Genotipificación de cagA y de la región intermedia de vacA en cepas de Helicobacter pylori aisladas de pacientes adultos colombianos y su asociación con enfermedades gástricas / Genotyping of cagA and the intermediate region of vacA in strains of Helicobacter pylori isolated from Colombian adult patients and associations with gastric diseases

Resumen Objetivo: este estudio caracteriza la diversidad de los genes de virulencia cagA (gen asociado con la citotoxina A) y vacA (citotoxina vacuolizante) en pacientes colombianos para determinar posibles asociaciones entre estos 2 genes y la severidad de los hallazgos endoscópicos teniendo en cuenta todos los genotipos reportados para el gen vacA (s, m e i). Materiales y métodos: Helicobacter pylori fue detectado por cultivo y por métodos moleculares en biopsias de 62 pacientes. Los genotipos de cagA y vacA (m/i/s) se determinaron por reacción en cadena de la polimerasa (PCR) y secuenciación. Resultados: se aislaron 124 cepas de 62 pacientes; de estas, el 48,5% (n = 48) fueron vacA s2/m2/i2-cagA (-) presente en su mayoría en pacientes con gastritis folicular; mientras el 32,3% (n = 32) fueron vacA s1/m1/i1-cagA (+) presentes mayormente en pacientes con gastritis folicular, gastritis crónica y posible metaplasia. Se encontró una asociación significativa entre la presencia de cagA y el genotipo vacA s1/m1/i1 y la ausencia de cagA y el genotipo vacA s2/m2/i2 (p <0,001). No se encontró una asociación significativa entre la severidad de los hallazgos endoscópicos y el estatus cagA-vacA de las cepas. Conclusión: se encontró una baja prevalencia de cepas cagA (+), el estatus cagA-vacA no es un predictor de riesgo en la población estudiada y la presencia de infecciones heterogéneas sin tropismo sugieren la necesidad de tomar biopsias tanto del cuerpo como del antro del estómago en la práctica clínica rutinaria.

Abstract Objective: This study characterizes the diversity of cagA and vacA virulence genes in Colombian patients to determine possible associations between them and the severity of endoscopic findings. It considers all four genotypes reported for the vacA gene (s, m and i). Materials and methods: Helicobacter pylori was detected in biopsies of 62 patients through culturing and by molecular methods. Genotypes of cagA and vacA (m/i/s) were determined by PCR and sequencing. Results: One hundred twenty four strains from 62 patients were isolated. Of these, 48.5% (n = 48) were vacA s2/m2/i2 - cagA (-) which were mostly found in patients with follicular gastritis; 32.3% (n = 32) were vacA s1/m1/i1-cagA (+) which were mostly found in patients with follicular gastritis, chronic gastritis and possible metaplasia. Significant associations were found between the presence of cagA and the vacA s1/m1/i1 genotype and the absence of cagA and the vacA s2/m2/i2 genotype (p <0.001). No significant association was found between the severity of endoscopic findings and the cagA-vacA status of the strains. Conclusion: We found a low prevalence of cagA (+) strains, the cagA-vacA status is not a predictor of risk in this population. Moreover, the presence of heterogenous infections without tropism suggests a need for biopsies from both the corpus and the antrum of the stomach in routine clinical practice.

CagA status and VacA subtypes of Helicobacter pylori in relation to histopathologic findings in Iranian population.

Background/Objective: The aim of this study was to detect dominant cagA/vacA genotypes of Helicobacter Pylori (H. pylori) and determine correlations between different cagA/vacA genotypes and histologic features of chronic gastritis in Iranian patients. Methods: Gastric biopsy was taken from 166 patients with nonulcer dyspepsia. The specimens were processed and DNA from each H. pylori isolate was extracted from multiple colony sweeps for identification of glmM gene. The vacA subtypes and cagA gene were tested by PCR . Histopathological features were recorded and graded according to partial Sydney system. Results: Of the 86 strains, 66 (76.7%) were cagA positive. The proportions of vacA gene subtypes s1, s2, m1 and m2 in the 78 strains isolated were 70.5%, 29.5%, 37.2% and 62.8%, respectively. About 83.3% of the vacA-positive strains had s1 allele. Twenty-six strains (33.3%) were positive for both cagA and m1 allele. Positive cagA status and vacA subtypes were not associated significantly with presence of neutrophil infiltration, intestinal metaplasia or H. pylori density. Only vacA s1 was significantly associated with more severe inflammation (P=0.02). The dominant genotype of H. pylori was vacA plus s1/m2. CagA gene positivity rate was not closely associated with severity of the disease. Conclusion: H. pylori strains showing vacA s1 genotype were associated with more severe gastritis. These findings show that vacA genotyping may have clinical relevance in Iran.