial TaqMan q-PCR assay targeting the ureA gene. Counts obtained from the latter assay were normalized to the human ACTB gene. A subject was considered to be infected if two or more assays were positive. Results: The detection rates were 42.1%, 52.6%, and 78.9% by culture, RUT and q-PCR, respectively. Bacterial density ranged 0.005 to 4800 bacteria per 100 human cells. Because q-PCR showed low initial specificity (45.7%), the cutoff value for the assay was recalculated as 1 bacterium per 100 human cells, using ROC curve analysis. Accordingly, the sensitivities and specificities were 79.5% and 97.3%, respectively, for culture; 94.9% and 91.9%, respectively, for RUT; and 94.9% and 94.6%, respectively, for q-PCR. By gold standard, 39 of the dyspeptic patients (51.3%) were found to be infected. Conclusions: With the identified cutoff value, the q-PCR assay diagnosed H. pylori infection with an accuracy slightly superior to that of RUT. However, the possibility that low counts detected only by q-PCR represent true infections warrants further investigation. Normalization of bacterial counts for standardization of q-PCR H. pylori assays is recommended.

Characteristics of gastric cancer according to Helicobacter pylori infection status

BACKGROUND AND AIMS

The definition and incidence of gastric cancer (GC) without Helicobacter pylori (Hp) infection varies between studies. The aim of our study was to compare the characteristics of GC according to Hp infection status.

METHODS

We evaluated the presence of Hp infection in 1833 GC patients with rapid urease tests, serology examinations, and histological evaluations. GC was classified as GC with current Hp infection (HpC-GC), GC with past Hp infection (HpP-GC), and GC not associated with Hp infection (HpN-GC). HpP-GC was defined as GC without current infection but with a positive serology test, glandular atrophy, and/or intestinal metaplasia. HpN-GC was defined as GC with negative Hp test results and no histological changes.

RESULTS

The numbers of HpC-GC, HpP-GC, and HpN-GC were 1378 (75.2%), 412 (22.5%), and 43 (2.3%), respectively. Among GCs without current infection, 90.5% (412/455) were associated with HpP-GC. HpP-GCs were more common in older and male patients, had an increased incidence of synchronous cancer, and less frequently had a diffuse-type histology than HpC-GCs. HpN-GCs were more common in younger, female patients; had a higher proportion of diffuse-type cancers; and more frequently showed distant metastasis than HpP-GCs. In the 40s, the proportion of HpP-GCs with diffuse-type histology (41.9%) was lower than that of HpC-GCs (60.3%) (P = 0.016). The difference was also significant in the 50s (29.1% vs 40.1%, respectively, P = 0.004).

CONCLUSIONS

Most GCs in Korea without current Hp infection showed evidence of past Hp infection. The proportion of GCs with diffuse-type histology decreased in patients with past infection.

[Epidemiology of infection Helicobacter pylori in Yaoundé: specificity of the African enigma]

Introduction

L'infection à Hélicobacter pylori concerne la moitié de la population mondiale, principalement dans les pays en voie de développement où l'infection atteint 80% de la population. Le but de notre étude était de déterminer la prévalence de l'infection à Hélicobacter pylori et de mettre en évidence les déterminants de l'infection ainsi que les maladies associées au Cameroun.

Méthodes

L’étude concernait 171 sujets symptomatiques référés pour une fibroscopie œsogastroduodénale au Centre Hospitalier et Universitaire de Yaoundé et au Centre Médical la Cathédrale. L'infection à H.pylori était objectivée par un test rapide à l'uréase kit commercial Pronto Dry^® (Medical Instruments Corporation, Solothurn, Switzerland).

