Kyu Park (Presenter)
ASTA Inc.
Authorship: Kyu H. Park (1), Eun-Kyeong Choi (1), Eun Gye Lee (2), Jaeseok Kim (2), Taek Soo Kim (3), Sue Shin (3), Hyung Soon Park (1), Yangsun Kim (1)
(1) ASTA Inc., Suwon, Korea, (2) Dept. of Laboratory Medicine, Hallym Univ. College of Medicine, Seoul, Korea, (3) Dept. of Laboratory Medicine, Seoul National Univ. College of Medicine, Seoul, Korea
| Short Abstract The use of MALDI-TOF MS has become a powerful and popular method to identify various pathogenic bacteria in many clinical laboratories. However, mycobacterium species are still challenging to correctly identify by MALDI-TOF MS. Fifty mycobacterial isolates obtained from patients were selected to include 20 species, identified by PCR analysis, and analyzed by a MALDI-TOF mass spectrometer to investigate the effect of culture condition, sample preparation, and MALDI peak selection. Phylogenetic trees based on MALDI spectrum were used to show the differentiation and the categorization of the isolates. |
Long Abstract
The use of MALDI-TOF MS has become a powerful and popular method to identify various pathogenic bacteria in many clinical laboratories. However, mycobacterium species are still challenging to correctly identify by MALDI-TOF MS.
Fifty mycobacterial isolates obtained from patients in Seoul National University Hospital were selected to include 20 species and identified by sequence analysis by PCR using 16S rRNA, rpoB, tuf genes. The isolates were cultured in solid and liquid media. The cytoplasmic molecules of the inactivated isolates were extracted by 70% formic acid and profiled by a MALDI-TOF mass spectrometer to investigate the effect of culture condition, sample preparation, and MALDI peak selection. The obtained MALDI spectra of each isolate were normalized and aligned using a lab-made program, SCAMPER. The processed MALDI spectra of each isolates were compared and combined to provide a reference spectrum of the isolate. The reference spectra were used to generate a phylogenetic tree of the 50 isolates.
Phylogenetic trees based on MALDI spectrum showed the differentiation and the categorization of the isolates according to the experimental condition. The presented multi-species comparison method can be useful to find out the optimum condition of sample preparation and data processing to maximize the differentiation between mycobacterium species and further identification by MALDI-TOF MS.
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