Increased risk of developing atrophic gastritis in patients infected with CagA+ Helicobacter pylori

Influence of laboratory-related and endoscopy-related factors on the assessment of serum pepsinogens and gastrin-17

BACKGROUND AND AIM

Serum pepsinogen I (PGI) and pepsinogen II (PGII) are noninvasive parameters in the detection of atrophic gastritis. The diagnostic add-on value of serum gastrin-17 (G-17) remains uncertain. The aim of this study was to assess the stability of these serum parameters over time and to evaluate the influence of clinical factors, such as upper gastrointestinal (GI) endoscopy and bowel cleansing, on serum PGI, PGII, and G-17 assessment.

PATIENTS AND METHODS

A prospective study was carried out in healthy individuals and patients. For the stability analyses, the plasma and serum samples from 23 individuals were processed at different time points with and without the addition of a stabilizer. Ten patients were included to evaluate the influence of upper GI endoscopy and 18 patients to evaluate the effect of bowel cleansing before colonoscopy.

RESULTS

PGI, PGII, and G-17 levels were not statistically different in the serum and plasma. PGI and PGII serum levels were stable over time. G-17 is associated with time-dependent degradation (P=0.0001). The addition of the G-17 stabilizer showed no improvement in stability. Upper GI endoscopy and bowel preparation before colonoscopy were associated with minimal variations in PGI and PGII, whereas G-17 showed patient-specific alterations.

CONCLUSION

PGI and PGII serum levels are stable over time. However, G-17 stability is strongly dependent on the time of processing and storage; therefore, samples for G-17 analysis need to be processed no later than 6 h after blood collection. Upper GI endoscopy and colonoscopy preparation lead to minimal nonsignificant changes in basal PGI, PGII, and G-17 levels.

Helicobacter pylori infection and atrophic gastritis

BACKGROUND

Helicobacter pylori-infection associated gastritis is known to be a significant risk factor of gastric cancer. Serum levels of Gastrin-17 and Pepsinogen1which are respectively biomarkers of gastric antral and corpus mucosal activity are well known parameters of atrophic gastritis.

OBJECTIVES

To determine the prevalence of Helicobacter pylori and atrophic gastritis amongst dyspeptic patients and to compare the production of PGI and G-17 in the various atrophic stages.

METHODS

A total of 139 dyspeptic patients aged 46.68±15.50 years [females 106 aged47.23±15.51years, males 33 aged 44.48±14.62] were included during the one year period, March 2008-april 2009 at the district hospital Tombel. The degree of atrophy was determined by the levels of serum pepsinogen1, and gastrin-17 and the presence of Helicobacter pylori antibodies detected by an enzyme immunoassay.

RESULTS

The prevalence of Helicobacter pylori was 79.82% and that for atrophic gastritis was 6.6%. A decrease in mean serum levels of gastin-17 along with increasing antral atrophy was observed; the mean serum levels of pepsinogen1 were reduced during progression of corpus atrophy.

CONCLUSION

A weak reverse correlation(r =-0.036) was found between Gastrin-17 and Helicobacter pylori antibodies.

Rationale in diagnosis and screening of atrophic gastritis with stomach-specific plasma biomarkers

BACKGROUND AND AIMS

Atrophic gastritis (AG) results most often from Helicobacter pylori (H. pylori) infection. AG is the most important single risk condition for gastric cancer that often leads to an acid-free or hypochlorhydric stomach. In the present paper, we suggest a rationale for noninvasive screening of AG with stomach-specific biomarkers.

METHODS

The paper summarizes a set of data on application of the biomarkers and describes how the test results could be interpreted in practice.

RESULTS

In AG of the gastric corpus and fundus, the plasma levels of pepsinogen I and/or the pepsinogen I/pepsinogen II ratio are always low. The fasting level of gastrin-17 is high in AG limited to the corpus and fundus, but low or non-elevated if the AG occurs in both antrum and corpus. A low fasting level of G-17 is a sign of antral AG or indicates high intragastric acidity. Differentiation between antral AG and high intragastric acidity can be done by assaying the plasma G-17 before and after protein stimulation, or before and after administration of the proton pump inhibitors (PPI). Amidated G-17 will rise if the antral mucosa is normal in structure. H. pylori antibodies are a reliable indicator of helicobacter infection, even in patients with AG and hypochlorhydria.

