Relatedness among coagulase-negative staphylococci: deoxyribonucleic acid reassociation and comparative immunological studies.

DNA-DNA-homology values were determined under restrictive to relaxed reassociation conditions with type strains and some additional strains of coagulase-negative staphylococci belonging to ten different species. The immunological relationship of the catalases present in the type strains of these species was also determined by applying double immunodiffusion and microcomplement fixation. The results of these studies support the previous proposal to subdivide the coagulase-negative staphylococci into at least ten separate species. However, it is evident that some of the species are more closely realted than others and can form species groups. According to the results presented in this study, the coagulase-negative staphylococci can be combined into five species groups: The Staphylococcus saprophyticus group is composed of S. saprophyticus, S. xylosus and S. cohnii. The S. epidermidis group comprises S. epidermis, S. capitis and S. warneri. The S. hominis group which exhibits a significant relationship to S. epidermidis includes S. hominis and S. haemolyticus. The species group S. sciuri consists of S. sciuri ssp. sciuri and S. sciuri ssp. lentus and the species group S. simulans is presently represented by the corresponding single species.