genotyping clinical isolates of Helicobacter pylori

AIM: H pylori genomes are highly diversified. This project was designed to genotype H pylori isolates by the polymerase chain reaction (PCR)-based randomly amplified polymorphic DNA (RAPD) fingerprinting technique and to verify its stability by Southern blotting and DNA sequencing. METHODS: Clinical isolates of H pylori were cultured from gastric antra and cardia of 73 individuals, and genomic DNA was prepared for each isolate. RAPD was carried out under optimized conditions. 23S rDNA was regarded as an internal control, and a 361 bp rDNA fragment (RDF) was used as a probe to screen the RAPD products by Southern blotting. Ten RDFs from different clinical isolates and the flanking regions (both upstream and downstream) of four RDFs were amplified and sequenced