Gut microbiome of treatment-naïve MS patients of different ethnicities early in disease course.

Although the intestinal microbiome has been increasingly implicated in autoimmune diseases, much is unknown about its roles in Multiple Sclerosis (MS). Our aim was to compare the microbiome between treatment-naïve MS subjects early in their disease course and controls, and between Caucasian (CA), Hispanic (HA), and African American (AA) MS subjects. From fecal samples, we performed 16S rRNA V4 sequencing and analysis from 45 MS subjects (15 CA, 16 HA, 14 AA) and 44 matched healthy controls, and whole metagenomic shotgun sequencing from 24 MS subjects (all newly diagnosed, treatment-naïve, and steroid-free) and 24 controls. In all three ethnic groups, there was an increased relative abundance of the same single genus, Clostridium, compared to ethnicity-matched controls. Analysis of microbiota networks showed significant changes in the network characteristics between combined MS cohorts and controls, suggesting global differences not restricted to individual taxa. Metagenomic analysis revealed significant enrichment of individual species within Clostridia as well as particular functional pathways in the MS subjects. The increased relative abundance of Clostridia in all three early MS cohorts compared to controls provides candidate taxa for further study as biomarkers or as etiologic agents in MS.

Helicobacter pylori in children with asthmatic conditions at school age, and their mothers.

BACKGROUND: Helicobacter pylori prevalence in Western countries has been declining simultaneously with increases in childhood asthma and allergic diseases; prior studies have linked these phenomena. AIMS: To examine the association between H. pylori colonisation in children and risk of asthma and related conditions at school age. We secondly examined additional effects of maternal H. pylori status by pairing with children's status. METHODS: This study was embedded in a multi-ethnic population-based cohort in Rotterdam, The Netherlands. We measured anti-H. pylori and anti-CagA antibodies in serum of children obtained at age 6 years, and of their mothers obtained during midpregnancy. Asthma or related conditions were reported for children at age 6 years. We used multivariate logistic regression analyses among 3797 subjects. RESULTS: In children, the H. pylori positivity rate was 8.7%, and 29.2% of these were CagA-positive. A child's colonisation with a CagA-negative-H. pylori strain was associated with an increased risk of asthma (Odds ratio 2.11; 95% CI 1.23-3.60), but this differed for European (3.64; 1.97-6.73) and non-European (0.52; 0.14-1.89) children. When taking into account maternal H. pylori status, only H. pylori-positive children with an H. pylori-negative mother had increased risk of asthma (2.42; 1.11-5.27), accounting for 3.4% of the asthma risk. CONCLUSIONS: Colonisation of a European child with a CagA-negative-H. pylori strain at age 6 was associated with an increased prevalence of asthma, but there was no association for non-European children. The underlying mechanisms for the observed risk differences require further research.

Genetic risk factors for inflammatory bowel disease in a North-eastern Mexican population.

The purpose of this study was to assess the role of Helicobacter pylori and several genetic polymorphisms in relation to inflammatory bowel disease (IBD). We studied 44 unrelated patients with IBD and 75 subjects with no history of IBD as controls. Using pyrosequencing technology, we identified gene polymorphisms in IL-10, TNF-A, ILB-31, and TLR4. H. pylori status was determined by serology. Individuals homozygous for IL10-592 A or IL10-1082 A genotypes show significantly lower occurrence of IBD (P=0.03 and P<0.01, respectively). Individuals heterozygous at IL10-1082 have significantly increased occurrence of IBD, both ulcerative colitis and Crohn's disease (P<0.01). There was no difference in the prevalence of H. pylori infection between cases and controls. This study provides evidence that variation in IL10 is correlated with IBD occurrence in this Mexican population.

The association of gastric leptin with oesophageal inflammation and metaplasia.