CONCLUSIONS

Stomach-specific biomarkers provide information about the stomach health and about the function of stomach mucosa and are a noninvasive tool for diagnosis and screening of AG and acid-free stomach.

Pancreatic cancer: Helicobacter pylori colonization, N-nitrosamine exposures, and ABO blood group

Thirty years of research with animal models has shown that pancreatic adenocarcinoma is induced by N-nitrosamine carcinogens, which damage DNA through adduct formation. Human risk factors for pancreatic cancer include gastric colonization by Helicobacter pylori, as well as dietary intake of those same N-nitrosamines or of nitrite which forms those N-nitrosamines in the stomach, and cigarette smoking which also contains those N-nitrosamines. Physiologic actions of H. pylori colonization enhance the carcinogenic effect of N-nitrosamines delivered by smoking or dietary sources. This effect is modulated by host inflammatory response to the organism, by various virulence and other properties of the Helicobacter itself, and by host-organism interactions. A recent genome-wide association study identified SNPs within the ABO 9q34 locus as statistically significantly associated with risk of pancreatic cancer. A number of recent and older studies going back 40 yr also support the ABO association. ABO-product antigens are expressed on gastrointestinal epithelium on which H. pylori binds, and ABO genotype is known to be associated with risks of duodenal and gastric ulcer and with risk of gastric cancer, conditions definitively related to Helicobacter colonization. We suspect that ABO genotype/phenotype status influences the behavior of H. pylori which in turn affects gastric and pancreatic secretory function, and these ultimately influence the pancreatic carcinogenicity of dietary- and smoking-related N-nitrosamine exposures, and thus risk of pancreatic cancer. Our study results on the interaction of ABO and H. pylori significantly confirm this hypothesis and together with other existing studies strongly implicate this organism in the disease etiology.

Decreased IgA antibody production in the stomach of gastric adenocarcinoma patients

Gastric adenocarcinoma is closely associated with Helicobacter pylori infection. It is also much more frequent in patients with common variable immunodeficiency or selective IgA-deficiency than in the general population. To investigate a possible link between local antibody production and gastric tumors, we studied gastric B cell infiltration and local IgA production in patients with H. pylori induced gastric adenocarcinomas. These studies showed that total and H. pylori-specific IgA antibody levels were substantially lower in gastric tissue from the cancer patients compared to those from asymptomatic H. pylori carriers. However, serum IgA levels were similar in the cancer patients and asymptomatic carriers. As could be expected, H. pylori infected asymptomatic carriers had considerably increased IgA antibody levels compared to uninfected subjects. We conclude that patients suffering from gastric adenocarcinoma have a dramatically decreased local IgA production in the stomach compared to asymptomatic H. pylori infected individuals.

Serum biomarkers for atrophic gastritis and antibodies against Helicobacter pylori in the elderly: Implications for vitamin B12, folic acid and iron status and response to oral vitamin therapy

OBJECTIVES

To investigate the prevalence of serological markers for chronic atrophic gastritis (AG) and Helicobacter pylori antibodies (HPAb) in an elderly population, and to examine the interrelationship and significance for cobalamin, folic acid and iron status and response to oral vitamin therapy.

MATERIAL AND METHODS

The study included community-dwelling subjects (n=209), mean age 76 years, randomized to 4 month of oral daily treatment with 0.5 mg cyanocobalamin, 0.8 mg folic acid and 3 mg vitamin B(6) or placebo (double-blind). Biochemical tests were carried out before and after treatment.

RESULTS

AG, as indicated by a pepsinogen I/II ratio <2.9, occurred in 14% (26/190) and HPAb in 54% (102/190) of the subjects. AG subjects had higher levels of serum methylmalonic acid (MMA) (p<0.001), plasma homocysteine (tHcy) (p<0.05), lower haemoglobin (Hb) (p<0.01) and a higher prevalence of vitamin B(12) deficiency (p<0.01). HPAb was associated with AG, whereas AG subjects without HPAb had higher tHcy and MMA levels. There was no correlation between AG and iron status. Oral vitamin treatment led to greater (albeit non-significant) improvements in MMA, tHcy and total cobalamins in AG subjects compared to non-AG subjects.

CONCLUSIONS

AG is a common condition and is a significant determinant of vitamin B(12) status. AG is correlated to HPAB and lower Hb. Elderly AG subjects respond at least as well as non-AG subjects to oral treatment with B-vitamins in the doses employed.

