DNA diversity among clinical isolates of<i>Helicobacter pylori</i>detected by PCR-based RAPD fingerprinting

TLDR

RAPD (or AP‑PCR) DNA fingerprinting was employed to differentiate clinical isolates of *Helicobacter pylori*, a bacterium linked to gastritis, peptic ulcers, and gastric carcinoma. The method relies on arbitrarily chosen oligonucleotides that prime DNA synthesis at fortuitously matched or nearly matched genomic sites. The study found that 10‑nt primers with 60 % GC content produced strain‑specific RAPD patterns of up to 15 fragments, while 50 % GC primers did not, and that 64 clinical isolates were uniquely identified by a single primer—demonstrating high genomic diversity—though paired biopsies from the same patient remained indistinguishable in three cases.

Abstract

The RAPD (or AP-PCR) DNA fingerprinting method was used to distinguish among clinical isolates of Helicobacter pylori , a bacterium whose long term carriage is associated with gastritis, peptic ulcers and gastric carcinomas. This method uses arbitrarily chosen oligonucleotides to prime DNA synthesis from genomlc sites to which they are fortuitously matched, or almost matched. Most 10-nt primers with ss 60% G + C yielded strain-specific arrays of up to 15 prominent fragments, as did most longer (≥ 17-nt) primers, whereas most 10-nt primers with 50% G + C did not. Each of 64 Independent H.pylori isolates, 60 of which were from patients in the same hospital, was distinguishable with a single RAPD primer, which suggests a high level of DNA sequence diversity within this species. In contrast, isolates from initial and followup biopsies were indistinguishable in each of three cases tested.