Antone R. Opekun

Water source as risk factor for Helicobacter pylori infection in Peruvian children

Helicobacter pylori infection is widespread among Peruvian adults by the age of 30, but the age at which children become infected, the prevalence of disease, and the role of socioeconomic status in the epidemiology of infection are not known. We used the 13C-urea breath test to study the prevalence of infection in 407 Peruvian children from Lima, aged 2 months to 12 years, from families of low and high socioeconomic status. Peruvian children acquire H pylori early in life and the number of infected individuals increases rapidly with age; overall prevalence was 48%. H pylori infection was independent of sex, but was highly correlated with socioeconomic status; prevalence of infection was higher among children from low-income families than among those from high-income families (56% vs 32%, p = 0.001). Children whose homes had external water sources were three times more likely to be infected than were those whose homes had internal water sources. Among families with internal water sources, there was no difference in H pylori infection associated with income. Children from high-income families whose homes were supplied with municipal water were 12 times more likely to be infected than were those from high-income families whose water supply came from community wells. The findings show that the prevalence of H pylori infection is high among young Peruvian children and that the municipal water supply seems to be an important source of infection among Lima children from families of both low and high socioeconomic status.

Norwalk virus shedding after experimental human infection.

Noroviruses are shed in feces up to 8 weeks after infection.

Visible small-intestinal mucosal injury in chronic NSAID users

BACKGROUND & AIMS Patients who regularly take nonsteroidal anti-inflammatory drugs (NSAIDs) have an increased risk for small-intestinal mucosal ulceration and bleeding, which may present as anemia of undetermined gastrointestinal origin or protein loss. The prevalence and severity of small-intestinal lesions remains unclear. Our aim was to assess the frequency of NSAID-induced small-bowel injury among chronic NSAID users. METHODS Ambulatory patients with various types of arthritides who took NSAIDs daily (>3 mo duration) or took either acetaminophen alone or nothing were enrolled in the study. All patients fasted overnight and underwent wireless video capsule endoscopy. Two investigators, blind to therapy, reviewed each video beginning after the pylorus. Lesions were scored as normal, red spots, small erosions, large erosions, or ulcers. An ulcer was defined as a larger lesion with apparent depth and a definite rim. RESULTS Forty-one patients, 36 men and 5 women, ages ranging from 22 to 66 years (mean age, 49.8 y) were analyzed including 21 chronic NSAID users and 20 control patients. Small-bowel injury was seen in 71% of NSAID users compared with 10% of controls (P < .001). Injury was mild (few or no erosions, absence of large erosions/ulcers) in 10 NSAID users compared with 2 controls. Five NSAID users had major (>4 erosions or large ulcers/ulcers) damage compared with none in the control group. There were no complications or problems with the capsule endoscopy procedure. CONCLUSIONS Endoscopically evident small-intestinal mucosal injury is very common among chronic NSAID users. The role of endoscopically evident injury in unexplained iron-deficiency anemia and hypoalbuminemia among chronic NSAID users remains undetermined.

Norovirus Vaccine against Experimental Human Norwalk Virus Illness

BACKGROUND Noroviruses cause epidemic and sporadic acute gastroenteritis. No vaccine is available to prevent norovirus illness or infection. METHODS We conducted a randomized, double-blind, placebo-controlled, multicenter trial to assess the safety, immunogenicity, and efficacy of an investigational, intranasally delivered norovirus viruslike particle (VLP) vaccine (with chitosan and monophosphoryl lipid A as adjuvants) to prevent acute viral gastroenteritis after challenge with a homologous viral strain, Norwalk virus (genotype GI.1). Healthy adults 18 to 50 years of age received two doses of either vaccine or placebo and were subsequently inoculated with Norwalk virus and monitored for infection and gastroenteritis symptoms. RESULTS Ninety-eight persons were enrolled and randomly assigned to receive vaccine (50 participants) or placebo (48 participants), and 90 received both doses (47 participants in the vaccine group and 43 in the placebo group). The most commonly reported symptoms after vaccination were nasal stuffiness, nasal discharge, and sneezing. Adverse events occurred with similar frequency among vaccine and placebo recipients. A Norwalk virus-specific IgA seroresponse (defined as an increase by a factor of 4 in serum antibody levels) was detected in 70% of vaccine recipients. Seventy-seven of 84 participants inoculated with Norwalk virus were included in the per-protocol analysis. Vaccination significantly reduced the frequencies of Norwalk virus gastroenteritis (occurring in 69% of placebo recipients vs. 37% of vaccine recipients, P=0.006) and Norwalk virus infection (82% of placebo recipients vs. 61% of vaccine recipients, P=0.05). CONCLUSIONS This norovirus VLP vaccine provides protection against illness and infection after challenge with a homologous virus. (Funded by LigoCyte Pharmaceuticals and the National Institutes of Health; ClinicalTrials.gov number, NCT00973284.).

