A new Helicobacter pylori vacuolating cytotoxin determinant, the intermediate region

Abstract number: P1987

Agudo S., Alarcón T., Pérez-Pérez G., Martínez J., López-Brea M.

Introduction: VacA, the vacuolating cytotoxin encoded by the vacA gene is a highly polymorphic. It has two regions: signal (s) and middle (m) that are well characterized markers of virulence. Functionally, s1/m1 strains cause more extensive vacuolation and clinically, are associated with gastric atrophy. Recently, a new polymorphic region of vacA designated intermediate (i) region, was described as a major determinant of vacA toxicity. The aim of this study was to determine the prevalence VacA genotypes and determine the association with VacA intermediate among H. pylori isolated in Madrid, Spain.

Methods: We obtained 118 biopsies from patients with gastric symptoms, from June 2008 to January 2009. Standard microbiological procedures were used for H. pylori culture. DNA extraction was carried out by the NucliSens easyMAG platform with the NucliSens magnetic extraction reagents (bioMérieux). VacA genotypes (s, m) were determined by PCR and agarose gel. VacA i genotype were determined by PCR and DNA sequencing in all s1m2 and in 10 random s2m2 and s1m1 strains. The criteria used for determining i-type (either i1 or i2) were based on the amino acid sequences.

Results: The results of VacA are showed in the table 1. Two i-region types were identified, i1 and i2. S1/m1 and s2/m2 strains were exclusively i1 and i2, respectively. 15 out of 16 (93.7%) s1m2 strains were i1.

Conclusions: The s2m2 was the most frequent vacA mosaicism, observed in 63% of our patients. This study shows the strong association between vacA i1 genotype and s1 allele of vacA gene. Further studies are needed in other to know if vacA i-region is an important marker of H. pylori toxicity.

Mixed strains43.4

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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