RESUMEN
BACKGROUND: Genetic diversity among Helicobacter pylori strains isolated from different patients has been debated. This study was undertaken to determine molecular types and genetic diversity among 20 isolates of H. pylori obtained from various gastroduodenal diseases, and also examined the association between molecular types of H. pylori and these diseases. METHODS: Antral biopsies were taken for culture from 38 patients with chronic gastritis, gastric ulcer and duodenal ulcer at the time of endoscopy. Biopsy specimens were primarily inoculated on chocolate agar and incubated microaerophilically at 37degree Cfor up to 7 days. H. pylori was identified by typical Gram stain morphology and biochemical tests. Random amplified polymorphic DNA (RAPD) fingerprinting was performed by 4 primers (OPA-07, 5'-GAAACGGGTG-3'; OPA-10, 5'-GTGATCGCAG-3'; OPA-11, 5'-CAATCGCCGT-3'; OPA-12, 5'-TCGGCGATAG-3'; Operon Technologies, Atlanta, GA). We used the NTSYS-pc (numerical taxonomy system and multivariate analysis system, version 1.50, Applied Biostatistics Inc., CA, USA) program to compose the phenogram for the differentiation of H. pylori strains. RESULTS: Twenty strains (52.6%) of H. pylori were isolated from 38 biopsy specimens. All isolates were divided into five molecular types (I-V) at similarity (S) value of 0.63; 7 strains (35%), 4 strains (20%), 4 strains (20%), 3 strains (15%) and 2 strains (10%) belonged to type II, III, IV, V and I, respectively. The distribution of genetic S value was 0.24 to 0.91 in all isolates, thus the isolates had a wide range of S values. The mean S values of all isolates, type I, II, III, IV and V were 0.69, 0.69, 0.73, 0.75 and 0.65, respectively. There was no specific correlation between molecular types and gastroduodenal diseases. CONCLUSION: H. pylori isolates had high level of genetic diversity. The RAPD molecular types of H. pylori were not disease-specific since the types were diverse in the isolates from various gastroduodenal diseases.