IDENTIFICATION OF CAMPYLOBACTER-JEJUNI AND CAMPYLOBACTER-COLI USING THE RPOB GENE AND A CRYPTIC DNA FRAGMENT FROM C-JEJUNI

Campylobacter jejuni (Cj) and C. coli (Cc) clinical isolates, obtained from three different sources, were characterized using two Cj DNA pro bes, CJ01 and CJ02. These probes were selected at random by virtue of their stability in Escherichia coli (Ec). CJ01 hybridized specifically with DNA from Cj reference strains, but not with DNA from Cc, C. lari (Cl) nor C. fetus (Cf) reference strains. Using clinical isolates cha racterized by genome-genome hybridization and biotype, CJ01 hybridized with DNA derived from all Cj strains. However, DNA from four out of t en Cc strains, from three different sources, also hybridized with CJ01 , suggestive of this region being heterogeneous between clinical isola tes of both species. The nucleotide sequence analysis of CJ01 reveals two incomplete open reading frames (ORFs) that did not show significan t homology with any other known sequences. CJ02 hybridized specificall y with DNA from Cj and Cc reference strains, but not with DNA from CI and Cf reference strains. The specificity and sensitivity were maintai ned upon hybridization with DNA from 31 clinical isolates. CJ02 has an uninterrupted ORF whose deduced amino-acid sequence showed extensive homology with the central region of the Ec and Salmonella typhimurium (St) RNA polymerase beta subunits (52 and 66% similarity, respectively ). The most conserved segments correspond to putative functional domai ns.