Evaluation of a commercial immunoblot, Helicoblot 2.1, for diagnosis of Helicobacter pylori infection

The best method to diagnose Helicobacter pylori infection in different clinical situations is controversial. The aim of the study was to assess the performance of a commercial immunoblot, Helicoblot 2.1. The study comprised 215 patients, who were grouped according to the presence of H. pylori infection (assessed by two gastroscopies including histology with a median interval of 7.1 years, enzyme immunoassay [EIA]-based serology, and history of previous H. pylori infections and eradication therapies) into four categories: no H. pylori infection ever, previous infection, ongoing infection, and EIA seropositivity as the only marker of a possible previous infection. The sensitivity of Helicoblot 2.1 to show an ongoing or previous H. pylori infection was 100% and 92%, respectively. Helicoblot 2.1 was negative in only 80% of individuals with no evidence of present or previous infection but in 96% of patients 50 years of age or younger. The current infection marker of the immunoblot was positive in 49% of patients with successful H. pylori eradication therapy. After successful eradication therapy, Helicoblot 2.1 sustained positive results in 87% of patients, and CagA positivity was detected in 87% of patients with follow-up samples for more than 10 years after therapy. Helicoblot 2.1 is a sensitive and, among patients of ages 50 years or younger, a specific test in the primary diagnosis of H. pylori infection. However, it does not discriminate between past and current infections. It can be used in epidemiological studies assessing the role of H. pylori in different late sequelae.

Association of Helicobacter pylori infection with chronic atrophic gastritis: Meta-analyses according to type of disease definition

Helicobacter pylori is a major risk factor for chronic atrophic gastritis (CAG). A large variety of definitions of CAG have been used in epidemiologic studies in the past. The aim of this work was to systematically review and summarize estimates of the association between H. pylori infection and CAG according to the various definitions of CAG. Articles on the association between H. pylori infection and CAG published until July 2007 were identified. Separate meta-analyses were carried out for studies defining CAG based on gastroscopy with biopsy, serum pepsinogen I (PG I) only, the pepsinogen I/pepsinogen II ratio (PG I/PG II ratio) only, or a combination of PG I and the PG I/PG II ratio. Numbers of identified studies and summary odds ratios (OR) (95% confidence intervals) were as follows: gastroscopy with biopsy: n = 34, OR = 6.4 (4.0-10.1); PG I only: n = 13, OR = 0.9 (0.7-1.2); PG I/PG II ratio: n = 8, OR = 7.2 (3.1-16.8); combination of PG I and the PG I/PG II ratio: n = 20, OR = 5.7 (4.4-7.5). Studies with CAG definitions based on gastroscopy with biopsy or the PG I/PG II ratio (alone or in combination with PG I) yield similarly strong associations of H. pylori with CAG. The association is missed entirely in studies where CAG is defined by PG I only.

Helicobacter pylori infection and gastroesophageal reflux in a population-based study (The HUNT Study)

BACKGROUND AND AIM

It has been suggested that Helicobacter pylori infection may prevent gastroesophageal reflux, possibly through gastric atrophy. Since, however, previous results are contradictory and no population-based studies are available, the relationship between H. pylori and reflux remains uncertain. The aim of this study was to investigate this relationship in a population-based, nested, case-control study.

METHODS

From a cohort of 65,363 individuals, representing 71.2% of the adult population in the Norwegian county of Nord-Trondelag, we randomly selected 472 persons with recurrent reflux symptoms (cases) and 472 without such symptoms (controls). Occurrence of H. pylori and its virulence factor cagA was determined serologically, using an immunoblot assay. Gastric atrophy was assessed through serum levels of pepsinogen I. Odds ratios (OR) with 95% confidence intervals (CI), adjusted for potential confounding factors, represented relative risks.

RESULTS

H. pylori infection was not associated with a decreased risk of reflux symptoms (OR 1.1, 95% CI 0.8-1.6), irrespective of positive cagA status (OR 1.1, 95% CI 0.8-1.5). Gastric atrophy reduced the risk of reflux symptoms (OR 0.2, 95% CI 0.0-0.6). Infection with H. pylori entailed a ninefold increase in the risk of gastric atrophy compared to non-infection (OR 8.9, 95% CI 2.0-39.9).