BACKGROUND: Gastro-oesophageal reflux disease complications may reflect imbalances between protective and injurious factors. Through its effects on cell growth, leptin may influence oesophageal mucosal homeostasis. AIMS: To determine whether leptin receptors are present in the oesophagus, and whether serum or gastric leptin levels are associated with oesophageal inflammation and metaplasia. METHODS: From patients referred for upper endoscopy, biopsies were obtained from the stomach and distal oesophagus, and serum samples were collected. Patients were classified as having normal, inflamed or Barrett's oesophagus. Quantitative immunohistochemistry was performed on representative sections, and leptin levels in plasma and gastric biopsy samples were determined by specific immunoassay. RESULTS: Of 269 individuals enrolled, 105 were Helicobacter pylori-negative. Of the 88 patients with complete oesophageal biopsies, 44 were normal, 24 were inflamed and 20 were Barrett's oesophagus. Receptors for leptin were highly expressed on oesophageal epithelial cells, with similar density and staining pattern in all three conditions, and plasma and antral leptin levels did not differ significantly. Patients with Barrett's had significantly (p = 0.01) higher fundic leptin levels (median 202 (interquartile range 123-333) pg/mg) compared with normal (126 (78-221) pg/mg) or inflamed (114 (76-195) pg/mg) oesophagus. In multivariate analysis, for every twofold increase in fundic leptin, the odds of having Barrett's was 3.4 times (95% CI 1.5 to 7.6) higher compared with having a normal oesophagus. CONCLUSIONS: Leptin receptor expression on oesophageal epithelial cells provides a pathway for leptin-mediated signal transduction. Variation in gastric leptin production could contribute to differential oesophageal healing and metaplasia progression.

[Helicobacter pylori erradication and its relation to antibiotic resistance and CYP2C19 status]. / Erradicación de H. pylori y su relación con la resistencia a los antibióticos y el estatus de CYP2C19.

OBJECTIVE: to assess the efficacy of rabeprazole (RPZ), amoxicillin (Am), and clarithromycin (Cla) (7 vs. 14 days) in the eradication of H. pylori, and to determine the effect of strain-specific antibiotic resistance and host CYP2C19 status. MATERIAL AND METHODS: first, we determined the CYP2C19 status of 100 healthy subjects to establish a sample size for the clinical trial. Then, 59 H. pylori-infected patients were randomized to receive RPZ (20 mg daily) plus Cla (500 mg b.d.) and Am (1,000 mg b.d.) for 7 vs. 14 days. The MIC for Am and Cla were determined using the agar dilution method. The CYP2C19 genotype was determined by the PCR-RFLP method. RESULTS: In the per-protocol analysis (PP) eradication rates were 89.7 and 72% for the 7- and 14-day groups (p = 0.159). In the intention to-treat analysis (ITT) eradication rates were 86.7 and 62.1% in the 7- and 14-day groups, respectively (p = 0.06). None of the strains was resistant to Am, and 4 strains were resistant to Cla: 3 (11.1%) in the 14-day group and 1 (4%) in the 7-day group. Neither strain-specific antibiotic resistance nor host CYP2C19 status influenced eradication rates. CONCLUSIONS: both 7- and 14-day therapies were effective for H. pylori eradication. Strain resistance and CYP2C19 status do not seem to influence eradication rates in the studied population.

Helicobacter pylori and oesophageal and gastric cancers in a prospective study in China.

