Genetic diversity of Helicobacter pylori indexed with respect to clinical symptomatology, using a 16S rRNA and a species‐specific DNA probe

Abstract

DNA probes are described which identify group and fingerprint strains of the human gastric pathogen Helicobacter pylori, on the basis of well‐defined band homologies. A 544 bp internal fragment of the 16S ribosomal RNA gene was generated by polymerase chain reaction (PCR) with primers derived from the Escherichia coli rRNA gene sequence. In genomic Southern blots this probe detected restriction site variation around these loci, generating simple but strain‐specific molecular fingerprints. A small conserved chromosomal fragment of 1.2 kbp, Hps, species‐specific for H. pylori, was obtained by cloning random Hind III fragments into pUC19. It was useful for dot‐blot identification, and also separated isolates into one major and two minor groups. When results for these two probes were combined, a baseline characterization of genotype was obtained. A band‐matching database of molecular fingerprints for the type strain and 63 clinical isolates of H. pylori from asymptomatic, ulcer and gastritis contexts is presented. No significant association between the genotypes at this level of definition and the associated clinical symptomatology of the isolates was detected.