Development of a novel matrix-assisted laser desorption/ionization time-of-flight mass spectrum (MALDI-TOF-MS)-based typing method to identify meticillin-resistant Staphylococcus aureus clones.
BACKGROUND
Mass spectrum analysis enables species- and subspecies-level identification, and can be used as an epidemiological tool in outbreak management. However, its reliability at clonal level has yet to be established.


OBJECTIVE
To establish a matrix-assisted laser desorption/ionization time-of-flight mass-spectrum-based method that enables bacterial clone identification with accuracy equivalent to pulsed-field gel electrophoresis/phage open-reading frame typing (PFGE/POT).


METHODS
Meticillin-resistant Staphylococcus aureus (MRSA) was used in this study. Mass spectra were obtained from a standard strain of S. aureus (ATCC29213) and 57 clinically isolated strains, categorized according to POT. Peaks associated with MRSA clone identification (N = 67) were extracted. Based on this peak information, the feasibility of MRSA clone identification was examined by cluster analysis.


RESULTS
In addition to the 58 strains used for peak extraction, mass spectrum analysis of 24 clinically isolated outbreak strains revealed that peak data could be used for successful identification of clones. These typing results were fully consistent with the PFGE and POT results.


CONCLUSIONS
This novel method enables simple and rapid typing with accuracy equivalent to PFGE/POT. This method would be suited to rapid outbreak analysis, offering accurate information to combat infectious diseases.
Microbiology Group, MM Business Unit, Siemens Healthcare Diagnostics KK, Tokyo, Japan; Department of Pathology and Microbiology, Faculty of Medicine, Saga University, Saga, Japan.
O
O
Ueda
Department of Clinical Laboratory, Saga University Hospital, Saga, Japan.
S
S
Tanaka
Department of Medical Technology and Sciences, School of Health Sciences at Fukuoka, International University of Health and Welfare, Fukuoka, Japan.
Z
Z
Nagasawa
Kitasato University Research Centre for Anti-infectious Drugs, Tokyo, Japan.
H
H
Hanaki
Department of Pathology and Microbiology, Faculty of Medicine, Saga University, Saga, Japan.
T
T
Shobuike
Department of Pathology and Microbiology, Faculty of Medicine, Saga University, Saga, Japan. Electronic address: miyamoth@cc.saga-u.ac.jp.
H
H
Miyamoto
D015373:Bacterial Typing Techniques / Q000379:methods*; D004269:DNA, Bacterial / Q000032:analysis*; D014644:Genetic Variation; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification* / Q000235:genetics*; D050505:Mutant Proteins / Q000032:analysis*; D015203:Reproducibility of Results; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D004269:DNA, Bacterial; D050505:Mutant Proteins
Matrix-assisted laser desorption/ionization time-of-flight; Meticillin-resistant Staphylococcus aureus; Phage open-reading frame typing; Pulsed-field gel electrophoresis; Typing