Carbapenem-resistant Klebsiella pneumoniae exacerbates virulence through oxidative stress, apoptosis induction and gut microbiota dysbiosis in zebrafish models.

Abstract

Carbapenem-resistant Klebsiella pneumoniae (CRKP), as a critical nosocomial pathogen, has emerged as a major global public health challenge due to its multidrug resistance and enhanced pathogenicity. This study systematically elucidated the virulence characteristics of CRKP and its host interaction mechanisms by comparing CRKP (ST258, blaKPC-positive) with carbapenem-susceptible K. pneumoniae (CSKP, ST86) in zebrafish infection models. We established dual infection models (adult intraperitoneal injection and larval immersion), revealing that ST258 CRKP strain exhibited significantly enhanced virulence: its median lethal dose (LD) was 7.3-fold lower than ST86 CSKP strain, with persistent proliferation in liver and intestinal tissues causing more severe histopathological damage. Mechanistic studies demonstrated that CRKP infection induced stronger oxidative stress and more pronounced apoptosis. 16S rRNA sequencing revealed CRKP-specific gut microbiota dysbiosis: a 147 % increase in Klebsiella abundance with significant depletion of protective Faecalibacterium and Cetobacterium, whereas CSKP infection primarily promoted Aeromonas and Citrobacter proliferation. Functional prediction analysis further identified CRKP-specific activation of drug metabolism pathways (e.g., cytochrome P450) and disruption of amino acid metabolism (e.g., suppressed cysteine/methionine pathways), which were closely associated with impaired host antioxidant defenses. This study provides zebrafish model evidence that the ST258 CRKP strain enhances pathogenicity through multiple mechanisms compared to the ST86 CSKP strain: enhanced tissue invasiveness, induction of oxidative stress and apoptosis, and disruption of gut microbial homeostasis. These findings offer novel insights into the pathogenesis of this high-risk CRKP clone and inform the development of microbiota-targeted therapeutic strategies against drug-resistant infections.