CONCLUSIONS

H. pylori infection, irrespective of cagA status, did not affect the occurrence of reflux symptoms in this population-based setting. Infected individuals are at increased risk of gastric atrophy, which in turn reduces reflux symptoms, but due to the low frequency of gastric atrophy among infected individuals overall, there was no association with reflux symptoms on a population level.

Comparison of prevalence of chronic atrophic gastritis in Japan, China, Tanzania, and the Dominican Republic

PURPOSE

To compare the prevalence of chronic atrophic gastritis (CAG) in Japan, China, Tanzania, and the Dominican Republic and to assess the usefulness of Helicobacter pylori infection and serum gastrin level as markers of CAG.

METHODS

The subjects were volunteers from local communities in Japan (n=859), China (n=1741), Tanzania (n=573), and the Dominican Republic (n=1215). Each individual underwent a health checkup and blood sampling for measurement of serum pepsinogen I and II, pepsinogen I /II ratio, serum gastrin, and H. pylori antibodies, and responded to a questionnaire on upper digestive tract diseases.

RESULTS

The prevalences of H. pylori infection (23.5-96.1%), CAG (5.6-60.4%), and serum gastrin (62.0-136.5 pg/ml) varied by age, sex, and country. Serum gastrin level for men differed in each country according to age. In Tanzanian men, the median gastrin level (101.0 pg/ml) was the highest in the 40 to 49 years age group (p < 0.01) while there was no significant difference among different age groups in Tanzanian women. Serum gastrin level in subjects > or = 70 years was higher than in other age groups in both sexes in the Dominican Republic (males, 92.5, females, 136.5 pg/ml). The prevalence of H. pylori infection increased (p < 0.01) with advancing age in Japan (only for women) and the Dominican Republic but was high in all age groups of both sexes in China and Tanzania. The prevalence of CAG increased (p < 0.01) with age in both sexes in Japan, China (women only), and the Dominican Republic, but not in Tanzania. The odds ratio of CAG in H. pylori infected subjects was 5.3 times that in H. pylori-negative subjects. The odds ratio of CAG increased by 0.6%/1 pg/ml increase in serum gastrin.

CONCLUSIONS

Our results indicated that H. pylori infection, serum gastrin, and advancing age are good markers of CAG and that the prevalence of CAG is the highest in Japan.

Chronic Helicobacter pylori infection in a population in southern Sweden analysed by histopathology, immunoblot and ELISA serology

BACKGROUND

Many individuals are infected with the bacterium Helicobacter pylori. Some develop ulcers or mucosal atrophy.

AIMS

To correlate the histological characteristics of the H. pylori -induced gastritis to the immunoblot pattern of the H. pylori infection and to compare the presence of H. pylori bacteria in tissue specimens with ELISA serology and immunoblot analysis.

METHODS

One hundred and sixty-six consecutive patients were referred to gastroscopy. Forty patients were excluded for various reasons and 126 were included in the study.

RESULTS

Twenty-three patients had ulcerations and 25 erosions. Ninety-two (73%) had a chronic gastritis and in 90 (71%) it involved both the antrum and corpus. Ninety-one (72%), of whom 96% had a chronic gastritis, had visible bacteria in the tissue specimens, used as the 'gold standard' for the detection of infection. In patients with chronic gastritis 65 (70%) had positive H. pylori ELISA serology, 27 (30%) had negative H. pylori ELISA, while 76 (83%) had a positive immunoblot pattern. The ELISA positive patients had more advanced chronic gastritis but a lower frequency of metaplasia and atrophy. Acute inflammatory activity in the chronic gastritis had a high immunoreactivity to 120 kDa (CagA) protein and was significantly correlated to antibody reactivity to proteins in the 53-65 kDa range (heat shock proteins) and to a 43 kDa subunit. Metaplasia and atrophy in antrum was associated with a 62 kDa protein band.

CONCLUSION

Almost all H. pylori-infected patients had a pangastritis, visible in both antrum and corpus. Acute inflammatory activity in the chronic gastritis and the presence of metaplasia and atrophy in antrum were associated with a specific immunoblot pattern, indicating infection with more virulent strains. Immunoblot analysis had a better sensitivity than ELISA H. pylori serology.

Diagnostic accuracy of the serum profile of gastric mucosa in relation to histological and morphometric diagnosis of atrophy

BACKGROUND

Histology is the gold standard for diagnosis of atrophy but is hampered by observer variation. A reliable method to overcome this issue is morphometric analysis of gastric mucosa. Serum pepsinogens and gastrin have been proposed in the diagnostic work-up of gastric atrophy although diagnostic accuracy of these tests is considered unsatisfactory.

