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No. 61 (PM 10)
Application of MALDI-TOF MS-based strain typing for characterization of
epidemiological relationships among bacterial strains
Megumi Oho 1) , Zenzo Nagasawa 1) , Koji Kusaba 1) , Takanori Higashitani 1) , Shoitiro Ohta 1) ,
Eisaburo Sueoka 1) , Hiroshi Miyamoto 2)
Department of Laboratory Medicine, Saga University Hospital 1) ,
Division of Microbiology, Department of Pathology and Microbiology,
Faculty of Medicine, Saga University 2) , Japan
【Purpose】MALDI-TOF MS-based strain typing for microorganisms is a fast and inexpensive
technology for identification of bacteria. We introduced MALDI Biotyper Ⓡ (Bruker Daltonics Inc,) as a
clinical diagnostic system for microbial infection since April this year. The system needs only 10
minutes from isolation of the target colonies and considerably accurate compared with genomic analysis
using 16S rRNA. We applied this system to characterize the epidemiological relationships among
bacterial strains.
【Samples and Methods】24 of MRSA and 48 of Pseudomonas aeruginosa strains, those genomic
pattern determined by pulsed-field gel electrophoresis (PFGE), were analyzed by MALDI Biotyper, and
the characteristic amino acid profiles were assessed by ClinProTools. For extraction of the proteins from
bacteria, an ethanol-formic acid extraction method was used, and the assays were conducted by
duplicate to obtain confirmative spectra. The spectra were analyzed by using ClinProTools (Bruker
Daltonics Inc.). ClinProTools is designed to facilitate the processing and comparison of multiple spectra
from each bacterium by automatically normalizing, baseline subtracting, peak defining, and
recalibrating.
【Results】We compared the results obtained from MALDI-TOF MS combined with ClinProTools and
those from PFGE. The epidemiological relationships examined by MALDI-TOF MS and PFGE among
MRSA and Pseudomonas aeruginosa strains were almost identical. The results were validated with
other molecular epidemiological examinations.
【Conclusion】The epidemiological relationships examined by MALDI-TOF MS showed comparable
data with PFGE. Since MALDI-TOF MS-based strain typing for microorganisms is a fast and
inexpensive technology for identification of bacteria, the technique combined with ClinProTools is
thought to be a useful tool for molecular epidemiological relationships among bacterial strains.
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