Polyclonal antibodies were raised against the membrane-bound penicillin-binding protein (PBP 2') present in methicillin-resistant strains of Staphylococcusaureus (MRSA) and were used to detect its presence in membranes from strains grown under varying conditions for the expression of resistance. The antibody preparation reacted with another membrane protein from methicillin-sensitive S. aureus (MSSA) which migrated to the same position as PBP 2' on SDS gel electrophoresis. Pretreatment of the antisera with membranes of sensitive strains removed antibodies recognising high-M r, proteins common to both MRSA and MSSA: the residual antibody then reacted specifically with PBP 2'. Antisera pretreated in this manner can be used as a probe for the definitive identification of MRSA strains.
