Whole cell matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identification of Leptospira spp. in Thailand and Lao PDR

Leptospirosis is a zoonosis with a worldwide distribution, caused by pathogenic spirochetes of the genus Leptospira . The classification and identification of leptospires can be conducted by both genotyping and serotyping which are time-consuming and established in few reference laboratories. This study used matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) as rapid and accurate tool for the identification of leptospires. The whole cell protein spectra of 116 Leptospira isolates including 15 references Leptospira spp. (pathogenic, n = 8; intermediate, n = 2; non-pathogenic, n = 5) and 101 Leptospira spp. clinical isolates was created as an in-house MALDI-TOF MS database. Ninety-seven clinical isolates from Thailand and Laos was validated with these protein spectra and revealed 98.9% correct identification when compared with 16S rRNA gene sequences method. Moreover, MALDI-TOF MS could identify spiked leptospires whole cell in urine. Biomarkers for differentiation of leptospires phylogeny and specific protein spectra for most found Leptospira spp. in this area ( L . interrogans , L . kirschneri , L . borgpetersenii) based on MALDI-MS algorithm were demonstrated.