Résultats

La prévalence globale de l'infection à Hélicobacter pylori était de 72,5% (124/171) (Intervalle de Confiance (IC) à 95% 65,2-79,1%) et dans chaque groupe d’âge (moins de 40ans, 40-50ans, plus de 50ans) de 83,1%(64/77), 67,4%(29/43) et 60,8%(31/51) respectivement. En analyse univariée, le risque de l'infection était significativement élevé dans le groupe de moins de 40ans comparé au groupe de 40-50ans (Risque Relatif (RR) 0,42 IC 95% 0,16-1,1, p = 0,04 pour le groupe 40-50ans) et comparé au groupe de plus de 50ans (RR 0,73; 0,57-0,93, p = 0,004 pour le groupe de plus de 50ans). La prévalence de l'infection à H.pylori était de 63,0% (17/27) pour l'ulcère duodénal, 50%(4/8) pour l'ulcère gastrique et 100%(2/2) pour le cancer gastrique.

Conclusion

A prévalence de l'infection à H.pylori au Cameroun est très élevée et significativement liée à l’âge de moins de 40 ans.

Staging of intestinal- and diffuse-type gastric cancers with the OLGA and OLGIM staging systems

BACKGROUND

Operative link on gastritis assessment (OLGA) and Operative link on gastric intestinal metaplasia assessment (OLGIM) staging systems have been proposed for gastric cancer (GC) risk estimation.

AIM

To validate the OLGA and OLGIM staging systems in a region with high risk of GC.

METHODS

This retrospective study included 474 GC patients and age- and sex-matched health screening control persons in a cancer centre hospital. We classified gastritis patterns according to the OLGA and OLGIM systems using the histological database that a pathologist prospectively evaluated using the updated Sydney system. GC risk according to the OLGA and OLGIM stages was evaluated using logistic regression analysis.

RESULTS

More GC patients had OLGA stages III-IV (46.2%) than controls (26.6%, P < 0.001), particularly among patients with intestinal-type GCs (62.2%) compared with diffuse-type GCs (30.9%). OLGA stages III and IV were significantly associated with increased risk of GC [odds ratios (ORs), 2.09; P = 0.008 and 2.04; P = 0.014 respectively] in multivariate analysis. The association was more significant for intestinal-type (ORs, 4.76; P = 0.001 and 4.19; P = 0.002 respectively), but not diffuse-type GC. OLGIM stages from I to IV were significantly associated with increased risk of both intestinal-type (ORs, 3.64, 5.15, 7.89 and 13.20 respectively) and diffuse-type GC (ORs, 1.84, 2.59, 5.08 and 6.32 respectively) with a significantly increasing trend.

CONCLUSION

As high OLGA and OLGIM stages are independent risk factors for gastric cancer, the staging systems may be useful for risk assessment in high-risk regions, especially for intestinal-type gastric cancer.

Randomised clinical trial: the effects of Helicobacter pylori eradication on glandular atrophy and intestinal metaplasia after subtotal gastrectomy for gastric cancer

BACKGROUND

Helicobacter pylori eradication is recommended for early gastric cancer (GC) patients after resection.

AIM

To evaluate whether H. pylori eradication improves glandular atrophy and intestinal metaplasia (IM) in GC patients undergoing subtotal gastrectomy.

METHODS

This randomised, double-blind trial was performed in tertiary care setting. Distal GC patients with H. pylori infection were randomised to receive proton pump inhibitor-based triple therapy or placebo. The histology was evaluated using the updated Sydney system before and at 36 months after surgery. The endpoints were the comparison of atrophy and IM score changes between the allocated groups and according to final H. pylori status.

RESULTS

Overall, 190 patients were randomised to the treatment and placebo groups. For lesser curvature of the corpus, mean atrophy and IM scores did not differ between the treatment and placebo groups. However, the H. pylori-eradicated patients had significantly lower mean scores than the H. pylori-persistent patients regarding atrophy (0.55 ± 0.95 vs. 1.05 ± 1.10 respectively; P = 0.0046) and IM (0.66 ± 0.99 vs. 1.05 ± 1.16 respectively; P = 0.0284). The percentage change from baseline was more marked in the H. pylori-negative than in the H. pylori-positive groups (-58.6% vs. -11.0% for atrophy and -60.5% vs. -35.6% for IM respectively). For greater curvature, mean atrophy score was lower in the H. pylori-negative group than in the H. pylori-positive group (0.14 ± 0.50 vs. 0.41 ± 0.75 respectively; P = 0.0281). The percentage change was -36.4% vs. 86.3%.

