Polynucleotide sequence divergence among some coagulase-negative staphylococci.

The degree of binding was determined, at both exacting and non-exacting temperatures, between deoxyribonucleic acid (DNA) preparations from coagulase-negative staphylococci and carbon (14C) labelled DNA from nine reference strains, Staphylococcus capitis LK499, S. cohnii GH137, S. epidermidis GH37, S. haemolyticus SM131, S. hominis DM122, S. saprophyticus CCM883, S. simulans SM128, S. warneri AW25 and S. xylosus KL162. The close similarity in nucleotide sequences found between five of the six representatives received as S. capitis, S. hominis and S. warneri indicate that these organisms are separated into too many species. In contrast, little homology was found between the pairs of strains representing S. cohnii and S. haemolyticus, respectively. The divergence indices of the nine reference strains were calculated and the relationship between them expressed in a sorted similarity matrix and dendrogram based upon the average linkage algorithm. The pattern of nucleotide heterogeneity was found by plotting the relative DNA bound at the exacting temperature against the divergence indices. The coagulase-negative staphylococci exhibit extensive genetic diversity due mainly to random mutation.