In a cohort of 29,584 residents of Linxian, China, followed from 1985 to 2001, we conducted a case-cohort study of the magnitude of the association of Helicobacter pylori seropositivity with cancer risk in a random sample of 300 oesophageal squamous cell carcinomas, 600 gastric cardia adenocarcinomas, all 363 diagnosed gastric non-cardia adenocarcinomas, and a random sample of the entire cohort (N=1050). Baseline serum was evaluated for IgG antibodies to whole-cell and CagA H. pylori antigens by enzyme-linked immunosorbent assay. Risks of both gastric cardia and non-cardia cancers were increased in individuals exposed to H. pylori (Hazard ratios (HRs) and 95% confidence intervals=1.64; 1.26-2.14, and 1.60; 1.15-2.21, respectively), whereas risk of oesophageal squamous cell cancer was not affected (1.17; 0.88-1.57). For both cardia and non-cardia cancers, HRs were higher in younger individuals. With longer time between serum collection to cancer diagnosis, associations became stronger for cardia cancers but weaker for non-cardia cancers. CagA positivity did not modify these associations. The associations between H. pylori exposure and gastric cardia and non-cardia adenocarcinoma development were equally strong, in contrast to Western countries, perhaps due to the absence of Barrett's oesophagus and oesophageal adenocarcinomas in Linxian, making all cardia tumours of gastric origin, rather than a mixture of gastric and oesophageal malignancies.

Association of interleukin-1B and interleukin-1RN polymorphisms with gastric cancer in a high-risk population of Costa Rica.

Several risk factors have been associated with gastric cancer, among them Helicobacter pylori infection. This bacterium yields inflammation, the degree of which depends on the bacterial strain and the severity of the host response. The inflammatory response involves a complex cytokine network. Recently, polymorphisms of the genes coding for interleukin-1beta (IL-1B), interleukin-1Ra (ILRN) and interleukin-10 have been associated with an increased risk of gastric cancer. In order to determine the association of the IL-1B, IL-1RN and IL-10 polymorphisms with gastric cancer in a high-risk Costa Rican population, we analysed purified DNA of 58 gastric cancer patients, 99 controls and 41 patients classified as group I or II, according to the Japanese classification. Genotyping was carried out by PCR, PCR-RFLP and pyrosequencing analysis. We did not find any association of the IL-1B-31, IL-1B-511 and IL-10 polymorphisms with the risk for developing gastric cancer in the studied population. Carriers of the IL-1B+3954T/- had an increased risk for developing gastric cancer (OR 3.7; 95%CI: 1.34-10.2). Also we found an increased risk for developing gastric cancer for allele 2 heterozygotes of the IL-1RN (OR 2.94; 95%CI: 1.09-7.93). This is the first time that IL-1B+3954 has been associated with gastric cancer. This is one of the first studies trying to describe the role played by IL-1B, IL-1RN and IL-10 genetic polymorphisms in gastric cancer in one of the highest risk American countries. Further investigation on American countries is needed.

High frequency of gastric colonization with multiple Helicobacter pylori strains in Venezuelan subjects.

Multiple Helicobacter pylori strains may colonize an individual host. Using enzyme-linked immunosorbent assay and line probe assay (LiPA) techniques, we analyzed the prevalence of mixed H. pylori colonization in 127 subjects from Venezuela, a country of high H. pylori prevalence, from three regions representing different population groups: the Andes (Merida), where Caucasian mestizos predominate, a major city near the coast (Caracas), where Amerindian-Caucasian-African mestizos predominate, and an Amazonian community (Puerto Ayacucho), where Amerindians predominate and mestizos reflect Amerindian and Caucasian ancestry. Among 121 H. pylori-positive persons, the prevalence of cagA-positive strains varied from 50% (Merida) to 86% (Puerto Ayacucho) by LiPA. Rates of mixed colonization also varied, as assessed by LiPA of the vacA s (mean, 49%) and m (mean, 26%) regions. In total, 55% of the individuals had genotypic evidence of mixed colonization. vacA s1c, a marker of Amerindian (East Asian) origin, was present in all three populations, especially from Puerto Ayacucho (86%). These results demonstrate the high prevalence of mixed colonization and indicate that the H. pylori East Asian vacA genotype has survived in all three populations tested.

Characterisation of Helicobacter pylori isolates from the north-eastern region of Mexico.