AIM

To evaluate the diagnostic accuracy of gastric serum profile in relation both to morphological and morphometric diagnosis of gastric atrophy.

METHODS

Ninety-four dyspeptic out-patients underwent upper endoscopy and evaluation of serum levels of PGI, PGII and 17-gastrin. Diagnostic accuracy of gastric serum profile was tested by receiver operating characteristic curves and by evaluation of sensitivity and specificity in relation to both histology and morphometric analyses.

RESULTS

As far as concern to histological evaluation, only PGI/PGII ratio showed an acceptable diagnostic accuracy in discrimination of gastric atrophy, while, when morphometric analysis was considered as reference, both serum PGI level and PGI/PGII ratio showed an excellent performance. However, both PGI and PGI/PGII ratio showed low sensitivity and high specificity.

CONCLUSIONS

Serological gastric profile corresponds better with the morphometric diagnosis of atrophy, even if, because of the low sensitivity, today this could only be used as screening test of chronic atrophic gastritis.

Analysis of the cag pathogenicity island and IS605 of Helicobacter pylori strains isolated from patients with gastric cancer in Japan

BACKGROUND

CagA protein is encoded by the cagA gene, which is part of the cag pathogenicity island (PAI) in Helicobacter pylori. Insertion sequence (IS) elements are a diverse set of specialized DNA segments that can move to new sites in bacterial genomes.

AIM

To determine the role of cagPAI and IS605 in the development of gastric cancer, we analysed cagPAI from patients with gastric cancer and compared the results with the host's CagA antibody status.

METHODS

H. pylori strains were isolated from 29 gastric cancer patients, and CagA status was determined by measuring serum antibody against CagA. The cagPAI region and IS605 were determined by PCR.

RESULTS

CagA seropositivity tended to be higher in the IS605/PAI+ group (5/7, 71.4%) than in the IS605/PAI- group (9/22, 40.9%). Association with cag13 was more frequent in the IS605+ group (92.3%; 12/13) than in the IS605- group (25.0%; 4/16; P = 0.0005).

CONCLUSIONS

cag13 may be associated with the presence of IS605 in gastric cancer patients.

Helicobacter pylori-CagA seropositivity and nitrite and ascorbic acid food intake as predictors for Gastric Cancer

A hospital-based case-control study was carried out between 1994 and 1996 to evaluate the risk of gastric cancer (GC) according to Helicobacter pylori-CagA (+) seropositivity, nitrite and ascorbic acid intake. Three geographical areas of Mexico were selected on the basis of their contrasting dietary patterns and H. pylori seroprevalence. Nitrite and ascorbic acid consumption were estimated by interview among 211 cases and 454 matched controls. Serum antibodies against IgG H. pylori and CagA were detected by immunosorbent assays. The adjusted risk for GC was significantly higher among CagA+ subjects compared with those that were CagA negative (Odds Ratio (OR)=2.04 95% Confidence Interval (CI) 1.37-3.02 P for trend P < 0.001), this effect remained significant among diffuse GC cases (OR 2.05 95% CI 1.25-3-36). No significant effects due to nitrite and ascorbic consumption or interactions of these nutrients with CagA seropositivity were detected. Seropositivity to H. pylori CagA+ strains may be an independent factor for diffuse GC in Mexico.

Anti-CagA and anti-VacA antibodies in Helicobacter pylori-infected patients with and without peptic ulcer disease in Serbia and Montenegro

BACKGROUND

The expression of two Helicobacter pylori proteins, CagA and VacA, is associated with more severe pathogenesis and clinical outcomes of the infection. However, this association varies among geographical regions and ethnic groups. We therefore evaluated CagA and VacA seroprevalence in H. pylori-positive dyspeptic patients in Serbia and Montenegro.

METHODS

In 173 consecutive dyspeptic patients referred to endoscopy (67M, mean age 49 +/- 15, 76 smokers), immunoblot assay was used to detect serum antibodies against CagA and VacA. Presence of H. pylori infection was assessed using a rapid urease test (RUT), routine histology and serology (anti-IgG ELISA). Duodenal ulcer (DU) was diagnosed in 28, gastric ulcer (GU) in 3 and non-ulcer dyspepsia (NUD) in the remaining 142 patients.

