Characterization of 23S rRNA domain V mutations in gastric biopsy patients from the eastern Amazon

Resistance of Helicobacter pylori to clarithromycin is characterised by simple point mutations in the 23S ribosomal RNA (rRNA) gene and is responsible for the majority of cases of failure to eradicate this bacterium. In this paper, we characterised the variability of the 23S rRNA gene in biopsies of patients with gastric pathologies in the eastern Amazon (Northern Region of Brazil) using PCR and sequencing. A total of 49 sequences of H. pylori strains were analysed and of those, 75.6 percent presented nucleotide substitutions: A2142G (3.3 percent), T2182C (12.9 percent), G2224A (6.45 percent), T2215C (61.3 percent), A2192G (3.3 percent), G2204C (6.4 percent) and T2221C (6.4 percent). Of the mutations identified, four are known mutations related to cases of resistance and 16.1 percent are not yet described, revealing a high prevalence of mutations in the H. pylori 23S rRNA gene among the strains circulating in the in the eastern Amazon. The high prevalence in individuals with gastric pathologies in the Northern Region of Brazil demonstrates the need for characterising the profile of these strains to provide correct therapy for patients, considering that mutations in this gene are normally associated with resistance to the primary medication used in controlling H. pylori infection.

Clinical and pathological importance of vacA allele heterogeneity and cagA status in peptic ulcer disease in patients from north Brazil

We have examined the prevalence of gene cagA and vacA alleles in 129 patients, 69 with gastritis and 60 with peptic ulcer diseases from North Brazil and their relation with histopathological data. vacA and cagA genotype were determined by polymerase chain reaction. Hematoxylin-eosin staining was used for histological diagnosis. 96.6 percent of the patients were colonized by Helicobacter pylori strains harboring single vacA genotype (nont-mixed infection). Among them, 11.8 percent had subtype s1a, 67.8 percent had subtype s1b, and 17 percent subtype s2. In regard to the middle region analysis, m1 alleles were found in 75.4 percent and m2 in 21.2 percent of patients. The cagA gene was detected in 78 percent patients infected with H. pylori and was associated with the s1-m1 vacA genotype. The H. pylori strains, vacA s1b m1/cagA-positive, were associated with increased risk of peptic ulcer disease and higher amounts of lymphocytic and neutrophilic infiltrates and the presence of intestinal metaplasia. These findings show that cagA and vacA genotyping may have clinical relevance in Brazil.

Expressäo dos antígenos ABH e Lewis na gastrite crônica e alteraçöes pré-neoplásica da mucosa gástrica / Expression of ABH and Lewis antigens in chronic gastritis and pre-neoplasic alterations in gastric mucosa

RACIONAL: A aderência do Helicobacter pylori à mucosa gástrica humana é pré-requisito para sua colonizaçäo e o desenvolvimento da gastrite crônica. Os antígenos de grupos sangüíneos, presentes no muco gástrico, säo descritos como prováveis receptores da bactéria neste epitélio. A expressäo alterada destes antígenos está associada ao desenvolvimento do câncer gástrico. OBJETIVOS: Verificar a ocorrência do Helicobacter pylori e a distribuiçäo da expressäo dos antígenos ABH e Lewis correlacionada com as alteraçöes histopatológicas de pacientes com gastrite crônica. PACIENTES E MÉTODOS: Analisaram-se 63 amostras de sangue, saliva e biopsias gástricas de pacientes com gastrite crônica através das técnicas dot-blot-ELISA, imunoperoxidase indireta e coloraçöes do Gram modificado e hematoxilina-eosina. RESULTADOS: Näo foram encontradas associaçöes significativas entre a presença da bactéria e os fenótipos de grupos sangüíneos ABH, Lewis e Secretor. Na maioria dos pacientes, a expressäo dos antígenos ABH e Lewis, estava restrita principalmente ao epitélio foveolar da mucosa gástrica, concordando com a expressäo ao nível salivar. A expressäo inapropriada desses antígenos ocorria sempre na infecçäo pelo Helicobacter pylori e/ou alteraçöes pré-neoplásicas da mucosa gástrica. Em áreas com metaplasia intestinal foi observada a reduçäo da reatividade para os antígenos H e Le b, e principalmente o aumento de Leª. CONCLUSÄO: Alteraçöes no padräo de glicosilaçäo destes antígenos refletem diferentes estágios de diferenciaçäo celular e säo marcadores potenciais na avaliaçäo diagnóstica e prognóstica das patologias gástricas