The vacA and cagA genotypes of 50 Helicobacter pylori isolates from patients in the north-eastern region of Mexico were characterised by PCR, and the correlation between genotypes and different clinical outcomes was investigated. Strains of H. pylori that are vacA s1/m1 and cagA positive have previously been associated with more severe clinical outcomes, and some studies have shown differences in the vacA and cagA genotypes in different geographical regions. The six possible combinations of the vacA signal (s) and middle (m) regions were identified in this population, and the most frequent genotype was s2/m2. Thirty-two (64%) isolates were identified as cagA-positive. The s region was not amplified from seven of the cagA-positive isolates, and the m region was not amplified from one cagA-negative isolate, indicating that additional subfamilies of s and m genotypes may exist. The s1/m1 genotype was associated with cagA-positive strains (p < 0.05). No association was found between the vacA and cagA genotypes and clinical outcomes.

Antibiotic susceptibility patterns of Helicobacter pylori strains isolated from northeastern Mexico.

There are reports of increased antibiotic resistance rates in Helicobacter pylori strains around the world. The aim of this study was to determine the susceptibility patterns in H. pylori strains isolated in Monterrey, Mexico. We studied 62 strains isolated from the same number of symptomatic adult patients. Metronidazole (Mtz), clarithromycin (Cla), amoxicillin (Amx) and tetracycline (Tet) were tested by the E-test method. We observed that 37.1% of the strains were resistant to Mtz (MIC > or = 8 mg/L), and 8.1% to Cla (MIC > or = 8 mg/L), but we did not observe resistance to Amx (MIC > or = 2 mg/L) or Tet (MIC > or = 4 mg/L). In northeastern Mexico, the percentage of resistant strains was similar to that observed in developed countries. These results confirm that it is necessary to evaluate the susceptibility patterns of H. pylori strains by geographic area.

Evidence that cagA(+) Helicobacter pylori strains are disappearing more rapidly than cagA(-) strains.

BACKGROUND AND AIMS: The prevalence of Helicobacter pylori colonisation in populations in developed country has been declining, as shown by community based serological surveys of adults in Vammala, Finland in 1973 and 1994. In this study, we determined whether the proportion of subjects colonised by cagA(+) or cagA(-) H pylori strains has changed as the overall prevalence of H pylori(+) has declined. METHODS: We examined 911 sera from Vammala's study for antibodies to the CagA antigen of H pylori using a truncated CagA protein as the antigen in an ELISA and we examined the trend in acquisition and carriage of cagA(+) strains. RESULTS: As expected, the prevalence of carriage of both cagA(+) and cagA(-) strains fell between 1973 and 1994 (p<0.001). However, the prevalence of cagA(+) strains among those <45 years declined (34% to 8%) significantly (p<0.001) more than for cagA(-) strains (12% to 6%). Of 221 subjects with paired serum samples, 12 (5.4%) changed H pylori status; the estimated seroconversion and reversion rates were 0.4% and 0.13% per year, respectively. Except for the few individuals who changed serostatus, absolute antibody levels to H pylori antigens, including CagA, changed little over the 21 year period. CONCLUSIONS: The decline in CagA seroprevalence predominantly reflects declining acquisition of cag(+) strains in younger subjects. In addition, these data confirm that H pylori acquisition chiefly occurs during childhood but continues to occur during adulthood, albeit at low rates, in developed countries.

Helicobacter pylori prevalence and CagA status among children in two counties of China with high and low risks of gastric cancer.

