title: Rapid discrimination between methicillin-sensitive and methicillin-resistant Staphylococcus aureus by intact cell mass spectrometry.
abstract: Rapid, accurate discrimination between methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains is essential for appropriate therapeutic management and timely intervention for infection control. A rapid method involving intact cell mass spectrometry (ICMS) is presented that shows promise for identification, discrimination of MSSA from MRSA and typing. In ICMS, cells from a bacterial colony are emulsified in a chemical matrix, added to a sample slide, dried and analysed by matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS). This technique examines the chemistry of the intact bacterial cell surface, yielding spectra consisting of a series of peaks from 500 to 10000, which represent the mass:charge (m:z) ratios. Each peak corresponds to a molecular fragment released from the cell surface during laser desorption. Specimens can be prepared in a few seconds from plate cultures and a spectrum can be obtained within 2 min. ICMS spectra for 20 staphylococcal isolates showed characteristic peaks, some of which were conserved at species level, some at strain level and some were characteristic of the methicillin susceptibility status of the strain. ICMS may have potential for MRSA identification and typing, and may improve infection control measures.
authors.affiliation: *Department of Biological Sciences, Manchester Metropolitan University, Chester Street, Manchester M1 5GD and †Manchester Public Health Laboratory, Withington Hospital, Nell Lane, West Didsbury, Manchester M20 8LR.
authors.forename: Valerie
authors.initials: V
authors.lastname: Edwards-Jones
authors.affiliation: *Department of Biological Sciences, Manchester Metropolitan University, Chester Street, Manchester M1 5GD and †Manchester Public Health Laboratory, Withington Hospital, Nell Lane, West Didsbury, Manchester M20 8LR.
authors.forename: M A
authors.initials: MA
authors.lastname: Claydon
authors.affiliation: *Department of Biological Sciences, Manchester Metropolitan University, Chester Street, Manchester M1 5GD and †Manchester Public Health Laboratory, Withington Hospital, Nell Lane, West Didsbury, Manchester M20 8LR.
authors.forename: D J
authors.initials: DJ
authors.lastname: Evason
authors.affiliation: *Department of Biological Sciences, Manchester Metropolitan University, Chester Street, Manchester M1 5GD and †Manchester Public Health Laboratory, Withington Hospital, Nell Lane, West Didsbury, Manchester M20 8LR.
authors.forename: J
authors.initials: J
authors.lastname: Walker
authors.affiliation: *Department of Biological Sciences, Manchester Metropolitan University, Chester Street, Manchester M1 5GD and †Manchester Public Health Laboratory, Withington Hospital, Nell Lane, West Didsbury, Manchester M20 8LR.
authors.forename: A J
authors.initials: AJ
authors.lastname: Fox
authors.affiliation: *Department of Biological Sciences, Manchester Metropolitan University, Chester Street, Manchester M1 5GD and †Manchester Public Health Laboratory, Withington Hospital, Nell Lane, West Didsbury, Manchester M20 8LR.
authors.forename: D B
authors.initials: DB
authors.lastname: Gordon
mesh_terms: D016000:Cluster Analysis; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D016106:Methicillin Resistance; D015203:Reproducibility of Results; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000737:chemistry / Q000187:drug effects / Q000302:isolation & purification*