CONCLUSION

Helicobacter pylori eradication in GC patients is beneficial, as reflected by lower scores of atrophy and IM at 36 months after subtotal gastrectomy. (ClinicalTrials.gov number, NCT01002443).

[Clinical practice guideline on the management of patients with dyspepsia. Update 2012]

The aim of the Clinical Practice Guideline (CPG) on the Management of Patients with Dyspepsia is to generate recommendations on the optimal approach to dyspepsia in the primary care and specialized outpatient setting. The main objective of this CPG is to help to optimize the diagnostic process, identifying patients with a low risk of a serious organic disease (mainly tumoral), who could be safely managed without the need for invasive diagnostic tests and/or referral to a specialist. The importance of this aim lies in the need to accurately diagnose patients with esophagogastric cancer and correctly treat peptic ulcer while, at the same time, reduce negative endoscopies in order to appropriately use the available healthcare resources. This CPG reviews the initial strategies that can be used in patients with uninvestigated dyspepsia and evaluates the possible decision to begin empirical therapy or to investigate the existence of a lesion that could explain the symptoms. This CPG also discusses functional dyspepsia, which encompasses all patients with dyspepsia with no demonstrable cause on endoscopy. Recommendations for the diagnosis and treatment of peptic ulcer and Helicobacter pylori infection are also made. To classify the scientific evidence and strengthen the recommendations, the GRADE (Grading of Recommendations Assessment, Development and Evaluation Working Group) system has been used (http://www.gradeworkinggroup.org/).

[Clinical practice guideline on the management of patients with dyspepsia. Update 2012]

The aim of the Clinical Practice Guideline (CPG) on the Management of Patients with Dyspepsia is to generate recommendations on the optimal approach to dyspepsia in the primary care and specialized outpatient setting. The main objective of this CPG is to help to optimize the diagnostic process, identifying patients with a low risk of a serious organic disease (mainly tumoral), who could be safely managed without the need for invasive diagnostic tests and/or referral to a specialist. The importance of this aim lies in the need to accurately diagnose patients with esophagogastric cancer and correctly treat peptic ulcer while, at the same time, reduce negative endoscopies in order to appropriately use the available healthcare resources.This CPG reviews the initial strategies that can be used in patients with uninvestigated dyspepsia and evaluates the possible decision to begin empirical therapy or to investigate the existence of a lesion that could explain the symptoms. This CPG also discusses functional dyspepsia, which encompasses all patients with dyspepsia with no demonstrable cause on endoscopy. Recommendations for the diagnosis and treatment of peptic ulcer and Helicobacter pylori infection are also made. To classify the scientific evidence and strengthen the recommendations, the GRADE (Grading of Recommendations Assessment, Development and Evaluation Working Group) system has been used (http://www.gradeworkinggroup.org/).

Detection of helicobacter pylori in benign laryngeal lesions by polymerase chain reaction: a cross sectional study

BACKGROUND

Although Helicobacter Pylori (HP) was detected in some cases of chronic laryngitis, the results were not confirmed by polymerase chain reaction (PCR). By this time, it has not been found in laryngeal lesions by in house PCR, the most sensitive method for detecting the genome tracks. Regarding the previous results and also few numbers of studies about the presence of HP in benign laryngeal lesions, specifically by PCR, we aimed to investigate the presence of HP in benign laryngeal lesions by in-house PCR.

METHODS

The samples were taken from 55 patients with benign laryngeal lesions and frozen in -20°C. One milliliter (ml) of lysis buffer was added to 100 mg (mg) of each sample and the tube was placed in 56°C overnight. Then DNA extraction was carried out.

