Molecular cloning of a species-specific DNA probe for Campylobacter jejuni

Conventional procedures for isolating and identifying Campylobacter jejuni are cumbersome and time-consuming. A simpler approach would be to use DNA probes to identify these organisms. To obtain such probes we cloned chromosomal DNA from C. jejuni into the lambda replacement vector EMBL 4. Recombinant phages were screened for C. jejuni-specific inserts by DNA hybridization using chromosomal DNA from either C. jejuni or C. coli which had been radioactively labelled with 32P. By this means, recombinant phages were identified which hybridized to C. jejuni but not to C. coli DNA. These phages were then subjected to further screening using DNA from other Campylobacter species. Three DNA fragments were identified which hybridized to DNA from eight ATCC (American Type Culture Collection) strains of C. jejuni but not to DNA from C. coli, C. laridis, C. fetus or a variety of other bacterial species. These DNA fragments are suitable for use as specific probes in DNA-based diagnostic tests for C. jejuni infections.