RESULTS

129 (74.6%) patients were H. pylori-positive, 27 (96.4%) with DU, 3 (100%) with GU and 99 (69.7%) with NUD (P < 0.01); 121 (93.8%) patients carried anti-CagA antibodies and there was no difference between the DU and NUD groups. VacA antibodies were detected in sera of 50 (38.75%) and were more prevalent in patients with DU compared to the NUD group (P < 0.05).

CONCLUSIONS

In Serbia and Montenegro there is high seroprevalence of CagA-positive H. pylori strains in dyspeptic patients with and without peptic ulcer, while VacA-positive strains are more closely related to peptic ulcer disease.

Etiology of pancreatic cancer, with a hypothesis concerning the role of N-nitroso compounds and excess gastric acidity

In the United States, pancreatic cancer is the fourth most frequent cause of cancer death in males as well as females, after lung, prostate or breast, and colorectal cancer. Each year, approximately 30 000 Americans are diagnosed with pancreatic cancer and about the same number die of it. Germline mutations in a few genes including p16 and BRCA2 have been implicated in a small fraction of cases, as has chronic pancreatitis. The one established risk factor for pancreatic cancer is cigarette smoking: current smokers have two to three times the risk of nonsmokers. Studies of dietary factors have not been entirely consistent but do suggest associations of higher risk with consumption of smoked or processed meats or with animal foods in general and lower risk with consumption of fruits and vegetables. Colonization by Helicobacter pylori appears to increase risk, and a history of diabetes mellitus may also increase risk. The purpose of this epidemiologic review is to consider the possibility that risk of pancreatic cancer is increased by factors associated with pancreatic N-nitrosamine or N-nitrosamide exposures and with chronic excess gastric or duodenal acidity. Host genetic variation in inflammatory cytokine mechanisms may also be involved in this process. Many features of the evidence bearing on the pathophysiology of pancreatic cancer appear to support connections with N-nitroso compounds and with gastric acidity.

Impact of CagA status on serum gastrin and pepsinogen I and II concentrations in Japanese children with Helicobacter pylori infection

The study aimed to determine the association between cytotoxin-associated gene product (CagA), serum gastrin and pepsinogen levels in Japanese children infected with Helicobacter pylori. Three hundred children were enrolled in the study. H. pylori infection was assessed using an enzyme-linked immunosorbent assay, and CagA status was assessed using immunoblotting. Serum gastrin and pepsinogen concentrations were measured by radioimmunoassay. H. pylori seroprevalence was 12.3% (37/300) and CagA status was identified in 28/37 H. pylori-seropositive children (75.7%). Serum pepsinogen I and II levels were significantly higher in CagA-seropositive than CagA-seronegative children with H. pylori infection. There was no significant relationship between CagA seropositivity and serum gastrin levels. In conclusion, CagA status has a significant impact on serum pepsinogen levels, possibly through enhanced gastric mucosal inflammation.

Transient and persistent Helicobacter pylori colonization in Native American children

Helicobacter pylori is chiefly acquired in childhood, but the exact timing of acquisition is not well understood. The main goal of this study was to assess H. pylori acquisition in a pediatric population. We studied two cohorts of Native American children: a birth cohort of 50 children and 58 older children (mean age, 53 months). We measured serum immunoglobulin G (IgG), IgM, and IgA antibodies to H. pylori whole-cell antigen and IgG antibodies to CagA. Among 44 birth cohort children monitored for more than 12 months, 24 (54.5%) had seroconversions, 7 (15.9%) were transient, and 17 (38.6%) were persistent. Among the older children, 49 (84.5%) of the 58 children were monitored for 1 year; 34 (69.4%) had H. pylori antibodies at study entry. During the next year, 7 (20.6%) children seroreverted, and of 15 initially negative children, 5 (33.3%) seroconverted. In both groups, evaluation of CagA antibodies increased the sensitivity of H. pylori detection. Serum pepsinogen I (PGI) levels in H. pylori-negative children rose significantly until age 6 months and remained constant for the next 19 months. At the time of H. pylori seroconversion, PGI peaked to levels significantly higher than in the never-seroconverted (P = 0.02) and the pre-seroconverted (P = 0.03) children, but then declined to levels paralleling those of H. pylori-negative children. Thus, H. pylori acquisition, accompanied by a transient PGI increase, was frequent in this population, especially in the second and third years of life, but often was brief.