Use of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide for rapid detection of methicillin-resistant Staphylococcus aureus by resonance light scattering.

A rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) using resonance light scattering (RLS) on an ordinary fluorescence spectrometer was developed. The viable MRSA reduced 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) to produce insoluble particles which displayed intense resonance scattering light. It showed a linear relationship between the number of viable MRSA and the RLS intensity. Dead MRSA were unable to reduce MTT. MRSA exposed to flavonoids extracted from Marchantia convoluta (MCF) showed a MCF concentration-dependent inhibition of the ability to reduce MTT. The RLS could, in combination with the MTT assay, be a rapid and sensitive detection method for vitro-cultured MRSA.