BACKGROUND: Studies in adult populations in selected countries with widely varying rates of gastric cancer have shown a weak correlation between gastric cancer mortality rates and the prevalence of CagA+ strains of H. pylori. However, only limited data are available in ethnically homogenous populations with varying rates in the same region. METHODS; We compared the prevalence of H. pylori in general and of CagA+ strains in particular among children in Shandong Province, China in areas at high (Linqu County) and low risk (Cangshan County) of gastric cancer. H. pylori status among children aged 3 to 12 years was determined by 13C-UBT, and CagA status was determined by enzyme-linked immunosorbent assay (ELISA). Because of the difficulty in obtaining blood from young children aged 3 to 4 years and from some children aged 5 years, CagA status was determined among part of children 5 years old and children 6 to 12 years old. RESULTS; Among 98 children aged 3 to 12 years in Linqu, 68 (69.4%) was H. pylori-positive, as compared with 29 (28.7%) among 101 children in Cangshan. Among children positive for 13C-UBT, the proportion of the CagA+ strains were identified was 46 (88.5%) of 52 in Linqu and 13 (81.3%) of 16 in Cangshan, respectively. CONCLUSIONS: The prevalence of H. pylori was nearly three times higher among children in Linqu than in Cangshan, which may contribute to the large differential in gastric cancer rates for two neighboring populations in Shandong Province.

Increased gastric epithelial cell apoptosis associated with colonization with cagA + Helicobacter pylori strains.

Gastric colonization by Helicobacter pylori is a risk factor for noncardia gastric cancer. The association between H. pylori and cancer may be attributable to increased epithelial cell turnover, possibly related to antigastric antibodies. Two previous studies reported a disproportionate increase in proliferation relative to apoptosis in patients with H. pylori strains expressing the virulence-related cagA gene. This has led to the hypothesis that an abrogation of apoptosis by cagA-positive strains may promote neoplasia. We, therefore, examined the effect of H. pylori on gastric epithelial proliferation, apoptosis, and the presence of serum antiparietal cell antibodies in a large prospective study. Proliferation and apoptosis were evaluated "blindly" using validated immunohistochemical methods in two antral and two gastric corpus biopsies from 60 patients with nonulcer dyspepsia, and results were correlated with the presence of serum antiparietal cell antibodies. H. pylori colonization was assessed by histology, biopsy urease test, and serology. Proliferation was increased 2-fold in both antrum and corpus in H. pylori-positive patients, was not related to H. pylori cagA status, and was positively correlated with histological gastritis. Apoptosis was increased in the antrum and body only in patients with cagA-positive H. pylori strains. Antiparietal cell antibodies were not more prevalent in H. pylori colonization, and their presence was inversely related to epithelial apoptosis scores we therefore conclude that in patients with nonulcer dyspepsia, H. pylori carriage is associated with increased proliferation. Futhermore the cag pathogenicity island is associated with increased apoptosis. Our results do not support the hypothesis that there is a relative deficiency of gastric epithelial cell apoptosis associated with the carriage of cagA-positive strains. Host factors may be more important than bacterial products in determining the long-term outcome of H. pylori colonization.

A comparison of Lewis x and Lewis y expression in Helicobacter pylori obtained from children and adults.

There are no reports, to our knowledge, on the expression of Lewis (Le) antigens in Helicobacter pylori isolates from children. The aim of this study was to compare the expression of Le antigens by H. pylori isolates from children and from adults. Totals of 278 clones from 22 children with recurrent abdominal pain and 293 clones from 22 adults with (n=10) or without (n=12) duodenal ulcer were studied. Expression of Le(x) and Le(y) antigens was determined by ELISA, using monoclonal anti-Le antibodies. The Le phenotype of the patients was determined in gastric juice with a hemagglutination assay. Clones expressing Le(x) were more common in children than in adults (55.4% vs. 33.4%, respectively; P<.001), and Le(y) was more common in adults than in children (81.6% vs. 66%, respectively; P<.01). A trend analysis showed a significant decline in frequency of clones expressing Le(x) with age (P=.021). In this community, expression of Le antigens differs in H. pylori isolates obtained from children versus adults.

Helicobacter pylori genotypes, host factors, and gastric mucosal histopathology in peptic ulcer disease.