RESULTS

To find HP DNA, in-house PCR was performed that revealed 5 positive results among 55 patients with benign laryngeal lesions. Of them, 3 were polyp, 1 was nodule and 1 was papilloma.

CONCLUSION

Although the number of positive results was not a lot in this study, it was in contrast with previous studies which could not find any HP tracks in benign laryngeal lesions by other methods. More studies about the prevalence of HP in benign laryngeal lesions improve judging about the effect of this infection on benign laryngeal lesions.

Detection of Helicobacter pylori: A faster urease test can save resources

AIM: To investigate whether differences in the rapidity of a positive result for Helicobacter pylori can save resources, by comparing two commercially available urease kits.

METHODS: One hundred and eighty-five adults (130 outpatients, 55 inpatients) undergoing gastroscopy were entered prospectively. Patients were divided into two groups: Group 1 (if they were not on PPIs, antibiotics, H₂A, bismuth or sucralfate for up to 14 d prior to the endoscopy) and Group 2 (if they were on, or had been on, any of the above medication in the previous 14 d). At endoscopy two sets of biopsies, taken in random order, were placed in the wells of the Campylobacter-like organism (CLO) test (Kimberly-Clark, Utah, USA) and the Quick test (Biohit Plc, Helsinki, Finland). Five additional gastric biopsies were taken for histology/Giemsa and immunohistochemical study. The two urease test slides were read at 2 min, 30 min, 2 h and 24 h. Sensitivity and specificity at 24 h were determined.

RESULTS: At 24 h, for all patients, there was no difference in sensitivity (100% vs 97.5%), specificity (99.3%), positive (97.5%) and negative predictive values (100% vs 99.3%) between the CLO and Quick tests, respectively. There was a positive result at 30 min in 17/41 (41.5%) CLO tests, and in 28/40 (70%) Quick tests, P = 0.05. Quick test enabled the prescription of eradication therapy before discharge in all 28/40 patients. Only 12 (30%) follow-up appointments were needed. If the CLO test had been used alone, only 17 (41.5%) prescriptions would have been possible prior to discharge and 24 (58%) follow-up appointments would be needed (P = 0.001). Of 2000 gastroscopies performed annually at our unit, a saving of 123 follow-up appointments (total: 8856 Euros or 11 808 USD) would be achieved if we switched to the Quick test.

CONCLUSION: Direct comparison of locally available urease test kits is worthwhile, since the appropriate choice results in a significant saving of resources. Local costs and follow-up protocols will determine the magnitude of these savings.

Risk factors associated with gastric cancer in patients with a duodenal ulcer

BACKGROUND

Although gastric cancer (GC) and duodenal ulcer (DU) are both strongly associated with Helicobacter pylori infection, a DU is negatively associated with the risk of GC. The aim of the study is to evaluate histologic risk factors for GC among patients with a DU.

MATERIALS AND METHODS

A total of 541 consecutive patients with GC were prospectively evaluated for the presence of a DU. Control patients with only a DU (n = 89) were recruited from health screening population. Histologic grading was assessed using the updated Sydney system for six gastric biopsies from three regions. GC risk among patients with a DU was evaluated using logistic regression analysis.

RESULTS

Among patients with GC, 7.6% (41/541) had a concomitant DU or an ulcer scar. Corpus-predominant/pangastritis were more frequently found in concomitant GC patients with a DU (90%) than in patients with a DU alone (62%) (p = .001). In patients with a DU, moderate-severe chronic inflammation at the lesser and greater curvatures of corpus was associated with GC risk (OR, 3.70; 95% CI, 1.46-9.36, and OR, 7.72; 95% CI, 3.18-18.7, respectively). Additionally, moderate-severe intestinal metaplasia (IM) at the antrum and corpus lesser curvature was associated with GC risk (OR, 7.52; 95% CI, 3.06-18.5, and OR, 9.25, 95% CI, 2.39-35.8, respectively).

