Identification of Leptospira Serovars by Maldi-Tof Mass-Spectrometry

Abstract

Aim. An attempt to use MALDI-TOF mass-spectrometry method for identification of leptospiral isolates on the serovar level. Materials and methods. 8 reference Leptospira spp. and 11 leptospira strains isolated from leptospiral patients and infected animals in the North-VNfestem region of Russia were included into the study. Mass-spectra of all the studied strains were obtained by direct profiling of cell extracts. The created main spectral profiles (MSP) of reference strains were used for identification of isolates. Evaluation of identification was carried out by calculating coefficients of matching rate of separate spectra of each isolate with MSP of all the reference strains. Results. Results of identification have shown the similarity of spectra of isolates belonging to Pomona, Icterohaemorrhagiae and Canicola serogroups, with MSP of saprophyte strain L. biflexa Patoc I. It is assumed that spectra of the studied strains contained peaks of polysaccharide O-antigens. Wherein maximum mean values of matching rate coefficients between spectra of isolates and MSP of pathogenic reference strains of leptospira correctly matched serovar type of the isolate. Conclusion. Further extended studies may form the base of development of a simple and rapid method of typing of leptospirosis causative agents on the level of serovars using MALDI-TOF mass-spectrometry.

Lethal Outcome of Leptospirosis in Southern Russia: Characterization of Leptospira Interrogans Isolated from a Deceased Teenager

“…Identification of the isolate was performed by comparison of the obtained mass spectrum with the main spectral profiles (MSP) of ten reference Leptospira strains for MAT (from Saint-Petersburg Pasteur Institute collection). The in-house MSP database was created previously [19] and exported to the main taxonomic library of reference spectra of software "Biotyper 3.1" (Bruker Daltonics GmbH, Germany). Identification was based on coincidence coefficients of the spectral peaks isolate and reference strains (logarithm of the total value of the coinciding peaks).…”

“…Identification was based on coincidence coefficients of the spectral peaks isolate and reference strains (logarithm of the total value of the coinciding peaks). Previously, we proposed a coefficient score value > 2.1 as the criteria to identify Leptospira strains at the serovar level [19].…”