Molecular characterization and susceptibility testing of Helicobacter pylori strains isolated in western Argentina

Objective: To characterize Helicobacter pylori isolates from western Argentina using virulence markers and antimicrobial susceptibility patterns in order to assess the association between virulent genotypes, antimicrobial resistance, and disease. DNA fingerprinting was also evaluated for the segregation of virulent or resistant strain clusters. Methods: Genotyping of 299 H. pylori isolates was performed by PCR using specific primers for the cagA, vacA and iceA genes. Random amplification of polymorphic DNA (RAPD)-PCR and rep-PCR genetic clustering were assessed using five random primers and BOXA1R and ERIC primers, respectively. Resistance to clarithromycin (Cla) and metronidazole (Mtz) was assessed by the agar dilution method. Results: It was observed that 40.8% of the genotypes were cagA-positive; 66.9% were vacA s1m1 genotype and the iceA1 allele was found in 40.8%. A significant correlation (p = 0.0000) was observed between cagA positivity and vacA s1m1/iceA1 genotypes. Triple virulent genotypes were statistically associated with peptic ulcer (PU) (p = 0.0001) and Cla resistance (p = 0.0000). RAPD fingerprints obtained with AO2 primers identified clusters that were strongly associated with PU, virulence markers, and resistance to Cla and Mtz. Conclusions: The H. pylori isolates that harbored two or three virulence markers were more resistant to Cla and Mtz. Combined analysis of virulent genotypes and resistance patterns may permit identification of high-risk patients to prevent PU later in life or to avoid antimicrobial treatment failure. (C) 2010 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.