THE ROLE AND IMPORTANCE OF SELECTED VIRULENCE FACTORS DETERMINING THE PATHOGENICITY OF UROPATHOGENIC ESCHERICHIA COLI STRAINS

The most frequent etiologic agents of the urinary tract infections (UTIs) are UPEC strains (Uropathogenic Escherichia coli), which are responsible for 75-95% of UTIs. The virulence factors of UPEC bacteria, as well as their ability to form biofihn, play a significant role in the pathogenicity of UTIs. Limiting iron availability is a major host defense against the growth of microorganisms within hosts. That is why UPEC strains produce various types of siderophores as well as siderophore receptors, which facilitate the uptake and transport of iron to the bacterial cell. Moreover, in order to modulate an inflammatory response and host signaling pathways, UPEC strains produce the following toxins: a-hemolysin (HlyA), cytotoxic necrotizing factor 1 (CNF-1) and vacuolating autotransporter toxin (VAT, Vat-like/ Vat-Ex Ec). Moreover, Usp is a novel genotoxin of UPEC strains which provokes DNA fragmentation and cell apoptosis. Furthermore, the presence of protein Ag43 enhances adhesion of UPEC within the urinary tract, aggregation and biofihn formation. It is important to underline that all of the virulence factors mentioned above and the ability to form biofilm facilitate and enable UPEC colonization and dissemination in the urinary tract. In conclusion, UPEC harbors an arsenal of virulence factors which promote persistence within the adverse settings of the host urinary tract and finally lead to the development of UTI.