CONCLUSIONS

A DU is not rare in patients with GC in a high-risk region of GC. Patients with a DU with chronic corpus gastritis and IM have an increased risk of GC, thus those patients should be followed up for GC development.

Effect of Helicobacter pylori infection and its eradication on reflux esophagitis and reflux symptoms

OBJECTIVES

We evaluated the association between current Helicobacter pylori infection and reflux esophagitis and the effect of H. pylori eradication on reflux esophagitis in a healthy screening population.

METHODS

A total of 10,102 subjects in a comprehensive screening cohort were enrolled, and 4,007 subjects had follow-up after a median of 2 years. Effects of H. pylori infection on reflux esophagitis were estimated with odds ratios (ORs) and 95% confidence intervals (CIs) using multiple logistic regression analysis. We evaluated the change in prevalence of reflux esophagitis and reflux symptoms after H. pylori eradication vs. persistence.

RESULTS

The prevalence of reflux esophagitis (as classified by the Los Angeles system) was 4.9% (490/10,102). Whereas the prevalence of reflux esophagitis was 6.4% (319/4,971) in subjects without H. pylori infection, it was 3.3% (171/5,131) in subjects with infection (P<0.001). H. pylori infection had a strong negative association with reflux esophagitis in multivariate analysis (OR 0.42; 95% CI, 0.34-0.51). Compared with the prevalence of reflux esophagitis in the persistent infection group, the prevalence of reflux esophagitis increased after successful H. pylori eradication (OR 2.34; 95% CI, 1.45-3.76; P<0.001), which was comparable to that of the H. pylori-negative group (OR 2.42; 95% CI, 1.73-3.36; P<0.001). However, reflux symptoms had no association with H. pylori infection or eradication.

CONCLUSIONS

In a healthy screening population, H. pylori infection had a strong negative association with reflux esophagitis, but H. pylori eradication increased the prevalence of erosive esophagitis to the level of H. pylori-negative individuals. Long-term clinical significance of newly developed erosive esophagitis after H. pylori eradication should be evaluated prospectively.

Risk factors associated with Helicobacter pylori infection treatment failure in a high prevalence area

Triple therapy is commonly used for the treatment of Helicobacter pylori infection. We determined risk factors associated with its failure in compliant patients focusing on H. pylori density, virulence marker and 23S ribosomal RNA (rRNA) point mutations associated with clarithromycin resistance. H. pylori infection was diagnosed by 14C urea breath test (14C UBT) and rapid urease test or histology. Triple therapy with esomeprazole 20 mg b.i.d., amoxicillin 1 g b.i.d. and clarithromycin 500 mg b.i.d. was prescribed for 10 days. 14C UBT was repeated 4 weeks after treatment. In total, 111 patients [69 (62%) males] with a mean age of 46±16 years were enrolled. The mean age of treatment failure was 39±14 years compared to 48±16 years with eradication (P=0·002). Treatment failure was associated with younger mean age, point mutations in the 23S rRNA gene of H. pylori and vacA s1a and m1 when associated with cagA negativity.

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.

Furazolidone, co-amoxiclav, colloidal bismuth subcitrate, and esomeprazole for patients who failed to eradicate Helicobacter pylori with triple therapy

There is increasing evidence of Helicobacter pylori (H. pylori) resistance to the classical triple therapy consisting of a proton-pump inhibitor and clarithromycin with either amoxicillin or metronidazole. This study is aimed at establishing the efficacy and safety of a 14-day regimen to eradicate H. pylori in patients who have failed with the classical triple therapy given for 14 days. One hundred seventy-six patients diagnosed to have H. pylori infection were given triple therapy for 14 days. Fifty-two patients who failed to respond as evident from positive 14C-urea breath test (UBT) done 4-6 weeks after the completion of triple therapy were offered a combination regimen comprised of furazolidone 200 mg b.i.d, co-amoxiclav 1 g b.i.d., colloidal bismuth subcitrate 240 mg b.i.d., and esomeprazole 40 mg b.i.d. for 14 days. The mean age of these patients was 41 +/- 13 years (range 20-67). Thirty-four were males. To document eradication of H. pylori, UBT was repeated 4 weeks after the completion of treatment. On an intention-to-treat analysis, the eradication rate was 81% (42 out of 52) whereas on per-protocol basis, the eradication rate was 82.4% (42 out of 51). In conclusion, this new regimen represents a suitable second-line therapy.

