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Capacitat d’adherència i invasió de Klebsiella pneumoniae en dos models de cèl·lules intestinals epitelials (INT-407 i Caco-2 diferenciades)

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Klebsiella pneumoniae is an encapsulated gram-negative bacillus, widely recognized as an opportunistic pathogen, although it can also be part of the intestinal microbiota as a commensal. Its ability to cause serious infections is related to several virulence factors, such as the capsule, siderophore production, biofilm formation and the ability to adhere to and invade epithelial cells. In recent years, a worrying increase in hypervirulent and multidrugresistant strains has been observed, which limits therapeutic options. This work aims to study the ability of adherence and invasion of several strains of K. pneumoniae using two models of human intestinal epithelial cells: the differentiated Caco-2 line and the INT-407 line. In order to design an appropriate experimental methodology, a bibliographic review has been carried out with 44 selected articles, of which 22 use Caco-2 and/or INT-407 cell models. This analysis has allowed us to identify a high variability in the protocols of the adhesion and invasion assays, as well as a preference for the use of the Caco2 line. At the experimental level, three strains of Klebsiella pneumoniae were studied: CECT143 (classical strain), ATCC43816 (hypervirulent strain) and ATCC700603 (multidrug-resistant strain). The results show that, in general, these strains present higher adhesion and invasion rates in the INT-407 cell model than in differentiated Caco-2. The ATCC43816 strain stood out for its adherence, while the ATCC700603 strain for its invasiveness. CECT143, on the other hand, showed almost zero values in both parameters. Adhesion kinetics were also analyzed, observing a peak at 4 h for strain ATCC43816, as well as for ATCC700603, although with a lower level and, in turn, low adhesion for CECT143. In invasion assays at 24 h, ATCC700603 showed the highest invasive capacity, indicating possible intracellular persistence. Samples were collected for future RNA extractions and gene expression analysis. These results suggest that the INT-407 model may be more sensitive to detect phenotypic differences between strains. These results provide a preliminary basis for future studies focused on better understanding the mechanisms involved in the colonization, persistence and pathogenesis of this bacterium

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