title: Electrospray ionization-tandem mass spectrometry analysis of the mycolic acid profiles for the identification of common clinical isolates of mycobacterial species.
abstract: Mycolic acids are unique and complex molecular structures found in mycobacterial species. In the present study, we investigated whether electrospray ionization-tandem mass spectrometry (ESI-MS/MS) can be used to identify mycobacterial species based on their mycolic acid profiles. Clinical isolates of Mycobacterium tuberculosis complex and 18 nontuberculosis mycobacterial (NTM) species identified by PCR-restriction fragment length polymorphism (RFLP) or real-time PCR were used for this analysis. Crude lipid extracts were prepared by saponifying 1-2 colonies of individual isolates of mycobacterial species and by chloroform and methanol (2:1, v/v) extraction. ESI-MS/MS in negative ion mode with high cone voltage and collision energy was used for mycolic acid profiling analysis. Combinatorial precursor ion scans of m/z 395, 367, and 339 in the range of m/z 1000-1400 resulted in spectra specific to individual mycobacteria. M. tuberculosis complex and M. pulveris showed major ions by performing precursor ion scans on m/z 395 and 367, while other NTM species showed major ions by performing scans on m/z 367 and 339. The different NTM species examined showed different species dependent mycolic acid profiles. In conclusion, we describe a rapid, reliable, and informative ESI-MS/MS protocol for mycolic acid profiling in mycobacterial species, which allows mycobacterial species to be easily identified in clinical laboratories.
authors.affiliation: Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Sang Hoon
authors.initials: SH
authors.lastname: Song
authors.forename: Kyoung Un
authors.initials: KU
authors.lastname: Park
authors.forename: Jae Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Eui Chong
authors.initials: EC
authors.lastname: Kim
authors.forename: Jin Q
authors.initials: JQ
authors.lastname: Kim
authors.forename: Junghan
authors.initials: J
authors.lastname: Song