Legionella pneumophila identifikācija, izmantojot MALDI-TOF MS un SBT metodes

Abstract

Legionella pneumophila identifikācijai un subtipēšanai tika pielietotas divas metodes – MALDI-TOF MS un SBT. Tika izmantoti 22 no ūdens izolēti ZI ”BIOR” Legionella pneumophila celmi. Ar lateksa aglutinācijas metodi tika noteiktas izmantojamās Legionella pneumophila serogrupas – 1, 2, 3 un 6. MALDI-TOF MS ekstrakcijas metode nodrošināja 100 % identifikāciju visiem Legionella pneumophila izolātiem. Pēc 17 iegūtajiem masas spektra signāliem celmi tika efektīvi subtipēti. Ar SBT metodi celmiem tika iegūti alēļu profili un sekvences tipa numuri, kopumā 15 dažādi Legionella pneumophila ST, no kuriem divi – ST2191 un ST2192 iepriekš nebija iekļauti starptautiskajā ESGLI datubāzē. Abu metožu iegūto dendrogrammu A klāsterī esošo celmu sakritība sastāda 100 %. Kopējā celmu sakritība abās dendrogrammās – 77, 3 %. MSP dendrogrammas C klāstera celmu sakritība ar SBT dendrogrammas B klāstera B1 daļu ir 80 %, bet B klāstera celmu sakritība ar B2 daļu ir 67 %. Pēc iegūtajiem rezultātiem var secināt, ka MALDI-TOF MS ir efektīva subtipēšanas metode, kuru pilnveidojot, iespējams aizstāt laikietilpīgo un dārgo SBT metodi.

Two methods – MALDI-TOF MS and SBT – were used for Legionella pneumophila identification and subtyping. In total, 22 Legionella pneumophila isolates from water samples were used in the study. Legionella pneumophila serogroups 1, 2, 3 and 6 were determined with latex agglutination test. 100 % identification of all Legionella pneumophila isolates was provided by MALDI-TOF MS extraction method. Strains were effectively subtyped by assessment of 17 mass spectrum signals. Allele profiles and sequence type numbers were obtained with SBT method. Overall 15 different Legionella pneumophila ST were found, and two of them – ST2191 and ST2192 – were not included in the international ESGLI database before. Similarity of dendrograms for both methods was 77, 3 %, while for A cluster strains similarity was 100 %. Similarity of C cluster in MSP dendrogram with B cluster part B1 in SBT dendrogram was 80 %, but similarity of B cluster with part B2 was 67 %. In conclusion, MALDI-TOF MS is an effective subtyping method which could be further improved in order to replace time-consuming and expensive SBT method.