HELICOBACTER-PYLORI POPULATIONS IN PERUVIAN PATIENTS

Helicobacter pylori is an extremely diverse species. The characterizat ion of strains isolated from individual patients should give insights into colonization and disease mechanisms and bacterial evolution. We s tudied H. pylori isolates from patients in the Japanese-Peruvian Polyc linic in Lima, Peru, by determining metronidazole susceptibility or re sistance and by random amplified polymorphic DNA (RAPD) fingerprinting (a measure of overall genotype). Strains isolated from several biopsy specimens from each of 24 patients were studied. Both metronidazole-s usceptible and -resistant strains were isolated from 13 patients, wher eas strains of more than one RAPD type were isolated from only seven p atients. We propose that the homogeneity in RAPD fingerprints for stra ins isolated from most persons reflects selection for particular H. py lori genotypes during chronic infection in individual hosts and the hu man diversity in traits that are important to this pathogen, Carriage of related metronidazole-resistant and -susceptible strains could refl ect frequent metronidazole use in Peru and alternating selection for r esistant and susceptible phenotypes during and after metronidazole the rapy.