From 183 patients undergoing upper gastrointestinal endoscopy, we used antral and corpus gastric biopsies for bacterial culture and histopathologic examination, blood samples to detect immunoglobulin G antibodies against Helicobacter pylori, and H pylori genomic DNA to analyze cytotoxin-associated gene A (cagA) and vacuolating cytotoxin (vacA) genotypes. As expected, among H pylori biopsy-positive patients, those with duodenal ulcer (DU) (n = 34) had significantly more severe chronic and acute inflammation (P <.001) and epithelial degeneration (P =.004) in the gastric antrum than in the gastric corpus. Each of those 3 parameters and H pylori density were significantly higher in the antrum of patients with DU than in patients with gastric ulcer (GU) or no ulcer. Colonization with vacA s1/cagA-positive strains of H pylori was associated with inflammation and epithelial degeneration in gastric mucosa and increased risk for peptic ulcer disease (PUD), whereas colonization with vacA s2m2/cagA-negative strains was associated with mild gastric histopathology and was not associated with any significant risk for PUD. The predominant H pylori strains in African Americans were vacA s1bm1/cagA-positive, whereas all genotypes were well represented in non-Hispanic-Caucasians. By multivariate analysis, H pylori colonization was significantly associated with DU (Adjusted odds ratio [AdjOR] = 3.2 [1.4-7.2]) and nonsteroidal anti-inflammatory drugs (NSAID) use was inversely associated (AdjOR = 0.3 [0.2-0.7]). NSAID use (AdjOR = 4.3 [1.02-18.5]) and African-American ethnicity (AdjOR = 10.9 [2.6-50]) were significantly associated with GU. Smoking and age were not significantly associated with either DU or GU. These data indicate that DU is associated with an antral-dominant gastritis, and H pylori genotype and NSAID use independently contribute to the pathogenesis of PUD. HUM PATHOL 32:264-273. This is a US Government work. There are no restrictions on its use.

Colonization with cagA-positive Helicobacter pylori strains inversely associated with reflux esophagitis and Barrett's esophagus.

AIM: The hypothesis that colonization with cagA(+) Helicobacter pylori strains protects against the development of gastroesophageal reflux disease (GERD) and its complications is tested. METHODS: Patients with reflux esophagitis and Barrett's esophagus were studied. Antral biopsy specimens were obtained for detection of H. pylori. A serum sample was obtained for determination of IgG antibodies to H. pylori and to the CagA protein. RESULTS: 736 patients were studied. 118 patients had reflux esophagitis, 36 had Barrett's esophagus, 108 had hiatal hernia without signs of inflammation (the reflux group), and 20 patients had esophageal or stomach cancer. The remaining 454 patients had no signs of GERD. The 262 patients with reflux disease had a significantly lower prevalence of H. pylori (34.9%) than the 454 controls (54.6%; p<0. 001). Among 310 H. pylori-positive patients from whom serum was available, colonization with cagA(+) strains was detected in 59% in the control group versus 35% in the reflux group (p<0.001). CONCLUSION: Patients with reflux esophagitis and Barrett's esophagus have a significantly lower prevalence of H. pylori colonization than controls, in particular of the cagA(+) type. These data suggest that colonization with cagA(+) H. pylori strains may be protective against the development of GERD

Anti-CagA immunoglobulin G responses correlate with interleukin-8 induction in human gastric mucosal biopsy culture.

