ABSTRACT
BACKGROUND: We evaluated several risk factors for gastric cancer in Costa Rican regions having contrasting gastric cancer incidence rates, despite the small dimensions of the country. METHODS: A total of 180 dyspeptic patients were classified into two groups according to the gastric cancer incidence (GCI) rate in their Costa Rican region: group A, with a high GCI rate (n = 91) and group B, with a low GCI rate (n = 89). Helicobacter pylori infection was detected by rapid urease test, Gram staining, and histological observation. Antral and corpus specimens were obtained to assess the grade of inflammation, topography of gastritis, gastric atrophy, and intestinal metaplasia by histological examination. Serum CagA antibody was measured by an antigen-specific enzyme-linked immunosorbent assay. RESULTS: There was no significant difference in H. pylori prevalence between groups A (73%) and B (63%); however, serum CagA antibody was more frequently detected in group A (79%) than in group B (54%) [P = 0.02; odds ratio (OR), 2.68]. Among patients under 60 years of age, serum CagA antibody was even more frequently detected in group A (81%) than in group B (49%) (P < 0.01; OR, 4.50). The prevalence of corpus-predominant gastritis, atrophic gastritis, and moderate/severe grades of neutrophilic infiltration was higher in serum CagA antibody-positive patients than in CagA antibody-negative patients (P = 0.003, 0.04, and 0.002, respectively). CONCLUSIONS: Infection with H. pylori possessing the cagA gene is associated with the development of severe gastric damage such as gastric atrophy, leading to gastric cancer, and probably influences the differences in GCI between Costa Rican regions.
Subject(s)
Antigens, Bacterial/metabolism , Bacterial Proteins/metabolism , Gastritis/epidemiology , Helicobacter Infections/complications , Helicobacter pylori/pathogenicity , Stomach Neoplasms/epidemiology , Adult , Aged , Antibodies, Bacterial/blood , Antigens, Bacterial/genetics , Antigens, Bacterial/immunology , Bacterial Proteins/genetics , Bacterial Proteins/immunology , Costa Rica/epidemiology , Female , Gastritis, Atrophic/epidemiology , Gastritis, Atrophic/etiology , Helicobacter Infections/epidemiology , Helicobacter Infections/microbiology , Helicobacter pylori/genetics , Helicobacter pylori/metabolism , Humans , Incidence , Male , Metaplasia , Middle Aged , Stomach Neoplasms/etiologyABSTRACT
Introducción. La frecuencia de aislamiento de Clostridium botulinum en Costa Rica y en otros sitios es baja, en tanto que C. perfringens es la especie toxigénia más abundante en la naturaleza. Se ha descrito que C. perfringens podría impedir el aislamiento de C. botulinum o la producción de su toxina a partir de muestras de suelo, razón por la cual se pensó en investigar el efecto al respecto, de cepas de C. perfringens aisladas de suelos costarricenses. Material y Métodos. Se analizaron 38 cepas de C. perfringens obtenidas de suelos costarricenses para demostra si los sobrenadantes de cultivo inhibían el crecimiento de C. botulinum A (ATCC 19399). Además, se realizaron cultivos mixtos de C. botulinum y C. perfringens para evaluar si se impedía el crecimiento y la producción de toxina botulínica. Resultados. El 58 por ciento de las cepas de C. perfringens tuvo efecto inhibitorio sobre el crecimiento de C. botulinum; al menos dos cepas inhibían totalmente el efecto de la toxina botulínica en los cultivos mixtos aún cuando se demostró la presencia de células viables de C. botulinum. El número mínimo de células de C. perfringens necesarias para lograr lo anterior fue de 10 a la octava células. Conclusión. Es posible que la presencia de C. perfringens limite el aislamiento o demostración de C. botulinum en suelos costarricenses. Se requiere investigar si las cepas nativas de C. perfringens tienen efecto sobre otras cepas y otros grupos de C. botulinum
