Adult zebrafish infected by clinically isolated Klebsiella pneumoniae with different virulence showed increased intestinal inflammation and disturbed intestinal microbial biodiversity.

Background: Klebsiella pneumoniae is a pathogen that often infects patients in clinical practice. Due to its high virulent and drug resistance, infected patients are difficult to treat. In clinical practice, Klebsiella pneumoniae can infect patients' intestines, intestines, blood, etc., causing pathological changes. However, there is relatively little information on the impact of Klebsiella pneumoniae on intestinal inflammation and microbial populations. Zebrafish is an excellent biomedical model that has been successfully applied to the virulence assessment of Klebsiella pneumoniae.

Methods: In this study, three clinically isolated representative strains of Klebsiella pneumoniae (high virulence non-resistant, high virulence resistant, and low virulence resistant) were used to infect zebrafish, and their effects on intestinal colonization, inflammation, pathology, and microbial diversity were tested.

Results: Enzyme-linked immunoassay (ELISA) showed that Klebsiella pneumoniae significantly increased levels of the cytokines interleukin-1α (Il-1α), interleukin-1β (Il-1β), and tumor necrosis factor-α (Tnf-α), which increased inflammatory symptoms. Hematoxylin eosin staining(H&S) showed that Klebsiella pneumoniae treatment caused intestinal lesions in zebrafish, in which KP1053 exposure significantly decreased the number of goblet cells, KP1195 caused epithelial dissolution and exfoliation. In addition, Klebsiella pneumoniae disturbed the composition of intestinal microbiota, and the Shannon index increased, which increased the number of harmful bacteria.

Conclusions: Klebsiella pneumoniae infection can lead to intestinal colonization, inflammation, pathological changes, and changes in microbial biodiversity. This study provides a reference for the intestinal pathology of clinical Klebsiella pneumoniae infection.