A study of the natural history of skin colonisation by coagulase-negative staphylococci
The staphylococcal skin floras of an isolated group of subjects were studied for a year. A wide variation in isolation patterns was found for different subjects, sites and staphylococcal species, and the dynamic nature of skin colonisation was revealed. Staphylococcus intermedius, previously thought to be of veterinary origin, was found to be part of the resident flora for some subjects, and this may indicate a wider role for it in clinical infection. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis on all S.capitis isolates, using protein staining and immunoblotting, indicated persistent skin colonisation at some sites; each region was colonised by only one clone of that species, although an adjacent area could be inhabited by a different clone. Nine clonal groups were identified by SDS-PAGE protein stain; there was a degree of specialisation between the groups with regard to the sites which they colonised. The interaction between staphylococcal species at a single site was less well defined, although some evidence of interaction was found. Non-colonising isolates of S.capitis often exhibited lower than expected phenotypic similarities when compared with their presumed source, and the implications of this are discussed. The results of SDS-PAGE protein stain were compared with the results of immunoblotting, antibiograms and biotyping. Attempts were made to demonstrate inter-species and inter-strain interference in vitro. The existing humoral response to staphylocci was studied by immunoblotting. The place of modern typing methods is reviewed within the context of staphylococcal taxonomy and current concepts of bacterial clonality; possible future developments in bacterial typing are discussed.