Biopsy site for detecting Helicobacter pylori infection in patients with gastric cancer

BACKGROUND

Helicobacter pylori eradication is recommended in post-gastric cancer resection, but premalignant changes may prevent the detection of H. pylori. The aim of this study was to determine appropriate biopsy site for detecting H. pylori in gastric cancer patients.

MATERIALS AND METHODS

Consecutive patients (194) with gastric adenocarcinoma were prospectively enrolled. Helicobacter pylori was evaluated by serology, histology and rapid urease test. Biopsy sites included antrum lesser curvature, upper body lesser curvature (UBLC) and upper body greater curvature (UBGC). Two biopsy specimens were obtained from each site for histological examination. One additional specimen was obtained from UBGC for the rapid urease test.

RESULTS

The overall infection rate of H. pylori was 84.0% (95% CI 78.9-89.2). The sensitivity of histology for detecting H. pylori at various sites was: antrum (54.9%; 95% CI 45.7-63.9), UBLC (80.3%; 95% CI 72.2-87.0) and UBGC (95.1%; 95% CI 89.6-98.2). Specificities of all three biopsy sites were more than 95%. Sensitivity and specificity of the rapid urease test performed at UBGC were 96% and 100%, respectively. Sensitivities of histology decreased in correlation with increasing severity of atrophy and intestinal metaplasia (both P < 0.001 using the chi-square test for trend). The proportions of moderate to marked atrophy/intestinal metaplasia at UBGC (12.8%/14.7%) were significantly lower than those at antrum (50.0%/57.8%, P < 0.001 respectively) or UBLC (40.0%/48.9%, P < 0.001 respectively).

CONCLUSIONS

The UBGC side is the most sensitive and specific biopsy site to detect H. pylori in gastric cancer patients due to less frequent atrophy and intestinal metaplasia than at the antrum or UBLC side.

Preoperative versus postoperative Helicobacter pylori eradication therapy in gastric cancer patients: a randomized trial

OBJECTIVES

Helicobacter pylori (H. pylori) eradication is strongly recommended for gastric cancer patients who undergo subtotal gastrectomy. The efficacy of proton pump inhibitor-based triple therapy for H. pylori eradication has not been adequately assessed in the gastric remnant. The aim of this study was to compare the efficacy of postoperative versus preoperative H. pylori eradication therapy.

METHODS

A total of 138 distal gastric cancer patients with H. pylori infection were randomized to receive either preoperative (preop, N = 68) or postoperative (postop, N = 70) proton pump inhibitor-based triple therapy for H. pylori eradication. The regimen consisted of rabeprazole 10 mg, clarithromycin 500 mg, and amoxicillin 1,000 mg, all twice daily for 7 days. Eradication was assessed by rapid urease test and histology 12 wk after surgery.

RESULTS

By intention-to-treat (ITT) analysis, H. pylori eradication rates were 84.6% (95% CI 73.5-92.4) in the preop group and 83.1% (95% CI 71.7-91.2) in the postop group (P= 0.99). By per protocol (PP) analysis, the rates were 87.3% (95% CI 76.5-94.4) in the preop group and 86.9% (95% CI 75.8-94.2) in the postop group (P= 0.99). In the postop group, eradication rates did not differ with reconstruction method (Billroth I vs II, 80.4%[95% CI 66.1-90.6]vs 89.5%[95% CI 66.9-98.7] by ITT analysis (P= 0.49), and 85.7%[95% CI 71.5-94.6]vs 89.5% (95% CI 66.9-98.7) by PP analysis, P= 0.99).

