Classification of coagulase-negative staphylococci in diagnostic practice

When the Schleifer and Kloos classification was used for the identification of 300 clinical isolates of coagulase-negative staphylococci (CNS), S. epidermidis together with S. saprophyticus was found to amount to 21.1%. A total of 48% of the cultures under test were identified. On the basis of these results and with respect to literary data the present authors propose to subdivide, in diagnostic studies, the mentioned microorganisms into groups of related species, i.e., the epidermidis group and the saprophyticus group, instead of classifying the CNS according to species. By means of the tests proposed (determination of phosphatase, fermentation of glucose, oxidation of mannitol, behaviour towards novobiocin), typical S. epidermidis and S. saprophyticus as well as cultures similar to them can be isolated within the groups. The method is easy to perform in diagnostic laboratories and, in contrast to methods practised up to now, enables us to characterize virtually all CNS variants isolated from patients, including the coagulase-negative S. aureus.