Replication of human noroviruses in stem cell–derived human enteroids

The major barrier to research and development of effective interventions for human noroviruses (HuNoVs) has been the lack of a robust and reproducible in vitro cultivation system. HuNoVs are the leading cause of gastroenteritis worldwide. We report the successful cultivation of multiple HuNoV strains in enterocytes in stem cell–derived, nontransformed human intestinal enteroid monolayer cultures. Bile, a critical factor of the intestinal milieu, is required for strain-dependent HuNoV replication. Lack of appropriate histoblood group antigen expression in intestinal cells restricts virus replication, and infectivity is abrogated by inactivation (e.g., irradiation, heating) and serum neutralization. This culture system recapitulates the human intestinal epithelium, permits human host-pathogen studies of previously noncultivatable pathogens, and allows the assessment of methods to prevent and treat HuNoV infections.

Sequential and Concomitant Therapy With Four Drugs Is Equally Effective for Eradication of H pylori Infection

BACKGROUND & AIMS Sequential therapy with a proton pump inhibitor (PPI) and amoxicillin followed by a PPI, clarithromycin, and an imidazole agent reportedly have a better rate of curing Helicobacter pylori infection than PPI, amoxicillin, and clarithromycin triple therapy. The concomitant administration of these 4 drugs (concomitant therapy) is also an effective treatment strategy. We compared the efficacies of sequential and concomitant therapy and analyzed the effects of antibiotic resistance in patients with H pylori infection. METHODS In a randomized trial of 232 H pylori-infected patients from 3 hospitals in Kaohsiung, Taiwan, patients were given 10 days of sequential (n = 115) or concomitant (n = 117) therapy. H pylori status was confirmed by endoscopy or urea breath test. RESULTS Intention-to-treat analysis demonstrated similar eradication rates for sequential (92.3%; 95% confidence interval [CI], 87.5%-97.1%) and concomitant therapy (93.0%; 95% CI, 88.3%-97.7%)(P = .83). Per-protocol eradication results were similar for sequential (93.1%; 95% CI, 90.7%-95.5%) and concomitant therapy (93.0%; 95% CI, 88.3%-97.7%) (P = .99). Univariate analysis showed that compliance and resistance to clarithromycin were independent determinants of eradication. Dual resistance did not influence the level of eradication in the concomitant group, but significantly affected that of the sequential therapy group. Clarithromycin resistance was less frequent than expected. CONCLUSIONS Sequential or concomitant therapy with a PPI, amoxicillin, clarithromycin, and an imidazole agent are equally effective and safe for eradication of H pylori infection. Resistance to clarithromycin, compliance, and adverse events reduced the level of eradication. Concomitant therapy may be more suitable for patients with dual resistance to antibiotics.

Recombinant Norwalk virus–like particles given orally to volunteers: Phase I study

BACKGROUND & AIMS Norwalk virus (NV) is a major cause of epidemic gastroenteritis. The NV capsid is composed of a single protein that forms recombinant (rNV) virus-like particles (VLPs). In mice, these VLPs are immunogenic when administered orally without adjuvant, and they elicit serum immunoglobulin (Ig) G and intestinal IgA responses. The aim of this study was to evaluate the safety and immunogenicity of rNV VLPs in healthy volunteers. METHODS Twenty antibody-positive adults were orally administered rNV VLPs in sterile Milli-Q water on days 1 and 21. Vaccine safety and serum rNV-specific total and subclass IgG and IgA antibody responses were monitored. The immune response induced by the VLPs was compared with the response elicited by replicating virus. RESULTS No side effects were observed or reported by the volunteers. Serum IgG responses to rNV VLPs were dose-dependent, and all vaccinees given 250 microgram of rNV VLPs responded with >/=4-fold increases in serum IgG titers. Most of the volunteers (83%; 15 of 18) responded after the first rNV VLP dose and showed no increase in serum IgG titer after the second dose. CONCLUSIONS Orally administered rNV VLPs are safe and immunogenic in healthy adults when administered without adjuvant and are useful to test the mucosal delivery of immunogens.