CONCLUSIONS

In distal gastric cancer patients, the effect of proton pump inhibitor-based triple therapy for H. pylori eradication was not different whether given postoperatively or preoperatively.

HUITAI rapid urease test: a new ultra-rapid biopsy urease test for the diagnosis of Helicobacter pylori infection

BACKGROUND

The gastric biopsy urease test is an accurate and robust diagnostic test for Helicobacter pylori infection. Large endoscopy units use their own homemade unbuffered ultra-rapid urease test for diagnosis of H. pylori infection but several commercial rapid urease tests are available.

OBJECTIVE

To compare the accuracy and reaction time of a new biopsy urease test, HUITAI rapid urease test, in the diagnosis of H. pylori infection.

METHODS

Consecutive patients presenting with dyspepsia to the endoscopy unit, University of Malaya Medical Center were recruited for the study. Patients who were previously treated for H. pylori infection or who had received antibiotics, proton pump inhibitors or bismuth compounds in the preceding 4 weeks were excluded. The H. pylori diagnosis was made based on the homemade rapid urease test, histology and culture of gastric biopsies. Biopsies from the antrum and corpus of the stomach were taken for this purpose. In addition, two antral and corpus biopsies were taken for the HUITAI rapid urease test. A positive diagnosis of H. pylori infection was made when the culture was positive or if both histology and the rapid urease test were positive. A negative diagnosis was made when all tests were negative. The positive reaction time of the HUITAI rapid urease test was carefully timed up to 60 min.

RESULTS

Two hundred and six patients were recruited in the study. One hundred and twelve were diagnosed as having an H. pylori infection while the other 94 patients were regarded as negative. There were no spoiled tests and no indeterminate results. The sensitivity of the HUITAI rapid urease test was 98.2% (95% confidence interval (CI): 93.7%, 99.8%), specificity, 99.0% (95% CI: 94.2%, 100%), positive predictive value, 99.0% (95% CI: 95.1%, 100%), negative predictive value, 97.9% (95% CI: 92.6%, 99.7%). The overall diagnostic accuracy for the HUITAI rapid urease test was 98.5% (95% CI: 96.6, 99.9). The median positive reaction time was 1.0 min (25-75% inter-quartile range [IQR]: 1.0-3.0 min).

CONCLUSIONS

The HUITAI rapid urease test is highly accurate for the diagnosis of an H. pylori infection and showed a very rapid positive reaction time.

Evaluation of the use of rapid urease test: Pronto Dry to detect H pylori in patients with dyspepsia in several cities in Indonesia

AIM: To evaluate Pronto Dry examination in patients with dyspepsia.

METHODS: The study was conducted in patients with dyspepsia who underwent endoscopic examination in several endoscopic centers of several cities in Indonesia from January 2003 until April 2004. Biopsies for histopathologic examination were fixed with formalin and sent to Histopathologic Department to be analyzed and confirm the presence of H pylori infection. If H pylori was found positive, the density was calculated semi quantitatively. Histopathologic examination from gastric biopsy samples was interpreted based on the updated Sydney system classification.

RESULTS: Of 550 patients, 309 (56%) were male and 241 (44%) were female with ages ranging from 15 to 82 years. Mean age was 44.98 ± 14.46 years. Mean age of male patients was 44.35 ± 13.85 years and mean age of female patients was 45.78 ± 15.19 years. Evaluation of endoscopic results showed gastric ulcer in 36 cases (6.5%) and duodenal ulcer in 20 cases (3.6%). Normal endoscopic finding was found in 45 cases (8.2%) and minimal disorder of gastritis and duodenitis were found in 246 cases (44.7%). One case of gastric cancer was identified. Of 56 cases which were positive based on the criteria used, 39 patients were positive with Pronto Dry and 17 patients were negative with Pronto Dry. Overall sensitivity and specificity of Pronto Dry were 69.7% and 95.7% respectively. Positive predictive value was 66.1% and negative predictive value was 96.4% and overall accurate rate was 92.9%.

