Análise das impressões digitais de DNA e de fatores de virulência de linhagens de Helicobacter pylori

cagE as a biomarker of the pathogenicity of Helicobacter pylori

INTRODUCTION

Helicobacter pylori infection is associated with gastro-duodenal diseases. Genes related to pathogenicity have been described for H. pylori and some of them appear to be associated with more severe clinical outcomes of the infection. The present study investigates the role of cagE as a pathogenicity biomarker of H. pylori compare it to cagA, vacA, iceA and babA2 genes and correlate with endoscopic diagnoses.

METHODS

Were collected biopsy samples of 144 dyspeptic patients at the Hospital of the Federal University of Rio Grande, Rio Grande do Sul, Brazil. After collection, the samples were sent for histological examination, DNA extraction and detection of all putative pathogenicity genes by PCR.

RESULTS

Of the 144 patients undergoing endoscopy, 57 (39.6%) presented H. pylori by histological examination and PCR by detection of the ureA gene. Based on the endoscopic diagnoses, 45.6% (26/57) of the patients had erosive gastritis, while 54.4% (31/57) had enanthematous gastritis. The genes cagA, cagE, vacAs1/m1, vacAs1/m2 and iceA1 were related to erosive gastritis, while the genes vacAs2/m2, iceA2 and babA2 were associated to enanthematous gastritis. We found a statistically significant association between the presence of cagE and the endoscopic diagnosis. However, we detect no statistically significant association between the endoscopic diagnosis and the presence of cagA, vacA, iceA and babA2, although a biological association has been suggested. Conclusions Thus, cagE could be a risk biomarker for gastric lesions and may contribute to a better evaluation of the H. pylori pathogenic potential and to the prognosis of infection evolution in the gastric mucosa.

Characterization of virulence genes cagA and vacA in Helicobacter Pylori and their prevalence in gastrointestinal disorders

Prevalence of H. pylori infection was determined using cultures of gastric biopsy samples of patients attended at the academic hospital of the Federal University of Paraná, Curitiba, Paraná, Brazil. Molecular methods were used to characterize the cagA and vacA genes from bacterial isolates associated with different diseases presented by patients. Out of a total of 81, forty-two gastric biopsy samples tested were positive for H. pylori, with a prevalence of 51.9%. No significant difference was found with regard to the gender (p=0.793) and age (p=0.183) of the patients. Genotype s1m1 vacA gene was found in 67% of the cases of peptic ulcer investigated (p=1.0), despite the limited number of patients with this disease (n=3). A correlation between the presence of less virulent strains (s2m2) and reflux esophagitis was found in the majority of the cases (45%), but without statistical significance. An association between the prevalence of cagA gene, found in 92% of isolates, and peptic ulcer was not observed (p=1.0), suggesting that this gene cannot be considered a specific marker of severity in our environment. The results reinforce the importance of conducting regional studies and the need to characterize H. pylori virulence genes associated with different diseases.

Detection of Helicobacter pylori by phenotypic and genotypic methods

AIMS

This research evaluated the utilization of a urease in-house test, culture and molecular method (ureA PCR) as a diagnostic tool for Helicobacter pylori infection. Furthermore, we assessed the presence of the cagA gene in the specimens and in isolated strains that were positive for ureA by PCR positive.

RESULTS

Sensitivity and specificity, respectively, were 100 and 95.8% for the urease in-house test 93.3 and 95.8 for the ureA PCR assay of the specimen and 100 and 100% for the culture. The presence of the cagA gene was observed in eight (53%) ureA-positive samples.

CONCLUSIONS

In this study, we found that the PCR technique has applicability in the study of cagA, and other genes related to the H. pylori pathogen. This method can be applied to samples directly from biopsy or isolated from the bacteria.