Immune and proliferative cellular responses to Helicobacter pylori infection in the gastric mucosa of Mexican children.

BACKGROUND: Helicobacter pylori infection occurs mostly during childhood, but few studies on this age group have addressed the innate immune and the proliferative response to this infection. Mexico has a high H. pylori prevalence in children, but a low risk of gastric cancer. The aim of this work was to study the cellular responses of the gastric mucosa to this infection in Mexican children. METHODS: Antral and corpus gastric biopsies were obtained from 44 H. pylori-infected children (mean age 12 +/- 3.2 years) and 44 uninfected children (mean age 10 +/- 3 years). Mucosal cellular responses were studied by immunohistochemistry, using anti-Ki67 antibodies for proliferation studies, antihuman tryptase for mast cells, and antihuman CD68 for macrophages. T and B lymphocytes were stained with a commercial integrated system. The intensity of cellular responses was estimated histologically using the software KS300. RESULTS: Epithelium proliferation and infiltration of macrophages and T and B lymphocytes were significantly higher in H. pylori-infected than in uninfected children. A balanced increase of CD4, CD8, and CD20 lymphocytes was observed in infected children. However, activated mast cells were decreased, and infiltration of neutrophil and mononuclear cells was low. Epithelial proliferation was associated with polymorphonuclear infiltration but not with infiltration of macrophages or lymphocytes. Inflammation and proliferation was higher in CagA (+)-infected children. CONCLUSIONS: Mexican children respond to H. pylori infection with a low inflammatory response, a balanced increase of T and B lymphocytes, and a high regenerative activity.

Identificación de genotipos de Helicobacter pylori, provenientes de muestras de placa dental en la población venezolana

La placa dental ha sido sugerida como un reservorio importante de Helicobacter pylori, pero la hipótesis de que esta bacteria pueda permanecer como parte integrante de la microbiota residente de la cavidad bucal. Estudios previos realizados en nuestro país demostraron la presencia del microorganismo en 12/32 pacientes, lo que representa un 37,6% de positividad. H. pylori se caracteriza por poseer una gran variabilidad genética, y se ha demostrado la presencia de genes bacterianos específicos que están asociados con la virulencia de las especies bacterianas. El objetivo de este estudio fue caracterizar los genotipos vacA y cagA de especies de H. pylori provenientes de placa dental de una muestra de la población venezolana con el fin de determinar los genotipos mas frecuentes de nuestra población a nivel de la cavidad bucal. Fueron evaluadas 69 muestras de placa dental de pacientes con indicación de endoscopia por enfermedad de las vías digestivas superiores, provenientes del Hospital Clínico Universitario de Caracas. Se tomaron muestras de placa dental de cada uno de los pacientes y se realizó la extracción de ADN para el análisis por Reacción en Cadena de la Polimerasa (RCP). Se amplificaron los segmentos de glm M, vac A and cag A. Los resultados demostraron que solo 1/69 muestras (1,4%) fue positiva para la amplificación de glmM. Ninguna de las muestras pudo ser tipificada para las diferentes formas alélicas de vacA , región media de vacA o cagA . Los resultados de la presente investigación demostraron que aún cuando en reportes previos observamos una importante prevalencia de H. pylori en muestras de placa dental, en esta investigación la prevalencia de la bacteria fue muy baja, no pudiéndose identificar los genotipos mas frecuentes a nivel de placa dental.

The aim of this study was to characterize the vacA and cagA genotypes of H. pylori strains from dental plaque of a Venezuelan population. 69 patients attending for routine gastroscopy were evaluated. Dental plaque samples were obtained for DNA extraction and PCR analysis. Amplification of glmM, vacA and cagA segments were performed as previously described. The results demonstrated that only 1/69 (1,4%) was positive for glmM amplification. None of the samples was typeable for vacA signal sequence genotype, vacA mid region or cagA. The results demonstrated that the prevalence of H. pylori in dental plaque of a Venezuelan population was not significant in this study and was not possible to identify the genotypes of H. pylori from dental plaque.

Validation of the string test for the recovery of Helicobacter pylori from gastric secretions and correlation of its results with urea breath test results, serology, and gastric pH levels.

The efficacy of the string culture test to isolate Helicobacter pylori from gastric secretions of 28 volunteers was studied. With the urea breath test (UBT) as the "gold standard," the string culture test showed a sensitivity of 75% and a specificity of 100%. The results of string culture did not correlate with the UBT results, with serum antibody levels, or with the pH levels of gastric secretions.

Helicobacter pylori strain-specific differences in genetic content, identified by microarray, influence host inflammatory responses.

Helicobacter pylori enhances the risk for ulcer disease and gastric cancer, yet only a minority of H. pylori-colonized individuals develop disease. We examined the ability of two H. pylori isolates to induce differential host responses in vivo or in vitro, and then used an H. pylori whole genome microarray to identify bacterial determinants related to pathogenesis. Gastric ulcer strain B128 induced more severe gastritis, proliferation, and apoptosis in gerbil mucosa than did duodenal ulcer strain G1.1, and gastric ulceration and atrophy occurred only in B128+ gerbils. In vitro, gerbil-passaged B128 derivatives significantly increased IL-8 secretion and apoptosis compared with G1.1 strains. DNA hybridization to the microarray identified several strain-specific differences in gene composition including a large deletion of the cag pathogenicity island in strain G1.1. Partial and complete disruption of the cag island in strain B128 attenuated induction of IL-8 in vitro and significantly decreased gastric inflammation in vivo. These results indicate that the ability of H. pylori to regulate epithelial cell responses related to inflammation depends on the presence of an intact cag pathogenicity island. Use of an H pylori whole genome microarray is an effective method to identify differences in gene content between H. pylori strains that induce distinct pathological outcomes in a rodent model of H. pylori infection.

