Molekularna opredelitev invazivnih izolatov bakterije Listeria monocytogenes

Vlahovič, Anja (author), Maver Vodičar, Polona (mentor), Triglav, Tina (comentor)

Listerioza je s hrano prenosljiva bolezen, ki jo povzroča bakterija Listeria monocytogenes. Za učinkovito obvladovanje L. monocytogenes je bistvenega pomena uporaba metod, ki omogočajo zaznavanje in razlikovanje te bakterije od drugih vrst iz rodu Listeria v živilskih, okoljskih in kliničnih vzorcih. Klinične izolate smo identificirali kot vrsto L. monocytogenes z metodo MALDI-TOF MS in metodo PCR v realnem času, metodama izbire za rutinsko identifikacijo patogenov v kliničnih okoljih. Ker je z napredkom v tehnologiji sekvenciranje celotnega genoma postalo ključno orodje za rutinski nadzor, smo se ga poslužili tudi pri naši raziskavi. Opredelili smo bakterijsko linijo, sekvenčni tip in klonalni kompleks. Izolati so pripadali linijama I in II, katerima pripada večina klinično pomembnih sevov. Določili smo tudi glavne genetske determinante virulence, saj poznavanje virulence lahko pomaga preprečiti prihodnje izbruhe listerioze. Glavni geni znotraj LIPI-1 so bili prisotni v vseh izolatih. SSI-1 je bil prisoten v sekvenčnih tipih 26, 155 in 224. Geni, ki so del LIPI-3, so bili prisotni le v liniji I, inlG in SSI-1 pa sta bila v večji meri prisotna v liniji II. Pri naših izolatih smo detektirali odpornost proti fosfomicinu, proti kateremu je L. monocytogenes naravno odporna, ter odpornost proti streptograminu A. Med našo raziskavo smo oblikovali dve drevesi podobnosti, enega z metodo FTIR, drugega na podlagi cgMLST. Razvrstitev izolatov v liniji I in II se je ujemala ne glede na uporabljeno metodo.

• Language: Slovenian
• Keywords: Listeria monocytogenes, listerioza, PCR, FTIR, MALDI-TOF MS, sekvenciranje celotnega genoma, bioinformacijska analiza
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [A. Vlahovič]
• Year: 2025
• PID: 20.500.12556/RUL-168835
• UDC: 579.25.088:575.112
• COBISS.SI-ID: 234383363
• Publication date in RUL: 27.04.2025

Secondary language

• Language: English
• Title: Molecular characterization of invasive Listeria monocytogenes isolates

Abstract

Listeriosis is a food-borne disease caused by bacterium Listeria monocytogenes. For the effective control of L. monocytogenes, it is essential to use methods that enable the detection and differentiation of this bacterium from other Listeria species in food, environmental, and clinical samples. Clinical isolates were identified as L. monocytogenes by MALDI-TOF MS and real-time PCR, both methods of choice for routine identification of pathogens in clinical settings. As advances in technology have made whole genome sequencing a key tool for routine surveillance, it was also used in our study. We identified the bacterial lineage, sequence type and clonal complex. The isolates belonged to lineages I and II, to which most clinically relevant strains belong. We also identified the main genetic determinants of virulence, as knowledge of virulence may help prevent future outbreaks of listeriosis. The main genes within LIPI-1 were present in all isolates. SSI-1 was present in sequence types 26, 155 and 224. The genes that are part of LIPI-3 were present only in lineage I, while inlG and SSI-1 were more abundant in lineage II. We detected resistance to fosfomycin in our isolates, to which L. monocytogenes is naturally resistant, and resistance to streptogramin A. In the course of our study, we obtained two similarity trees, one by FTIR and the other by cgMLST. The isolates were uniformly assigned to lineages I and II regardless of the method used.

• Keywords: Listeria monocytogenes, listeriosis, PCR, FTIR, MALDI-TOF MS, whole genome sequencing, bioinformatic analysis