[A simple and rapid method capable of detecting methicillin-resistant Staphylococcus aureus (MRSA) by single culture on an agar plate].

A novel simple agar plate capable of detecting methicillin-resistant Staphylococcus aureus (MRSA) by single culture was developed. The agar plate included 1) mannitol and a pH indicator, and 4-methylumbelliferyl phosphoric acid, both for identification of Staphylococcus aureus by its ability to digest mannitol and produce phosphatase; detection of the former by change in color of pH indicator and the latter by fluorescence of 4-methylumbelliferone, 2) oxacillin at a minimum concentration just to eliminate methicillin-sensitive Staphylococcus aureus (MSSA), and 3) phenylethyl alcohol to inhibit growth of most gram negative rods. The method was simple, sensitive, time-saving, and quite effective in the identification of MRSA directly from clinical specimens. Neither false positive nor false negative results were observed by the present method.