Sensitivity of the Esophageal Mucosa to pH in Gastroesophageal Reflux Disease

To determine the relation between the sensation of pain in gastroesophageal reflux and the pH of the refluxate, we studied 25 individuals with symptomatic gastroesophageal reflux and positive Bernstein tests. We quantitatively assessed the sensitivity of the esophageal mucosa to pain associated with the intraesophageal infusion of eight different HCl solutions (pH 1, 1.5, 2, 2.5, 3, 4, 5, and 6). Test solutions were infused at 8 ml/min through an eight-lumen catheter with the orifices placed 5 cm above the lower esophageal sphincter. Each subject received all eight solutions in a double-blind randomized fashion. The time-to-pain onset increased with increasing pH; i.e., there was a highly significant difference between the time-to-pain and pH (p less than 0.001), with the time-to-pain significantly longer with increasing pH (r = 0.77). In addition to more rapid onset of pain, all subjects experienced pain with the pH 1 and 1.5 solutions, 80% had pain with the pH 2.0 solution, and half had pain with solutions of pH 2.5-6. Fifteen of these subjects underwent 24-h pH monitoring and these tests were examined for factors associated with pain. Only 64% of all pain episodes were associated with a pH drop of less than 4; the lowest pH obtained was not different between episodes with and without pain. Reflux episodes resulting in pain were significantly longer than those without pain and were more often associated with a recently preceding painful episode. Overall, none of the data from the 24-h pH monitoring was useful for predicting pain. The acid infusion studies and the 24-h pH data, taken together, suggest episodes of pain sensitize the patient for subsequent pain.

Cimetidine, cigarette smoking, and recurrence of duodenal ulcer.

Three hundred seventy patients with recently healed duodenal ulcer entered into a one-year, double-blind, randomized multicenter trial comparing placebo with three different dose schedules of cimetidine (200 mg twice a day, 300 mg twice a day, and 400 mg at bedtime) for the prevention of recurrent duodenal ulcer. By the end of one year, the cumulative symptomatic recurrence rate as demonstrated by endoscopy was similar for the patients receiving the three dosages of cimetidine (19 per cent, 15 per cent, and 13 per cent, respectively; not significant), whereas the placebo-treated group had a 34.7 per cent symptomatic recurrence rate (P less than 0.01 as compared with each cimetidine group). Cigarette smoking was found to be an important variable; among the placebo recipients ulcer recurrence was significantly more likely in smokers (72 per cent) than in nonsmokers (21 per cent, P less than 0.001). The frequency of ulcer recurrence in smokers was significantly reduced by treatment with cimetidine (from 72 per cent to 34 per cent, P less than 0.). Smokers who received cimetidine were at least as likely to have a recurrence as were nonsmokers who received placebo (34 per cent vs. 21 per cent, not significant). Thus, smoking appears to be a major factor in recurrence of duodenal ulcer, and in smokers, giving up smoking may be more important in the prevention of ulcer recurrences than administration of cimetidine.

Serological Correlate of Protection against Norovirus-Induced Gastroenteritis

BACKGROUND Norovirus infection is the leading cause of acute nonbacterial gastroenteritis. Histoblood group antigens (HBGAs) are host susceptibility determinants for Norwalk virus (NV) infection. We hypothesized that antibodies that block NV-HBGA binding are associated with protection from clinical illness following NV exposure. METHODS We developed an HBGA blocking assay to examine the ability of human serum to block the interaction of NV viruslike particles with H type 1 and H type 3 glycans. Serum samples from persons who were experimentally challenged with NV were evaluated. RESULTS There was a high correlation between the H type 1 and H type 3 synthetic glycan assays (r = 0.977; P < .001); the H type 1 assay had higher quantitative sensitivity (P < .001). Among 18 infected secretor-positive individuals, blocking titers peaked by day 28 after challenge and were higher for individuals who did not develop gastroenteritis than for those who developed gastroenteritis on days 0, 14, 28, and 180 (P < .05 for each). In addition, 6 of 6 subjects without gastroenteritis had measurable prechallenge blocking titers (>25), compared with 2 of 12 subjects with gastroenteritis (P = .002). CONCLUSIONS Blocking antibodies correlate with protection against clinical NV gastroenteritis. This knowledge will help guide the evaluation of new vaccine strategies and the elucidation of the nature of immunity to the virus. Trial registration. ClinicalTrials.gov identifier: NCT00138476.