Effect of treatment failure on the CagA EPIYA motif in strains from Colombian subjects.

AIM

To evaluate effect of treatment failure on and genotypes in () isolates from Colombia.

METHODS

One hundred and seventy-six participants infected with from Colombia were treated during 14 d with the triple-standard therapy. Six weeks later, eradication was evaluated by C-Urea breath test. Patients with treatment failure were subjected to endoscopy control; biopsies obtained were used for histopathology and culture. DNA from isolates was amplified using primers specific for and genes. The phylogenetic relationships among isolates obtained before and after treatment were established by conglomerate analysis based on random amplified polymorphic DNA (RAPD) fingerprinting.

RESULTS

Treatment effectiveness was at 74.6%. Of the participants with treatment failure, 25 accepted subjected to a second endoscopy. Prevalence of post-treatment infection was 64% (16/25) and 40% (10/25) by histology and culture, respectively. Upon comparing the and genotypes found before and after therapy, multiple genotypes (-positive and -negative) were found before treatment; in contrast, -negative genotypes decreased after treatment. genotype was highly prevalent in patients before and after therapy. The 3' region was successfully amplified in 95.5% (21/22) of the isolates obtained before and in 81.8% (18/22) of the isolates obtained after treatment. In the isolates obtained from patients with treatment failure, it was found that 72.7% (16/22) presented alterations in the number of EPIYA motifs, compared to isolates found before treatment.

CONCLUSION

Unsuccessful treatment limits colonization by low-virulence strains resulting in partial and selective eradication in mixed infections, and acts on the -positive strains inducing genetic rearrangements in variable region that produces a loss or gain of EPIYA repetitions.