ABO, Lewis, secretor and non-secretor phenotypes in patients infected or uninfected by the Helicobacter pylori bacillus

CONTEXT: Epidemiological studies have demonstrated higher frequencies of the O blood group and the non-secretor phenotype of ABH antigens among patients suffering from peptic ulcers. Since Helicobacter pylori has been established as the main etiological factor in this disease, controversies about the associations of the ABO and Lewis blood group phenotypes and secretor and non-secretor phenotypes in relation to susceptibility towards infection by this bacillus have been presented. OBJECTIVE: To verify the frequencies of ABO, Lewis blood group phenotypes, secretor and non-secretor phenotypes in patients infected or uninfected by H. pylori. DESIGN: Cross-sectional study. SETTING: Outpatient clinic. PARTICIPANTS: One hundred and twenty patients with dyspeptic symptoms who underwent endoscopy.MAIN MEASUREMENTS: ABO and Lewis blood group phenotypes were determined by a standard hemagglutination test and the secretor and non-secretor phenotypes were evaluated by saliva samples using the inhibitor hemagglutination test. RESULTS: The diagnosis of infection, made via breath and urea tests and confirmed using polymerase chain reaction (PCR) in gastric biopsy fragments, showed the presence of H. pylori in 61.7 percent of the patients and absence in 38.3 percent. The differences between the frequencies of the ABO blood group phenotypes among infected (A 27.0 percent; B 12.2 percent; AB 4.0 percent and O 56.8 percent) and uninfected patients (A 58.7 percent; B 13.0 percent; AB 4.3 percent and O 24.0 percent) were significant. The Lewis blood type, secretor and non-secretor phenotypes showed homogeneous distribution between the groups of patients analyzed. CONCLUSIONS: Our results suggest that the infection of H. pylori can be related to ABO blood groups but not to the Lewis blood group nor to secretor and non-secretor phenotypes

Aplicaçäo da PCR no diagnóstico molecular do Helicobacter pylori / Application of the PCR in the molecular diagnostic method for Helicobacter pylori

A infecçäo pelo bacilo Gram-positivo Helicobacter pylori está associada a maior risco de gastrite crônica ativa, úlceras pépticas e câncer gástrico. Diferentes métodos têm sido usados para diagnosticar a infecçäo por esse bacilo, porém, como a PCR apresenta elevada sensibilidade e especificidade, ela tem sido de grande utilidade no diagnóstico dessa infecçäo. O objetivo deste trabalho foi avaliar a possibilidade de uso do método PCR na identificaçäao do H. pylori em biópsias de antro gástrico. Foram avaliados 120 pacientes adultos com sintomas de dispepsias e indicaçäo de endoscopia digestiva alta. O DNA genômico foi extraído por um método salino e amplificado em posiçöes específicas, sendo os fragmentos resultantes da amplificaçäo e compatíveis com a presença de infecçäo revelados em gel de agarose a 2 por cento. A metodologia da PCR permitiu detectar o H. pylori a partir de material de biópsia, sendo verificada a sua presença em 61,7 por cento (74/120) dos pacientes e ausência em 38,3 por cento(46/120). Esses resultados reforçam a utilidade da PCR como método diagnóstico dessa infecçäo.