Diversity among clinical isolates of Helicobacter pylori in Korea.

Eleven strains of Helicobacter pylori were isolated from biopsy specimens obtained at the A-San Medical Center from December, 1995 to February, 1996. Every H. pylori positive patient was diagnosed to have chronic, erosive, or mild superficial gastritis. To determine the diversity in clinical isolates, the following were studied: total protein profile, plasmid profile, presence of cagA, and variation in DNA sequence. Protein profiles of nine isolates were similar to each other while two isolates had a 35 kDa protein which did not appear in others. The presence of cagA was detected with PCR in seven isolates (63%). Among eleven isolates, seven (63%) carried plasmids. Each isolate showed a big diversity with a PCR-based randomly amplified polymorphic DNA method. Even though all H. pylori isolates used in this study were isolated from gastritis patients at the same hospital, their molecular and biological characteristics were quite different from another showing a big diversity in H. pylori.