CONCLUSION: Pronto Dry seems promising as a diagnostic tool to detect H pylori more rapidly and accurately.

Role of rapid urease test and histopathology in the diagnosis of Helicobacter pylori infection in a developing country

Background

The aim of this study was to determine the effect of commonly self-prescribed proton pump inhibitors (PPI) on the results of rapid urease test and histology for the diagnosis of H. pylori infection.

Methods

One hundred-nine consecutive patients with dyspeptic symptoms attending the endoscopy suite were enrolled in this study. Antrum biopsy specimens were collected at endoscopy for the rapid urease test (Pronto Dry, Medical Instrument Corp, France) and histopathology. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and like-hood ratio of a positive and negative of Pronto Dry test were compared against histology. The gold standard test for the diagnosis of H. pylori infection was histopathology.

Results

Sixty-one percent (66/109) patients were males with mean age of 43 ± 14.1 years and age range 17–80 years. Fifty-two percent (57/109) were not on any medications while 48% (52/109) used PPI before presentation to the outpatients. Pronto Dry was positive in 40% (44/109) and negative in 60% (65/109). Histopathology was positive for H. pylori in 57% (62/109) and negative in 43% (47/109). The sensitivity, specificity, PPV, NPV and like-hood ratio of a positive and negative Pronto Dry test with and without PPI were 43.3%, 86.4%, 81.3%, 3.18, 0.656 and 52.8% vs 71.9%, 80%, 82.1%, 69%, 3.59 and 0.35.

Conclusion

This study shows that the sensitivity, specificity, NPV and PPV of rapid urease test was reduced in patients who are on PPI. The exclusive use of the rapid urease test for the diagnosis of Helicobacter pylori cannot be recommended in patients with prior PPI use.

Diagnosis of Helicobacter pylori Infection

A large number of studies on diagnostic tests have been published this year. New tests were proposed for the detection of Helicobacter pylori antigens in stools and new molecular methods (real-time polymerase chain reaction) to look for antimicrobial susceptibility. The other standard tests have been applied in different situations to improve the diagnosis of the infection.

SLC26A9 is expressed in gastric surface epithelial cells, mediates Cl-/HCO3- exchange, and is inhibited by NH4+

HCO3- secretion by gastric mucous cells is essential for protection against acidic injury and peptic ulcer. Herein we report the identification of an apical HCO3- transporter in gastric surface epithelial cells. Northern hybridization and RT-PCR demonstrate the expression of this transporter, also known as SLC26A9, in mouse and rat stomach and trachea (but not kidney). In situ hybridization in mouse stomach showed abundant expression of SLC26A9 in surface epithelial cells with apical localization on immunofluorescence labeling. Functional studies in HEK-293 cells demonstrated that SLC26A9 mediates Cl-/HCO3- exchange and is also capable of Cl--independent HCO3- extrusion. Unlike other anion exchangers or transport proteins reported to date, SLC26A9 activity is inhibited by ammonium (NH4+). The inhibitory effect of NH4+ on gastric HCO3- secretion was also indicated by reduced gastric juxtamucosal pH (pHjm) in rat stomach in vivo. This report is the first to describe the inhibition of HCO3- transport in vitro and the reduction of pHjm in stomach in vivo by NH4+. Given its critical localization on the apical membrane of surface epithelial cells, its ability to transport HCO3-, and its inhibition by NH4+, we propose that SLC26A9 mediates HCO3- secretion in surface epithelial cells and is essential for protection against acidic injury in the stomach. Disease states that are associated with increased ammonia (NH3)/NH4+ generation (e.g., Helicobacter pylori) may impair gastric HCO3- secretion and therefore predispose patients to peptic ulcer by inhibiting SLC26A9.