[Comparison of 2 schedules based on pantoprazole for eradication of Helicobacter pylori in patients with active duodenal ulcer]. / Comparación de dos esquemas basados en pantoprazol para erradicación de Helicobacter pylori en pacientes con úlcera duodenal activa.

OBJECTIVE: To compare the efficacy and tolerability of a triple vs dual pantoprazole based therapy to eradicate Helicobacter pylori (H. pylori) in mexican patients with florid duodenal ulcer. BACKGROUND: The treatment of peptic ulcer disease was revolutionized by the fact that H. pylori generally induces chronic gastritis and peptic ulcer disease and that the cure of the infection prevents ulcer relapses. MATERIAL AND METHODS: 74 H. pylori positive patients with florid duodenal ulcer were randomized to receive either pantoprazole 40 mg bid in combination with clarithromycin 500 mg tid and amoxicillin 1 g bid (triple regimen PAC) or pantoprazole in combination with clarithromycin and placebo (dual regimen PC) during 14 days. To ensure complete ulcer healing all patients received an additional 2 weeks treatment with pantoprazole 40 mg od. 14C Urea Breath test (UBT) was the main criteria used to determine eradication rate with < 150 disintegrations per minute (DPM) to consider a patient eradicated. In all patients culture, antibiotic susceptibility (E-test) and histology were performed. RESULTS: In the per protocol analysis (n = 66) the eradication rate was: PAC 93.5% vs PC 54.3% (p < 0.001). 76% of H. pylori strains were resistant to metronidazole. Tolerance and compliance were excellent in both groups. CONCLUSIONS: Triple therapy (PAC) was shown to be superior to dual therapy (PC) for H. pylori eradication in mexican patients with florid duodenal ulcer.

Hospital-acquired diarrhea in adults: a prospective case-controlled study in Mexico.

OBJECTIVE: To know the incidence, etiology, risk factors, morbidity, and mortality of nosocomial diarrhea in adults. DESIGN: Nested case-control study, matched by service, length of stay, date of admission, and presence of leukopenia and/or the acquired immunodeficiency syndrome (AIDS). Cases were those who developed nosocomial diarrhea. Controls were those who did not develop nosocomial diarrhea during a comparative period nor during the next ten days. Stool samples were processed in search for parasites, yeasts, bacteria, and rotavirus. SETTING: Third-level referral center, in Mexico City, Mexico, for general internal medicine and surgical problems. PATIENTS: Eligible subjects were all new admissions to the hospital from November 1987 to September 1988. Reasons for exclusion were presence of chronic diarrheal disease or melena. There were 115 cases and 111 controls. RESULTS: Overall risk of acquiring nosocomial diarrhea was 5.5%, or 1.8 episodes per 100 patient-weeks. A potential pathogen was found in 59%. Yeasts and Entamoeba histolytica were the most frequently isolated pathogens. Mortality in cases was 18%, as compared with 5% in controls (p less than .01). Multivariate analysis showed enteral feeding, recent enemas, presence of Candida species, use of antacids/H2-blockers, and presence of nasogastric tubes as significant risk factors for nosocomial diarrhea. CONCLUSIONS: Diarrhea is a common complication in hospitalized patients. It occurs more often than previously suspected and is linked with a substantial mortality. The spectrum of etiologic agents is different from that reported in pediatric hospitals. Given that nosocomial diarrhea may constitute, at least, a marker of severity of illness, it should receive more attention in general hospitals.

Colonization by Clostridium difficile in hospitalized children: risk factors and typification of the isolated strains.

The frequency of colonization by Clostridium difficile in 273 hospitalized children under 15 years of age was studied. Feces were collected from patients attending the infectious disease service at the Pediatric Hospital IMSS, during a period of 11 months. No colonization was detected in 16 neonates; whereas 10 of 103 children (9.7%) under one year of age, 7 of 84 children (8.3%) from one to five years and 3 of 70 children (4.2%) from five to 15 years of age were colonized. The use of antibiotics and the nutritional state were studied as possible risk factors for colonization. The frequency of colonization was not influenced by the nutritional state, whereas the treatment with antibiotics decreased significantly the colonization in children under one year of age but not in those children over one year of age. In children under one year of age, the cytotoxin was more frequent in cases of diarrhea, and in those over one year no association was found. The 50 strains isolated from these children were classified according to: toxigenicity, sensitivity to antibiotics, phages and bacteriocins. Strains acquired before hospitalization were more toxigenic than those acquired intrahospital. Twelve resistotypes were detected; one of them (V) was more frequent in intrahospital strains. Ten phagobacteriocin types were found, and two of then (D and I) were present only in intrahospital strains. Using this classification scheme, it was found that eight patients were colonized with two different strains at the same time.