Bacillus licheniformis as a therapeutic alternative for Klebsiella pneumoniae infection

Klebsiella pneumoniae is a significant zoonotic pathogen. In recent years, the frequent emergence of hypervirulent (hvKP) and multidrug-resistant (MDR) strains has posed serious threats to both human and animal health, becoming a major concern for global public health security. This study characterized the phenotype of a K. pneumoniae strain (KP-01) isolated from a red panda and investigated the protective effects of Bacillus licheniformis against this pathogen through animal experiments, aiming to explore alternative therapeutic approaches for K. pneumoniae infections. KP-01 was identified as a hypervirulent K. pneumoniae (hvKP) strain, which was susceptible to most clinically relevant antibiotics except for intermediate susceptibility to imipenem and kanamycin. Despite lacking hypermucoviscosity, carried hallmark hvKP virulence genes ( iroB , rmpA2 , peg-344 , and iucA ). Pre-treatment with B. licheniformis significantly reduced bacterial burden in infected tissues, suppressed inflammatory cytokine expression, and ameliorated histopathological damage. B. licheniformis exhibits significant protective effects against K. pneumoniae infection and may serve as a potential antibiotic-alternative therapy.