Ana Palha

Antibiotic-resistant Helicobacter pylori strains in Portuguese children.

Background: Data concerning the effectiveness of Helicobacter pylori eradication regimens based in antibiotic susceptibility testing are scanty in children. Aims: To identify the prevalence of antibiotic resistance in H. pylori strains isolated from Portuguese children in 1999–2003; to evaluate eradication rate after antibiotic susceptibility testing-based treatment; and to identify factors associated with resistance and eradication outcome. Methods: Included were 109 children with a gastric biopsy culture positive for H. pylori. First treatment (amoxicillin, omeprazole and clarithromycin or metronidazole) was guided by susceptibility testing (E test), and eradication was assessed by [13C]urea breath test. Results: Strains were susceptible to amoxicillin and tetracycline; 39.4% were resistant to clarithromycin, 16.5% to metronidazole and 4.5% to ciprofloxacin. No significant association was found between resistance and sex, age, clinical status, gastritis scores, H. pylori density scores and genotype. Clarithromycin resistance was significantly associated with European origin [odds ratio (OR), 3.9], previous H. pylori empiric therapy (OR 2.8) and amoxicillin minimal inhibitory concentration, ≥0.016 (OR 6.0). Eradication rate after susceptibility-based treatment was 74.7% (59 of 79; 95% confidence interval, 65.9–82.9), and a significant association was found between eradication failure and presence of resistance to 1 or more antibiotics (P < 0.05). Conclusions: The prevalence of H. pylori antibiotic resistance was high in the studied population. The modest therapeutic success of clarithromycin and metronidazole susceptibility-based regimens suggests that in addition to resistance, other factors may be involved. The need of susceptibility-based treatment studies in children and of antimicrobial resistance surveillance in high prevalence areas for H. pylori are emphasized.

Cytokine expression in pediatric Helicobacter pylori infection

ABSTRACT Helicobacter pylori infection is one of the most common gastrointestinal infections worldwide and almost invariably causes chronic gastritis in the infected host. A predominant Th1 profile has been demonstrated in H. pylori-infected mucosa from adults, but no previous study has evaluated in situ cytokine expression in children. We therefore examined expression of proinflammatory, anti-inflammatory, and regulatory cytokines by immunohistochemistry in cryopreserved antral biopsy specimens from 10 H. pylori-infected and 10 uninfected children and correlated expression of cytokines with histology scores. Concomitant expression of interleukin-8 (IL-8), gamma interferon (IFN-γ), IL-4, transforming growth factor β, and tumor necrosis factor alpha was seen in 8/10 H. pylori-infected cases and in 5/10 noninfected cases; all H. pylori-infected subjects showed staining for at least two of the cytokines. The proportion of epithelial cytokine-specific staining did not differ significantly between the groups, either in surface or glandular epithelium. Furthermore, no significant differences were noticed between intraepithelial or lamina propria lymphocyte staining in the groups. There was, however, a tendency of higher numbers of IFN-γ- and IL-8-positive cells in the H. pylori-infected group. IFN-γ and IL-8 lamina propria lymphocyte expression correlated significantly with antrum chronic inflammation, but there was no correlation between histology scores and epithelial cytokine expression. When the same techniques were used, the cytokine response appeared to be smaller in H. pylori-infected children than in adults, and there was no clear Th1 dominance. These results therefore suggest a different mucosal immunopathology in children. It remains to be determined whether the gastric immune response is downregulated in children with H. pylori infection and whether this is relevant to the outcome of infection.

Relationship among serum pepsinogens, serum gastrin, gastric mucosal histology and H. pylori virulence factors in a paediatric population.

Objective. Serum pepsinogens and gastrin have been proposed as markers of gastritis, but have seldom been studied in children. In this study the aim was to identify host- and Helicobacter pylori-related factors linked to variations in serum gastrin, PGI, PGII, and to evaluate the potential of these biomarkers for diagnosing gastritis, whether H. pylori-associated or not. Material and methods. Ninety-two dyspeptic children referred for endoscopy (peptic ulcer exclusion) were included in the study. H. pylori status (urease, culture, histology) was assessed, and genotype determined (PCR) in H. pylori-positive subjects. Serum gastrin, PGI and PGII levels were measured by standard radioimmunoassay (RIA). Results. PGI and PGII levels were significantly higher in H. pylori-positive subjects (p=0.007; p=0.012, respectively). Gastrin levels were significantly higher in H. pylori-negative subjects (p=0.035). PGI and PGII were associated significantly with higher antrum inflammation scores (p=0.002; p=0.016, respectively); only PGI was associated with age, after controlling for inflammation (p=0.033) and for activity (p=0.037). The contribution of virulence factors could not be assessed owing to the low number of virulent strains. After multivariate analysis, only antrum inflammation was independently associated with PGI level (p=0.012). Receiver operating characteristic (ROC) analysis showed a low PGI and PGII discriminant power for predicting antrum inflammation. Conclusions. Pepsinogen levels as measured in this study seem predominantly to reflect antral inflammation, but they are not an effective screening test for gastritis (H. pylori-positive or -negative) in dyspeptic children.

