Characterisation of Helicobacter pylori isolates from the north-eastern region of Mexico.

The vacA and cagA genotypes of 50 Helicobacter pylori isolates from patients in the north-eastern region of Mexico were characterised by PCR, and the correlation between genotypes and different clinical outcomes was investigated. Strains of H. pylori that are vacA s1/m1 and cagA positive have previously been associated with more severe clinical outcomes, and some studies have shown differences in the vacA and cagA genotypes in different geographical regions. The six possible combinations of the vacA signal (s) and middle (m) regions were identified in this population, and the most frequent genotype was s2/m2. Thirty-two (64%) isolates were identified as cagA-positive. The s region was not amplified from seven of the cagA-positive isolates, and the m region was not amplified from one cagA-negative isolate, indicating that additional subfamilies of s and m genotypes may exist. The s1/m1 genotype was associated with cagA-positive strains (p < 0.05). No association was found between the vacA and cagA genotypes and clinical outcomes.