Modern Features of Pathogenic Leptospira Isolation and Identification in Siberia and the Far East

Abstract

Recently, pathogenic Leptospira culture isolation is an extremely rare phenomenon in Russia.The aim of our work was to synthesize the lessons learned at the Irkutsk Anti-Plague Institute from Leptospira culture isolation and identification since 2011.Materials and methods. Material from eight individuals with suspected leptospirosis and from 942 small mammals (SM) was examined using PCR and microscopic agglutination test (MAT), from humans and 260 SM, applying bacteriological method. Bacteriological temperature test, MAT, PCR, MLST and MALDI-TOF mass spectrometry with the original Leptospira protein profiles base were used to identify cultures. Six complete genomes were generated at the Central Research Institute of Epidemiology of the Rospotrebnadzor.Results and discussion. Leptospira have not been isolated from humans against the background of taking antibiotics, despite the positive PCR and MAT results. Four cultures of Leptospira borgpetersenii of the Javanica serogroup and three L. kirschneri (Grippotyphosa) have been isolated from SM. The results of identification using MLST scheme No. 1 and MALDI-TOF MS are identical. MLST in silico has shown the uniformity of two Grippotyphosa serogroup strains from Primorie and Khabarovsk with a sequence-type (ST) profile 110:100:94. ST146 is determined in four Javanica serogroup strains according to scheme No. 1, and unique single nucleotide polymorphisms are detected according to schemes No. 2–3. Thus, in Siberia and the Far East, between 2012 and 2016, seven pathogenic Leptospira cultures were isolated from carriers in natural foci; carrier infection rate being12.0–48.9 %. Javanica serogroup strains differ in the MLST profile characteristics and adapt to nutrient media for a longer time than Grippotyphosa serogroup strains.