Laurita Klimkaitė defended her thesis entitled "Virulence strategies for the opportunistic pathogen Stenotrophomonas maltophilia" for the degree of Doctor of Science in Biochemistry.
Scientific supervisor: Assoc. prof. dr. Julija Armalytė (Vilnius University, Natural Sciences, Biochemistry).
Composition of the Dissertation Defense Board: Chairperson - Prof. Dr. Rolandas Meškys (Vilnius University, Natural Sciences, Biochemistry); Prof. Dr. Rimantas Daugelavičius (Vytautas Magnus University, Natural Sciences, Biochemistry); Dr. Aušra Ražanskienė (UAB Nomads, Natural Sciences, Biochemistry); Dr. Milda Plečkaitytė (Vilnius University, Natural Sciences, Biochemistry); Dr. Augustinas Šilalė (Newcastle University, United Kingdom, Natural Sciences, Biochemistry).
Stenotrophomonas maltophilia is a poorly studied Gram-negative opportunistic pathogen with multidrug resistance, causing infections with high mortality rates in immunocompromised individuals. This dissertation analyzed clinical and environmental S. maltophilia isolates in order to identify the key bacterial traits that determine its ability to cause infections. It was found that bacterial growth and the expression of virulence-associated phenotypic traits at human body temperature are more characteristic of clinical S. maltophilia isolates; therefore, temperature tolerance could be considered a critical feature distinguishing clinical from environmental isolates. In addition, previously undescribed mechanisms underlying the ability of S. maltophilia to evade the host immune system were identified and characterized—namely, the formation of a polysaccharide capsule and the synthesis of secreted proteases that degrade human complement system proteins. The results obtained expand current knowledge of the virulence strategies employed by this important opportunistic pathogen S. maltophilia.
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