Nucleic acids in the classification of Campylobacters.
The importance of campylobacters in human disease has stimulated improvements in the methods for identification of strains from hospitals and the environment. Reliable and accurate identification depends on a sound classification for which nucleic acid analyses provide fundamental information about species relationships. Studies on the genus Campylobacter show that the genome DNA of species have base compositions of 29 to 38 mol% G + C and molecular weights of 1.54 X 10(9) to 2.31 X 10(9). Campylobacter fetus, the type species, has a mean G + C content of 35.7 mol% whereas those of the thermophilic species Campylobacter jejuni, Campylobacter coli and the NARTC group (Campylobacter laridis) are between 31.5 and 32.6 mol%. DNA-DNA hybridizations, which are useful in clarifying relationships at the species level, show clear differences between most Campylobacter taxa. Distinct DNA sequence relatedness differences confirmed Campylobacter jejuni, Campylobacter coli and the NARTC group were separate species. The correlations between nucleic acid data and conventional biochemical test results, serology and fatty acid profiles are discussed. Further work is needed on the nucleic acids of Campylobacter sputorum and the various allied campylobacters.