Helicobacter pylori persists in the human stomach despite eliciting both cellular and humoral immune responses and inducing proinflammatory cytokines. To determine whether local humoral and cytokine responses are related to each other and to histologic responses, we studied 66 Japanese patients who underwent gastroscopy. Using specific enzyme-linked immunosorbent assays, we examined gastric antral mucosal-organ biopsy culture supernatants to assess interleukin-6 (IL-6) and interleukin-8 (IL-8) levels and antibody responses to H. pylori whole-cell antigens CagA, HspA, and HspB. Of the patients studied, 11 were H. pylori negative and 55 were H. pylori positive; by PCR, all strains were cagA(+). As expected, compared to H. pylori-negative patients, H. pylori-positive patients had significantly higher humoral responses to all H. pylori antigens and had higher IL-8 (47.8+/-3.5 versus 10.1+/-4.3 ng/mg of biopsy protein; P<0.001) and IL-6 levels (2.8+/-0.3 versus 0.26+/-0.2 ng/mg of protein; P<0.001). Among the H. pylori-positive patients, supernatant anti-CagA immunoglobulin G (IgG) levels were significantly associated with H. pylori density (P<0.005) and neutrophil infiltration (P<0.005) scores. Anti-CagA immunoglobulin A levels were correlated with intestinal metaplasia (P<0.05). Mononuclear cell infiltration scores were significantly associated with supernatant IL-6 levels (P<0.005) and with IgG responses to whole-cell antigens (P<0.05). Supernatant IL-8 levels were significantly associated with anti-CagA IgG (r = 0.75, P<0.001). Anti-CagA responses correlated with neutrophil infiltration, intestinal metaplasia, H. pylori density, and IL-8 levels, suggesting that the absolute levels of these antibodies may be markers for gastric inflammation and premalignant changes in individual hosts.

CagA-positive strains of Helicobacter pylori may protect against Barrett's esophagus.

OBJECTIVE: Helicobacter pylori (H. pylori) colonization is associated with chronic gastritis, peptic ulcer disease, and adenocarcinoma of the distal stomach. However, the role of H. pylori strain variation in complicated gastroesophageal reflux disease, especially Barrett's esophagus, is unknown. Therefore, the aim of this study was to evaluate the prevalence of colonization by cagA+ and cagA- H. pylori strains in the spectrum of gastroesophageal reflux disease, including Barrett's esophagus. METHODS: A total of 251 patients undergoing endoscopy were categorized into four groups: controls, patients with gastroesophageal reflux disease alone, and patients with short- and long-segment Barrett's esophagus. All patients underwent upper endoscopies with biopsies and serum collections. H. pylori and degree of mucosal inflammation in gastric biopsies were assessed and serological assessment made for H. pylori and cagA status. RESULTS: The overall prevalence of H. pylori colonization in the study population was 35% (95% confidence interval = 29.5-41.4%) which did not differ significantly among the groups. However, colonization by cagA+ H. pylori strains was significantly more prevalent among controls (11/25; 44%) and patients with gastroesophageal reflux disease (13/36; 36%) than in patients with short-segment (2/10; 20%) or long-segment Barrett's esophagus (0/18; 0%). Patients with Barrett's esophagus were less likely to be colonized by cagA+ H. pylori strains than reflux patients without Barrett's esophagus (odds ratio = 0.27, 95% confidence interval = 0.11-0.67, p = 0.004). CONCLUSIONS: Colonization by cagA+ H. pylori strains may be protective against the formation of short- and long-segment Barrett's esophagus and its malignant complications.

Seroprevalence and ethnic differences in Helicobacter pylori infection among adults in the United States.

The seroprevalence of Helicobacter pylori infection was examined in the adult US population and among different ethnic groups. Stored sera from 7465 adult participants in the first phase of the third National Health and Nutritional Examination Survey (1988-1991) were tested with a sensitive and specific IgG ELISA, to diagnose infection. Seroprevalence of H. pylori among all participants was 32. 5%. This increased with age, from 16.7% for persons 20-29 years old to 56.9% for those > or =70 years old. Age-adjusted prevalence was substantially higher among non-Hispanic blacks (52.7%) and Mexican Americans (61.6%) than among non-Hispanic whites (26.2%). After controlling for age and other associated factors, the odds ratios relative to non-Hispanic whites decreased for non-Hispanic blacks, from 3.9 (95% confidence interval [CI], 3.1-4.9) to 3.3 (95% CI, 2. 6-4.2), and for Mexican Americans, from 6.3 (95% CI, 4.8-8.3) to 2.3 (95% CI, 1.6-3.5). The high prevalence of H. pylori infection among non-Hispanic blacks and Mexican Americans is partially explained by other factors associated with infection.