Identification of methicillin resistant staphylococcus aureus (mrsa)

A method for identifying methicillin resistant Staphylococcus aureus (MRSA) in a bacterial sample comprising the steps:

• classifying bacteria in the sample as Staphylococcus aureus (SA),
• directly depositing whole bacteria cells on a MALDI time of flight (MALDI-TOF) mass spectrometer target plate without prior extraction,
• acquiring a MALDI-TOF mass spectrum of the whole bacteria,
• determining the presence or absence of a variant of the phenol soluble modulin peptide (PSM-mec) wherein the presence of the variant of the PSM-mec peptide is determined by the presence of a mass signal in the MALDI-TOF mass spectrum centered at m/z 2415, and
• indicating the classified Staphylococcus aureus as a methicillin resistant Staphylococcus aureus when the variant of the PSM-mec peptide is present.