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Characterization of pathogenicity and chemical signaling of prototype strains and clinical samples of uropathogenic Escherichia coli against LED209

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Bruna Cardinali Lustri
Total Authors: 1
Document type: Master's Dissertation
Press: Araraquara. 2019-09-26.
Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Farmacêuticas. Araraquara
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Advisor: Cristiano Gallina Moreira

Urinary tract infections are found commonly worldwide, whereas Uropathogenic Escherichia coli (UPEC) is the most prevalent pathogen, responsible for utmost cases of cystitis and acute pyelonephritis. The pathogenicity of UPECs is related to the expression of several virulence factors, and the regulation of the expression of these factors is mediated by chemical signaling molecules. The communication allow inter-intra-kingdom and cell-to-cell facilitates the process of colonization and establishment of pathogenesis. QseBC two-component system is capable of recognizing signals produced by the host leading to regulation of pathogen virulence gene expression. This system consists of membrane sensing protein (QseC) and a cytoplasmic response regulator (QseB) that mediate the entire cascade of virulence genes. Studies conducted by our group showed attenuation of the virulence of Gram-negative pathogens in the absence of the qseC gene, leading to the development of molecules that act by inhibiting this pathway such as LED209. The aim of the present study was to characterize UPEC multidrug-resistant strains (MDR) from clinical isolates. Investigate, in vitro and in vivo, the involvement of the QseBC pathway in the pathogenesis and virulence of UPEC strains and clinical isolates. The use of LED209 and the 3,4-dihydroximandelic acid (DHMA), norepinephrine intermediate metabolite, as chemoattractant, were employed to attenuate of virulence against these pathogens. The results showed a high level of β-lactamases produced by clinical isolates. The motility phenotype of wild UPEC strains was influenced by DHMA at 10 µM concentration, which was not observed for the ∆qseC mutant. It was also verified by qRT-PCR that at 10 µM DHMA concentration, there was a reduction in qseC gene expression, overexpression of visP and fimH in UPEC strains. DHMA showed inhibitory effect on biofilm formation at 30 ° C and 37 ° C for all strains. Experiments with LED209 showed significant effect on reducing biofilm formation in the tested strains, however, showed no significant effect on motility swimming test. The results of the in vivo experiments showed no significant differences in bladder colonization between the UPEC strains and the ∆qseC mutant. These results have opened perspectives to further study the influence of DHMA and LED209 on virulence gene expression of UPEC, as well as point out the need to understand the role played by QseC in these worrisome bacterial pathogens infection. (AU)