Helicobacter pylori genotypes in children from a population at high gastric cancer risk: no association with gastroduodenal histopathology.

OBJECTIVES:Both bacterial and host determinants underlying differences in histopathology and clinical outcome in H. pylori pediatric infection, as compared to adults, are still poorly documented. Pediatric studies may provide important insights on H. pylori infection immunopathogenesis, particularly in high gastric cancer risk populations. The present study concerns H. pylori genotypic diversity of isolates in children from a population with high gastric cancer risk, and its association with demographic and clinical variables, including gastroduodenal endoscopic and histopathological features.METHODS:A total of 119 subjects (mean age 10.3 yr, 1.5–18.0 yr) with H. pylori infection were studied. H. pylori vacA, cagA, and iceA genotypes were determined (PCR) in antral-obtained primary cultures; histopathological evaluation was performed in corpus, antrum, and duodenum biopsy specimens.RESULTS:cagA−, vacA s2m2, and iceA2 were the most prevalent genotypes. No association was observed between H. pylori genotypes and subject demographic and clinical variables, with the exception of a significant association between vacA s2 genotype and lower corpus inflammation score (p< 0.03).CONCLUSIONS:In this pediatric cohort, H. pylori genotype profiles were distinct from those reported in adult subjects in the same area, with a lower prevalence of the putative more virulent genotypes. Moreover, they were not associated with clinical expression of gastroduodenal disease, suggesting the potential role of host and/or environmental factors for the development of clinical disease at a later age.

Autoimmune gastritis presenting as iron deficiency anemia in childhood

AIM To characterize clinical, laboratorial, and histological profile of pediatric autoimmune gastritis in the setting of unexplained iron deficiency anemia investigation. METHODS A descriptive, observational study including pediatric patients with a diagnosis of autoimmune gastritis (positive parietal cell antibody and gastric corpus atrophy) established in a 6 year period (2006-2011) in the setting of refractory iron deficiency anemia (refractoriness to oral iron therapy for at least 6 mo and requirement for intravenous iron therapy) investigation, after exclusion of other potentially contributing causes of anemia. Helicobacter pylori (H. pylori) infection and anti-secretory therapy were also excluded. Data were retrospectively collected from clinical files, including: demographic data (age, gender, and ethnic background), past medical history, gastrointestinal symptoms, familial history, laboratorial evaluation (Hb, serum ferritin, serum gastrin, pepsinogen I/ pepsinogen II, B12 vitamin, intrinsic factor autoantibodies, thyroid autoantibodies, and anti-transglutaminase antibodies), and endoscopic and histological findings (HE, Periodic Acid-Schiff/Alcian blue, gastrin, chromogranin A and immunochemistry analysis for CD3, CD20 and CD68). Descriptive statistical analysis was performed (mean, median, and standard deviation). RESULTS We report a case-series concerning 3 girls and 2 boys with a mean age of 13.6 ± 2.8 years (3 Caucasian and 2 African). One girl had type I diabetes. Familial history was positive in 4/5 cases, respectively for autoimmune thyroiditis (2/5), sarcoidosis (1/5) and multiple myeloma (1/5). Laboratorial evaluation on admission included: Hb: 9.5 ± 0.7 g/dL; serum ferritin: 4.0 ± 0.9 ng/mL; serum gastrin: 393 ± 286 pg/mL; low pepsinogen I/ pepsinogen II ratio in 1/5 patients; normal vitamin B12 levels (analyzed in 3 patients). Endoscopy findings included: duodenal nodularity (2/5) and gastric fold softening (2/5), and histological evaluation showed corpus atrophic gastritis with lymphocytic infiltration (5/5), patchy oxyntic gland mononuclear cell infiltration (5/5), intestinal and/or pseudo-pyloric metaplasia in corpus mucosa (4/5), and enterochromaffin cell hyperplasia (4/5). Immunochemistry for gastrin on corpus biopsies was negative in all cases. Duodenal histology was normal. All biopsies were negative for H. pylori (Giemsa staining and cultural examination). CONCLUSION We highlight autoimmune gastritis as a diagnosis to be considered when investigating refractory iron deficiency anemia in children, particularly in the setting of a personal/familial history of autoimmune disease, as well as the diagnostic contribution of a careful immunohistological evaluation.