New method for typing Staphylococcus aureus resistant to methicillin based on sulphur-35 methionine labelled proteins: its application in an outbreak.

Sodium dodecyl sulphate polyacrylamide gel electrophoresis of sulphur-35 methionine labelled cellular proteins of Staphylococcus aureus resistant to methicillin was used as a typing method during an outbreak on a cardiothoracic ward. This showed that the outbreak strain was indistinguishable from the epidemic strain of methicillin resistant S aureus prevalent in London. In contrast, 44 epidemiologically separate strains of S aureus gave individually distinct radiolabelled protein profiles. This method permitted rapid confirmation that an epidemic strain was responsible and indicated the need for urgent control measures.