Mupirocin resistance in coagulase-negative staphylococci.

High-level mupirocin resistance in coagulase-negative staphylococci isolated from patients undergoing peritoneal dialysis was investigated by transfer of the resistance determinants, usually in the form of a plasmid, to Staphylococcus aureus strains, cleavage of the plasmid by restriction endonuclease and hybridisation with a probe comprising a 4.05 kb EcoRI fragment of a plasmid from a S. aureus strain. In most instances the mupirocin-resistant staphylococci isolated from each patient were different according to the species, antibiogram and plasmid profile data. The mupirocin resistance determinant was carried on various plasmids as judged by EcoRI restriction fragment length polymorphisms. All hybridised at about 4 kb with the S. aureus probe.